{"action":"closed","issue":{"url":"https://api.github.com/repos/JuliaStats/DataFrames.jl/issues/75","labels_url":"https://api.github.com/repos/JuliaStats/DataFrames.jl/issues/75/labels{/name}","comments_url":"https://api.github.com/repos/JuliaStats/DataFrames.jl/issues/75/comments","events_url":"https://api.github.com/repos/JuliaStats/DataFrames.jl/issues/75/events","html_url":"https://github.com/JuliaStats/DataFrames.jl/issues/75","id":8718394,"number":75,"title":"return Bool and PooledDataVec to read_table","user":{"login":"HarlanH","id":130809,"avatar_url":"https://avatars.githubusercontent.com/u/130809?v=3","gravatar_id":"","url":"https://api.github.com/users/HarlanH","html_url":"https://github.com/HarlanH","followers_url":"https://api.github.com/users/HarlanH/followers","following_url":"https://api.github.com/users/HarlanH/following{/other_user}","gists_url":"https://api.github.com/users/HarlanH/gists{/gist_id}","starred_url":"https://api.github.com/users/HarlanH/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/HarlanH/subscriptions","organizations_url":"https://api.github.com/users/HarlanH/orgs","repos_url":"https://api.github.com/users/HarlanH/repos","events_url":"https://api.github.com/users/HarlanH/events{/privacy}","received_events_url":"https://api.github.com/users/HarlanH/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/JuliaStats/DataFrames.jl/labels/feature","name":"feature","color":"0000ff"}],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":3,"created_at":"2012-11-27T12:47:36Z","updated_at":"2015-01-12T23:51:17Z","closed_at":"2015-01-12T23:51:17Z","body":"I'd suggest using a Dict to store unique items for each column during the first pass. If the number of unique items in a column exceeds 2^8, stop storing for that column. If the column ends up having a string type and not too many items, use the Dict to seed a PDV for the second pass. If the column ends up being either integral with only 0/1/(NA), or string with only T/F/(NA) or TRUE/FALSE(NA) or similar, make the column a Bool. "}}