Allow ALTER TABLE ONLY on partitioned tables

There is no need to forbid ALTER TABLE ONLY on partitioned tables,
when no partitions exist yet.  This can be handy for users who are
building up their partitioned table independently and will create actual
partitions later.

In addition, this is how pg_dump likes to operate in certain instances.

Author: Amit Langote, with some error message word-smithing by me

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 340c961b3feff98dc553f1196cbe83e0a4b0ba49..84c4f209909072a755c993eaf2ba53e16f6eec6f 100644 (file)
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -2944,17 +2944,23 @@ VALUES ('Albany', NULL, NULL, 'NY');
        Both <literal>CHECK</literal> and <literal>NOT NULL</literal>
        constraints of a partitioned table are always inherited by all its
        partitions.  <literal>CHECK</literal> constraints that are marked
-       <literal>NO INHERIT</literal> are not allowed.
+       <literal>NO INHERIT</literal> are not allowed to be created on
+       partitioned tables.
       </para>
      </listitem>
 
      <listitem>
       <para>
-       The <literal>ONLY</literal> notation used to exclude child tables
-       will cause an error for partitioned tables in the case of
-       schema-modifying commands such as most <literal>ALTER TABLE</literal>
-       commands.  For example, dropping a column from only the parent does
-       not make sense for partitioned tables.
+       Using <literal>ONLY</literal> to add or drop a constraint on only the
+       partitioned table is supported when there are no partitions.  Once
+       partitions exist, using <literal>ONLY</literal> will result in an error
+       as adding or dropping constraints on only the partitioned table, when
+       partitions exist, is not supported.  Instead, constraints can be added
+       or dropped, when they are not present in the parent table, directly on
+       the partitions.  As a partitioned table does not have any data
+       directly, attempts to use <command>TRUNCATE</command>
+       <literal>ONLY</literal> on a partitioned table will always return an
+       error.
       </para>
      </listitem>
 

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a02904c85c98c433da28378154b4c0d9dedd9060..a35713096d9da68743b3d54770b463bfc001b1fc 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1259,7 +1259,8 @@ ExecuteTruncate(TruncateStmt *stmt)
                else if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
                        ereport(ERROR,
                                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
-                                        errmsg("must truncate child tables too")));
+                                        errmsg("cannot truncate only a partitioned table"),
+                                        errhint("Do not specify the ONLY keyword, or use truncate only on the partitions directly.")));
        }
 
        /*
@@ -5578,14 +5579,20 @@ static void
 ATPrepDropNotNull(Relation rel, bool recurse, bool recursing)
 {
        /*
-        * If the parent is a partitioned table, like check constraints, NOT NULL
-        * constraints must be dropped from child tables.
+        * If the parent is a partitioned table, like check constraints, we do
+        * not support removing the NOT NULL while partitions exist.
         */
-       if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
-               !recurse && !recursing)
-               ereport(ERROR,
-                               (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-                                errmsg("constraint must be dropped from child tables too")));
+       if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+       {
+               PartitionDesc   partdesc = RelationGetPartitionDesc(rel);
+
+               Assert(partdesc != NULL);
+               if (partdesc->nparts > 0 && !recurse && !recursing)
+                       ereport(ERROR,
+                                       (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+                                        errmsg("cannot remove constraint from only the partitioned table when partitions exist"),
+                                        errhint("Do not specify the ONLY keyword.")));
+       }
 }
 static ObjectAddress
 ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
@@ -5746,13 +5753,19 @@ ATPrepSetNotNull(Relation rel, bool recurse, bool recursing)
 {
        /*
         * If the parent is a partitioned table, like check constraints, NOT NULL
-        * constraints must be added to the child tables.
+        * constraints must be added to the child tables.  Complain if requested
+        * otherwise and partitions exist.
         */
-       if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
-               !recurse && !recursing)
-               ereport(ERROR,
-                               (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-                                errmsg("constraint must be added to child tables too")));
+       if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+       {
+               PartitionDesc   partdesc = RelationGetPartitionDesc(rel);
+
+               if (partdesc && partdesc->nparts > 0 && !recurse && !recursing)
+                       ereport(ERROR,
+                                       (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+                                        errmsg("cannot add constraint to only the partitioned table when partitions exist"),
+                                        errhint("Do not specify the ONLY keyword.")));
+       }
 }
 
 static ObjectAddress
@@ -6547,7 +6560,8 @@ ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
                if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE && !recurse)
                        ereport(ERROR,
                                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-                                        errmsg("column must be dropped from child tables too")));
+                                        errmsg("cannot drop column from only the partitioned table when partitions exist"),
+                                        errhint("Do not specify the ONLY keyword.")));
 
                attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);
                foreach(child, children)
@@ -8561,16 +8575,6 @@ ATExecDropConstraint(Relation rel, const char *constrName,
                }
        }
 
