Re: pgsql: Use streaming read I/O in VACUUM's third phase

On Fri, Feb 14, 2025 at 12:59 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> Use streaming read I/O in VACUUM's third phase
>
> Make vacuum's third phase (its second pass over the heap), which reaps
> dead items collected in the first phase and marks them as reusable, use
> the read stream API. This commit adds a new read stream callback,
> vacuum_reap_lp_read_stream_next(), that looks ahead in the TidStore and
> returns the next block number to read for vacuum.
>
> Author: Melanie Plageman <melanieplageman@gmail.com>
> Co-authored-by: Thomas Munro <thomas.munro@gmail.com>
> Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
> Discussion: https://postgr.es/m/CA%2BhUKGKN3oy0bN_3yv8hd78a4%2BM1tJC9z7mD8%2Bf%2ByA%2BGeoFUwQ%40mail.gmail.com
>
> Branch
> ------
> master
>
> Details
> -------
> https://git.postgresql.org/pg/commitdiff/c3e775e608f2a6d0bcfba147bf08a506827cc567
>
> Modified Files
> --------------
> src/backend/access/heap/vacuumlazy.c | 55 ++++++++++++++++++++++++++++++++----
> 1 file changed, 49 insertions(+), 6 deletions(-)

I'm looking into the valgrind failures [1].

==1526248== VALGRINDERROR-END
{
   <insert_a_suppression_name_here>
   Memcheck:Addr1
   fun:lazy_scan_heap
   fun:heap_vacuum_rel
   fun:table_relation_vacuum
   fun:vacuum_rel
   fun:vacuum_rel
   fun:vacuum
   fun:ExecVacuum
   fun:standard_ProcessUtility
   fun:ProcessUtility
   fun:PortalRunUtility
   fun:PortalRunMulti
   fun:PortalRun
   fun:exec_simple_query
}
**1526248** Valgrind detected 492 error(s) during execution of "VACUUM FREEZE;

==1526248== VALGRINDERROR-END
{
   <insert_a_suppression_name_here>
   Memcheck:Addr8
   fun:TidStoreGetBlockOffsets
   fun:lazy_vacuum_heap_rel
   fun:lazy_vacuum
   fun:lazy_scan_heap
   fun:heap_vacuum_rel
   fun:table_relation_vacuum
   fun:vacuum_rel
   fun:vacuum
   fun:ExecVacuum
   fun:standard_ProcessUtility
   fun:ProcessUtility
   fun:PortalRunUtility
   fun:PortalRunMulti
}
==152



[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2025-02-14%2018%3A00%3A12