Re: strange slow query - lost lot of time somewhere

Pavel Stehule <pavel.stehule@gmail.com>

From: Pavel Stehule <pavel.stehule@gmail.com>
To: Jakub Wartak <Jakub.Wartak@tomtom.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-05-05T07:26:03Z
Lists: pgsql-hackers
čt 5. 5. 2022 v 8:51 odesílatel Jakub Wartak <Jakub.Wartak@tomtom.com>
napsal:

> Hi Pavel,
>
> > I have not debug symbols, so I have not more details now
> > Breakpoint 1 at 0x7f557f0c16c0
> > (gdb) c
> > Continuing.
>
> > Breakpoint 1, 0x00007f557f0c16c0 in mmap64 () from /lib64/libc.so.6
> > (gdb) bt
> > #0  0x00007f557f0c16c0 in mmap64 () from /lib64/libc.so.6
> > #1  0x00007f557f04dd91 in sysmalloc () from /lib64/libc.so.6
> > #2  0x00007f557f04eaa9 in _int_malloc () from /lib64/libc.so.6
> > #3  0x00007f557f04fb1e in malloc () from /lib64/libc.so.6
> > #4  0x0000000000932134 in AllocSetAlloc ()
> > #5  0x00000000009376cf in MemoryContextAllocExtended ()
> > #6  0x00000000006ad915 in ExecInitMemoize ()
>
> Well the PGDG repo have the debuginfos (e.g. postgresql14-debuginfo) rpms
> / dpkgs(?) so I hope you are basically 1 command away of being able to
> debug it further what happens in ExecInitMemoize()
> Those packages seem to be safe as they modify only /usr/lib/debug so
> should not have any impact on production workload.
>

I just have to wait for admin action - I have no root rights for the server.



>
> -J.
>
>
>

Commits

  1. Correct Memoize's estimated cache hit ratio calculation

  2. Fix incorrect row estimates used for Memoize costing

  3. Allow Memoize to operate in binary comparison mode