Re: Improving collation-dependent indexes in system catalogs

I wrote:
> While fooling with the idea of making type "name" collation
> aware, it occurred to me that there's a better, more general
> answer, which is to insist that collation-aware system catalog
> columns must be marked with C collation.  This rule would apply
> without modification to both "text" and "name" columns.  In the
> wake of commit 5e0928005, it also means that pg_statistic data
> for such a column would port safely across a database collation
> change, which up to now it does not.  And I think we could have
> the bootstrap code apply the rule automatically, making for one
> less way to screw up when changing catalog definitions.

Concretely, this ...

            regards, tom lane

diff --git a/src/backend/access/common/scankey.c b/src/backend/access/common/scankey.c
index 781516c..5be4fe8 100644
*** a/src/backend/access/common/scankey.c
--- b/src/backend/access/common/scankey.c
*************** ScanKeyEntryInitialize(ScanKey entry,
*** 64,72 ****
   * It cannot handle NULL arguments, unary operators, or nondefault operators,
   * but we need none of those features for most hardwired lookups.
   *
!  * We set collation to DEFAULT_COLLATION_OID always.  This is appropriate
!  * for textual columns in system catalogs, and it will be ignored for
!  * non-textual columns, so it's not worth trying to be more finicky.
   *
   * Note: CurrentMemoryContext at call should be as long-lived as the ScanKey
   * itself, because that's what will be used for any subsidiary info attached
--- 64,72 ----
   * It cannot handle NULL arguments, unary operators, or nondefault operators,
   * but we need none of those features for most hardwired lookups.
   *
!  * We set collation to C_COLLATION_OID always.  This is the correct value
!  * for all collation-aware columns in system catalogs, and it will be ignored
!  * for other column types, so it's not worth trying to be more finicky.
   *
   * Note: CurrentMemoryContext at call should be as long-lived as the ScanKey
   * itself, because that's what will be used for any subsidiary info attached
*************** ScanKeyInit(ScanKey entry,
*** 83,89 ****
      entry->sk_attno = attributeNumber;
      entry->sk_strategy = strategy;
      entry->sk_subtype = InvalidOid;
!     entry->sk_collation = DEFAULT_COLLATION_OID;
      entry->sk_argument = argument;
      fmgr_info(procedure, &entry->sk_func);
  }
--- 83,89 ----
      entry->sk_attno = attributeNumber;
      entry->sk_strategy = strategy;
      entry->sk_subtype = InvalidOid;
!     entry->sk_collation = C_COLLATION_OID;
      entry->sk_argument = argument;
      fmgr_info(procedure, &entry->sk_func);
  }
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 7caab64..8e42255 100644
*** a/src/backend/bootstrap/bootstrap.c
--- b/src/backend/bootstrap/bootstrap.c
*************** DefineAttr(char *name, char *type, int a
*** 744,749 ****
--- 744,758 ----
              attrtypes[attnum]->attndims = 0;
      }

+     /*
+      * If a system catalog column is collation-aware, force it to use C
+      * collation, so that its behavior is independent of the database's
+      * collation.  This is essential to allow template0 to be cloned with a
+      * different database collation.
+      */
+     if (OidIsValid(attrtypes[attnum]->attcollation))
+         attrtypes[attnum]->attcollation = C_COLLATION_OID;
+
      attrtypes[attnum]->attstattarget = -1;
      attrtypes[attnum]->attcacheoff = -1;
      attrtypes[attnum]->atttypmod = -1;
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index 8e2a248..115e4c6 100644
*** a/src/backend/catalog/genbki.pl
--- b/src/backend/catalog/genbki.pl
*************** my $GenbkiNextOid = $FirstGenbkiObjectId
*** 167,172 ****
--- 167,175 ----
  my $BOOTSTRAP_SUPERUSERID =
    Catalog::FindDefinedSymbolFromData($catalog_data{pg_authid},
      'BOOTSTRAP_SUPERUSERID');
+ my $C_COLLATION_OID =
+   Catalog::FindDefinedSymbolFromData($catalog_data{pg_collation},
+     'C_COLLATION_OID');
  my $PG_CATALOG_NAMESPACE =
    Catalog::FindDefinedSymbolFromData($catalog_data{pg_namespace},
      'PG_CATALOG_NAMESPACE');
*************** sub morph_row_for_pgattr
*** 693,699 ****

