Horton

Re: pg14b1 stuck in lazy_scan_prune/heap_page_prune of pg_statistic

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Peter Geoghegan <pg@bowt.ie>, Alvaro Herrera <alvherre@alvh.no-ip.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2021-06-11T00:58:07Z
Lists: pgsql-hackers 
Hi,

On 2021-06-08 19:18:18 -0500, Justin Pryzby wrote:
> I reproduced the issue on a new/fresh cluster like this:
> 
> ./postgres -D data -c autovacuum_naptime=1 -c autovacuum_analyze_scale_factor=0.005 -c log_autovacuum_min_duration=-1
> psql -h /tmp postgres -c "CREATE TABLE t(i int); INSERT INTO t SELECT generate_series(1,99999); CREATE INDEX ON t(i);"
> time while psql -h /tmp postgres -qc 'REINDEX (CONCURRENTLY) INDEX t_i_idx'; do :; done&
> time while psql -h /tmp postgres -qc 'ANALYZE pg_attribute'; do :; done&
> 
> TRAP: FailedAssertion("restarts == 0", File: "vacuumlazy.c", Line: 1803, PID: 10367)

Has anybody looked at getting test coverage for the retry path? Not with
the goal of triggering an assertion, just to have at least basic
coverage.

The problem with writing a test is likely to find a way to halfway
reliably schedule a transaction abort after pruning, but before the
tuple-removal loop? Does anybody see a trick to do so?

Greetings,

Andres Freund

Commits

  1. Deduplicate choice of horizon for a relation procarray.c.

  2. Use correct horizon when vacuuming catalog relations.

  3. Truncate line pointer array during VACUUM.

  4. Remove tupgone special case from vacuumlazy.c.

  5. Refactor lazy_scan_heap() loop.

  6. snapshot scalability: Don't compute global horizons while building snapshots.