| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Jeevan Ladhe <jeevan(dot)ladhe(at)enterprisedb(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Binary search in fmgr_isbuiltin() is a bottleneck. |
| Date: | 2017-09-27 18:58:36 |
| Message-ID: | 10360.1506538716@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andres Freund <andres(at)anarazel(dot)de> writes:
> Honestly before going there I'd rather just have
> an oid indexed array, computed at compile time.
Yeah, I'd been kind of wondering about that approach too. We could have,
say, a table of int16s indexed by OIDs from 0 to 9999, containing zero or
an index into the table of FmgrBuiltin structs. So 20000 bytes of
constant data, and O(negligible) lookup time other than possible cache
misses on this table. But a dynahash-ish hash table built for 2800+
entries would probably be about that size ...
regards, tom lane
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