      # set attndims if it's an array type
      $row->{attndims} = $type->{typcategory} eq 'A' ? '1' : '0';
!     $row->{attcollation} = $type->{typcollation};

      if (defined $attr->{forcenotnull})
      {
--- 696,705 ----

      # set attndims if it's an array type
      $row->{attndims} = $type->{typcategory} eq 'A' ? '1' : '0';
!
!     # collation-aware catalog columns must use C collation
!     $row->{attcollation} = $type->{typcollation} != 0 ?
!         $C_COLLATION_OID : 0;

      if (defined $attr->{forcenotnull})
      {
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index b31fd5a..fdbd6a0 100644
*** a/src/backend/utils/cache/catcache.c
--- b/src/backend/utils/cache/catcache.c
***************
*** 22,27 ****
--- 22,28 ----
  #include "access/tuptoaster.h"
  #include "access/valid.h"
  #include "access/xact.h"
+ #include "catalog/pg_collation.h"
  #include "catalog/pg_operator.h"
  #include "catalog/pg_type.h"
  #include "miscadmin.h"
*************** CatalogCacheInitializeCache(CatCache *ca
*** 1014,1021 ****
          /* Fill in sk_strategy as well --- always standard equality */
          cache->cc_skey[i].sk_strategy = BTEqualStrategyNumber;
          cache->cc_skey[i].sk_subtype = InvalidOid;
!         /* Currently, there are no catcaches on collation-aware data types */
!         cache->cc_skey[i].sk_collation = InvalidOid;

          CACHE4_elog(DEBUG2, "CatalogCacheInitializeCache %s %d %p",
                      cache->cc_relname,
--- 1015,1022 ----
          /* Fill in sk_strategy as well --- always standard equality */
          cache->cc_skey[i].sk_strategy = BTEqualStrategyNumber;
          cache->cc_skey[i].sk_subtype = InvalidOid;
!         /* If a catcache key requires a collation, it must be C collation */
!         cache->cc_skey[i].sk_collation = C_COLLATION_OID;

          CACHE4_elog(DEBUG2, "CatalogCacheInitializeCache %s %d %p",
                      cache->cc_relname,
diff --git a/src/include/catalog/indexing.h b/src/include/catalog/indexing.h
index 2359b4c..f0c52d9 100644
*** a/src/include/catalog/indexing.h
--- b/src/include/catalog/indexing.h
*************** DECLARE_UNIQUE_INDEX(pg_default_acl_oid_
*** 310,319 ****
  DECLARE_UNIQUE_INDEX(pg_db_role_setting_databaseid_rol_index, 2965, on pg_db_role_setting using btree(setdatabase
oid_ops,setrole oid_ops)); 
  #define DbRoleSettingDatidRolidIndexId    2965

! DECLARE_UNIQUE_INDEX(pg_seclabel_object_index, 3597, on pg_seclabel using btree(objoid oid_ops, classoid oid_ops,
objsubidint4_ops, provider text_pattern_ops)); 
  #define SecLabelObjectIndexId                3597

! DECLARE_UNIQUE_INDEX(pg_shseclabel_object_index, 3593, on pg_shseclabel using btree(objoid oid_ops, classoid oid_ops,
providertext_pattern_ops)); 
  #define SharedSecLabelObjectIndexId            3593

  DECLARE_UNIQUE_INDEX(pg_extension_oid_index, 3080, on pg_extension using btree(oid oid_ops));
--- 310,319 ----
  DECLARE_UNIQUE_INDEX(pg_db_role_setting_databaseid_rol_index, 2965, on pg_db_role_setting using btree(setdatabase
oid_ops,setrole oid_ops)); 
  #define DbRoleSettingDatidRolidIndexId    2965

! DECLARE_UNIQUE_INDEX(pg_seclabel_object_index, 3597, on pg_seclabel using btree(objoid oid_ops, classoid oid_ops,
objsubidint4_ops, provider text_ops)); 
  #define SecLabelObjectIndexId                3597

! DECLARE_UNIQUE_INDEX(pg_shseclabel_object_index, 3593, on pg_shseclabel using btree(objoid oid_ops, classoid oid_ops,
providertext_ops)); 
  #define SharedSecLabelObjectIndexId            3593

  DECLARE_UNIQUE_INDEX(pg_extension_oid_index, 3080, on pg_extension using btree(oid oid_ops));
*************** DECLARE_UNIQUE_INDEX(pg_policy_polrelid_
*** 333,339 ****
  DECLARE_UNIQUE_INDEX(pg_replication_origin_roiident_index, 6001, on pg_replication_origin using btree(roident
oid_ops));
  #define ReplicationOriginIdentIndex 6001

! DECLARE_UNIQUE_INDEX(pg_replication_origin_roname_index, 6002, on pg_replication_origin using btree(roname
text_pattern_ops));
  #define ReplicationOriginNameIndex 6002

