| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Cc: | Julien Rouhaud <rjuju123(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Nikita Glukhov <n(dot)gluhov(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Marc Cousin <cousinmarc(at)gmail(dot)com> |
| Subject: | Re: Avoid full GIN index scan when possible |
| Date: | 2020-01-17 21:48:10 |
| Message-ID: | 18357.1579297690@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> writes:
> On Wed, Jan 15, 2020 at 2:03 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Hmm ... yeah, these test cases are not large enough to exercise any
>> lossy-page cases, are they? I doubt we should try to make a new regression
>> test that is that big. (But if there is one already, maybe we could add
>> more test queries with it, instead of creating whole new tables?)
> I've checked that none of existing tests for GIN can produce lossy
> bitmap page with minimal work_mem = '64kB'. I've tried to generate
> sample table with single integer column to get lossy page. It appears
> that we need at least 231425 rows to get it. With wider rows, we
> would need less number of rows, but I think total heap size wouldn't
> be less.
> So, I think we don't need so huge regression test to exercise this corner case.
Ugh. Yeah, I don't want a regression test case that big either.
v15 looks good to me.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | legrand legrand | 2020-01-17 22:07:48 | pg13 PGDLLIMPORT list |
| Previous Message | Alvaro Herrera | 2020-01-17 21:35:46 | Re: Crash in BRIN summarization |