title: Entity–attribute–value model

text: This data representation is analogous to space-efficient methods of storing a sparse matrix, where only non-empty values are stored. In an EAV data model, each attribute–value pair is a fact describing an entity, and a row in an EAV table stores a single fact. EAV tables are often described as "long and skinny": "long" refers to the number of rows, "skinny" to the few columns.


title: Entity–attribute–value model

text: Consider how one would try to represent a general-purpose clinical record in a relational database. Clearly creating a table (or a set of tables) with thousands of columns is not feasible, because the vast majority of columns would be null. To complicate things, in a longitudinal medical record that follows the patient over time, there may be multiple values of the same parameter: the height and weight of a child, for example, change as the child grows. Finally, the universe of clinical findings keeps growing: for example, diseases emerge and new lab tests are devised; this would require constant addition of columns, and constant revision of the user interface. (The situation where the list of attributes changes frequently is termed "attribute volatility" in database parlance.)


title: Entity–attribute–value model

text: The following shows a selection of rows of an EAV table for clinical findings from a visit to a doctor for a fever on the morning of 1/5/98. The entries shown within angle brackets are references to entries in other tables, shown here as text rather than as encoded foreign key values for ease of understanding. In this example, the values are all literal values, but they could also be pre-defined value lists. The latter are particularly useful when the possible values are known to be limited (i.e., enumerable).


title: Entity–attribute–value model

text: The EAV data described above is comparable to the contents of a supermarket sales receipt (which would be reflected in a Sales Line Items table in a database). The receipt lists only details of the items actually purchased, instead of listing every product in the shop that the customer might have purchased but didn't. Like the clinical findings for a given patient, the sales receipt is sparse.


title: Entity–attribute–value model

text: Row modeling, where facts about something (in this case, a sales transaction) are recorded as multiple "rows" rather than multiple "columns", is a standard data modeling technique. The differences between row modeling and EAV (which may be considered a "generalization" of row-modeling) are:


title: Entity–attribute–value model

text: In a clinical data repository, row modeling also finds numerous uses; the laboratory test subschema is typically modeled this way, because lab test results are typically numeric, or can be encoded numerically.


title: Entity–attribute–value model

text: Certain ("hybrid") classes have some attributes that are non-sparse (present in all or most instances), while other attributes are highly variable and sparse. The latter are suitable for EAV modeling. For example, descriptions of products made by a conglomerate corporation depend on the product category, e.g., the attributes necessary to describe a brand of light bulb are quite different from those required to describe a medical imaging device, but both have common attributes such as packaging unit and per-item cost.


title: Entity–attribute–value model

text: In clinical data, the entity is typically a clinical event, as described above. In more general-purpose settings, the entity is a foreign key into an "objects" table that records common information about every "object" (thing) in the database – at the minimum, a preferred name and brief description, as well as the category/class of entity to which it belongs. Every record (object) in this table is assigned a machine-generated object ID.


title: Entity–attribute–value model

text: The "objects table" approach was pioneered by Tom Slezak and colleagues at Lawrence Livermore Laboratories for the Chromosome 19 database, and is now standard in most large bioinformatics databases. The use of an objects table does not mandate the concurrent use of an EAV design: conventional tables can be used to store the category-specific details of each object.


title: Entity–attribute–value model

text: The major benefit to a central objects table is that, by having a supporting table of object synonyms and keywords, one can provide a standard Google-like search mechanism across the entire system where the user can find information about any object of interest without having to first specify the category that it belongs to. (This is important in bioscience systems where a keyword like "acetylcholine" could refer either to the molecule itself, which is a neurotransmitter, or the biological receptor to which it binds.)


title: Entity–attribute–value model

text: In the EAV table itself, this is just an attribute ID, a foreign key into an Attribute Definitions table, as stated above. However, there are usually multiple metadata tables that contain attribute-related information, and these are discussed shortly.


title: Entity–attribute–value model

text: Coercing all values into strings, as in the EAV data example above, results in a simple, but non-scalable, structure: constant data type inter-conversions are required if one wants to do anything with the values, and an index on the value column of an EAV table is essentially useless. Also, it is not convenient to store large binary data, such as images, in Base64 encoded form in the same table as small integers or strings. Therefore, larger systems use separate EAV tables for each data type (including binary large objects, "BLOBS"), with the metadata for a given attribute identifying the EAV table in which its data will be stored. This approach is actually quite efficient because the modest amount of attribute metadata for a given class or form that a user chooses to work with can be cached readily in memory. However, it requires moving of data from one table to another if an attribute’s data type is changed.


title: Entity–attribute–value model

text: EAV, as a general-purpose means of knowledge representation, originated with the concept of "association lists" (attribute–value pairs). Commonly used today, these were first introduced in the language LISP.


title: Entity–attribute–value model

text: Attribute–value pairs are widely used for diverse applications, such as configuration files (using a simple syntax like "attribute = value"). An example of non-database use of EAV is in UIMA (Unstructured Information Management Architecture), a standard now managed by the Apache Foundation and employed in areas such as natural language processing. Software that analyzes text typically marks up ("annotates") a segment: the example provided in the UIMA tutorial is a program that performs named-entity recognition (NER) on a document, annotating the text segment "President Bush" with the annotation–attribute–value triple "(Person, Full_Name, "George W. Bush")". Such annotations may be stored in a database table.


title: Entity–attribute–value model

text: While EAV does not have a direct connection to AV-pairs, Stead and Hammond appear to be the first to have conceived of their use for persistent storage of arbitrarily complex data.


title: Entity–attribute–value model

text: The first medical record systems to employ EAV were the Regenstrief electronic medical record (the effort led by Clement MacDonald), William Stead and Ed Hammond's TMR (The Medical Record) system and the HELP Clinical Data Repository (CDR) created by Homer Warner's group at LDS Hospital, Salt Lake City, Utah. (The Regenstrief system actually used a Patient-Attribute-Timestamp-Value design: the use of the timestamp supported retrieval of values for a given patient/attribute in chronological order.) All these systems, developed in the 1970s, were released before commercial systems based on E.F. Codd's relational database model were available, though HELP was much later ported to a relational architecture and commercialized by the 3M corporation. (Note that while Codd's landmark paper was published in 1970, its heavily mathematical tone had the unfortunate effect of diminishing its accessibility among non-computer-science types and consequently delaying the model's acceptance in IT and software-vendor circles. The value of the subsequent contribution of Christopher J. Date, Codd's colleague at IBM, in translating these ideas into accessible language, accompanied by simple examples that illustrated their power, cannot be overestimated.)


title: Entity–attribute–value model

text: A group at the Columbia-Presbyterian Medical Center were the first to use a relational database engine as the foundation of an EAV system.


title: Entity–attribute–value model

text: The open-source TrialDB clinical study data management system of Nadkarni et al. was the first to use multiple EAV tables, one for each DBMS data type.


title: Entity–attribute–value model

text: The EAV/CR framework, designed primarily by Luis Marenco and Prakash Nadkarni, overlaid the principles of object orientation onto EAV; it built on Tom Slezak's object table approach (described earlier in the "Entity" section). SenseLab, a publicly accessible neuroscience database, is built with the EAV/CR framework.


title: Entity–attribute–value model

text: The term "EAV database" refers to a database design where a significant proportion of the data is modeled as EAV. However, even in a database described as "EAV-based", some tables in the system are traditional relational tables.


title: Entity–attribute–value model

text: As noted above, EAV modeling makes sense for categories of data, such as clinical findings, where attributes are numerous and sparse. Where these conditions do not hold, standard relational modeling (i.e., one column per attribute) is preferable; using EAV does not mean abandoning common sense or principles of good relational design. In clinical record systems, the subschemas dealing with patient demographics and billing are typically modeled conventionally. (While most vendor database schemas are proprietary, VistA, the system used throughout the United States Department of Veterans Affairs (VA) medical system, known as the Veterans Health Administration (VHA), is open-source and its schema is readily inspectable, though it uses a MUMPS database engine rather than a relational database.)


title: Entity–attribute–value model

text: As discussed shortly, an EAV database is essentially unmaintainable without numerous supporting tables that contain supporting metadata. The metadata tables, which typically outnumber the EAV tables by a factor of at least three or more, are typically standard relational tables. An example of a metadata table is the Attribute Definitions table mentioned above.


title: Entity–attribute–value model

text: In a simple EAV design, the values of an attribute are simple or primitive data types as far as the database engine is concerned. However, in EAV systems used for representation of highly diverse data, it is possible that a given object (class instance) may have substructure: that is, some of its attributes may represent other kinds of objects, which in turn may have substructure, to an arbitrary level of complexity. A car, for example, has an engine, a transmission, etc., and the engine has components such as cylinders. (The permissible substructure for a given class is defined within the system's attribute metadata, as discussed later. Thus, for example, the attribute "random-access-memory" could apply to the class "computer" but not to the class "engine".)


title: Entity–attribute–value model

text: To represent substructure, one incorporates a special EAV table where the value column contains references to "other" entities in the system (i.e., foreign key values into the objects table). To get all the information on a given object requires a recursive traversal of the metadata, followed by a recursive traversal of the data that stops when every attribute retrieved is simple (atomic). Recursive traversal is necessary whether details of an individual class are represented in conventional or EAV form; such traversal is performed in standard object–relational systems, for example. In practice, the number of levels of recursion tends to be relatively modest for most classes, so the performance penalties due to recursion are modest, especially with indexing of object IDs.


title: Entity–attribute–value model

text: EAV/CR (EAV with Classes and Relationships) refers to a framework that supports complex substructure. Its name is somewhat of a misnomer: while it was an outshoot of work on EAV systems, in practice, many or even most of the classes in such a system may be represented in standard relational form, based on whether the attributes are sparse or dense. EAV/CR is really characterized by its very detailed metadata, which is rich enough to support the automatic generation of browsing interfaces to individual classes without having to write class-by-class user-interface code. The basis of such browser interfaces is that it is possible to generate a batch of dynamic SQL queries that is independent of the class of the object, by first consulting its metadata and using metadata information to generate a sequence of queries against the data tables, and some of these queries may be arbitrarily recursive. This approach works well for object-at-a-time queries, as in Web-based browsing interfaces where clicking on the name of an object brings up all details of the object in a separate page: the metadata associated with that object's class also facilitates presentation of the object's details, because it includes captions of individual attributes, the order in which they are to be presented as well as how they are to be grouped.


