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From:Ann W. Harrison Date:June 8 2009 7:25pm Subject:Re: Worklog
#4284 and on-line DDL View as plain text   >> ... >>    Adding a
column on-line should not block concurrent access to the >>
table, including inserts, updates, and deletes. >>    Because of
the way Falcon handles table descriptions, dropping >> and
altering a column can be done without blocking DML operations.
>> (Tables have formats.  Records carry the version number of
the >> format under which they were created.  Requests include
the format >> version they expect.  Falcon converts between
formats on the fly >> in memory.  Records on disk change format
when they are updated. > No, at the moment there is no provision
for a truly online DDL > operations in the server, WL#4284
doesn't change that, yet it > doesn't make matters worse.
Actually, for Falcon, it does. > The way ALTER TABLE works today
is: > 1) Get a shared metadata lock on the table. > 2) Create a
copy table that contains th