From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
cc: Postgres hackers <pgsql-hackers@lists.postgresql.org>,
        Masao Fujii <FujiiMasaomasao.fujii@gmail.com>
Subject: Re: REINDEX INDEX results in a crash for an index of pg_class since
 9.6
In-reply-to: <20190418011430.GA19133@paquier.xyz>
References: <20190418011430.GA19133@paquier.xyz>
Comments: In-reply-to Michael Paquier <michael@paquier.xyz>
	message dated "Thu, 18 Apr 2019 10:14:30 +0900"
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Date: Tue, 23 Apr 2019 16:47:19 -0400
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Michael Paquier <michael@paquier.xyz> writes:
> Fujii-san has sent me a report offline about REINDEX.  And since 9.6,
> trying to REINDEX directly an index of pg_class fails lamentably on an
> assertion failure (mbsync failure if bypassing the assert):

So ... I can't reproduce this on HEAD.  Nor the back branches.

regression=# \d pg_class
...
Indexes:
    "pg_class_oid_index" UNIQUE, btree (oid)
    "pg_class_relname_nsp_index" UNIQUE, btree (relname, relnamespace)
    "pg_class_tblspc_relfilenode_index" btree (reltablespace, relfilenode)

regression=# reindex index pg_class_relname_nsp_index;
REINDEX
regression=# reindex index pg_class_oid_index;
REINDEX
regression=# reindex index pg_class_tblspc_relfilenode_index;
REINDEX
regression=# reindex table pg_class;         
REINDEX
regression=# reindex index pg_class_tblspc_relfilenode_index;
REINDEX

Is there some precondition you're not mentioning?

			regards, tom lane