title: Entity–attribute–value model

text: One approach to EAV/CR is to allow columns to hold JSON structures, which thus provide the needed class structure. For example, PostgreSQL, as of version 9.4, offers JSON binary column (JSONB) support, allowing JSON attributes to be queried, indexed and joined.


title: Entity–attribute–value model

text: In the words of Prof. Dr. Daniel Masys (formerly Chair of Vanderbilt University's Medical Informatics Department), the challenges of working with EAV stem from the fact that in an EAV database, the "physical schema" (the way data are stored) is radically different from the "logical schema" – the way users, and many software applications such as statistics packages, regard it, i.e., as conventional rows and columns for individual classes. (Because an EAV table conceptually mixes apples, oranges, grapefruit and chop suey, if you want to do any analysis of the data using standard off-the-shelf software, in most cases you have to convert subsets of it into columnar form. The process of doing this, called pivoting, is important enough to be discussed separately.)


title: Entity–attribute–value model

text: Metadata helps perform the sleight of hand that lets users interact with the system in terms of the logical schema rather than the physical: the software continually consults the metadata for various operations such as data presentation, interactive validation, bulk data extraction and ad hoc query. The metadata can actually be used to customize the behavior of the system.


title: Entity–attribute–value model

text: EAV systems trade off simplicity in the physical and logical structure of the data for complexity in their metadata, which, among other things, plays the role that database constraints and referential integrity do in standard database designs. Such a tradeoff is generally worthwhile, because in the typical mixed schema of production systems, the data in conventional relational tables can also benefit from functionality such as automatic interface generation. The structure of the metadata is complex enough that it comprises its own subschema within the database: various foreign keys in the data tables refer to tables within this subschema. This subschema is standard-relational, with features such as constraints and referential integrity being used to the hilt.


title: Entity–attribute–value model

text: The correctness of the metadata contents, in terms of the intended system behavior, is critical and the task of ensuring correctness means that, when creating an EAV system, considerable design efforts must go into building user interfaces for metadata editing that can be used by people on the team who know the problem domain (e.g., clinical medicine) but are not necessarily programmers. (Historically, one of the main reasons why the pre-relational TMR system failed to be adopted at sites other than its home institution was that all metadata was stored in a single file with a non-intuitive structure. Customizing system behavior by altering the contents of this file, without causing the system to break, was such a delicate task that the system's authors only trusted themselves to do it.)


title: Entity–attribute–value model

text: Where an EAV system is implemented through RDF, the RDF Schema language may conveniently be used to express such metadata. This Schema information may then be used by the EAV database engine to dynamically re-organize its internal table structure for best efficiency.


title: Entity–attribute–value model

text: Validation, presentation and grouping metadata make possible the creation of code frameworks that support automatic user interface generation for both data browsing as well as interactive editing. In a production system that is delivered over the Web, the task of validation of EAV data is essentially moved from the back-end/database tier (which is powerless with respect to this task) to the middle /Web server tier. While back-end validation is always ideal, because it is impossible to subvert by attempting direct data entry into a table, middle tier validation through a generic framework is quite workable, though a significant amount of software design effort must go into building the framework first. The availability of open-source frameworks that can be studied and modified for individual needs can go a long way in avoiding wheel reinvention.


title: Entity–attribute–value model

text: EAV modeling, under the alternative terms "generic data modeling" or "open schema", has long been a standard tool for advanced data modelers. Like any advanced technique, it can be double-edged, and should be used judiciously.


title: Entity–attribute–value model

text: Also, the employment of EAV does not preclude the employment of traditional relational database modeling approaches within the same database schema. In EMRs that rely on an RDBMS, such as Cerner, which use an EAV approach for their clinical-data subschema, the vast majority of tables in the schema are in fact traditionally modeled, with attributes represented as individual columns rather than as rows.


title: Entity–attribute–value model

text: The modeling of the metadata subschema of an EAV system, in fact, is a very good fit for traditional modeling, because of the inter-relationships between the various components of the metadata. In the TrialDB system, for example, the number of metadata tables in the schema outnumber the data tables by about ten to one. Because the correctness and consistency of metadata is critical to the correct operation of an EAV system, the system designer wants to take full advantages of all of the features that RDBMSs provide, such as referential integrity and programmable constraints, rather than having to reinvent the RDBMS-engine wheel. Consequently, the numerous metadata tables that support EAV designs are typically in third-normal relational form.


title: Entity–attribute–value model

text: Commercial electronic health record Systems (EHRs) use row-modeling for classes of data such as diagnoses, surgical procedures performed on and laboratory test results, which are segregated into separate tables. In each table, the "entity" is a composite of the patient ID and the date/time the diagnosis was made (or the surgery or lab test performed); the attribute is a foreign key into a specially designated lookup table that contains a controlled vocabulary - e.g., ICD-10 for diagnoses, Current Procedural Terminology for surgical procedures, with a set of value attributes. (E.g., for laboratory-test results, one may record the value measured, whether it is in the normal, low or high range, the ID of the person responsible for performing the test, the date/time the test was performed, and so on.) As stated earlier, this is not a full-fledged EAV approach because the domain of attributes for a given table is restricted, just as the domain of product IDs in a supermarket's Sales table would be restricted to the domain of Products in a Products table.


title: Entity–attribute–value model

text: However, to capture data on parameters that are not always defined in standard vocabularies, EHRs also provide a "pure" EAV mechanism, where specially designated power-users can define new attributes, their data type, maximum and minimal permissible values (or permissible set of values/codes), and then allow others to capture data based on these attributes. In the Epic (TM) EHR, this mechanism is termed "Flowsheets", and is commonly used to capture inpatient nursing observation data.


title: Entity–attribute–value model

text: The typical case for using the EAV model is for highly sparse, heterogeneous attributes, such as clinical parameters in the electronic medical record (EMRs), as stated above. Even here, however, it is accurate to state that the EAV modeling principle is applied to a "sub-schema" of the database rather than for all of its contents. (Patient demographics, for example, are most naturally modeled in one-column-per-attribute, traditional relational structure.)


title: Entity–attribute–value model

text: Consequently, the arguments about EAV vs. "relational" design reflect incomplete understanding of the problem: An EAV design should be employed only for that sub-schema of a database where sparse attributes need to be modeled: even here, they need to be supported by third normal form metadata tables. There are relatively few database-design problems where sparse attributes are encountered: this is why the circumstances where EAV design is applicable are relatively rare. Even where they are encountered, a set of EAV tables is not the only way to address sparse data: an XML-based solution (discussed below) is applicable when the maximum number of attributes per entity is relatively modest, and the total volume of sparse data is also similarly modest. An example of this situation is the problems of capturing variable attributes for different product types.


title: Entity–attribute–value model

text: Sparse attributes may also occur in E-commerce situations where an organization is purchasing or selling a vast and highly diverse set of commodities, with the details of individual categories of commodities being highly variable. The Magento E-commerce software employs an EAV approach to address this issue.


title: Entity–attribute–value model

text: Another application of EAV is in modeling classes and attributes that, while not sparse, are dynamic, but where the number of data rows per class will be relatively modest – a couple of hundred rows at most, but typically a few dozen – and the system developer is also required to provide a Web-based end-user interface within a very short turnaround time. "Dynamic" means that new classes and attributes need to be continually defined and altered to represent an evolving data model. This scenario can occur in rapidly evolving scientific fields as well as in ontology development, especially during the prototyping and iterative refinement phases.


title: Entity–attribute–value model

text: While creation of new tables and columns to represent a new category of data is not especially labor-intensive, the programming of Web-based interfaces that support browsing or basic editing with type- and range-based validation is. In such a case, a more maintainable long-term solution is to create a framework where the class and attribute definitions are stored in metadata, and the software generates a basic user interface from this metadata dynamically.


title: Entity–attribute–value model

text: The EAV/CR framework, mentioned earlier, was created to address this very situation. Note that an EAV data model is not essential here, but the system designer may consider it an acceptable alternative to creating, say, sixty or more tables containing a total of not more than two thousand rows. Here, because the number of rows per class is so few, efficiency considerations are less important; with the standard indexing by class ID/attribute ID, DBMS optimizers can easily cache the data for a small class in memory when running a query involving that class or attribute.


title: Entity–attribute–value model

text: In the dynamic-attribute scenario, it is worth noting that Resource Description Framework (RDF) is being employed as the underpinning of Semantic-Web-related ontology work. RDF, intended to be a general method of representing information, is a form of EAV: an RDF triple comprises an object, a property, and a value.


title: Entity–attribute–value model

text: At the end of Jon Bentley's book "Writing Efficient Programs", the author warns that making code more efficient generally also makes it harder to understand and maintain, and so one does not rush in and tweak code unless one has first determined that there is a performance problem, and measures such as code profiling have pinpointed the exact location of the bottleneck. Once you have done so, you modify only the specific code that needs to run faster. Similar considerations apply to EAV modeling: you apply it only to the sub-system where traditional relational modeling is known "a priori" to be unwieldy (as in the clinical data domain), or is discovered, during system evolution, to pose significant maintenance challenges. Database Guru (and currently a vice-president of Core Technologies at Oracle Corporation) Tom Kyte, for example, correctly points out drawbacks of employing EAV in traditional business scenarios, and makes the point that mere "flexibility" is not a sufficient criterion for employing EAV. (However, he makes the sweeping claim that EAV should be avoided in "all" circumstances, even though Oracle's Health Sciences division itself employs EAV to model clinical-data attributes in its commercial systems ClinTrial and Oracle Clinical.)


