Fix handling of inherited check constraints in ALTER COLUMN TYPE.

This case got broken in 8.4 by the addition of an error check that
complains if ALTER TABLE ONLY is used on a table that has children.
We do use ONLY for this situation, but it's okay because the necessary
recursion occurs at a higher level.  So we need to have a separate
flag to suppress recursion without making the error check.

Reported and patched by Pavan Deolasee, with some editorial adjustments by
me.  Back-patch to 8.4, since this is a regression of functionality that
worked in earlier branches.

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d963f6985b8557f70241c58e7e3aba000bd836e0..d88e3dee3faa905b899e67dc4782691582f14772 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -335,13 +335,15 @@ static void ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
               IndexStmt *stmt, bool is_rebuild, LOCKMODE lockmode);
 static void ATExecAddConstraint(List **wqueue,
                    AlteredTableInfo *tab, Relation rel,
-                Constraint *newConstraint, bool recurse, LOCKMODE lockmode);
+                   Constraint *newConstraint, bool recurse, bool is_readd,
+                   LOCKMODE lockmode);
 static void ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
                         IndexStmt *stmt, LOCKMODE lockmode);
 static void ATAddCheckConstraint(List **wqueue,
                     AlteredTableInfo *tab, Relation rel,
                     Constraint *constr,
-                    bool recurse, bool recursing, LOCKMODE lockmode);
+                    bool recurse, bool recursing, bool is_readd,
+                    LOCKMODE lockmode);
 static void ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
                          Constraint *fkconstraint, LOCKMODE lockmode);
 static void ATExecDropConstraint(Relation rel, const char *constrName,
@@ -2757,6 +2759,7 @@ AlterTableGetLockLevel(List *cmds)
            case AT_ColumnDefault:
            case AT_ProcessedConstraint:        /* becomes AT_AddConstraint */
            case AT_AddConstraintRecurse:       /* becomes AT_AddConstraint */
+           case AT_ReAddConstraint:            /* becomes AT_AddConstraint */
            case AT_EnableTrig:
            case AT_EnableAlwaysTrig:
            case AT_EnableReplicaTrig:
@@ -3248,11 +3251,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
            break;
        case AT_AddConstraint:  /* ADD CONSTRAINT */
            ATExecAddConstraint(wqueue, tab, rel, (Constraint *) cmd->def,
-                               false, lockmode);
+                               false, false, lockmode);
            break;
        case AT_AddConstraintRecurse:   /* ADD CONSTRAINT with recursion */
            ATExecAddConstraint(wqueue, tab, rel, (Constraint *) cmd->def,
-                               true, lockmode);
+                               true, false, lockmode);
+           break;
+       case AT_ReAddConstraint:    /* Re-add pre-existing check constraint */
+           ATExecAddConstraint(wqueue, tab, rel, (Constraint *) cmd->def,
+                               false, true, lockmode);
            break;
        case AT_AddIndexConstraint:     /* ADD CONSTRAINT USING INDEX */
            ATExecAddIndexConstraint(tab, rel, (IndexStmt *) cmd->def, lockmode);
@@ -5499,7 +5506,8 @@ ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
  */
 static void
 ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
-                 Constraint *newConstraint, bool recurse, LOCKMODE lockmode)
+                   Constraint *newConstraint, bool recurse, bool is_readd,
+                   LOCKMODE lockmode)
 {
    Assert(IsA(newConstraint, Constraint));
 
@@ -5512,7 +5520,8 @@ ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
    {
        case CONSTR_CHECK:
            ATAddCheckConstraint(wqueue, tab, rel,
-                                newConstraint, recurse, false, lockmode);
+                                newConstraint, recurse, false, is_readd,
+                                lockmode);
            break;
 
        case CONSTR_FOREIGN:
@@ -5564,11 +5573,18 @@ ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
  * AddRelationNewConstraints would normally assign different names to the
  * child constraints.  To fix that, we must capture the name assigned at
  * the parent table and pass that down.
+ *
+ * When re-adding a previously existing constraint (during ALTER COLUMN TYPE),
+ * we don't need to recurse here, because recursion will be carried out at a
+ * higher level; the constraint name issue doesn't apply because the names
+ * have already been assigned and are just being re-used.  We need a separate
+ * "is_readd" flag for that; just setting recurse=false would result in an
+ * error if there are child tables.
  */
 static void
 ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
                     Constraint *constr, bool recurse, bool recursing,
-                    LOCKMODE lockmode)
+                    bool is_readd, LOCKMODE lockmode)
 {
    List       *newcons;
    ListCell   *lcon;
@@ -5633,9 +5649,11 @@ ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
        return;
 
