Design problems were discovered in the handling of composite types and
record types that would cause some relevant versions not to be recorded.
Misgivings were also expressed about the use of the pg_depend catalog
for this purpose. We're out of time for this release so we'll revert
and try again.
Commits reverted:
1bf946bd: Doc: Document known problem with Windows collation versions.
cf002008: Remove no-longer-relevant test case.
ef387bed: Fix bogus collation-version-recording logic.
0fb0a050: Hide internal error for pg_collation_actual_version(<bad OID>).
ff942057: Suppress "warning: variable 'collcollate' set but not used".
d50e3b1f: Fix assertion in collation version lookup.
f24b1569: Rethink extraction of collation dependencies.
257836a7: Track collation versions for indexes.
cd6f479e: Add pg_depend.refobjversion.
7d1297df: Remove pg_collation.collversion.
Discussion: https://postgr.es/m/CA%2BhUKGLhj5t1fcjqAu8iD9B3ixJtsTNqyCCD4V0aTO9kAKAjjA%40mail.gmail.com
When using collations provided by the ICU library, the ICU-specific version
of the collator is recorded in the system catalog when the collation object
is created. When the collation is used, the current version is
checked against the recorded version, and a warning is issued when there is
a mismatch, for example:
<screen>
WARNING: collation "xx-x-icu" has version mismatch
DETAIL: The collation in the database was created using version 1.2.3.4, but the operating system provides version 2.3.4.5.
HINT: Rebuild all objects affected by this collation and run ALTER COLLATION pg_catalog."xx-x-icu" REFRESH VERSION, or build PostgreSQL with the right library version.
</screen>
A change in collation definitions can lead to corrupt indexes and other
problems because the database system relies on stored objects having a
certain sort order. Generally, this should be avoided, but it can happen
in legitimate circumstances, such as when
using <command>pg_upgrade</command> to upgrade to server binaries linked
with a newer version of ICU. When this happens, all objects depending on
the collation should be rebuilt, for example,
using <command>REINDEX</command>. When that is done, the collation version
can be refreshed using the command <literal>ALTER COLLATION ... REFRESH
VERSION</literal>. This will update the system catalog to record the
current collator version and will make the warning go away. Note that this
does not actually check whether all affected objects have been rebuilt
correctly.
</para>
<para>
When using collations provided by <literal>libc</literal> and
<productname>PostgreSQL</productname> was built with the GNU C library, the
C library's version is used as a collation version. Since collation
definitions typically change only with GNU C library releases, this provides
some defense against corruption, but it is not completely reliable.
</para>
<para>
Currently, there is no version tracking for the database default collation.
</para>
<para>
The following query can be used to identify all collations in the current
database that need to be refreshed and the objects that depend on them:
<programlisting><![CDATA[
SELECT pg_describe_object(refclassid, refobjid, refobjsubid) AS "Collation",
pg_describe_object(classid, objid, objsubid) AS "Object"
FROM pg_depend d JOIN pg_collation c
ON refclassid = 'pg_collation'::regclass AND refobjid = c.oid
WHERE c.collversion <> pg_collation_actual_version(c.oid)
@ -25,7 +25,6 @@ ALTER INDEX [ IF EXISTS ] <replaceable class="parameter">name</replaceable> RENA
ALTER INDEX [ IF EXISTS ] <replaceable class="parameter">name</replaceable> SET TABLESPACE <replaceable class="parameter">tablespace_name</replaceable>
ALTER INDEX <replaceable class="parameter">name</replaceable> ATTACH PARTITION <replaceable class="parameter">index_name</replaceable>
ALTER INDEX <replaceable class="parameter">name</replaceable> [ NO ] DEPENDS ON EXTENSION <replaceable class="parameter">extension_name</replaceable>
ALTER INDEX <replaceable class="parameter">name</replaceable> ALTER COLLATION <replaceable class="parameter">collation_name</replaceable> REFRESH VERSION
ALTER INDEX [ IF EXISTS ] <replaceable class="parameter">name</replaceable> SET ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] )
ALTER INDEX [ IF EXISTS ] <replaceable class="parameter">name</replaceable> RESET ( <replaceable class="parameter">storage_parameter</replaceable> [, ... ] )
ALTER INDEX [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ALTER [ COLUMN ] <replaceable class="parameter">column_number</replaceable>
@ -113,20 +112,6 @@ ALTER INDEX ALL IN TABLESPACE <replaceable class="parameter">name</replaceable>
"\n-- For binary upgrade, clobber new index's collation versions\n");
appendPQExpBuffer(buffer,
"UPDATE pg_catalog.pg_depend SET refobjversion = 'unknown' WHERE objid = '%u'::pg_catalog.oid AND refclassid = 'pg_catalog.pg_collation'::regclass AND refobjversion IS NOT NULL;\n",
indxinfo->dobj.catId.oid);
}
/* Restore the versions that were recorded by the old cluster (if any). */
"UPDATE pg_catalog.pg_depend SET refobjversion = %s WHERE objid = '%u'::pg_catalog.oid AND refclassid = 'pg_catalog.pg_collation'::regclass AND refobjversion IS NOT NULL AND refobjid = ",
Thomas Munro
4 years ago