On Thu, Jul 16, 2015 at 10:36 PM, Michael Paquier <michael.paqu...@gmail.com>
wrote:
>
> I had a look at this patch, and here are some minor comments:
> 1) In alter_table.sgml, you need a space here:
> [ IF NOT EXISTS ]<replaceable
Fixed.
> 2)
> + check_for_column_name_collision(targetrelation, newattname,
false);
> (void) needs to be added in front of check_for_column_name_collision
> where its return value is not checked or static code analyzers are
> surely going to complain.
Fixed.
> 3) Something minor, some lines of codes exceed 80 characters, see
> declaration of check_for_column_name_collision for example...
Fixed.
> 4) This comment needs more precisions?
> /* new name should not already exist */
> - check_for_column_name_collision(rel, colDef->colname);
> + if (!check_for_column_name_collision(rel, colDef->colname,
> if_not_exists))
> The new name can actually exist if if_not_exists is true.
>
Improved the comment.
> Except that the implementation looks sane to me.
>
Thank you for the review.
Att,
--
Fabrízio de Royes Mello
Consultoria/Coaching PostgreSQL
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diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 207fec1..5a71c3c 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -36,7 +36,7 @@ ALTER TABLE ALL IN TABLESPACE <replaceable class="PARAMETER">name</replaceable>
<phrase>where <replaceable class="PARAMETER">action</replaceable> is one of:</phrase>
- ADD [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable class="PARAMETER">collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
+ ADD [ COLUMN ] [ IF NOT EXISTS ] <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable class="PARAMETER">collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column_name</replaceable> [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">data_type</replaceable> [ COLLATE <replaceable class="PARAMETER">collation</replaceable> ] [ USING <replaceable class="PARAMETER">expression</replaceable> ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
@@ -96,11 +96,12 @@ ALTER TABLE ALL IN TABLESPACE <replaceable class="PARAMETER">name</replaceable>
<variablelist>
<varlistentry>
- <term><literal>ADD COLUMN</literal></term>
+ <term><literal>ADD COLUMN [ IF NOT EXISTS ]</literal></term>
<listitem>
<para>
This form adds a new column to the table, using the same syntax as
- <xref linkend="SQL-CREATETABLE">.
+ <xref linkend="SQL-CREATETABLE">. If <literal>IF NOT EXISTS</literal>
+ is specified and the column already exists, no error is thrown.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 1c7eded..05fbe51 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -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);
+ /* skipp 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;
}
/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 2b02a2e..ea36cdf 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -1942,6 +1942,16 @@ alter_table_cmd:
AlterTableCmd *n = makeNode(AlterTableCmd);
n->subtype = AT_AddColumn;
n->def = $2;
+ n->missing_ok = false;
+ $$ = (Node *)n;
+ }
+ /* ALTER TABLE <name> ADD IF NOT EXISTS <coldef> */
+ | ADD_P IF_P NOT EXISTS columnDef
+ {
+ AlterTableCmd *n = makeNode(AlterTableCmd);
+ n->subtype = AT_AddColumn;
+ n->def = $5;
+ n->missing_ok = true;
$$ = (Node *)n;
}
/* ALTER TABLE <name> ADD COLUMN <coldef> */
@@ -1950,6 +1960,16 @@ alter_table_cmd:
AlterTableCmd *n = makeNode(AlterTableCmd);
n->subtype = AT_AddColumn;
n->def = $3;
+ n->missing_ok = false;
+ $$ = (Node *)n;
+ }
+ /* ALTER TABLE <name> ADD COLUMN IF NOT EXISTS <coldef> */
+ | ADD_P COLUMN IF_P NOT EXISTS columnDef
+ {
+ AlterTableCmd *n = makeNode(AlterTableCmd);
+ n->subtype = AT_AddColumn;
+ n->def = $6;
+ n->missing_ok = true;
$$ = (Node *)n;
}
/* ALTER TABLE <name> ALTER [COLUMN] <colname> {SET DEFAULT <expr>|DROP DEFAULT} */
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 8d12496..028d6ed 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -2605,3 +2605,92 @@ ALTER TABLE logged1 SET UNLOGGED; -- silently do nothing
DROP TABLE logged3;
DROP TABLE logged2;
DROP TABLE logged1;
+-- test ADD COLUMN IF NOT EXISTS
+CREATE TABLE test_add_column(c1 integer);
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN c2 integer;
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN c2 integer; -- fail because c2 already exists
+ERROR: column "c2" of relation "test_add_column" already exists
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer; -- skipping because c2 already exists
+NOTICE: column "c2" of relation "test_add_column" already exists, skipping
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN c2 integer, -- fail because c2 already exists
+ ADD COLUMN c3 integer;
+ERROR: column "c2" of relation "test_add_column" already exists
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer, -- skipping because c2 already exists
+ ADD COLUMN c3 integer; -- fail because c3 already exists
+NOTICE: column "c2" of relation "test_add_column" already exists, skipping
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+ c3 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer, -- skipping because c2 already exists
+ ADD COLUMN IF NOT EXISTS c3 integer; -- skipping because c3 already exists
+NOTICE: column "c2" of relation "test_add_column" already exists, skipping
+NOTICE: column "c3" of relation "test_add_column" already exists, skipping
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+ c3 | integer |
+
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer, -- skipping because c2 already exists
+ ADD COLUMN IF NOT EXISTS c3 integer, -- skipping because c3 already exists
+ ADD COLUMN c4 integer;
+NOTICE: column "c2" of relation "test_add_column" already exists, skipping
+NOTICE: column "c3" of relation "test_add_column" already exists, skipping
+\d test_add_column
+Table "public.test_add_column"
+ Column | Type | Modifiers
+--------+---------+-----------
+ c1 | integer |
+ c2 | integer |
+ c3 | integer |
+ c4 | integer |
+
+DROP TABLE test_add_column;
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index 3feed7c..aefb5c9 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -1724,3 +1724,34 @@ ALTER TABLE logged1 SET UNLOGGED; -- silently do nothing
DROP TABLE logged3;
DROP TABLE logged2;
DROP TABLE logged1;
+
+-- test ADD COLUMN IF NOT EXISTS
+CREATE TABLE test_add_column(c1 integer);
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN c2 integer;
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN c2 integer; -- fail because c2 already exists
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer; -- skipping because c2 already exists
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN c2 integer, -- fail because c2 already exists
+ ADD COLUMN c3 integer;
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer, -- skipping because c2 already exists
+ ADD COLUMN c3 integer; -- fail because c3 already exists
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer, -- skipping because c2 already exists
+ ADD COLUMN IF NOT EXISTS c3 integer; -- skipping because c3 already exists
+\d test_add_column
+ALTER TABLE test_add_column
+ ADD COLUMN IF NOT EXISTS c2 integer, -- skipping because c2 already exists
+ ADD COLUMN IF NOT EXISTS c3 integer, -- skipping because c3 already exists
+ ADD COLUMN c4 integer;
+\d test_add_column
+DROP TABLE test_add_column;
--
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