    /*
-    * Adding a NO INHERIT constraint? No need to find our children
+    * If adding a NO INHERIT constraint, no need to find our children.
+    * Likewise, in a re-add operation, we don't need to recurse (that will be
+    * handled at higher levels).
     */
-   if (constr->is_no_inherit)
+   if (constr->is_no_inherit || is_readd)
        return;
 
    /*
@@ -5670,7 +5688,7 @@ ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 
        /* Recurse to child */
        ATAddCheckConstraint(wqueue, childtab, childrel,
-                            constr, recurse, true, lockmode);
+                            constr, recurse, true, is_readd, lockmode);
 
        heap_close(childrel, NoLock);
    }
@@ -7884,6 +7902,10 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
    /*
     * Attach each generated command to the proper place in the work queue.
     * Note this could result in creation of entirely new work-queue entries.
+    *
+    * Also note that we have to tweak the command subtypes, because it turns
+    * out that re-creation of indexes and constraints has to act a bit
+    * differently from initial creation.
     */
    foreach(list_item, querytree_list)
    {
@@ -7941,6 +7963,7 @@ ATPostAlterTypeParse(Oid oldId, char *cmd,
                                if (con->contype == CONSTR_FOREIGN &&
                                    !rewrite && !tab->rewrite)
                                    TryReuseForeignKey(oldId, con);
+                               cmd->subtype = AT_ReAddConstraint;
                                tab->subcmds[AT_PASS_OLD_CONSTR] =
                                    lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
                                break;

diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index e6f1df7feb0f12759a94616de90a5375798e6ee5..2997a2ab69e844d1cf3615291587dd847e42a747 100644 (file)
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1227,7 +1227,9 @@ typedef enum AlterTableType
    AT_DropInherit,             /* NO INHERIT parent */
    AT_AddOf,                   /* OF <type_name> */
    AT_DropOf,                  /* NOT OF */
-   AT_GenericOptions           /* OPTIONS (...) */
+   AT_GenericOptions,          /* OPTIONS (...) */
+   /* this will be in a more natural position in 9.3: */
+   AT_ReAddConstraint          /* internal to commands/tablecmds.c */
 } AlterTableType;
 
 typedef struct AlterTableCmd   /* one subcommand of an ALTER TABLE */

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 60ced86f490767dc7842987fa9375b37bce085ee..8e9d22836ac63eabcfba91a01c7254747d50127d 100644 (file)
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -1804,6 +1804,28 @@ where oid = 'test_storage'::regclass;
  t
 (1 row)
 
+-- ALTER TYPE with a check constraint and a child table (bug before Nov 2012)
+CREATE TABLE test_inh_check (a float check (a > 10.2));
+CREATE TABLE test_inh_check_child() INHERITS(test_inh_check);
+ALTER TABLE test_inh_check ALTER COLUMN a TYPE numeric;
+\d test_inh_check
+Table "public.test_inh_check"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | numeric | 
+Check constraints:
+    "test_inh_check_a_check" CHECK (a::double precision > 10.2::double precision)
+Number of child tables: 1 (Use \d+ to list them.)
+
+\d test_inh_check_child
+Table "public.test_inh_check_child"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | numeric | 
+Check constraints:
+    "test_inh_check_a_check" CHECK (a::double precision > 10.2::double precision)
+Inherits: test_inh_check
+
 --
 -- lock levels
 --

diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index 0f9cb380e1662749295cc2fca959346a8d1b84c6..dcf8121d70c1dd7ac2db2ffaf58ce20bca2ec742 100644 (file)
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -1239,6 +1239,13 @@ select reltoastrelid <> 0 as has_toast_table
 from pg_class
 where oid = 'test_storage'::regclass;
 
+-- ALTER TYPE with a check constraint and a child table (bug before Nov 2012)
+CREATE TABLE test_inh_check (a float check (a > 10.2));
+CREATE TABLE test_inh_check_child() INHERITS(test_inh_check);
+ALTER TABLE test_inh_check ALTER COLUMN a TYPE numeric;
+\d test_inh_check
+\d test_inh_check_child
+
 --
 -- lock levels
 --