| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Neil Conway <neilc(at)samurai(dot)com> |
| Cc: | Pailloncy Jean-Gerard <jg(at)rilk(dot)com>, Hannu Krosing <hannu(at)tm(dot)ee>, pgsql(at)mohawksoft(dot)com, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, "Victor Y(dot) Yegorov" <viy(at)mits(dot)lv> |
| Subject: | Re: bitmap AM design |
| Date: | 2005-03-04 14:59:54 |
| Message-ID: | 27279.1109948394@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Neil Conway <neilc(at)samurai(dot)com> writes:
> (BTW, is poor concurrency really the biggest issue with hash indexes? If
> so, there is some low-hanging fruit that I noticed a few years ago, but
> never got around to fixing: _hash_doinsert() write-locks the hash
> metapage on every insertion merely to increment a tuple counter.
Given the short amount of time that lock is held, this wouldn't
win anything worth noticing. Also, it's not "merely" to increment a
counter --- the counter drives decisions about whether to split buckets,
so any decrease in accuracy would lead directly to losses in overall
performance.
The lack of WAL support is a much bigger issue.
regards, tom lane
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