From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | Peter Geoghegan <pg(at)heroku(dot)com> |
Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Bug in point releases 9.3.6 and 9.2.10? |
Date: | 2015-03-13 00:21:50 |
Message-ID: | 20150313002150.GA18401@alap3.anarazel.de |
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Thread: | |
Lists: | pgsql-hackers |
Hi,
On 2015-03-12 16:42:24 -0700, Peter Geoghegan wrote:
> We want to create a new role when this happens, for various reasons.
> This occurs after recovery ends, but before the database has been
> "unfenced". The template code that generates various ALTER ROLE
> statements in our internal provisioning system - which has apparently
> worked just fine for a long time - is:
Is this all the code that's exececuted after recovery? How are these
forks brought up? Promoted how? Is it a common 'source' database?
> db.execute("ALTER ROLE #{old_database_user} RENAME TO #{database_user}")
> db.execute("ALTER ROLE #{database_user} PASSWORD '#{database_password}' LOGIN")
> db.execute("CREATE ROLE \"#{old_database_user}\" PASSWORD
> '#{old_database_password}' IN ROLE \"#{database_user}\" LOGIN")
>
> I've seen multiple reports of apparent corruption, appearing as the
> resulting ALTER ROLE statements are executed:
>
> PG::DataCorrupted: ERROR: could not read block 0 in file
> "global/12811": read only 0 of 8192 bytes
> or:
> PG::DataCorrupted: ERROR: could not read block 0 in file
> "global/12785": read only 0 of 8192 bytes
> or:
> PG::DataCorrupted: ERROR: could not read block 0 in file
> "global/12811": read only 0 of 8192 bytes
Have you looked at these files? Are they indeed zero bytes when this
error occurs?
Do you still have a base backup from the relevant time, so you could
repeat the whole thing?
> The only common factor is that this occurs on the latest point
> releases (either 9.3.6 and 9.2.10, at least so far). In all cases I've
> seen so far, the relation in question is the pg_auth_members heap
> relation. For example:
Any chance that the new nodes also use a different kernel version or
such?
> redacteddb=# select pg_relation_filenode(oid), oid, relname, relkind
> from pg_class where pg_relation_filenode(oid) = 12785;
> pg_relation_filenode | oid | relname | relkind
> ----------------------+------+-----------------+---------
> 12785 | 1261 | pg_auth_members | r
> (1 row)
This filenode got to be pg_auth_member's original one, given it's below
FirstNormalObjectId. I get a lower value, but that's probably caused by
having fewer collations and other data generated during initdb. That
implies that the table hasn't ever been rewritten.
What's 12811?
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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