Re: making queries more effecient
От | Josh Berkus |
---|---|
Тема | Re: making queries more effecient |
Дата | |
Msg-id | 200211011409.01771.josh@agliodbs.com обсуждение исходный текст |
Ответ на | making queries more effecient ("Peter T. Brown" <peter@memeticsystems.com>) |
Список | pgsql-sql |
Peter, For the rest of our sakes, in the future, please format your SQL before posting it to request help. > CREATE TEMP TABLE temp20561149207391 AS SELECT DISTINCT ON ("VisitorID") > "VisitorID","Type" FROM "ProgramEvent" WHERE "ProgramID" = 10 ORDER BY > "VisitorID","Created" DESC;INSERT INTO "VisitorPointer839" ("VisitorID") > SELECT temp20561149207391."VisitorID" FROM temp20561149207391 WHERE > temp20561149207391."Type" = 0 Can be re-written as: INSERT INTO "VisitorPointer839" ("VisitorID") SELECT "VisitorID" FROM (SELECT DISTINCT ON ("VisitorID") "VisitorID","Type" FROM "ProgramEvent" WHERE "ProgramID" = 10 ORDERBY "VisitorID","Created" DESC ) v_first WHERE v_first."Type" = 0; Please also keep in mind that the SELECT DISTINCT ON syntax is a PostgreSQL-specific extension and is not portable. -- -Josh BerkusAglio Database SolutionsSan Francisco
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