Fix concurrent indexing operations with temporary tables

Attempting to use CREATE INDEX, DROP INDEX or REINDEX with CONCURRENTLY
on a temporary relation with ON COMMIT actions triggered unexpected
errors because those operations use multiple transactions internally to
complete their work.  Here is for example one confusing error when using
ON COMMIT DELETE ROWS:
ERROR:  index "foo" already contains data

Issues related to temporary relations and concurrent indexing are fixed
in this commit by enforcing the non-concurrent path to be taken for
temporary relations even if using CONCURRENTLY, transparently to the
user.  Using a non-concurrent path does not matter in practice as locks
cannot be taken on a temporary relation by a session different than the
one owning the relation, and the non-concurrent operation is more
effective.

The problem exists with REINDEX since v12 with the introduction of
CONCURRENTLY, and with CREATE/DROP INDEX since CONCURRENTLY exists for
those commands.  In all supported versions, this caused only confusing
error messages to be generated.  Note that with REINDEX, it was also
possible to issue a REINDEX CONCURRENTLY for a temporary relation owned
by a different session, leading to a server crash.

The idea to enforce transparently the non-concurrent code path for
temporary relations comes originally from Andres Freund.

Reported-by: Manuel Rigger
Author: Michael Paquier, Heikki Linnakangas
Reviewed-by: Andres Freund, Álvaro Herrera, Heikki Linnakangas
Discussion: https://postgr.es/m/CA+u7OA6gP7YAeCguyseusYcc=uR8+ypjCcgDDCTzjQ+k6S9ksQ@mail.gmail.com
Backpatch-through: 9.4

diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml
index 32b424e8f650b3e49f841f7a152897f343262021..ef0dff6c81859deb707f42485474642ac34d611c 100644 (file)
--- a/doc/src/sgml/ref/create_index.sgml
+++ b/doc/src/sgml/ref/create_index.sgml
@@ -123,6 +123,11 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] <replaceable class=
         &mdash; see <xref linkend="SQL-CREATEINDEX-CONCURRENTLY"
         endterm="SQL-CREATEINDEX-CONCURRENTLY-title">.
        </para>
+       <para>
+        For temporary tables, <command>CREATE INDEX</command> is always
+        non-concurrent, as no other session can access them, and
+        non-concurrent index creation is cheaper.
+       </para>
       </listitem>
      </varlistentry>
 

diff --git a/doc/src/sgml/ref/drop_index.sgml b/doc/src/sgml/ref/drop_index.sgml
index d66d30edf7442c6a63b4cb68263415e6a5a5d9f6..96e5f049f28e3aec47701d0aed6ae1ebc6dfa26b 100644 (file)
--- a/doc/src/sgml/ref/drop_index.sgml
+++ b/doc/src/sgml/ref/drop_index.sgml
@@ -58,6 +58,11 @@ DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] <replaceable class="PARAMETER">name</r
       performed within a transaction block, but
       <command>DROP INDEX CONCURRENTLY</> cannot.
      </para>
+     <para>
+      For temporary tables, <command>DROP INDEX</command> is always
+      non-concurrent, as no other session can access them, and
+      non-concurrent index drop is cheaper.
+     </para>
     </listitem>
    </varlistentry>
 

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index e707934f5075dd33edb8594df1aab74c0a593a76..f1a944ffd551582d59c1bc890c11e897376167ff 100644 (file)
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1362,6 +1362,15 @@ index_drop(Oid indexId, bool concurrent)
    LOCKTAG     heaplocktag;
    LOCKMODE    lockmode;
 
+   /*
+    * A temporary relation uses a non-concurrent DROP.  Other backends can't
+    * access a temporary relation, so there's no harm in grabbing a stronger
+    * lock (see comments in RemoveRelations), and a non-concurrent DROP is
+    * more efficient.
+    */
+   Assert(get_rel_persistence(indexId) != RELPERSISTENCE_TEMP ||
+          !concurrent);
+
    /*
     * To drop an index safely, we must grab exclusive lock on its parent
     * table.  Exclusive lock on the index alone is insufficient because

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index f4fd3c128e4f2853805e27034985e1525f7bec12..7313310f110d4df117901b93bdc974e9cf2ddaf0 100644 (file)
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -303,6 +303,7 @@ DefineIndex(Oid relationId,
            bool skip_build,
            bool quiet)
 {
+   bool        concurrent;
    char       *indexRelationName;
    char       *accessMethodName;
    Oid        *typeObjectId;
@@ -332,6 +333,18 @@ DefineIndex(Oid relationId,
    Snapshot    snapshot;
    int         i;
 