title: Entity–attribute–value model

text: The Achilles heel of EAV is the difficulty of working with large volumes of EAV data. It is often necessary to transiently or permanently inter-convert between columnar and row-or EAV-modeled representations of the same data; this can be both error-prone if done manually as well as CPU-intensive. Generic frameworks that utilize attribute and attribute-grouping metadata address the former but not the latter limitation; their use is more or less mandated in the case of mixed schemas that contain a mixture of conventional-relational and EAV data, where the error quotient can be very significant.


title: Entity–attribute–value model

text: The conversion operation is called pivoting. Pivoting is not required only for EAV data but also for any form of row-modeled data. (For example, implementations of the Apriori algorithm for Association Analysis, widely used to process supermarket sales data to identify other products that purchasers of a given product are also likely to buy, pivot row-modeled data as a first step.) Many database engines have proprietary SQL extensions to facilitate pivoting, and packages such as Microsoft Excel also support it. The circumstances where pivoting is necessary are considered below.


title: Entity–attribute–value model

text: However, the structure of EAV data model is a perfect candidate for Relational Division, see relational algebra. With a good indexing strategy it's possible to get a response time in less than a few hundred milliseconds on a billion row EAV table. Microsoft SQL Server MVP Peter Larsson has proved this on a laptop and made the solution general available.


title: Entity–attribute–value model

text: Obviously, no matter what approaches you take, querying EAV will not be as fast as querying standard column-modeled relational data for certain types of query, in much the same way that access of elements in sparse matrices are not as fast as those on non-sparse matrices if the latter fit entirely into main memory. (Sparse matrices, represented using structures such as linked lists, require list traversal to access an element at a given X-Y position, while access to elements in matrices represented as 2-D arrays can be performed using fast CPU register operations.) If, however, you chose the EAV approach correctly for the problem that you were trying to solve, this is the price that you pay; in this respect, EAV modeling is an example of a space (and schema maintenance) versus CPU-time tradeoff.


title: Entity–attribute–value model

text: Originally postulated by Maier, Ullman and Vardi, the "Universal Data Model" (UDM) seeks to simplify the query of a complex relational schema by naive users, by creating the illusion that everything is stored in a single giant "universal table". It does this by utilizing inter-table relationships, so that the user does not need to be concerned about what table contains what attribute. C.J. Date, however, pointed out that in circumstances where a table is multiply related to another (as in genealogy databases, where an individual's father and mother are also individuals, or in some business databases where all addresses are stored centrally, and an organization can have different office addresses and shipping addresses), there is insufficient metadata within the database schema to specify unambiguous joins. When UDM has been commercialized, as in SAP BusinessObjects, this limitation is worked around through the creation of "Universes", which are relational views with predefined joins between sets of tables: the "Universe" developer disambiguates ambiguous joins by including the multiply-related table in a view multiple times using different aliases.


title: Entity–attribute–value model

text: Apart from the way in which data is explicitly modeled (UDM simply uses relational views to intercede between the user and the database schema), EAV differs from Universal Data Models in that it also applies to transactional systems, not only query oriented (read-only) systems as in UDM. Also, when used as the basis for clinical-data query systems, EAV implementations do not necessarily shield the user from having to specify the class of an object of interest. In the EAV-based i2b2 clinical data mart, for example, when the user searches for a term, she has the option of specifying the category of data that the user is interested in. For example, the phrase "lithium" can refer either to the medication (which is used to treat bipolar disorder), or a laboratory assay for lithium level in the patient's blood. (The blood level of lithium must be monitored carefully: too much of the drug causes severe side effects, while too little is ineffective.)


title: Entity–attribute–value model

text: An Open Schema implementation can use an XML column in a table to capture the variable/sparse information. Similar ideas can be applied to databases that support JSON-valued columns: sparse, hierarchical data can be represented as JSON. If the database has JSON support, such as PostgreSQL and (partially) SQL Server 2016 and later, then attributes can be queried, indexed and joined. This can offer performance improvements of over 1000x over naive EAV implementations., but does not necessarily make the overall database application more robust.


title: Entity–attribute–value model

text: Note that there are two ways in which XML or JSON data can be stored: one way is to store it as a plain string, opaque to the database server; the other way is to use a database server that can "see into" the structure. There are obviously some severe drawbacks to storing opaque strings: these cannot be queried directly, one cannot form an index based on their contents, and it is impossible to perform joins based on the content.


title: Entity–attribute–value model

text: Building an application that has to manage data gets extremely complicated when using EAV models, because of the extent of infrastructure that has to be developed in terms of metadata tables and application-framework code. Using XML solves the problem of server-based data validation (which must be done by middle-tier and browser-based code in EAV-based frameworks), but has the following drawbacks:


title: Entity–attribute–value model

text: All of the above drawbacks are remediable by creating a layer of metadata and application code, but in creating this, the original "advantage" of not having to create a framework has vanished. The fact is that modeling sparse data attributes robustly is a hard database-application-design problem no matter which storage approach is used. Sarka's work, however, proves the viability of using an XML field instead of type-specific relational EAV tables for the data-storage layer, and in situations where the number of attributes per entity is modest (e.g., variable product attributes for different product types) the XML-based solution is more compact than an EAV-table-based one. (XML itself may be regarded as a means of attribute–value data representation, though it is based on structured text rather than on relational tables.)


title: Entity–attribute–value model

text: There exist several other approaches for the representation of tree-structured data, be it XML, JSON or other formats, such as the nested set model, in a relational database. On the other hand, database vendors have begun to include JSON and XML support into their data structures and query features, like in IBM Db2, where XML data is stored as XML separate from the tables, using XPath queries as part of SQL statements, or in PostgreSQL, with a JSON data type that can be indexed and queried. These developments accomplish, improve or substitute the EAV model approach.


title: Entity–attribute–value model

text: The uses of JSON and XML are not necessarily the same as the use of an EAV model, though they can overlap. XML is preferable to EAV for arbitrarily hierarchical data that is relatively modest in volume for a single entity: it is not intended to scale up to the multi-gigabyte level with respect to data-manipulation performance. XML is not concerned per-se with the sparse-attribute problem, and when the data model underlying the information to be represented can be decomposed straightforwardly into a relational structure, XML is better suited as a means of data interchange than as a primary storage mechanism. EAV, as stated earlier, is specifically (and only) applicable to the sparse-attribute scenario. When such a scenario holds, the use of datatype-specific attribute–value tables that can be indexed by entity, by attribute, and by value and manipulated through simple SQL statements is vastly more scalable than the use of an XML tree structure. The Google App Engine, mentioned above, uses strongly-typed-value tables for a good reason.


title: Entity–attribute–value model

text: An alternative approach to managing the various problems encountered with EAV-structured data is to employ a graph database. These represent entities as the nodes of a graph or hypergraph, and attributes as links or edges of that graph. The issue of table joins are addressed by providing graph-specific query languages, such as Apache TinkerPop, or the OpenCog atomspace pattern matcher.


title: Entity–attribute–value model

text: PostgreSQL version 9.4 includes support for JSON binary columns (JSONB), which can be queried, indexed and joined. This allows performance improvements by factors of a thousand or more over traditional EAV table designs.


title: Entity–attribute–value model

text: A DB schema based on JSONB always has fewer tables: one may nest attribute–value pairs in JSONB type fields of the Entity table. That makes the DB schema easy to comprehend and SQL queries concise.


title: Entity–attribute–value model

text: The programming code to manipulate the database objects on the abstraction layer turns out much shorter.


title: Entity–attribute–value model

text: Microsoft SQL Server 2008 offers a (proprietary) alternative to EAV. Columns with an atomic data type (e.g., numeric, varchar or datetime columns) can be designated as "sparse" simply by including the word SPARSE in the column definition of the CREATE TABLE statement. Sparse columns optimize the storage of NULL values (which now take up no space at all) and are useful when the majority records in a table will have NULL values for that column. Indexes on sparse columns are also optimized: only those rows with values are indexed. In addition, the contents of all sparse columns in a particular row of a table can be collectively aggregated into a single XML column (a column set), whose contents are of the form codice_1 In fact, if a column set is defined for a table as part of a CREATE TABLE statement, all sparse columns subsequently defined are typically added to it. This has the interesting consequence that the SQL statement codice_2 will not return the individual sparse columns, but concatenate all of them into a single XML column whose name is that of the column set (which therefore acts as a virtual, computed column). Sparse columns are convenient for business applications such as product information, where the applicable attributes can be highly variable depending on the product type, but where the total number of variable attributes per product type are relatively modest.


title: Entity–attribute–value model

text: However, this approach to modeling sparse attributes has several limitations: rival DBMSs have, notably, chosen not to borrow this idea for their own engines. Limitations include:


title: Entity–attribute–value model

text: Many cloud computing vendors offer data stores based on the EAV model, where an arbitrary number of attributes can be associated with a given entity. Roger Jennings provides an in-depth comparison of these. In Amazon's offering, SimpleDB, the data type is limited to strings, and data that is intrinsically non-string must be coerced to string (e.g., numbers must be padded with leading zeros) if you wish to perform operations such as sorting. Microsoft's offering, Windows Azure Table Storage, offers a limited set of data types: byte[], bool, DateTime, double, Guid, int, long and string . The Google App Engine offers the greatest variety of data types: in addition to dividing numeric data into int, long, or float, it also defines custom data types such as phone number, E-mail address, geocode and hyperlink. Google, but not Amazon or Microsoft, lets you define metadata that would prevent invalid attributes from being associated with a particular class of entity, by letting you create a metadata model.


title: Entity–attribute–value model

text: Google lets you operate on the data using a subset of SQL; Microsoft offer a URL-based querying syntax that is abstracted via a LINQ provider; Amazon offer a more limited syntax. Of concern, built-in support for combining different entities through joins is currently (April '10) non-existent with all three engines. Such operations have to be performed by application code. This may not be a concern if the application servers are co-located with the data servers at the vendor's data center, but a lot of network traffic would be generated if the two were geographically separated.


