Re: [ADMIN] pg_upgrade from 9.1.3 to 9.2 failed - Mailing list pgsql-hackers

于2012年9月17日 12:32:36,Bruce Momjian写到:
> On Sun, Sep 16, 2012 at 06:04:16PM -0400, Tom Lane wrote:
>> Bruce Momjian <bruce@momjian.us> writes:
>>> On Sun, Sep 16, 2012 at 12:38:37PM +0800, Rural Hunter wrote:
>>>> I ran the pg_upgrade with the patch and found the problematic object
>>>> is a toast object.
>>
>>> OK, this is exactly what I wanted to see, and it explains why pg_dump
>>> didn't show it.  Can you find out what table references this toast
>>> table?  Try this query on the old cluster:
>>
>>>     select oid, * from pg_class WHERE reltoastrelid = 16439148;
>>
>>> I believe it will have an oid of 16439145, or it might not exist.
>>
>> Most likely what's happened is that the table has a toast table that
>> it doesn't need, as a result of having dropped the only wide column(s)
>> in it.  So when the table is recreated in the new cluster, there's no
>> toast table for it.
>>
>> So what you need to do is get rid of that check, or relax it so that it
>> doesn't insist on toast tables matching up exactly.  It seems possible
>> that there could be discrepancies in the other direction too, ie,
>> new cluster created a toast table when old cluster didn't have one.
>
> pg_dump.c already has this code:
>
>          if (OidIsValid(pg_class_reltoastrelid))
>          {
>              /*
>               * One complexity is that the table definition might not require
>               * the creation of a TOAST table, and the TOAST table might have
>               * been created long after table creation, when the table was
>               * loaded with wide data.  By setting the TOAST oid we force
>               * creation of the TOAST heap and TOAST index by the backend so we
>               * can cleanly copy the files during binary upgrade.
>               */
>
>              appendPQExpBuffer(upgrade_buffer,
>                                "SELECT binary_upgrade.set_next_toast_pg_class_oid('%u'::pg_catalog.oid);\n",
>                                pg_class_reltoastrelid);
>
>              /* every toast table has an index */
>              appendPQExpBuffer(upgrade_buffer,
>                                "SELECT binary_upgrade.set_next_index_pg_class_oid('%u'::pg_catalog.oid);\n",
>                                pg_class_reltoastidxid);
>          }
>
> As you can see, we look at the existing TOAST usage and force the new
> cluster to match.  As I remember we replay the DROP COLUMN in binary
> upgrade mode so the new cluster always matches the old cluster's TOAST
> usage.  I certainly have never seen this bug reported before.
>
> I think the big question is why did this case fail?  I can say that the
> query that pulls details from each cluster skips information_schema or
> oid < FirstNormalObjectId.  I wonder if there is a mismatch between what
> pg_dump filters out and pg_upgrade.  Can you tell us the schema of the
> 'sql_features' table?
# select * from pg_tables where tablename='sql_features';    schemaname     |  tablename   | tableowner | tablespace |

hasindexes | hasrules | hastriggers
--------------------+--------------+------------+------------+------------+----------+-------------information_schema |
sql_features| postgres   |            | f         | f        | f
 
(1 row)
>
> Also, does it appear in the pg_dump --schema-only output?  I don't think
> it does because it wasn't reported in the pg_dump --schema-only diff I
> requested, and pg_dump wouldn't have dumped it from the new cluster.
right. I checked the dump from the old cluster and it's not there.
>
> What that means is that 'sql_features' got a TOAST table in the old
> cluster but while 'sql_features' also has a TOAST table in the new
> cluster, it isn't processed by pg_upgrade because it is in the
> information schema and has an oid < FirstNormalObjectId.
>