+   /*
+    * Force non-concurrent build on temporary relations, even if CONCURRENTLY
+    * was requested.  Other backends can't access a temporary relation, so
+    * there's no harm in grabbing a stronger lock, and a non-concurrent DROP
+    * is more efficient.  Do this before any use of the concurrent option is
+    * done.
+    */
+   if (stmt->concurrent && get_rel_persistence(relationId) != RELPERSISTENCE_TEMP)
+       concurrent = true;
+   else
+       concurrent = false;
+
    /*
     * count attributes in index
     */
@@ -357,7 +370,7 @@ DefineIndex(Oid relationId,
     * relation.  To avoid lock upgrade hazards, that lock should be at least
     * as strong as the one we take here.
     */
-   lockmode = stmt->concurrent ? ShareUpdateExclusiveLock : ShareLock;
+   lockmode = concurrent ? ShareUpdateExclusiveLock : ShareLock;
    rel = heap_open(relationId, lockmode);
 
    relationId = RelationGetRelid(rel);
@@ -547,8 +560,8 @@ DefineIndex(Oid relationId,
    indexInfo->ii_ExclusionStrats = NULL;
    indexInfo->ii_Unique = stmt->unique;
    /* In a concurrent build, mark it not-ready-for-inserts */
-   indexInfo->ii_ReadyForInserts = !stmt->concurrent;
-   indexInfo->ii_Concurrent = stmt->concurrent;
+   indexInfo->ii_ReadyForInserts = !concurrent;
+   indexInfo->ii_Concurrent = concurrent;
    indexInfo->ii_BrokenHotChain = false;
 
    typeObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
@@ -599,7 +612,7 @@ DefineIndex(Oid relationId,
     * A valid stmt->oldNode implies that we already have a built form of the
     * index.  The caller should also decline any index build.
     */
-   Assert(!OidIsValid(stmt->oldNode) || (skip_build && !stmt->concurrent));
+   Assert(!OidIsValid(stmt->oldNode) || (skip_build && !concurrent));
 
    /*
     * Make the catalog entries for the index, including constraints. Then, if
@@ -613,8 +626,8 @@ DefineIndex(Oid relationId,
                     coloptions, reloptions, stmt->primary,
                     stmt->isconstraint, stmt->deferrable, stmt->initdeferred,
                     allowSystemTableMods,
-                    skip_build || stmt->concurrent,
-                    stmt->concurrent, !check_rights,
+                    skip_build || concurrent,
+                    concurrent, !check_rights,
                     stmt->if_not_exists);
 
    ObjectAddressSet(address, RelationRelationId, indexRelationId);
@@ -630,7 +643,7 @@ DefineIndex(Oid relationId,
        CreateComments(indexRelationId, RelationRelationId, 0,
                       stmt->idxcomment);
 
-   if (!stmt->concurrent)
+   if (!concurrent)
    {
        /* Close the heap and we're done, in the non-concurrent case */
        heap_close(rel, NoLock);

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index b8d2e321014a08e840521e84ffb38db7e11c9973..7fcc3db14cb5f76e9a2e7dcec899cfe88d323ed8 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -812,7 +812,11 @@ RemoveRelations(DropStmt *drop)
    /* DROP CONCURRENTLY uses a weaker lock, and has some restrictions */
    if (drop->concurrent)
    {
-       flags |= PERFORM_DELETION_CONCURRENTLY;
+       /*
+        * Note that for temporary relations this lock may get upgraded
+        * later on, but as no other session can access a temporary
+        * relation, this is actually fine.
+        */
        lockmode = ShareUpdateExclusiveLock;
        Assert(drop->removeType == OBJECT_INDEX);
        if (list_length(drop->objects) != 1)
@@ -903,6 +907,18 @@ RemoveRelations(DropStmt *drop)
            continue;
        }
 
+       /*
+        * Decide if concurrent mode needs to be used here or not.  The
+        * relation persistence cannot be known without its OID.
+        */
+       if (drop->concurrent &&
+           get_rel_persistence(relOid) != RELPERSISTENCE_TEMP)
+       {
+           Assert(list_length(drop->objects) == 1 &&
+                  drop->removeType == OBJECT_INDEX);
+           flags |= PERFORM_DELETION_CONCURRENTLY;
+       }
+
        /* OK, we're ready to delete this one */
        obj.classId = RelationRelationId;
        obj.objectId = relOid;