title: Entity–attribute–value model

text: An EAV approach is justified only when the attributes that are being modeled are numerous and sparse: if the data being captured does not meet this requirement, the cloud vendors' default EAV approach is often a mismatch for applications that require a true back-end database (as opposed to merely a means of persistent data storage). Retrofitting the vast majority of existing database applications, which use a traditional data-modeling approach, to an EAV-type cloud architecture, would require major surgery. Microsoft discovered, for example, that its database-application-developer base was largely reluctant to invest such effort. More recently, therefore, Microsoft has provided a premium offering – a cloud-accessible full-fledged relational engine, SQL Server Azure, which allows porting of existing database applications with modest changes.


title: Entity–attribute–value model

text: One limitation of SQL Azure is that physical databases are limited to 500 GB in size . Microsoft recommends that data sets larger than this be split into multiple physical databases and accessed with parallel queries.


title: Nitzer Ebb

text: Nitzer Ebb () are a British EBM group formed in 1982 by Essex school friends Vaughan "Bon" Harris (programming, synthesizers, drums, vocals), Douglas McCarthy (vocals), and David Gooday (drums).


title: Nitzer Ebb

text: The group released their demo "Basic Pain Procedure" in 1983, but it was two years until they met PWL producer Phil Harding, who produced their 1985 debut single "Isn't It Funny How Your Body Works?" and helped them set up their own label, Power Of Voice Communications. The band at the time was inspired by the post-punk scene and specifically acts like "Siouxsie and the Banshees, Killing Joke and Bauhaus who were having a big influence on us, in some ways stylistically but also in the energy that they gave".


title: Nitzer Ebb

text: They released three more singles on their own label, "Warsaw Ghetto" (1985), "Warsaw Ghetto Remixes" (1986) and "Let Your Body Learn" (1986), before signing to Mute Records in 1986. The singles "Murderous" (1986) and "Let Your Body Learn" (1987) followed, building their reputation in the Industrial Rock and EBM scenes, as well as making inroads into the developing Chicago House scene.


title: Nitzer Ebb

text: "Join In The Chant" (1987) became part of the Balearic beat scene that influenced the UK acid house scene.


title: Nitzer Ebb

text: Their debut album "That Total Age" was released in 1987. Depeche Mode, longtime friends and label mates of the band, invited them to open for the European leg of their successful Music For The Masses Tour in 1987.


title: Nitzer Ebb

text: David Gooday left after the tour and they completed their next album "Belief" (1989) as a duo. Mark 'Flood' Ellis became their new producer. They recruited Julian Beeston to assist them on their own world tour, and he soon became a regular contributor both on and off stage.


title: Nitzer Ebb

text: In 1989, they teamed with German EBM pioneers Die Krupps to rerecord their 1981 single "Wahre Arbeit - Wahrer Lohn" as "The Machineries of Joy".


title: Nitzer Ebb

text: The third Nitzer Ebb album "Showtime", released in 1990, revealed a less confrontational sound. The single "Fun to Be Had" (1990) featured a remix by George Clinton and was a hit on the US dance chart.


title: Nitzer Ebb

text: Their fourth album, "Ebbhead" (1991), showcased a more traditional songwriting style with an emphasis on melodic choruses was produced by Alan Wilder from Depeche Mode and Flood. They promoted the album with a global tour that took them from the southern U.S. to northern Siberia.


title: Nitzer Ebb

text: Their fifth album ,"Big Hit" (1995), featured a greater use of 'real' instruments, especially guitars and drums. McCarthy and Harris recruited Jason Payne (percussion), to their main line-up and brought in John Napier (guitar, percussion) to assist with live performances.


title: Nitzer Ebb

text: "Big Hit" was the final release by the band for almost 15 years. McCarthy was a regular collaborator with Alan Wilder's Recoil project, and he records with French electronic producer Terence Fixmer as Fixmer/McCarthy. Bon Harris moved to Los Angeles, where he became a successful producer and recorded as 13mg and as a member of Maven.


title: Nitzer Ebb

text: Nitzer Ebb began work on new material in Los Angeles in early 2007, with a retrospective documentary still in the pipeline. During 2007, Nitzer Ebb continued its trend of replacing drummers as Kourtney Klein left the band to be replaced by Jason Payne. A first track, "Once You Say," with Depeche Mode songwriter Martin L. Gore on backing vocals, was played in June 2007 by Dave Clarke in his White Noise show on VPRO's 3 Voor 12. This track, along with "Payroll," were debuted live as Nitzer Ebb played a handful of shows and festivals during 2007. These tracks were then featured on Nitzer Ebb's album, "Industrial Complex".


title: Nitzer Ebb

text: McCarthy and Harris reunited up with Jason Payne and producer Flood to finish up the first new Nitzer Ebb record in over a decade. In the meantime, "Fixmer/McCarthy" released its second album in June 2008, "Into the Night".


title: Nitzer Ebb

text: The band announced a US tour for fall–winter 2009 and were selected as the opening act of the January and February European and Russian dates of Depeche Mode's Tour of the Universe in 2010.


title: Nitzer Ebb

text: In 2019, the band announced a North American tour that included the original band members David Gooday and Simon Granger. In 2021, the band continued more tour dates including in Europe.


title: Nitzer Ebb

text: During the COVID-19 pandemic, Harris and McCarthy got together to work on a side project called D-R-A-G.


title: Nitzer Ebb

text: In November 2021, McCarthy collapsed before a show in Palm Beach, Florida and had to go to the hospital. The band emphasized it was due to complications from a pre-existing illness and it had nothing to do with COVID-19. The band went on to perform with Harris on lead vocals.


title: Nitzer Ebb

text: The single "Murderous" has been sampled by other electronic music acts, such as Information Society (on "Now That I Have You") and Kode IV (on "Success"). Nitzer Ebb's early tracks also made inroads to techno culture, notably in Richie Hawtin's 1999 DJ mix, "Decks, EFX & 909".


title: The Call (band)

text: The Call was an American rock band formed in Santa Cruz, California in 1980. The main lineup consisted of members Michael Been, Scott Musick, Tom Ferrier and Jim Goodwin. The band released nine studio albums over the next two decades before disbanding in 2000. Their 1986 song, "I Still Believe (Great Design)", was covered by Tim Cappello and included in the 1987 film "The Lost Boys". The band also achieved significant success with "Let the Day Begin" in 1989 which reached No. 1 on the "Billboard" U.S. Mainstream Rock chart and was later used as a campaign theme song for Al Gore's 2000 Presidential Campaign.


title: The Call (band)

text: The original lineup of the Call was Been (lead vocals, guitar), Musick (drums, percussion), Ferrier (guitar) and Greg Freeman (bass). This lineup grew to include Steve Huddleston on keyboards from 1981 through 1983. Goodwin joined the band as keyboardist in 1983, replacing Huddleston. Freeman departed in 1984 with Joe Read taking over bass duties for "Scene Beyond Dreams". Both Been and Musick were originally from Oklahoma but didn't meet until independently moving to California. The Call were earlier known as Motion Pictures and served as Phil Seymour's band at that time.


title: The Call (band)

text: Beginning with their self-titled debut in 1982, they went on to produce and release nine studio albums by 2000. The eponymous premiere album was recorded in England, and Been recalled in a 1987 interview that the band was in an exploratory phase at this point. He further noted, ""The Call" was a compassionate album, but it probably came out as anger." Peter Gabriel liked the band so much that he called them the "future of American music" and asked them to open for him during his 1982–1983 "Plays Live" tour.


title: The Call (band)

text: Their next album, "Modern Romans", was notable for its political content. Been later stated, "There was a great deal happening politically—Grenada, Lebanon, or the government saying the Russians are evil and the Russian government probably saying the same about us. That kind of thinking inspired me to write the last lines of 'Walls Came Down'." Garth Hudson of the Band played keyboards on these first two records.


title: The Call (band)

text: This was followed by "Scene Beyond Dreams". Been referred to it as the Call's "metaphysical" album. With a strong poetic sense to the lyrics and a change in instrumentation, the change in sound is notable.


title: The Call (band)

text: The band's next album, "Reconciled", was recorded in mid-1985. Prior to this, the band had not had a recording contract for two years, due to what Been described as "legal bickering" between the Call's former record label, Mercury, and their management company." However, when a new deal was signed with Elektra Records, the band produced their most commercially successful album to date. Peter Gabriel, Simple Minds' Jim Kerr, Hudson and Hudson's bandmate Robbie Robertson—both of the Band—all performed as guests on the album, which was released in 1986. Several tracks from the album became hits on the Mainstream Rock Chart, and one of these tracks, "I Still Believe (Great Design)" (aka "I Still Believe") appears on the soundtrack of the 1986 film "The Whoopee Boys".


title: The Call (band)

text: The following year, "I Still Believe" was covered by Tim Cappello for the film "The Lost Boys". In the film, Cappello memorably stole the scene as a shirtless saxophonist belting out the tune on the beach. The song was also covered by contemporary Christian musician Russ Taff on his 1987 self-titled album, and more recently by the Protomen as part of their 2015 cover album. In 2017 Klayton from Celldweller Covered "Too Many Tears" on "The Cover Up". In 2018, a cover version of "I Still Believe" appeared in the Paramount television series "Waco" about the Branch Davidian tragedy.


title: The Call (band)

text: The band released "Into the Woods" in 1987, which Been referred to as his favorite album. In 1989 they released "Let the Day Begin", whose title track reached No. 1 on the US Mainstream Rock chart. Their label under-ordered physical copies of the album and the resultant decline in sales limited their chart position.


title: The Call (band)

text: "Red Moon", the group's final studio album for a major label, was released in 1990. The album included background vocals by U2's Bono on the track "What's Happened to You". The album took a turn into the new genre of Americana, and was out of step with the shock of grunge music taking over the airwaves. Following the "Red Moon" tour, the band took an "extended break".


title: The Call (band)

text: Rumors regarding the band's dissolution were fueled by Been's solo releases in the early 1990s including the song "To Feel This Way" for the 1992 film "Light Sleeper" and a 1994 solo album "On the Verge of a Nervous Breakthrough"; however, in 1996, Warner Bros. Records. released "The Best of The Call", which featured a selection of old favorites and a few new songs including two of Been's solo songs, "Us" and "To Feel This Way", which had been re-recorded with the full band.


