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Rearrange "add column" logic to merge columns at exec time.

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The previous coding set attinhcount too high in some cases, resulting in
an undumpable, undroppable column.  Per bug #5856, reported by Naoya
Anzai.  See also commit 31b6fc06d8, which
fixes a similar bug in ALTER TABLE .. ADD CONSTRAINT.

Patch by Noah Misch.
This commit is contained in:
Robert Haas
2011-04-03 21:52:47 -04:00
parent cabf5d84b6
commit 6c57239985
4 changed files with 119 additions and 73 deletions
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161
src/backend/commands/tablecmds.c
View File

@ -285,16 +285,15 @@ static void ATSimplePermissions(Relation rel, int allowed_targets);
static void ATWrongRelkindError(Relation rel, int allowed_targets);
static void ATSimpleRecursion(List **wqueue, Relation rel,
AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode);
static void ATOneLevelRecursion(List **wqueue, Relation rel,
AlterTableCmd *cmd, LOCKMODE lockmode);
static void ATTypedTableRecursion(List **wqueue, Relation rel, AlterTableCmd *cmd,
LOCKMODE lockmode);
static List *find_typed_table_dependencies(Oid typeOid, const char *typeName,
DropBehavior behavior);
static void ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
AlterTableCmd *cmd, LOCKMODE lockmode);
static void ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
ColumnDef *colDef, bool isOid, LOCKMODE lockmode);
static void ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
ColumnDef *colDef, bool isOid,
bool recurse, bool recursing, LOCKMODE lockmode);
static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid, Oid collid);
static void ATPrepAddOids(List **wqueue, Relation rel, bool recurse,
AlterTableCmd *cmd, LOCKMODE lockmode);
@ -2775,15 +2774,15 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
case AT_AddColumn: /* ADD COLUMN */
ATSimplePermissions(rel,
ATT_TABLE|ATT_COMPOSITE_TYPE|ATT_FOREIGN_TABLE);
/* Performs own recursion */
ATPrepAddColumn(wqueue, rel, recurse, recursing, cmd, lockmode);
/* Recursion occurs during execution phase */
pass = AT_PASS_ADD_COL;
break;
case AT_AddColumnToView: /* add column via CREATE OR REPLACE
* VIEW */
ATSimplePermissions(rel, ATT_VIEW);
/* Performs own recursion */
ATPrepAddColumn(wqueue, rel, recurse, recursing, cmd, lockmode);
/* Recursion occurs during execution phase */
pass = AT_PASS_ADD_COL;
break;
case AT_ColumnDefault: /* ALTER COLUMN DEFAULT */
@ -2885,9 +2884,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
break;
case AT_AddOids: /* SET WITH OIDS */
ATSimplePermissions(rel, ATT_TABLE);
/* Performs own recursion */
if (!rel->rd_rel->relhasoids || recursing)
ATPrepAddOids(wqueue, rel, recurse, cmd, lockmode);
/* Recursion occurs during execution phase */
pass = AT_PASS_ADD_COL;
break;
case AT_DropOids: /* SET WITHOUT OIDS */
@ -3043,7 +3042,12 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
case AT_AddColumn: /* ADD COLUMN */
case AT_AddColumnToView: /* add column via CREATE OR REPLACE
* VIEW */
ATExecAddColumn(tab, rel, (ColumnDef *) cmd->def, false, lockmode);
ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
false, false, false, lockmode);
break;
case AT_AddColumnRecurse:
ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
false, true, false, lockmode);
break;
case AT_ColumnDefault: /* ALTER COLUMN DEFAULT */
ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
@ -3121,7 +3125,14 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
case AT_AddOids: /* SET WITH OIDS */
/* Use the ADD COLUMN code, unless prep decided to do nothing */
if (cmd->def != NULL)
ATExecAddColumn(tab, rel, (ColumnDef *) cmd->def, true, lockmode);
ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
true, false, false, lockmode);
break;
case AT_AddOidsRecurse: /* SET WITH OIDS */
/* Use the ADD COLUMN code, unless prep decided to do nothing */
if (cmd->def != NULL)
ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
true, true, false, lockmode);
break;
case AT_DropOids: /* SET WITHOUT OIDS */
@ -3842,37 +3853,6 @@ ATSimpleRecursion(List **wqueue, Relation rel,
}
}
/*
* ATOneLevelRecursion
*
* Here, we visit only direct inheritance children. It is expected that
* the command's prep routine will recurse again to find indirect children.
* When using this technique, a multiply-inheriting child will be visited
* multiple times.
*/
static void
ATOneLevelRecursion(List **wqueue, Relation rel,
AlterTableCmd *cmd, LOCKMODE lockmode)
{
Oid relid = RelationGetRelid(rel);
ListCell *child;
List *children;
children = find_inheritance_children(relid, lockmode);
