Re: [SQL] "SELECT IN" Still Broken in 7.4b - Mailing list pgsql-hackers

From Josh Berkus
Subject Re: [SQL] "SELECT IN" Still Broken in 7.4b
Date
Msg-id 200308211419.47226.josh@agliodbs.com
Whole thread Raw
In response to Re: [SQL] "SELECT IN" Still Broken in 7.4b  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom,

> I'm toying with the notion of ripping out that logic and instead
> building an in-memory hashtable of already-returned TIDs.  This could
> theoretically run out of memory if the multiple indexscan returns enough
> tuples, but I think in practice that wouldn't happen because the planner
> wouldn't choose an indexscan when very large numbers of tuples are being
> selected.

Don't forget all of the tyros who tune their queries through "set
enable_seqscan=false".  I think we'd need some kind of memory safety valve on
this, like sandboxing it in sort_mem.

--
-Josh BerkusAglio Database SolutionsSan Francisco



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