title: The Call (band)

text: In 1997 they released a new studio album, "To Heaven and Back", on Fingerprint Records. A few years later, a music fan tracked Been down and helped him master and release their first and only live album, a recording from their 1990 tour, which was released as "Live Under the Red Moon" in 2000 on the indie label Conspiracy Music. The band disbanded that same year.


title: The Call (band)

text: Al Gore used "Let the Day Begin" as his campaign song in the 2000 U.S. Presidential Election and Tom Vilsack used it as his song during his brief 2008 U.S. Presidential Election campaign.


title: The Call (band)

text: A 2009 temporary exhibition at the Oklahoma History Center about rock music in the state was called "Another Hot Oklahoma Night: A Rock & Roll Exhibit". The name of the exhibition was taken from a line in the band's song, "Oklahoma", which was also one of the ten finalists in a 2009 vote for Oklahoma's official state rock song. A book was published of the same name featuring the Call and numerous other Oklahoma musicians.


title: The Call (band)

text: Michael Been died on August 19, 2010, after suffering a heart attack backstage at the Pukkelpop music festival in Hasselt, Belgium, where he was working as sound engineer for his son's, Robert Levon Been, band Black Rebel Motorcycle Club.


title: The Call (band)

text: On April 18 and 19, 2013, band members Scott Musick, Tom Ferrier, and Jim Goodwin reunited for a series of shows in San Francisco and Los Angeles with Robert Levon Been of BRMC taking over the role of bass and vocals. "A Tribute to Michael Been featuring Robert Levon Been (of BRMC)" was released on September 2, 2014. The songs were recorded during the 2013 show. The CD version included 14 songs while the special CD and DVD combo pack, and a digital deluxe version had 19. A limited edition vinyl release was also released. In 2015, an hour-long TV special using footage from the DVD was shown on VH1 Classic and Palladia.


title: The Call (band)

text: On April 22, 2017, the Call reunited and played a show in New Orleans, Louisiana at Siberia, with special guest vocalists Ray Ganucheau, Michael Divita and J.D. Buhl.


title: The Call (band)

text: On August 28, 2021, The Call was inducted into the Oklahoma Music Hall of Fame. Scott Musick and Steve Huddleston were present to accept their awards. Michael Been's sister accepted his posthumous award on his behalf.


title: Radical symbol

text: In mathematics, the radical sign, radical symbol, root symbol, radix, or surd is a symbol for the square root or higher-order root of a number. The square root of a number formula_1 is written as


title: Radical symbol

text: Each positive real number has two square roots, one positive and the other negative. The square root symbol refers to the principal square root, which is the positive one. The two square roots of a negative number are both imaginary numbers, and the square root symbol refers to the principal square root, the one with a positive imaginary part. For the definition of the principal square root of other complex numbers, see Square root#Principal square root of a complex number.


title: Radical symbol

text: The origin of the root symbol √ is largely speculative. Some sources imply that the symbol was first used by Arab mathematicians. One of those mathematicians was Abū al-Hasan ibn Alī al-Qalasādī (1421–1486). Legend has it that it was taken from the Arabic letter "" ("ǧīm"), which is the first letter in the Arabic word "" ("jadhir", meaning "root"). However, Leonhard Euler believed it originated from the letter "r", the first letter of the Latin word "radix" (meaning "root"), referring to the same mathematical operation.


title: Radical symbol

text: The symbol was first seen in print without the vinculum (the horizontal "bar" over the numbers inside the radical symbol) in the year 1525 in "Die Coss" by Christoff Rudolff, a German mathematician. In 1637 Descartes was the first to unite the German radical sign √ with the vinculum to create the radical symbol in common use today.


title: Radical symbol

text: However, these characters differ in appearance from most mathematical typesetting by omitting the overline connected to the radical symbol, which surrounds the argument of the square root function. The OpenType math table allows adding this overline following the radical symbol.


title: Radical symbol

text: The Symbol font displays the character without any vinculum whatsoever; the overline may be a separate character at 0x60. The JIS, Wansung and CNS 11643 code charts include a short overline attached to the radical symbol, whereas the GB 2312 and GB 18030 charts do not.


title: Radical symbol

text: Additionally a "Radical Symbol Bottom" (U+23B7, ⎷) is available in the Miscellaneous Technical block. This was used in contexts where box-drawing characters are used, such as in the technical character set of DEC terminals, to join up with box drawing characters on the line above to create the vinculum.


title: Rachel, Nevada

text: Rachel is a census-designated place (CDP) in Lincoln County, Nevada, United States. As of the 2020 census, it had a population of 48. As the closest settlement to the Nellis Air Force Range and Area 51, Rachel enjoys a modest celebrity status, particularly among aviation enthusiasts and UFO hunters.


title: Rachel, Nevada

text: Rachel is over north of Las Vegas in the Great Basin Desert, along Nevada Highway 375 (the "Extraterrestrial Highway") in Nevada. The tiny town receives a substantial number of visitors and tourists, catered to by a small tourist shop, a 12-room motel, and an alien-themed restaurant and bar, the Little A'Le'Inn.


title: Rachel, Nevada

text: Rachel's resident population generally numbers around 50, with some of them involved in ranching. Most of the year-round inhabitants live in mobile homes. Rachel has never had a post office. The children are bused to Alamo, approximately away, for school. North of the town is the Quinn Canyon Range that has the ghost town of Adaven.


title: Rachel, Nevada

text: Rachel was founded in May 1973 by a local alfalfa farmer named D.C. Day. The community was first known as Tempiute Village, and then later as Sand Springs.


title: Rachel, Nevada

text: On February 15, 1978, the town was renamed to Rachel after the first baby born in the valley, Rachel Jones (1978–1980). Rachel Jones died on May 24, 1980. In memory of her, Rachel residents created a cemetery and memorial park. Rachel Jones was not buried at Rachel Cemetery.


title: Rachel, Nevada

text: Electricity arrived in Rachel on March 22, 1978, supplied to the Penoyer Valley by the Penoyer Valley Electric Cooperative.


title: Rachel, Nevada

text: In 1980, the Rachel Baptist Mission, Rachel's only church, began service in a donated mobile home. Since then, a part-time pastor has come to Rachel for religious services every Sunday morning.


title: Rachel, Nevada

text: On July 10, 1986, at about 4:10 pm, two F-16s of the Norwegian Air Force collided in mid-air while participating in Red Flag exercises near Rachel. One of them crashed within Rachel, only from the edge of a mobile home park. The pilot of the downed fighter had ejected safely before the crash, and the other F-16 made it back to Nellis Air Force Base. The pilot of the downed F-16 suffered only minor injuries, and was transported from the crash site within 20 minutes of the incident by a U.S. Air Force helicopter.


title: Rachel, Nevada

text: In 1995, the Rachel Baptist Mission moved into a permanent building at the same site that it had occupied previously.


title: Rachel, Nevada

text: In 2006, KFC created a giant company logo on the ground at the north edge of Rachel and claimed it to be the first logo visible from space. Constructed in early November, it took six days to assemble the 65,000 colored tiles on of flat desert terrain. The logo also had a hidden message on the tie area of the logo that featured an impostor colonel holding a sign over his head, reading "Finger Lickin' Good". The logo was removed in mid-2007.


title: Rachel, Nevada

text: Rachel was featured in an episode of "Louis Theroux's Weird Weekends" which covered the UFO subculture. Rachel was mentioned in a two-part episode of "The X-Files" entitled "Dreamland", in which a secret agent aware of the hidden backstory of the show, played by Michael McKean, resided in the town. It is also a key place in the first-person shooter game "".


title: Rachel, Nevada

text: In 1996 the producers of the movie "Independence Day", which filmed some scenes in Rachel, gave the town a time capsule, which is installed near the inn and is intended to be opened in 2050.


title: Rachel, Nevada

text: Beginning September 19, 2019, the day before the Area 51 Raid people were reported showing up and camping around Rachel in preparation for the raid.


title: Rachel, Nevada

text: Alien Cowpoke Gas Station and General Store opened in Oct. 2020 and a planned campground and RV hookup ready to open by Fall 2021.


title: Rachel, Nevada

text: As of the census of 2010, there were 54 people, 32 households, and 14 families residing in the CDP. The racial makeup was 94.44% White, 3.70% Asian, and 1.85% from other races. 11.11% were Hispanic or Latino of any race.


title: Rachel, Nevada

text: Of the 32 households, 6.25% had children under the age of 18, 25.00% were married couples, 6.25% had a male householder with no wife present, and 12.50% had a female householder with no husband present. 56.25% of households were made up of individuals, and 9.38% had someone living alone who was 65 years of age or older. The average household size was 1.69 and the average family size was 2.50.


title: Rachel, Nevada

text: In the CDP, the population was spread out, with 16.67% ages 15 to 24, 59.26% ages 35 to 64, and 24.07% aged 65 and over. The median age was 52.5 years. 59.26% of the residents were male, and 40.74% were female.


title: Rachel, Nevada

text: Rachel has a cold desert climate (Köppen climate classification "BWk"), with cold winters, warm summers and a high diurnal temperature variation. The average annual high temperature is , while the average annual low temperature is . July has the highest average high at and the highest average low at . January has the lowest average high at . December has the lowest average low at . The highest temperature ever recorded was in July and the lowest temperature ever recorded was in January.


title: Rachel, Nevada

text: Rachel receives of precipitation, with the climate being consistently dry like the rest of the Great Basin. July, the wettest month, receives of rainfall on average. September, the driest month, receives of rainfall on average. Rachel receives a few inches of snowfall every winter.


title: Rachel, Nevada

text: While a local tungsten mine was operative, the community numbered over 500 inhabitants, but after the mine's closing in 1988, the population rapidly dwindled.


title: Rachel, Nevada

text: D.C. Day, Rachel's founder, died on July 25, 1997. Fay Day, his widow, died on March 13, 2011. She was buried in the Rachel Cemetery on March 19, 2011.


