Clarify use of temporary tables within partition trees

Since their introduction, partition trees have been a bit lossy
regarding temporary relations.  Inheritance trees respect the following
patterns:
1) a child relation can be temporary if the parent is permanent.
2) a child relation can be temporary if the parent is temporary.
3) a child relation cannot be permanent if the parent is temporary.
4) The use of temporary relations also imply that when both parent and
child need to be from the same sessions.

Partitions share many similar patterns with inheritance, however the
handling of the partition bounds make the situation a bit tricky for
case 1) as the partition code bases a lot of its lookup code upon
PartitionDesc which does not really look after relpersistence.  This
causes for example a temporary partition created by session A to be
visible by another session B, preventing this session B to create an
extra partition which overlaps with the temporary one created by A with
a non-intuitive error message.  There could be use-cases where mixing
permanent partitioned tables with temporary partitions make sense, but
that would be a new feature.  Partitions respect 2), 3) and 4) already.

It is a bit depressing to see those error checks happening in
MergeAttributes() whose purpose is different, but that's left as future
refactoring work.

Back-patch down to 10, which is where partitioning has been introduced,
except that default partitions do not apply there.  Documentation also
includes limitations related to the use of temporary tables with
partition trees.

Reported-by: David Rowley
Author: Amit Langote, Michael Paquier
Reviewed-by: Ashutosh Bapat, Amit Langote, Michael Paquier
Discussion: https://postgr.es/m/CAKJS1f94Ojk0og9GMkRHGt8wHTW=ijq5KzJKuoBoqWLwSVwGmw@mail.gmail.com

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 025839115402f0edccfef82123712555ea5dd757..50dc25f87f8e91806a91120084a20a210e9526c4 100644 (file)
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -3353,6 +3353,16 @@ ALTER TABLE measurement ATTACH PARTITION measurement_y2008m02
        on individual partitions, not the partitioned table.
       </para>
      </listitem>
+
+     <listitem>
+      <para>
+       Mixing temporary and permanent relations in the same partition tree is
+       not allowed.  Hence, if the partitioned table is permanent, so must be
+       its partitions and likewise if the partitioned table is temporary.  When
+       using temporary relations, all members of the partition tree have to be
+       from the same session.
+      </para>
+     </listitem>
     </itemizedlist>
     </para>
     </sect3>

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 8b848f91a7c7baeffb024b127afa61ccef6a9162..7c0cf0d7eeabf828eed521f16b4405778a15fb52 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1985,6 +1985,19 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                         errmsg("inherited relation \"%s\" is not a table or foreign table",
                                                        parent->relname)));
+
+               /*
+                * If the parent is permanent, so must be all of its partitions.  Note
+                * that inheritance allows that case.
+                */
+               if (is_partition &&
+                       relation->rd_rel->relpersistence != RELPERSISTENCE_TEMP &&
+                       relpersistence == RELPERSISTENCE_TEMP)
+                       ereport(ERROR,
+                                       (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+                                        errmsg("cannot create a temporary relation as partition of permanent relation \"%s\"",
+                                                       RelationGetRelationName(relation))));
+
                /* Permanent rels cannot inherit from temporary ones */
                if (relpersistence != RELPERSISTENCE_TEMP &&
                        relation->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
@@ -14135,6 +14148,14 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
                                                   RelationGetRelationName(rel),
                                                   RelationGetRelationName(attachrel))));
 
+       /* If the parent is permanent, so must be all of its partitions. */
+       if (rel->rd_rel->relpersistence != RELPERSISTENCE_TEMP &&
+               attachrel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
+               ereport(ERROR,
+                               (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+                                errmsg("cannot attach a temporary relation as partition of permanent relation \"%s\"",
+                                               RelationGetRelationName(rel))));
+
        /* Temp parent cannot have a partition that is itself not a temp */
        if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP &&
                attachrel->rd_rel->relpersistence != RELPERSISTENCE_TEMP)