  DECLARE_UNIQUE_INDEX(pg_partitioned_table_partrelid_index, 3351, on pg_partitioned_table using btree(partrelid
oid_ops));
--- 333,339 ----
  DECLARE_UNIQUE_INDEX(pg_replication_origin_roiident_index, 6001, on pg_replication_origin using btree(roident
oid_ops));
  #define ReplicationOriginIdentIndex 6001

! DECLARE_UNIQUE_INDEX(pg_replication_origin_roname_index, 6002, on pg_replication_origin using btree(roname
text_ops));
  #define ReplicationOriginNameIndex 6002

  DECLARE_UNIQUE_INDEX(pg_partitioned_table_partrelid_index, 3351, on pg_partitioned_table using btree(partrelid
oid_ops));
diff --git a/src/test/regress/expected/opr_sanity.out b/src/test/regress/expected/opr_sanity.out
index 6072f6b..52cd7b9 100644
*** a/src/test/regress/expected/opr_sanity.out
--- b/src/test/regress/expected/opr_sanity.out
*************** ORDER BY 1;
*** 2060,2077 ****
  -- a representational error in pg_index, but simply wrong catalog design.
  -- It's bad because we expect to be able to clone template0 and assign the
  -- copy a different database collation.  It would especially not work for
! -- shared catalogs.  Note that although text columns will show a collation
! -- in indcollation, they're still okay to index with text_pattern_ops,
! -- so allow that case.
  SELECT indexrelid::regclass, indrelid::regclass, iclass, icoll
  FROM (SELECT indexrelid, indrelid,
               unnest(indclass) as iclass, unnest(indcollation) as icoll
        FROM pg_index
        WHERE indrelid < 16384) ss
! WHERE icoll != 0 AND iclass !=
!     (SELECT oid FROM pg_opclass
!      WHERE opcname = 'text_pattern_ops' AND opcmethod =
!            (SELECT oid FROM pg_am WHERE amname = 'btree'));
   indexrelid | indrelid | iclass | icoll
  ------------+----------+--------+-------
  (0 rows)
--- 2060,2073 ----
  -- a representational error in pg_index, but simply wrong catalog design.
  -- It's bad because we expect to be able to clone template0 and assign the
  -- copy a different database collation.  It would especially not work for
! -- shared catalogs.  Collation-sensitive indexes should have "C" collation.
  SELECT indexrelid::regclass, indrelid::regclass, iclass, icoll
  FROM (SELECT indexrelid, indrelid,
               unnest(indclass) as iclass, unnest(indcollation) as icoll
        FROM pg_index
        WHERE indrelid < 16384) ss
! WHERE icoll != 0 AND
!     icoll != (SELECT oid FROM pg_collation WHERE collname = 'C');
   indexrelid | indrelid | iclass | icoll
  ------------+----------+--------+-------
  (0 rows)
diff --git a/src/test/regress/sql/opr_sanity.sql b/src/test/regress/sql/opr_sanity.sql
index 91c68f4..5cf4df1 100644
*** a/src/test/regress/sql/opr_sanity.sql
--- b/src/test/regress/sql/opr_sanity.sql
*************** ORDER BY 1;
*** 1333,1348 ****
  -- a representational error in pg_index, but simply wrong catalog design.
  -- It's bad because we expect to be able to clone template0 and assign the
  -- copy a different database collation.  It would especially not work for
! -- shared catalogs.  Note that although text columns will show a collation
! -- in indcollation, they're still okay to index with text_pattern_ops,
! -- so allow that case.

  SELECT indexrelid::regclass, indrelid::regclass, iclass, icoll
  FROM (SELECT indexrelid, indrelid,
               unnest(indclass) as iclass, unnest(indcollation) as icoll
        FROM pg_index
        WHERE indrelid < 16384) ss
! WHERE icoll != 0 AND iclass !=
!     (SELECT oid FROM pg_opclass
!      WHERE opcname = 'text_pattern_ops' AND opcmethod =
!            (SELECT oid FROM pg_am WHERE amname = 'btree'));
--- 1333,1344 ----
  -- a representational error in pg_index, but simply wrong catalog design.
  -- It's bad because we expect to be able to clone template0 and assign the
  -- copy a different database collation.  It would especially not work for
! -- shared catalogs.  Collation-sensitive indexes should have "C" collation.

  SELECT indexrelid::regclass, indrelid::regclass, iclass, icoll
  FROM (SELECT indexrelid, indrelid,
               unnest(indclass) as iclass, unnest(indcollation) as icoll
        FROM pg_index
        WHERE indrelid < 16384) ss
! WHERE icoll != 0 AND
!     icoll != (SELECT oid FROM pg_collation WHERE collname = 'C');