title: Rachel, Nevada

text: The Area 51 Research Center, a small UFO souvenir shop, closed in the fall of 2001. It has since re-opened in a corner of the Little A'Le'Inn. The community's only gas station went out of business in the winter of 2006–07, shortly after being acquired by a new owner, an investor from California. The gas station later reopened with gas and a store under the name Alien Cowpoke in October of 2020.


title: Rachel, Nevada

text: The Little A'Le'Inn, previously the Rachel Bar and Grill, is a small bar, restaurant and motel located in Rachel, along the Extraterrestrial Highway. The business has been running for over 20 years and is frequented by visitors to the local Area 51. The business has a variety of Area 51 and UFO related merchandise for sale such as maps of the area, posters, postcards, and toys, and offers an "Alien Burger".


title: Rachel, Nevada

text: The inn opened circa 1989. The original owners were Joe (now deceased) and Pat Travis. In 1991 Joe and Pat wanted something unique for the Bar and Grill because they felt that "Joe and Pat's" was not exciting (according to patron Bruce Hooker). They held a contest won by Bruce Hooker with "A'le'Inn" (a play on "alien"). The current owners of the Little A'Le'Inn are Pat and her daughter Connie.


title: Rachel, Nevada

text: In "", the Little A'Le'Inn is referenced. It can be found in Bone County, San Andreas in the vicinity of Area 69, the game's parallel to Area 51, using the name "Lil' Probe'Inn".


title: 12 oz. Mouse

text: 12 oz. Mouse is an American adult animated television series created by Matt Maiellaro for Cartoon Network's late-night programming block, Adult Swim. The series revolves around Mouse Fitzgerald, nicknamed "Fitz" (voiced by Maiellaro), an alcoholic mouse who performs odd jobs so he can buy more beer. Together with his chinchilla companion Skillet, Fitz begins to recover suppressed memories that he once had a wife and a child who have now vanished. This leads him to seek answers about his past and the shadowy forces that seem to be manipulating his world.


title: 12 oz. Mouse

text: In producing the series, Maiellaro crudely designed the characters as a cost-cutting measure; the series is animated by Radical Axis. He intended for the series to lack continuity starting from the pilot but established a serial format after starting the second episode. He had constructed an ending for the series as well as a detailed map of characters; however, the series finale concluded differently from planned. Maiellaro cast people around his office for the characters, starring himself as the protagonist and Nine Pound Hammer vocalist Scott Luallen as the voice of Roostre; the band also performs the opening theme.


title: 12 oz. Mouse

text: The pilot episode for "12 oz. Mouse", "Hired", premiered on June 19, 2005. The series became a regular staple of Adult Swim's lineup on October 23 of that year and originally ended on December 17, 2006. A stand-alone webisode was released online on May 16, 2007. Critical reception was mixed; some praised the series' experimental nature, while others felt confounded by it.


title: 12 oz. Mouse

text: In 2018, a double-length special, entitled "Invictus", aired on October 14 and it was announced that "12 oz. Mouse" was also revived as a series. The third season, consisting of 11 episodes, premiered on July 20, 2020, and ended on July 31. The ending credits of both "Invictus" and the season 3 episodes feature a song by Amaranthe and animation by Awesome Inc.


title: 12 oz. Mouse

text: The show revolves around a mouse named Mouse Fitzgerald (voiced by Matt Maiellaro), nicknamed "Fitz", who is fond of beer and caught in a world of espionage, love, and the delights of odd jobs. The show employs a serial format, and its ongoing storyline developed from absurdist comedy to include mystery and thriller elements. Fitz begins to recover suppressed memories that he once had a wife and a child who have now vanished. This leads him to seek answers about his past and the shadowy forces that seem to be manipulating his world.


title: 12 oz. Mouse

text: Fitz suspects there is a sinister conspiracy involving fields of "asprind" pills beneath the city, and Shark (Adam Reed), Clock, and Rectangular Businessman's (Kurt Soccolich) attempt to control the nature of time and reality. Fitz and Skillet receive help from Liquor (Matt Harrigan), Roostre (Scott Luallen), Stoned Peanut Cop (Nick Weidenfeld) and others as they engage in gun battles, blow things up, and try to understand cryptic hints. The show also sometimes contains surreal "subliminal" images that flash across the screen during key plot moments, including skulls, mustached snake beasts and people screaming.


title: 12 oz. Mouse

text: The series concludes with the revelation that Fitz has been kidnapped and placed into a simulation by the Shadowy Figure. He is about to be killed by Shark and the Rectangular Businessman, in their true forms outside the simulation, when he is rescued by the true form of Peanut Cop and a nurse who works in the simulation chamber. They kill Shark and Rectangle Businessman, but it is unknown if they are truly dead because the simulation in which most of the show takes place is probably taking place in another simulation. One of the purposes of the simulation seen in most of the show was to extract information from Fitz. The conclusion to episode 20 is ambiguous as to whether or not it is actually the end of the series, as some aspects of the plot remain unresolved – Golden Joe says "I thought this was done," to which Fitz replies, "I thought so too. I guess we're not."


title: 12 oz. Mouse

text: One webisode was made in 2007, showing Fitz and his friends escaping the city to live in a desert. Golden Joe is carried away by birds, while later one night, Peanut Cop mysteriously disappears. Fitz and Skillet later meet a woman, Lee, who turns out to be a werewolf. Their fate at the end of the episode was unknown.


title: 12 oz. Mouse

text: In 2018, a half-hour special episode aired, which continued the story. Fitz, now with a mustache and suffering from amnesia, is shown to be living in a new city during an unspecified amount of time after the original finale. Shark and Square Guy have returned somehow, and are trying to kidnap Fitz so they can return to the "real" world with the help of exterminator bee, Buzby (Dana Snyder). Skillet, Roostre, Peanut Cop, Golden Joe, and The New Guy (Mike Lazzo) must find and escape the simulation with Fitz before Shark and Square Guy do.


title: 12 oz. Mouse

text: According to Maiellaro, the series was pitched as a table read to the network. He jokingly stated that they accepted it after claiming that production costs would total "five dollars and will take some of the paper sitting in the copier." Maiellaro borrowed inspiration from surrealism and the films of David Lynch. He intended for the series to lack continuity starting from the pilot, but established a serial format after starting to work on the second episode. He had constructed an ending for the series as well as a detailed map of characters; however, the series finale concluded differently from planned. In November 2006, Maiellaro mentioned the possibility of continuing the series with webisodes, and he wrote five additional scripts for ending the series, but finally, he only produced one webisode, entitled "Enter the Sandmouse".


title: 12 oz. Mouse

text: Radical Axis provided animation for the series using Final Cut Pro. Described as "lo-fi animation", Maiellaro crudely designed the characters as a cost-cutting measure, with the exception of Amalockh, a many-armed monster summoned in the season two episode "Corndog Chronicles", which was drawn and animated by Todd Redner at the studio, and Shark, which was borrowed from the "Space Ghost Coast to Coast" episode "Kentucky Nightmare". In a behind-the-scenes clip of the show, Maiellaro explained that to animate the series, he would first grab a nearby sheet of copy paper, draw something, and then scan it, followed by him sending the file to an animator. Rhoda, a character from the series, was drawn on the back of a script page for "Perfect Hair Forever". A scan of the paper revealed the textual contents behind it, which Maiellaro decided to leave in.


title: 12 oz. Mouse

text: Maiellaro cast people around his office to voice the characters. He provides the voice of the protagonist, Mouse Fitzgerald. He originally only gave the scratch dialogue for the character during the production of the pilot episode but chose himself to voice Mouse regularly after hearing his lines assembled in the final cut. Kurt Soccolich was chosen by Maiellaro to voice Rectangular Businessman, who "already had that sort of smooth arrogance in his voice", making him a "perfect" fit for him. Matt Harrigan was selected to voice Liquor, who is "always looking to make light of a situation", according to Maiellaro.


title: 12 oz. Mouse

text: Nick Weidenfeld provides the voice of Peanut Cop; Melissa Warrenburg portrays an annoying woman in a green sweater, who Maiellaro dubs "Robogirl". Bonnie Rosmarin voices Man/Woman, picked for what Maiellaro stated is a "pouty, stand-offish quality" in her delivery. Nick Ingkatanuwat voices The Eye and Adam Reed plays Shark. Vocalist of Nine Pound Hammer Scott Luallen voices Roostre; the band also composed the opening theme song for the series. Golden Joe is voiced by Vishal Roney; after hearing his first take on the character, Maiellaro explained that he was left unable to write any of his lines. He proceeded to only provide the basic structure of his lines in the script, instructing him to retroscript the rest.


title: 12 oz. Mouse

text: Maiellaro spent three weeks working with Ingkatanuwat on putting together the set for the opening title sequence. The set was filmed with a motion control camera and was inserted with miniature explosives and smoke bombs for special effect. Nine Pound Hammer composed the opening theme song; Maiellaro sought a song representing the "carefree" lifestyle of Mouse who "does things like drive drunk, film porno and shoot guns." Maiellaro, who plays the electric guitar in his free time, also composed the song "F-Off", featured in both the first episode and in "Auraphull", which he wrote while working on "Space Ghost Coast to Coast". Swedish heavy metal band Amaranthe performed the credits theme song for the 2018 special, "Invictus".


title: 12 oz. Mouse

text: The June 14, 2018 episode of the Adult Swim streaming series "Development Meeting" featured a new clip from "12 oz. Mouse", which featured Seth Green as Fitz, hinting at a return to the series. It was later announced on September 18 of that year that the series would return for a half-hour special entitled "Invictus", which aired a month later on October 14. On the day of the special's airing, another announcement was made that the series would return for an 11-episode third season which aired in late July 2020. On March 31, 2020, the third season premiere aired unannounced at 2:45 AM EST with many other new episodes from Adult Swim shows as part of Adult Swim's annual April Fools Prank. The whole third season premiered on July 20, 2020, and ended on July 31st. In February 2021, Maiellaro confirmed that the series was not picked up for a fourth season, citing management changes at Adult Swim.


