Re: error context for vacuum to include block number

On Tue, 21 Jan 2020 at 06:49, Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
>
> On Mon, Jan 20, 2020 at 11:11:20AM -0800, Andres Freund wrote:
> > This I do not get. I didn't yet fully wake up, so I might just be slow?
>
> It was needlessly cute at the cost of clarity (meant to avoid setting
> error_context_stack in lazy_scan_heap and again immediately on its return).
>
> On Mon, Jan 20, 2020 at 11:13:05AM -0800, Andres Freund wrote:
> > I was thinking that you could just use LVRelStats.
>
> Done.
>
> On Mon, Jan 20, 2020 at 11:11:20AM -0800, Andres Freund wrote:
> > Alternatively we could push another context for each index inside
> > lazy_vacuum_all_indexes(). There's been plenty bugs in indexes
> > triggering problems, so that could be worthwhile.
>
> Did this too, although I'm not sure what kind of errors it'd find (?)
>
> I considered elimating other uses of RelationGetRelationName, or looping over
> vacrelstats->blkno instead of local blkno. I did that in an additional patch
> (that will cause conflicts if you try to apply it, due to other vacuum patch in
> this branch).
>
> CREATE TABLE t AS SELECT generate_series(1,99999)a;
>
> postgres=# SET client_min_messages=debug;SET statement_timeout=39; VACUUM (VERBOSE, PARALLEL 0) t;
> INFO: vacuuming "public.t"
> 2020-01-20 15:46:14.993 CST [20056] ERROR: canceling statement due to statement timeout
> 2020-01-20 15:46:14.993 CST [20056] CONTEXT: while scanning block 211 of relation "public.t"
> 2020-01-20 15:46:14.993 CST [20056] STATEMENT: VACUUM (VERBOSE, PARALLEL 0) t;
> ERROR: canceling statement due to statement timeout
> CONTEXT: while scanning block 211 of relation "public.t"
>
> SELECT 'CREATE INDEX ON t(a)' FROM generate_series(1,11);\gexec
> UPDATE t SET a=a+1;
>
> postgres=# SET client_min_messages=debug;SET statement_timeout=99; VACUUM (VERBOSE, PARALLEL 0) t;
> INFO: vacuuming "public.t"
> DEBUG: "t_a_idx": vacuuming index
> 2020-01-20 15:47:36.338 CST [20139] ERROR: canceling statement due to statement timeout
> 2020-01-20 15:47:36.338 CST [20139] CONTEXT: while vacuuming relation "public.t_a_idx"
> 2020-01-20 15:47:36.338 CST [20139] STATEMENT: VACUUM (VERBOSE, PARALLEL 0) t;
> ERROR: canceling statement due to statement timeout
> CONTEXT: while vacuuming relation "public.t_a_idx"
>
> I haven't found a good way of exercizing the "vacuuming heap" path, though.

Some of them conflicts with the current HEAD(62c9b52231). Please rebase them.

Regards,

--
Masahiko Sawada http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services