Horton

Re: [HACKERS] WAL logging problem in 9.4.3?

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: robertmhaas@gmail.com, pgsql-hackers@postgresql.org, 9erthalion6@gmail.com, andrew.dunstan@2ndquadrant.com, hlinnaka@iki.fi, michael@paquier.xyz
Date: 2020-01-27T04:57:00Z
Lists: pgsql-hackers 
On Mon, Jan 27, 2020 at 01:44:13PM +0900, Kyotaro Horiguchi wrote:
> At Sun, 26 Jan 2020 20:22:01 -0800, Noah Misch <noah@leadboat.com> wrote in 
> > Diffing the two latest versions of one patch:
> > > --- v32-0002-Fix-the-defect-1.patch	2020-01-18 14:32:47.499129940 -0800
> > > +++ v33-0002-Fix-the-defect-1.patch	2020-01-26 16:23:52.846391035 -0800
> > > +@@ -2978,8 +3054,8 @@ AssertPendingSyncs_RelationCache(void)
> > > + 			LOCKTAG_RELATION)
> > > + 			continue;
> > > + 		relid = ObjectIdGetDatum(locallock->tag.lock.locktag_field2);
> > > +-		r = RelationIdGetRelation(relid);
> > > +-		if (r == NULL)
> > > ++		r = RelationIdGetRelationCache(relid);
> > 
> > The purpose of this loop is to create relcache entries for rels locked in the
> > current transaction.  (The "r == NULL" case happens for rels no longer visible
> > in catalogs.  It is harmless.)  Since RelationIdGetRelationCache() never
> > creates a relcache entry, calling it defeats that purpose.
> > RelationIdGetRelation() is the right function to call.
> 
> I thought that the all required entry exist in the cache but actually
> it's safer that recreate dropped caches. Does the following works?
> 
> 	r = RelationIdGetRelation(relid);
> +       /* if not found, fetch a "dropped" entry if any  */
> +	if (r == NULL)
> +	    r = RelationIdGetRelationCache(relid);
> 	if (r == NULL)
> 	    continue;

That does not materially change the function's behavior.  Notice that the
function does one thing with "r", which is to call RelationClose(r).  The
function calls RelationIdGetRelation() for its side effects, not for its
return value.

Commits

  1. Add perl2host call missing from a new test file.

  2. Skip WAL for new relfilenodes, under wal_level=minimal.

  3. Revert "Skip WAL for new relfilenodes, under wal_level=minimal."

  4. Back-patch log_newpage_range().

  5. During heap rebuild, lock any TOAST index until end of transaction.

  6. In log_newpage_range(), heed forkNum and page_std arguments.

  7. Back-patch src/test/recovery and PostgresNode from 9.6 to 9.5.

  8. Reduce pg_ctl's reaction time when waiting for postmaster start/stop.

  9. Accelerate end-of-transaction dropping of relations

  10. Redesign the planner's handling of index-descent cost estimation.

  11. Make TRUNCATE do truncate-in-place when processing a relation that was created