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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