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Add IF NOT EXISTS processing to ALTER TABLE ADD COLUMN

Browse Source 
Fabrízio de Royes Mello, reviewed by Payal Singh, Alvaro Herrera and
Michael Paquier.
This commit is contained in:
Andrew Dunstan
2015-07-29 21:30:00 -04:00
parent 632cd9f892
commit 2cd40adb85
5 changed files with 182 additions and 18 deletions
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52
src/backend/commands/tablecmds.c
View File

@ -328,8 +328,9 @@ static void ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recu
bool is_view, AlterTableCmd *cmd, LOCKMODE lockmode);
static ObjectAddress ATExecAddColumn(List **wqueue, AlteredTableInfo *tab,
Relation rel, ColumnDef *colDef, bool isOid,
bool recurse, bool recursing, LOCKMODE lockmode);
static void check_for_column_name_collision(Relation rel, const char *colname);
bool recurse, bool recursing, bool if_not_exists, LOCKMODE lockmode);
static bool check_for_column_name_collision(Relation rel, const char *colname,
bool if_not_exists);
static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid);
static void add_column_collation_dependency(Oid relid, int32 attnum, Oid collid);
static void ATPrepAddOids(List **wqueue, Relation rel, bool recurse,
@ -2304,7 +2305,7 @@ renameatt_internal(Oid myrelid,
oldattname)));
/* new name should not already exist */
check_for_column_name_collision(targetrelation, newattname);
(void) check_for_column_name_collision(targetrelation, newattname, false);
/* apply the update */
namestrcpy(&(attform->attname), newattname);
@ -3455,11 +3456,11 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
case AT_AddColumnToView: /* add column via CREATE OR REPLACE
* VIEW */
address = ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
false, false, false, lockmode);
false, false, false, false, lockmode);
break;
case AT_AddColumnRecurse:
address = ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
false, true, false, lockmode);
false, true, false, cmd->missing_ok, lockmode);
break;
case AT_ColumnDefault: /* ALTER COLUMN DEFAULT */
address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
@ -3572,14 +3573,14 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
if (cmd->def != NULL)
address =
ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
true, false, false, lockmode);
true, false, false, cmd->missing_ok, lockmode);
break;
case AT_AddOidsRecurse: /* SET WITH OIDS */
/* Use the ADD COLUMN code, unless prep decided to do nothing */
if (cmd->def != NULL)
address =
ATExecAddColumn(wqueue, tab, rel, (ColumnDef *) cmd->def,
true, true, false, lockmode);
true, true, false, cmd->missing_ok, lockmode);
break;
case AT_DropOids: /* SET WITHOUT OIDS */
@ -4677,7 +4678,7 @@ ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
static ObjectAddress
ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
ColumnDef *colDef, bool isOid,
bool recurse, bool recursing, LOCKMODE lockmode)
bool recurse, bool recursing, bool if_not_exists, LOCKMODE lockmode)
{
Oid myrelid = RelationGetRelid(rel);
Relation pgclass,
@ -4771,8 +4772,14 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
elog(ERROR, "cache lookup failed for relation %u", myrelid);
relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
/* new name should not already exist */
check_for_column_name_collision(rel, colDef->colname);
/* skip if the name already exists and if_not_exists is true */
if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
{
heap_close(attrdesc, RowExclusiveLock);
heap_freetuple(reltup);
heap_close(pgclass, RowExclusiveLock);
return InvalidObjectAddress;
}
/* Determine the new attribute's number */
if (isOid)
@ -5002,7 +5009,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
/* Recurse to child; return value is ignored */
ATExecAddColumn(wqueue, childtab, childrel,
colDef, isOid, recurse, true, lockmode);
colDef, isOid, recurse, true,
if_not_exists, lockmode);
heap_close(childrel, NoLock);
}
@ -5013,10 +5021,11 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
/*
* If a new or renamed column will collide with the name of an existing
* column, error out.
* column and if_not_exists is false then error out, else do nothing.
*/
static void
check_for_column_name_collision(Relation rel, const char *colname)
static bool
check_for_column_name_collision(Relation rel, const char *colname,
bool if_not_exists)
{
HeapTuple attTuple;
int attnum;
@ -5029,7 +5038,7 @@ check_for_column_name_collision(Relation rel, const char *colname)
ObjectIdGetDatum(RelationGetRelid(rel)),
PointerGetDatum(colname));
if (!HeapTupleIsValid(attTuple))
return;
return true;
attnum = ((Form_pg_attribute) GETSTRUCT(attTuple))->attnum;
ReleaseSysCache(attTuple);
@ -5045,10 +5054,23 @@ check_for_column_name_collision(Relation rel, const char *colname)
errmsg("column name \"%s\" conflicts with a system column name",
colname)));
else
{
if (if_not_exists)
{
ereport(NOTICE,
(errcode(ERRCODE_DUPLICATE_COLUMN),
errmsg("column \"%s\" of relation \"%s\" already exists, skipping",
colname, RelationGetRelationName(rel))));
return false;
}
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_COLUMN),
errmsg("column \"%s\" of relation \"%s\" already exists",
colname, RelationGetRelationName(rel))));
}
return true;
}
/*