title: 12 oz. Mouse

text: The pilot episode for "12 oz. Mouse", "Hired", premiered in June 2005 and became a regular series in the Adult Swim lineup in October 2005. An Adult Swim bumper shown with the sixth installment claimed that twenty additional episodes were being produced and taunted viewers who had complained they couldn't understand the absurdist presentation. On December 31, 2005, a marathon of the series aired, replaying all six episodes followed by the premiere of the then-unfinished seventh episode "Adventure Mouse". The second season aired on Adult Swim on Monday mornings at 12:45 a.m. EST from September 24, 2006 to December 17, 2006. On May 16, 2007, the 21st episode, entitled "Enter the Sandmouse", premiered as a webisode. On October 14, 2018, a half-hour special titled "Invictus" premiered on TV after having been released online two days earlier. Simultaneously, Adult Swim announced the series would be returning for a third season. The third season premiered unexpectedly on March 31, 2020 as part of that year's Adult Swim's April Fools Prank.


title: 12 oz. Mouse

text: In Canada, "12 oz. Mouse" previously aired on Teletoon's Teletoon at Night block, and currently airs on the Canadian version of Adult Swim.


title: 12 oz. Mouse

text: The season two episodes, "Auraphull" and "Meat Warrior", were respectively seen by 460,000 and 431,000 viewers upon broadcast. In addition, the episodes ranked as the thirteenth and twelfth most-watched episodes aired by the network for the week of October 23, 2006, also respectively.


title: 12 oz. Mouse

text: The series has received generally positive critical reception; About.com's Nancy Basile gave the series four out of five stars, opining that the series is "what Adult Swim should be ... experimental, but in a cheap, simple, not-trying-to-be-cool way." She found the crude animation "refreshing" but joked that the series "can kill" viewers not used to the slow pace. Writing for AOL TV, Adam Finley regarded the show as "the most simplistically drawn of all the Adult Swim shows, and yet the most complex in terms of story." He contrasted it with other Williams Street productions, finding it "instead unravels slowly, revealing a little bit more of what's underneath the surface while also piling on more and more questions." Rob Mitchum of Pitchfork Media called it "the asymptote of the block's crude style".


title: 12 oz. Mouse

text: Justin Heckert of "Atlanta" magazine opined that "the animation and art look like they were done by daycare students".


title: 12 oz. Mouse

text: The hip hop duo Danger Doom have produced a song inspired by "12 oz. Mouse" entitled "Korn Dogz" from their EP "Occult Hymn". The song uses audio clips from the episode "Rooster", with the line "Corn dogs for the pickin'" being recited by Danger Doom's MC MF Doom and Mouse Fitzgerald. A scene from the episode "Sharktasm" is visible in "Aqua Teen Hunger Force Colon Movie Film for Theaters".


title: 12 oz. Mouse

text: A DVD release of the first 2 seasons was released February 29, 2008 (leap year), exclusively on the Williams Street shop. The DVD cover depicts Leonardo's "The Last Supper" with the series' characters replacing Christ and the twelve apostles. However, under a black light, the cover depicts the skeletons of the characters, as well as letters and symbols which make out an email address. The series is presented as a single, continuous movie, with newly produced footage bridging the gaps between episodes. It also features production footage, new music, the episode "Auraphull" in its entirety and collected fan art.


title: GameShark

text: GameShark is the brand name of a line of video game cheat cartridges and other products for a variety of console video game systems and Windows-based computers. Currently, the brand name is owned by Mad Catz, which marketed GameShark products for the Sony PlayStation, Xbox, and Nintendo game consoles. Players load cheat codes from GameShark discs or cartridges onto the console's internal or external memory, so that when the game is loaded, the selected cheats can be applied.


title: GameShark

text: When the original GameShark was released, it came with 4,000 preloaded codes. Codes could be entered, but unlike the Game Genie, codes were saved in the onboard flash memory and could be accessed later rather than having to be reentered. The cartridges also acted as memory cards, with equal or greater storage capacity to the consoles' first party memory cards. It was originally released for the Sega Saturn and Sony PlayStation consoles in January 1996. It was a runner-up for "Electronic Gaming Monthly"s Best Peripheral of 1996 (behind the Saturn analog controller). Models for the PlayStation had an Explorer option that allowed gamers to access most PlayStation disc files, and it was possible to view FMV files stored on the CD. The later models of the GameShark also had a Use Enhancement Disc option. The Enhancement Disc, which InterAct sold for $4.95, allowed users to upgrade the GameShark and add codes to the code list from the disc. Only a few examples of these Upgrade CDs were known to have been published.


title: GameShark

text: The PlayStation GameShark had the following standard features: View Video Image, which allowed users to see the last image stored in the PlayStation's Video RAM, View CD Image, which allowed a user to search the game CD for image files, Play Music, which would play the CD audio, and View CD Movie, a function that allowed a user to view FMV (full motion video) files found on the disc. Also included was the option to use an Enhancement CD in order to upgrade the GameShark and add new codes found on the disc.


title: GameShark

text: The GameShark Pro series contained a feature that allowed players to find their own codes. During gameplay, the user presses a button on the device to open a code search menu. Finding code is done by searching memory locations either for specific values or for values that have changed in a certain way (increased, decreased, not changed, etc.) since the last search. After the first search, subsequent searches only look at memory locations that match the specified criteria from the last search. By performing multiple searches the list of matching locations is gradually reduced. Once the list is reasonably small the user must determine which of the found locations is the correct one by modifying them one at a time and seeing what effect it has on the game.


title: GameShark

text: In some games, the resulting code may only work in one level or it may cause problems in other parts of the game due to memory locations being dynamically assigned. In these cases, the user has two options: attempt to locate a pointer to the data block that their code is attempting to modify or change the game's programming which is usually located at the same place every time. If a pointer is found, and the device supports it, a new code can be made which determines the correct location to modify from the pointer. If the device does not support pointers the game programming must be changed instead. Generally, the user must use external tools to find the code that accesses this data. If the code is reading from memory it may be changed to read a constant value; if it is writing, it may be changed to not perform the write. These changes may not have the same overall effects as when actually modifying the game's code. For example, a user may disable the routine that causes the player character to lose health when touched by enemies, only to find that health is still lost from other hazards.


title: GameShark

text: A GameShark was released for the Nintendo 64 in late August 1997. The Nintendo 64 GameShark was the most popular cheating device available for the system, becoming popular after well-known titles such as "GoldenEye 007" and "" were released. Because of the complex nature of these games, there were many aspects of them which could be modified to produce unique effects. For example, unused content was discovered such as a distant tower on the "Dam" level of "GoldenEye 007".


title: GameShark

text: The Nintendo 64 GameShark Pro featured an in-game code search menu. Versions 3.1, 3.2 and 3.3 had a parallel port on the back, allowing the device to be connected to a PC with a program called SharkLink. This was intended primarily to make entering a large number of codes easier but was also used for advanced hacking. The in-game code search required that an Expansion Pak be installed and that the game did not actively use the Pak for memory.


title: GameShark

text: The Nintendo 64 GameShark also bypasses the console's regional lockout, allowing games from any region to be played on the same unit.


title: GameShark

text: The PlayStation GameShark Pro contained much of the same functionality as the standard PlayStation GameShark, as well as unique features only found on the Pro. The advanced features were: Code Creation, which gave users the option to save newly created codes to a standard PlayStation memory card to share with others, and V-Mem (Virtual Memory), which gave users access to an onboard Memory Card feature where they could store up to 8 full memory cards worth of saves. The Shark Link software suffered from the same problems that plagued the N64 version. The final firmware/software update for the PlayStation GameShark Pro hardware was version 3.2 (v3.2), which was made available on physical media titled "The BigWave 4".


title: GameShark

text: With the introduction of the 9000 model of the PlayStation, the parallel port was removed. This had been the only way to use the GameShark, as it plugged directly into that port. InterAct then created a GameShark that did not need it. The GameShark CDX came with a boot CD along with a card resembling a standard memory card, which stored the codes. Even though the CDX could be upgraded, it is not known if InterAct created an upgrade for the CDX. The CDX is not compatible with either PS2 system.


title: GameShark

text: The GameShark 2 was very much like the CDX Game Shark that came out for the original PlayStation, but for the PlayStation 2. It even included features that could only be found on the GameShark Pro, but like the CDX Game Shark that came out for the original PlayStation, codes could be saved to a memory card, one which resembled that came with the CDX version. It was released the Fall of 2000 and included a CD-only Game Shark 2 for the original PlayStation 2 containing over 14,000 codes.


title: GameShark

text: Released in 1998 for the Game Boy and Game Boy Color, it came preloaded with codes for 158 games. This list was revised with new games with each Gameshark version/revision, as well as the ability to add your own game folders and codes. Codes were saved as a string of HEX values that represented a specific game state or attribute at a specific memory location within the game ROM. When the Game Boy attempted to execute code at said memory address, the Game Shark would overwrite it with its own modified code (Cheat Code). This allowed for everything from invincibility, extra lives, unlimited ammo, rapid fire, sprite modifications, and much more.


title: GameShark

text: With a feature called Snapshot, a player could take a ROM image of the current state of the attached Game Cartridge. The result was the ability to restore the game state to a single previous Snapshot, a precursor of sorts to save states more commonly enjoyed in modern ROM emulation software. With the V3.1 revision, Snapshots could also be saved or downloaded from the PC via an included cable that connected to the link-cable port on the Game Boy and a PC's Printer/Parallel Port. Game Cartridges that featured a save function utilized a battery backup in order to prevent volatile-RAM from losing power when the Game Boy was switched off. However, as these batteries ran dry, the ability to save game data became impossible. The Gameshark on the other hand utilized non-volatile memory that didn't require a battery backup. So Snapshots and game codes could be stored indefinitely. A Gameshark was known as a temporary workaround for saving games with a depleted battery backup. Gameshark PC Software allowed for the creation and management of codes on the PC, profiles, even Gameshark Menu wallpapers and themes when used with a Game Boy Color. There was also a message board where players could share codes and Game Snapshots with each other.