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 702bf9fe986ddc1e23e1721ef5541d33e591915e..b9fd6d1d1c50cfdbfc276341239fc86a55172f4a 100644 (file)
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -3894,3 +3894,16 @@ alter table defpart_attach_test_d add check (a > 1);
 alter table defpart_attach_test attach partition defpart_attach_test_d default;
 INFO:  partition constraint for table "defpart_attach_test_d" is implied by existing constraints
 drop table defpart_attach_test;
+-- check combinations of temporary and permanent relations when attaching
+-- partitions.
+create table perm_part_parent (a int) partition by list (a);
+create temp table temp_part_parent (a int) partition by list (a);
+create table perm_part_child (a int);
+create temp table temp_part_child (a int);
+alter table temp_part_parent attach partition perm_part_child default; -- error
+ERROR:  cannot attach a permanent relation as partition of temporary relation "temp_part_parent"
+alter table perm_part_parent attach partition temp_part_child default; -- error
+ERROR:  cannot attach a temporary relation as partition of permanent relation "perm_part_parent"
+alter table temp_part_parent attach partition temp_part_child default; -- ok
+drop table perm_part_parent cascade;
+drop table temp_part_parent cascade;

diff --git a/src/test/regress/expected/create_table.out b/src/test/regress/expected/create_table.out
index 470fca0cab763cfcbf36d10013126e6a2d8ca210..672719e5d5e7a20b254eb30c09b058ef74b865dd 100644 (file)
--- a/src/test/regress/expected/create_table.out
+++ b/src/test/regress/expected/create_table.out
@@ -899,3 +899,13 @@ Partitions: boolspart_f FOR VALUES IN (false),
             boolspart_t FOR VALUES IN (true)
 
 drop table boolspart;
+-- partitions mixing temporary and permanent relations
+create table perm_parted (a int) partition by list (a);
+create temporary table temp_parted (a int) partition by list (a);
+create table perm_part partition of temp_parted default; -- error
+ERROR:  cannot create a permanent relation as partition of temporary relation "temp_parted"
+create temp table temp_part partition of perm_parted default; -- error
+ERROR:  cannot create a temporary relation as partition of permanent relation "perm_parted"
+create temp table temp_part partition of temp_parted default; -- ok
+drop table perm_parted cascade;
+drop table temp_parted cascade;

diff --git a/src/test/regress/expected/foreign_data.out b/src/test/regress/expected/foreign_data.out
index 339a43ff9e47b5c4934c3d20a80d295685dd2506..75365501d4a4f64393ff279ac416d80033b9e3c4 100644 (file)
--- a/src/test/regress/expected/foreign_data.out
+++ b/src/test/regress/expected/foreign_data.out
@@ -2045,6 +2045,17 @@ TRUNCATE fd_pt2;  -- ERROR
 ERROR:  "fd_pt2_1" is not a table
 DROP FOREIGN TABLE fd_pt2_1;
 DROP TABLE fd_pt2;
+-- foreign table cannot be part of partition tree made of temporary
+-- relations.
+CREATE TEMP TABLE temp_parted (a int) PARTITION BY LIST (a);
+CREATE FOREIGN TABLE foreign_part PARTITION OF temp_parted DEFAULT
+  SERVER s0;  -- ERROR
+ERROR:  cannot create a permanent relation as partition of temporary relation "temp_parted"
+CREATE FOREIGN TABLE foreign_part (a int) SERVER s0;
+ALTER TABLE temp_parted ATTACH PARTITION foreign_part DEFAULT;  -- ERROR
+ERROR:  cannot attach a permanent relation as partition of temporary relation "temp_parted"
+DROP FOREIGN TABLE foreign_part;
+DROP TABLE temp_parted;
 -- Cleanup
 DROP SCHEMA foreign_schema CASCADE;
 DROP ROLE regress_test_role;                                -- ERROR

diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index 854b553d0aeaa46e190d42407ac61126c0dff815..9059147e171d9f3f9d1962a3c02eaf44bbacc88b 100644 (file)
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -3086,3 +3086,24 @@ NOTICE:  drop cascades to 2 other objects
 \set VERBOSITY default
 reset enable_partition_pruning;
 reset constraint_exclusion;
+-- Check pruning for a partition tree containing only temporary relations
+create temp table pp_temp_parent (a int) partition by list (a);
+create temp table pp_temp_part_1 partition of pp_temp_parent for values in (1);
+create temp table pp_temp_part_def partition of pp_temp_parent default;
+explain (costs off) select * from pp_temp_parent where true;
+             QUERY PLAN             
+------------------------------------
+ Append
+   ->  Seq Scan on pp_temp_part_1
+   ->  Seq Scan on pp_temp_part_def
+(3 rows)
+
+explain (costs off) select * from pp_temp_parent where a = 2;
+             QUERY PLAN             
+------------------------------------
+ Append
+   ->  Seq Scan on pp_temp_part_def
+         Filter: (a = 2)
+(3 rows)
+
+drop table pp_temp_parent;

diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index d508a6945648c22a3d3ddd78f88d9dd0e5c1a4cb..3a5b80ea815e81e828f0066fb3f7633b154cc2df 100644 (file)
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2573,3 +2573,15 @@ alter table defpart_attach_test_d add check (a > 1);
 alter table defpart_attach_test attach partition defpart_attach_test_d default;
 
 drop table defpart_attach_test;
+
+-- check combinations of temporary and permanent relations when attaching
+-- partitions.
+create table perm_part_parent (a int) partition by list (a);
+create temp table temp_part_parent (a int) partition by list (a);
+create table perm_part_child (a int);
+create temp table temp_part_child (a int);
+alter table temp_part_parent attach partition perm_part_child default; -- error
+alter table perm_part_parent attach partition temp_part_child default; -- error
+alter table temp_part_parent attach partition temp_part_child default; -- ok
+drop table perm_part_parent cascade;
+drop table temp_part_parent cascade;

diff --git a/src/test/regress/sql/create_table.sql b/src/test/regress/sql/create_table.sql
index 140bf41f7657ab42f6d444ded525dcd72c083f42..78944950fef52ad7af65f178ff5238c520c7da85 100644 (file)
--- a/src/test/regress/sql/create_table.sql
+++ b/src/test/regress/sql/create_table.sql
@@ -726,3 +726,12 @@ create table boolspart_t partition of boolspart for values in (true);
 create table boolspart_f partition of boolspart for values in (false);
 \d+ boolspart
 drop table boolspart;
+
+-- partitions mixing temporary and permanent relations
+create table perm_parted (a int) partition by list (a);
+create temporary table temp_parted (a int) partition by list (a);
+create table perm_part partition of temp_parted default; -- error
+create temp table temp_part partition of perm_parted default; -- error
+create temp table temp_part partition of temp_parted default; -- ok
+drop table perm_parted cascade;
+drop table temp_parted cascade;

diff --git a/src/test/regress/sql/foreign_data.sql b/src/test/regress/sql/foreign_data.sql
index c029b2465d958b28803f2e1b1b6b378b9d41844a..dab9b62900e93b1740b9bec301a86ecfe2a113e5 100644 (file)
--- a/src/test/regress/sql/foreign_data.sql
+++ b/src/test/regress/sql/foreign_data.sql
@@ -805,6 +805,16 @@ TRUNCATE fd_pt2;  -- ERROR
 DROP FOREIGN TABLE fd_pt2_1;
 DROP TABLE fd_pt2;
 
+-- foreign table cannot be part of partition tree made of temporary
+-- relations.
+CREATE TEMP TABLE temp_parted (a int) PARTITION BY LIST (a);
+CREATE FOREIGN TABLE foreign_part PARTITION OF temp_parted DEFAULT
+  SERVER s0;  -- ERROR
+CREATE FOREIGN TABLE foreign_part (a int) SERVER s0;
+ALTER TABLE temp_parted ATTACH PARTITION foreign_part DEFAULT;  -- ERROR
+DROP FOREIGN TABLE foreign_part;
+DROP TABLE temp_parted;
+
 -- Cleanup
 DROP SCHEMA foreign_schema CASCADE;
 DROP ROLE regress_test_role;                                -- ERROR

diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index ae361b52f9f07eb59f04bfebfe0c4815e8688d7d..11b92bfada620cd6ecc72b78fd8c3ea93b057a67 100644 (file)
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -813,3 +813,11 @@ drop table inh_lp cascade;
 
 reset enable_partition_pruning;
 reset constraint_exclusion;
+
+-- Check pruning for a partition tree containing only temporary relations
+create temp table pp_temp_parent (a int) partition by list (a);
+create temp table pp_temp_part_1 partition of pp_temp_parent for values in (1);
+create temp table pp_temp_part_def partition of pp_temp_parent default;
+explain (costs off) select * from pp_temp_parent where true;
+explain (costs off) select * from pp_temp_parent where a = 2;
+drop table pp_temp_parent;