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Date: Thu, 13 Jul 2023 09:49:42 +0300
From: Alexander Pyhalov <a.pyhalov@postgrespro.ru>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Ilya Gladyshev <ilya.v.gladyshev@gmail.com>,
 pgsql-hackers@lists.postgresql.org, Masahiko Sawada <sawada.mshk@gmail.com>,
 Michael Paquier <michael@paquier.xyz>, =?UTF-8?Q?=E6=9D=8E=E6=9D=B0=28?=
 =?UTF-8?Q?=E6=85=8E=E8=BF=BD=29?= <adger.lj@alibaba-inc.com>,
 =?UTF-8?Q?=E6=9B=BE=E6=96=87=E6=97=8C=28=E4=B9=89=E4=BB=8E=29?=
 <wenjing.zwj@alibaba-inc.com>, Alvaro Herrera <alvherre@2ndquadrant.com>
Subject: Re: CREATE INDEX CONCURRENTLY on partitioned index
In-Reply-To: <ZK9hLNhTMXFcAcRG@telsasoft.com>
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Justin Pryzby писал 2023-07-13 05:27:
> On Mon, Mar 27, 2023 at 01:28:24PM +0300, Alexander Pyhalov wrote:
>> Justin Pryzby писал 2023-03-26 17:51:
>> > On Sun, Dec 04, 2022 at 01:09:35PM -0600, Justin Pryzby wrote:
>> > > This currently handles partitions with a loop around the whole CIC
>> > > implementation, which means that things like WaitForLockers() happen
>> > > once for each index, the same as REINDEX CONCURRENTLY on a partitioned
>> > > table.  Contrast that with ReindexRelationConcurrently(), which handles
>> > > all the indexes on a table in one pass by looping around indexes within
>> > > each phase.
>> >
>> > Rebased over the progress reporting fix (27f5c712b).
>> >
>> > I added a list of (intermediate) partitioned tables, rather than looping
>> > over the list of inheritors again, to save calling rel_get_relkind().
>> >
>> > I think this patch is done.
>> 
>> Overall looks good to me. However, I think that using 'partitioned' as 
>> list
>> of partitioned index oids in DefineIndex() is a bit misleading - we've 
>> just
>> used it as boolean, specifying if we are dealing with a partitioned
>> relation.
> 
> Right.  This is also rebased on 8c852ba9a4 (Allow some exclusion
> constraints on partitions).

Hi.
I have some more question.
In the following code (indexcmds.c:1640 and later)

1640                         rel = table_open(relationId, 
ShareUpdateExclusiveLock);
1641                         heaprelid = rel->rd_lockInfo.lockRelId;
1642                         table_close(rel, ShareUpdateExclusiveLock);
1643                         SET_LOCKTAG_RELATION(heaplocktag, 
heaprelid.dbId, heaprelid.relId);

should we release ShareUpdateExclusiveLock before getting session lock 
in DefineIndexConcurrentInternal()?
Also we unlock parent table there between reindexing childs in the end 
of DefineIndexConcurrentInternal():

1875         /*
1876          * Last thing to do is release the session-level lock on 
the parent table.
1877          */
1878         UnlockRelationIdForSession(&heaprelid, 
ShareUpdateExclusiveLock);
1879 }


Is it safe? Shouldn't we hold session lock on the parent table while 
rebuilding child indexes?


-- 
Best regards,
Alexander Pyhalov,
Postgres Professional