title: GameShark

text: Game Trainer allowed the player to "find new cheat codes" by comparing actively running code with recent changes in the game state. For instance, a player would turn on the Game Trainer saving the current game state much like a Snapshot. If Mario were to then take damage from an enemy, a HEX value would change in the game code causing Mario to shrink or die. The player would then have the Game Trainer search for all the HEX changes (sometimes in the 100s depending on the game complexity) since Mario took damage. Through trial and error, this list can be further reduced until the specific HEX value for Mario's damage state is found. A "cheat code" could then be saved that keeps Mario's health state from changing, thus preventing him from taking damage.


title: GameShark

text: One such popular use of the Gameshark for Game Boy was unlocking disabled content. By using cheat codes to modify the move set of Pokémon Yellow's Pikachu to include the move "surf", it would unlock a Surfing Pikachu Mini-Game; a feat that previously required a lengthy and obscure process in Pokemon Stadium while the Pokémon Yellow Cartridge was inserted into the N64 Transfer Pack. A Gameshark was the only way to unlock the mythical Pokémon Mew without knowledge of a very tricky game exploit/glitch or the incredibly rare Nintendo World Mew Distribution Event. Subsequently, a Gameshark was also the only way to unlock the Mythical Pokémon Celebi from the 2nd generation of Pokemon Games Silver, Gold, Crystal, and Pokémon Stadium 2. This was because the distribution method to catch the mythical Pokémon was disabled in North America due to hardware limitations. A Japanese cell phone link cable was required.


title: GameShark

text: Attempting to use a Gameshark with the N64 Transfer pack would result in Pokémon Stadium claiming the inserted cartridge was corrupted. However, if the player saved the Pokémon Game while Gameshark cheats were enabled, they would be saved to the game cartridge permanently. Thus allowing the modifications to pass Pokémon Stadium's Game Boy Cartridge check. This could lead to some unusual in-game battle animations if Pokemon were given moves they couldn't normally perform. A booklet was included with Gameshark version 3.1 with over 2,000 codes to modify Pokemon games and their monsters.


title: GameShark

text: The GameShark for the Game Boy can also be used with the Game Boy Advance, as long as the cart connected is either for Game Boy or for Game Boy Color. It cannot be used for Game Boy Advance carts. The original Game Boy GameShark could be used with the Game Boy Color, which it predated. However, due to the low height of the outside cartridge slot, the connected game cartridge would be pushed outward by the Game Boy Color's battery compartment, which, unlike those of previous Game Boy models, curved outward from the rear surface of the device. The later GameShark Pro featured a longer cartridge which held the connected game cartridge higher so as to avoid this flaw.


title: GameShark

text: Almost as soon as the GameShark made its appearance on the store shelves, new codes began to appear in the gaming magazines of the day. In order to create more interest as well as a way to get the word out on their new products, InterAct created a newsletter called 'Dangerous Waters' (which was published eight times a year starting in 1996 and featured new codes), a phone number which players could call for the up-to-the-minute latest codes, and a website with exclusive codes that could only be accessed by those with a full Dangerous Waters membership. GameShark.com also first appeared on the net around this time. Due to the increasing popularity of Dangerous Waters, it went from a black and white 8-page newsletter to full color bimonthly by 1999 and featured game reviews as well as tricks. Then, in June 2000, Dangerous Waters was transformed into a full-fledged magazine called "GameShark Magazine" and continued to be published bimonthly, reaching up to 20 pages long and containing many more codes. However, due to problems with Mad Catz, "GameShark Magazine" ceased publication with the Holiday 2001 issue. This last issue was a double issue, containing the last GameShark Magazine issue, as well as a special issue by IGN as it was their 2001 Buyer's Guide. It featured new games and systems that were available at the time. It also included a Game Shark CD Sampler disc which featured codes for the PlayStation 2, as well as a handful of game saves.


title: GameShark

text: When the Game Boy device was first released, InterAct acquired the rights to sell Datel's Action Replay and Pro Action Replay devices in North America; these devices were sold under the GameShark and GameShark Pro names. InterAct released GameShark devices for the Game Boy, Game Boy Color, Game Boy Advance, PlayStation, PlayStation 2, Saturn, Dreamcast and Nintendo 64. After InterAct's parent company, Recoton, went bankrupt, the rights to the GameShark name were acquired by Mad Catz, who relinquished the North American Action Replay distribution rights. Following this, Mad Catz sold game save devices under the GameShark name instead of the traditional cheat device, and Datel marketed the Action Replay in North America directly. Since acquired by Mad Catz the original site for GameShark has been shut down, and no products associated with GameShark have been sold on their site.


title: Formwork

text: Formwork is molds into which concrete or similar materials are either precast or cast-in-place. In the context of concrete construction, the falsework supports the shuttering molds. In specialty applications formwork may be permanently incorporated into the final structure, adding insulation or helping reinforce the finished structure.


title: Formwork

text: Some of the earliest examples of concrete slabs were built by Roman engineers. Because concrete is quite strong in resisting compressive loads, but has relatively poor tensile or torsional strength, these early structures consisted of compression-resistant arches, vaults and domes. The most notable concrete structure from this period is the Pantheon in Rome. To mould this structure, temporary scaffolding and formwork or falsework was built in the future shape of the structure. These building techniques were not isolated to pouring concrete, but were and are widely used in masonry construction. Because of the complexity and the limited production capacity of the building material, concrete's rise as a favored building material did not occur until the invention of Portland cement and reinforced concrete.


title: Formwork

text: Similar to the traditional method, but stringers and joists are typically replaced with engineered wood beams and supports are replaced with adjustable metal props. This makes this method more systematic and reusable.


title: Formwork

text: On the dawn of the revival of concrete in slab structures, building techniques for the temporary structures were derived again from masonry and carpentry. The traditional slab formwork technique consists of supports out of lumber or young tree trunks, that support rows of stringers assembled roughly 3 to 6 feet or 1 to 2 metres apart, depending on thickness of slab. Between these stringers, joists are positioned roughly apart, upon which boards or plywood are placed. The stringers and joists are usually 4 by 4 inch or 4 by 6 inch lumber. The most common imperial plywood thickness is inch and the most common metric thickness is 18 mm.


title: Formwork

text: Similar to the traditional method, but stringers and joist are replaced with aluminium forming systems or steel beams and supports are replaced with metal props. This also makes this method more systematic and reusable. Aluminum beams are fabricated as telescoping units which allows them to span supports that are located at varying distances apart. Telescoping aluminium beams can be used and reused in the construction of structures of varying size.


title: Formwork

text: These systems consist of prefabricated timber, steel or aluminum beams and formwork modules. Modules are often no larger than 3 to 6 feet or 1 to 2 metres in size. The beams and formwork are typically set by hand and pinned, clipped, or screwed together. The advantages of a modular system are: does not require a crane to place the formwork, speed of construction with unskilled labor, formwork modules can be removed after concrete sets leaving only beams in place prior to achieving design strength.


title: Formwork

text: These systems consist of slab formwork "tables" that are reused on multiple stories of a building without being dismantled. The assembled sections are either lifted per elevator or "flown" by crane from one story to the next. Once in position the gaps between the tables or table and wall are filled with temporary formwork. Table forms vary in shape and size as well as their building material, with some supported by integral trusses. The use of these systems can greatly reduce the time and manual labor involved in setting and striking (or "stripping") the formwork. Their advantages are best used by large area and simple structures. It is also common for architects and engineers to design building around one of these systems.


title: Formwork

text: A table is built pretty much the same way as a beam formwork but the single parts of this system are connected together in a way that makes them transportable. The most common sheathing is plywood, but steel and fiberglass are used. The joists are either made from timber, engineered lumber (often in the form of I-beams), aluminium or steel. The stringers are sometimes made of wood I-beams but usually from steel channels. These are fastened together (screwed, weld or bolted) to become a "deck". These decks are usually rectangular but can also be other shapes.


title: Formwork

text: All support systems have to be height adjustable to allow the formwork to be placed at the correct height and to be removed after the concrete is cured. Normally adjustable metal props similar to (or the same as) those used by beam slab formwork are used to support these systems. Some systems combine stringers and supports into steel or aluminum trusses. Yet other systems use metal frame shoring towers, which the decks are attached to. Another common method is to attach the formwork decks to previously cast walls or columns, thus eradicating the use of vertical props altogether. In this method, adjustable support shoes are bolted through holes (sometimes tie holes) or attached to cast anchors.


title: Formwork

text: This technique is fairly common in the United States and east Asian countries. The advantages of this approach are the further reduction of manual labour time and cost per unit area of slab and a simple and systematic building technique. The disadvantages of this approach are the necessary high lifting capacity of building site cranes, additional expensive crane time, higher material costs and little flexibility.


title: Formwork

text: By this approach the tables are limited in size and weight. Typical widths are between , typical lengths are between , though table sizes may vary in size and form. The major distinction of this approach is that the tables are lifted either with a crane transport fork or by material platform elevators attached to the side of the building. They are usually transported horizontally to the elevator or crane lifting platform singlehandedly with shifting trolleys depending on their size and construction. Final positioning adjustments can be made by trolley. This technique enjoys popularity in the US, Europe and generally in high labor cost countries. The advantages of this approach in comparison to beam formwork or modular formwork is a further reduction of labor time and cost. Smaller tables are generally easier to customize around geometrically complicated buildings, (round or non rectangular) or to form around columns in comparison to their large counterparts. The disadvantages of this approach are the higher material costs and increased crane time (if lifted with crane fork).


title: Formwork

text: Tunnel forms are large, room size forms that allows walls and floors to be cast in a single pour. With multiple forms, the entire floor of a building can be done in a single pour. Tunnel forms require sufficient space exterior to the building for the entire form to be slipped out and hoisted up to the next level. A section of the walls is left uncasted to remove the forms. Typically castings are done with a frequency of 4 days. Tunnel forms are most suited for buildings that have the same or similar cells to allow re-use of the forms within the floor and from one floor to the next, in regions which have high labor prices.Tunnel formwork saves the time and the cost.