foreach(child, children)
{
Oid childrelid = lfirst_oid(child);
Relation childrel;
/* find_inheritance_children already got lock */
childrel = relation_open(childrelid, NoLock);
CheckTableNotInUse(childrel, "ALTER TABLE");
ATPrepCmd(wqueue, childrel, cmd, true, true, lockmode);
relation_close(childrel, NoLock);
}
}
/*
* ATTypedTableRecursion
*
@ -4060,6 +4040,12 @@ find_typed_table_dependencies(Oid typeOid, const char *typeName, DropBehavior be
* CHECK, NOT NULL, and FOREIGN KEY constraints will be removed from the
* AT_AddColumn AlterTableCmd by parse_utilcmd.c and added as independent
* AlterTableCmd's.
*
* ADD COLUMN cannot use the normal ALTER TABLE recursion mechanism, because we
* have to decide at runtime whether to recurse or not depending on whether we
* actually add a column or merely merge with an existing column. (We can't
* check this in a static pre-pass because it won't handle multiple inheritance
* situations correctly.)
*/
static void
ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
@ -4070,43 +4056,17 @@ ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("cannot add column to typed table")));
/*
* Recurse to add the column to child classes, if requested.
*
* We must recurse one level at a time, so that multiply-inheriting
* children are visited the right number of times and end up with the
* right attinhcount.
*/
if (recurse)
{
AlterTableCmd *childCmd = copyObject(cmd);
ColumnDef *colDefChild = (ColumnDef *) childCmd->def;
/* Child should see column as singly inherited */
colDefChild->inhcount = 1;
colDefChild->is_local = false;
ATOneLevelRecursion(wqueue, rel, childCmd, lockmode);
}
else
{
/*
* If we are told not to recurse, there had better not be any child
* tables; else the addition would put them out of step.
*/
if (find_inheritance_children(RelationGetRelid(rel), NoLock) != NIL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
errmsg("column must be added to child tables too")));
}
if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
ATTypedTableRecursion(wqueue, rel, cmd, lockmode);
if (recurse)
cmd->subtype = AT_AddColumnRecurse;
}
static void
ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
ColumnDef *colDef, bool isOid, LOCKMODE lockmode)
ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
ColumnDef *colDef, bool isOid,
bool recurse, bool recursing, LOCKMODE lockmode)
{
Oid myrelid = RelationGetRelid(rel);
Relation pgclass,
@ -4121,12 +4081,20 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
Oid collOid;
Form_pg_type tform;
Expr *defval;
List *children;
ListCell *child;
/* At top level, permission check was done in ATPrepCmd, else do it */
if (recursing)
ATSimplePermissions(rel, ATT_TABLE);
attrdesc = heap_open(AttributeRelationId, RowExclusiveLock);
/*
* Are we adding the column to a recursion child? If so, check whether to
* merge with an existing definition for the column.
* merge with an existing definition for the column. If we do merge,
* we must not recurse. Children will already have the column, and
* recursing into them would mess up attinhcount.
*/
if (colDef->inhcount > 0)
{
@ -4389,6 +4357,50 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
* Add needed dependency entries for the new column.
*/
add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid, attribute.attcollation);
/*
* 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
* use find_all_inheritors to do it in one pass.
*/
children = find_inheritance_children(RelationGetRelid(rel), lockmode);
/*
* If we are told not to recurse, there had better not be any child
* tables; else the addition would put them out of step.
*/
if (children && !recurse)
ereport(ERROR,
(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
errmsg("column must be added to child tables too")));
/* Children should see column as singly inherited */
if (!recursing)
{
colDef = copyObject(colDef);
colDef->inhcount = 1;
colDef->is_local = false;
}
foreach(child, children)
{
Oid childrelid = lfirst_oid(child);
Relation childrel;
AlteredTableInfo *childtab;
/* find_inheritance_children already got lock */
childrel = heap_open(childrelid, NoLock);
CheckTableNotInUse(childrel, "ALTER TABLE");
/* Find or create work queue entry for this table */
childtab = ATGetQueueEntry(wqueue, childrel);
/* Recurse to child */
ATExecAddColumn(wqueue, childtab, childrel,
colDef, isOid, recurse, true, lockmode);
heap_close(childrel, NoLock);
}
}
/*
@ -4440,6 +4452,9 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
cmd->def = (Node *) cdef;
}
ATPrepAddColumn(wqueue, rel, recurse, false, cmd, lockmode);
if (recurse)
cmd->subtype = AT_AddOidsRecurse;
}
/*