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 542b1d8ee06141139fbb1f45ae91558466dd2de2..37886945ff0712012cdaae261f3837f8f8d76cc4 100644 (file)
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1768,6 +1768,28 @@ get_rel_tablespace(Oid relid)
        return InvalidOid;
 }
 
+/*
+ * get_rel_persistence
+ *
+ *     Returns the relpersistence associated with a given relation.
+ */
+char
+get_rel_persistence(Oid relid)
+{
+   HeapTuple   tp;
+   Form_pg_class reltup;
+   char        result;
+
+   tp = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+   if (!HeapTupleIsValid(tp))
+       elog(ERROR, "cache lookup failed for relation %u", relid);
+   reltup = (Form_pg_class) GETSTRUCT(tp);
+   result = reltup->relpersistence;
+   ReleaseSysCache(tp);
+
+   return result;
+}
+
 
 /*             ---------- TRANSFORM CACHE ----------                        */
 

diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 971153843296d55612f201ace510af8ccbee8cdd..9e7c03388b62b34f6e6dea05b9e37d418a2e1e33 100644 (file)
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -102,6 +102,7 @@ extern Oid  get_rel_namespace(Oid relid);
 extern Oid get_rel_type_id(Oid relid);
 extern char get_rel_relkind(Oid relid);
 extern Oid get_rel_tablespace(Oid relid);
+extern char get_rel_persistence(Oid relid);
 extern Oid get_transform_fromsql(Oid typid, Oid langid, List *trftypes);
 extern Oid get_transform_tosql(Oid typid, Oid langid, List *trftypes);
 extern bool get_typisdefined(Oid typid);

diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index d7930fe7f5e72a159b1a234db5210e5a24e0eb94..b8eba4cdf5d59b171d2cd91b13818ea572b7886d 100644 (file)
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2495,6 +2495,31 @@ Indexes:
     "concur_index5" btree (f2) WHERE f1 = 'x'::text
     "std_index" btree (f2)
 
+-- Temporary tables with concurrent builds and on-commit actions
+-- CONCURRENTLY used with CREATE INDEX and DROP INDEX is ignored.
+-- PRESERVE ROWS, the default.
+CREATE TEMP TABLE concur_temp (f1 int, f2 text)
+  ON COMMIT PRESERVE ROWS;
+INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar');
+CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1);
+DROP INDEX CONCURRENTLY concur_temp_ind;
+DROP TABLE concur_temp;
+-- ON COMMIT DROP
+BEGIN;
+CREATE TEMP TABLE concur_temp (f1 int, f2 text)
+  ON COMMIT DROP;
+INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar');
+-- Fails when running in a transaction.
+CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1);
+ERROR:  CREATE INDEX CONCURRENTLY cannot run inside a transaction block
+COMMIT;
+-- ON COMMIT DELETE ROWS
+CREATE TEMP TABLE concur_temp (f1 int, f2 text)
+  ON COMMIT DELETE ROWS;
+INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar');
+CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1);
+DROP INDEX CONCURRENTLY concur_temp_ind;
+DROP TABLE concur_temp;
 --
 -- Try some concurrent index drops
 --

diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index f17edc9c5c2ef05a099a87e8ac6d6b84aa891c2c..793b2f5ae3be5cff2af5f0d474785abbd6412f1c 100644 (file)
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -785,6 +785,31 @@ VACUUM FULL concur_heap;
 REINDEX TABLE concur_heap;
 \d concur_heap
 
+-- Temporary tables with concurrent builds and on-commit actions
+-- CONCURRENTLY used with CREATE INDEX and DROP INDEX is ignored.
+-- PRESERVE ROWS, the default.
+CREATE TEMP TABLE concur_temp (f1 int, f2 text)
+  ON COMMIT PRESERVE ROWS;
+INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar');
+CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1);
+DROP INDEX CONCURRENTLY concur_temp_ind;
+DROP TABLE concur_temp;
+-- ON COMMIT DROP
+BEGIN;
+CREATE TEMP TABLE concur_temp (f1 int, f2 text)
+  ON COMMIT DROP;
+INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar');
+-- Fails when running in a transaction.
+CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1);
+COMMIT;
+-- ON COMMIT DELETE ROWS
+CREATE TEMP TABLE concur_temp (f1 int, f2 text)
+  ON COMMIT DELETE ROWS;
+INSERT INTO concur_temp VALUES (1, 'foo'), (2, 'bar');
+CREATE INDEX CONCURRENTLY concur_temp_ind ON concur_temp(f1);
+DROP INDEX CONCURRENTLY concur_temp_ind;
+DROP TABLE concur_temp;
+
 --
 -- Try some concurrent index drops
 --