-       /*
-        * In case of a partitioned table, the constraint must be dropped from the
-        * partitions too.  There is no such thing as NO INHERIT constraints in
-        * case of partitioned tables.
-        */
-       if (!recurse && rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-               ereport(ERROR,
-                               (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-                                errmsg("constraint must be dropped from child tables too")));
-
        /*
         * Propagate to children as appropriate.  Unlike most other ALTER
         * routines, we have to do this one level of recursion at a time; we can't
@@ -8581,6 +8585,18 @@ ATExecDropConstraint(Relation rel, const char *constrName,
        else
                children = NIL;
 
+       /*
+        * For a partitioned table, if partitions exist and we are told not to
+        * recurse, it's a user error.  It doesn't make sense to have a constraint
+        * be defined only on the parent, especially if it's a partitioned table.
+        */
+       if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
+               children != NIL && !recurse)
+               ereport(ERROR,
+                               (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+                                errmsg("cannot remove constraint from only the partitioned table when partitions exist"),
+                                errhint("Do not specify the ONLY keyword.")));
+
        foreach(child, children)
        {
                Oid                     childrelid = lfirst_oid(child);

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 883a5c9864fc26398723d69606357dafa3e8f210..375a0f618a3265a1691f9337acbf40db0c79c794 100644 (file)
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -3295,7 +3295,8 @@ DROP TABLE part_3_4;
 ALTER TABLE ONLY list_parted2 ADD COLUMN c int;
 ERROR:  column must be added to child tables too
 ALTER TABLE ONLY list_parted2 DROP COLUMN b;
-ERROR:  column must be dropped from child tables too
+ERROR:  cannot drop column from only the partitioned table when partitions exist
+HINT:  Do not specify the ONLY keyword.
 -- cannot add a column to partition or drop an inherited one
 ALTER TABLE part_2 ADD COLUMN c text;
 ERROR:  cannot add column to a partition
@@ -3306,24 +3307,37 @@ ALTER TABLE part_2 RENAME COLUMN b to c;
 ERROR:  cannot rename inherited column "b"
 ALTER TABLE part_2 ALTER COLUMN b TYPE text;
 ERROR:  cannot alter inherited column "b"
--- cannot add NOT NULL or check constraints to *only* the parent (ie, non-inherited)
+-- cannot add/drop NOT NULL or check constraints to *only* the parent, when
+-- partitions exist
 ALTER TABLE ONLY list_parted2 ALTER b SET NOT NULL;
+ERROR:  cannot add constraint to only the partitioned table when partitions exist
+HINT:  Do not specify the ONLY keyword.
+ALTER TABLE ONLY list_parted2 ADD CONSTRAINT check_b CHECK (b <> 'zz');
 ERROR:  constraint must be added to child tables too
-ALTER TABLE ONLY list_parted2 add constraint check_b check (b <> 'zz');
-ERROR:  constraint must be added to child tables too
-ALTER TABLE list_parted2 add constraint check_b check (b <> 'zz') NO INHERIT;
-ERROR:  cannot add NO INHERIT constraint to partitioned table "list_parted2"
+ALTER TABLE list_parted2 ALTER b SET NOT NULL;
+ALTER TABLE ONLY list_parted2 ALTER b DROP NOT NULL;
+ERROR:  cannot remove constraint from only the partitioned table when partitions exist
+HINT:  Do not specify the ONLY keyword.
+ALTER TABLE list_parted2 ADD CONSTRAINT check_b CHECK (b <> 'zz');
+ALTER TABLE ONLY list_parted2 DROP CONSTRAINT check_b;
+ERROR:  cannot remove constraint from only the partitioned table when partitions exist
+HINT:  Do not specify the ONLY keyword.
+-- It's alright though, if no partitions are yet created
+CREATE TABLE parted_no_parts (a int) PARTITION BY LIST (a);
+ALTER TABLE ONLY parted_no_parts ALTER a SET NOT NULL;
+ALTER TABLE ONLY parted_no_parts ADD CONSTRAINT check_a CHECK (a > 0);
+ALTER TABLE ONLY parted_no_parts ALTER a DROP NOT NULL;
+ALTER TABLE ONLY parted_no_parts DROP CONSTRAINT check_a;
+DROP TABLE parted_no_parts;
 -- cannot drop inherited NOT NULL or check constraints from partition
 ALTER TABLE list_parted2 ALTER b SET NOT NULL, ADD CONSTRAINT check_a2 CHECK (a > 0);
 ALTER TABLE part_2 ALTER b DROP NOT NULL;
 ERROR:  column "b" is marked NOT NULL in parent table
 ALTER TABLE part_2 DROP CONSTRAINT check_a2;
 ERROR:  cannot drop inherited constraint "check_a2" of relation "part_2"
--- cannot drop NOT NULL or check constraints from *only* the parent
-ALTER TABLE ONLY list_parted2 ALTER a DROP NOT NULL;
-ERROR:  constraint must be dropped from child tables too
-ALTER TABLE ONLY list_parted2 DROP CONSTRAINT check_a2;
-ERROR:  constraint must be dropped from child tables too
+-- Doesn't make sense to add NO INHERIT constraints on partitioned tables
+ALTER TABLE list_parted2 add constraint check_b2 check (b <> 'zz') NO INHERIT;
+ERROR:  cannot add NO INHERIT constraint to partitioned table "list_parted2"
 -- check that a partition cannot participate in regular inheritance
 CREATE TABLE inh_test () INHERITS (part_2);
 ERROR:  cannot inherit from partition "part_2"

diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
index b652562f5b61e399cef20d3c5718b1d07d37d860..d967e8dd21b244e58e45d4ea5e2eba0434155369 100644 (file)
--- a/src/test/regress/expected/truncate.out
+++ b/src/test/regress/expected/truncate.out
@@ -452,7 +452,15 @@ LINE 1: SELECT nextval('truncate_a_id1');
                        ^
 -- partitioned table
 CREATE TABLE truncparted (a int, b char) PARTITION BY LIST (a);
+-- error, can't truncate a partitioned table
+TRUNCATE ONLY truncparted;
+ERROR:  cannot truncate only a partitioned table
+HINT:  Do not specify the ONLY keyword, or use truncate only on the partitions directly.
 CREATE TABLE truncparted1 PARTITION OF truncparted FOR VALUES IN (1);
 INSERT INTO truncparted VALUES (1, 'a');
+-- error, must truncate partitions
+TRUNCATE ONLY truncparted;
+ERROR:  cannot truncate only a partitioned table
+HINT:  Do not specify the ONLY keyword, or use truncate only on the partitions directly.
 TRUNCATE truncparted;
 DROP TABLE truncparted;

diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index eb1b4b536ffa7c26abb608f41073e710f230d159..85c848f6201c9cc65b6bd19282933b64a9c263c5 100644 (file)
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -2173,19 +2173,31 @@ ALTER TABLE part_2 DROP COLUMN b;
 ALTER TABLE part_2 RENAME COLUMN b to c;
 ALTER TABLE part_2 ALTER COLUMN b TYPE text;
 
--- cannot add NOT NULL or check constraints to *only* the parent (ie, non-inherited)
+-- cannot add/drop NOT NULL or check constraints to *only* the parent, when
+-- partitions exist
 ALTER TABLE ONLY list_parted2 ALTER b SET NOT NULL;
-ALTER TABLE ONLY list_parted2 add constraint check_b check (b <> 'zz');
-ALTER TABLE list_parted2 add constraint check_b check (b <> 'zz') NO INHERIT;
+ALTER TABLE ONLY list_parted2 ADD CONSTRAINT check_b CHECK (b <> 'zz');
+
+ALTER TABLE list_parted2 ALTER b SET NOT NULL;
+ALTER TABLE ONLY list_parted2 ALTER b DROP NOT NULL;
+ALTER TABLE list_parted2 ADD CONSTRAINT check_b CHECK (b <> 'zz');
+ALTER TABLE ONLY list_parted2 DROP CONSTRAINT check_b;
+
+-- It's alright though, if no partitions are yet created
+CREATE TABLE parted_no_parts (a int) PARTITION BY LIST (a);
+ALTER TABLE ONLY parted_no_parts ALTER a SET NOT NULL;
+ALTER TABLE ONLY parted_no_parts ADD CONSTRAINT check_a CHECK (a > 0);
+ALTER TABLE ONLY parted_no_parts ALTER a DROP NOT NULL;
+ALTER TABLE ONLY parted_no_parts DROP CONSTRAINT check_a;
+DROP TABLE parted_no_parts;
 
 -- cannot drop inherited NOT NULL or check constraints from partition
 ALTER TABLE list_parted2 ALTER b SET NOT NULL, ADD CONSTRAINT check_a2 CHECK (a > 0);
 ALTER TABLE part_2 ALTER b DROP NOT NULL;
 ALTER TABLE part_2 DROP CONSTRAINT check_a2;
 
--- cannot drop NOT NULL or check constraints from *only* the parent
-ALTER TABLE ONLY list_parted2 ALTER a DROP NOT NULL;
-ALTER TABLE ONLY list_parted2 DROP CONSTRAINT check_a2;
+-- Doesn't make sense to add NO INHERIT constraints on partitioned tables
+ALTER TABLE list_parted2 add constraint check_b2 check (b <> 'zz') NO INHERIT;
 
 -- check that a partition cannot participate in regular inheritance
 CREATE TABLE inh_test () INHERITS (part_2);

diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
index 9d3d8de54a2ee6674c1166927fc8c6c81f02cad4..fbd1d1a8a519274859c675c59f010faf7de34f1b 100644 (file)
--- a/src/test/regress/sql/truncate.sql
+++ b/src/test/regress/sql/truncate.sql
@@ -236,7 +236,11 @@ SELECT nextval('truncate_a_id1'); -- fail, seq should have been dropped
 
 -- partitioned table
 CREATE TABLE truncparted (a int, b char) PARTITION BY LIST (a);
+-- error, can't truncate a partitioned table
+TRUNCATE ONLY truncparted;
 CREATE TABLE truncparted1 PARTITION OF truncparted FOR VALUES IN (1);
 INSERT INTO truncparted VALUES (1, 'a');
+-- error, must truncate partitions
+TRUNCATE ONLY truncparted;
 TRUNCATE truncparted;
 DROP TABLE truncparted;