Update MERGE docs to mention that ONLY is supported.

Commit 7103ebb7aa added support for MERGE, which included support for
inheritance hierarchies, but didn't document the fact that ONLY could
be specified before the source and/or target tables to exclude tables
inheriting from the tables specified.

Update merge.sgml to mention this, and while at it, add some
regression tests to cover it.

Dean Rasheed, reviewed by Nathan Bossart.

Backpatch to 15, where MERGE was added.

Discussion: https://postgr.es/m/CAEZATCU0XM-bJCvpJuVRU3UYNRqEBS6g4-zH%3Dj9Ye0caX8F6uQ%40mail.gmail.com

3 files changed, 115 insertions, 4 deletions

diff --git a/doc/src/sgml/ref/merge.sgml b/doc/src/sgml/ref/merge.sgml
index e07addaea42..0995fe0c046 100644
--- a/doc/src/sgml/ref/merge.sgml
+++ b/doc/src/sgml/ref/merge.sgml
@@ -22,13 +22,13 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 [ WITH <replaceable class="parameter">with_query</replaceable> [, ...] ]
-MERGE INTO <replaceable class="parameter">target_table_name</replaceable> [ [ AS ] <replaceable class="parameter">target_alias</replaceable> ]
+MERGE INTO [ ONLY ] <replaceable class="parameter">target_table_name</replaceable> [ * ] [ [ AS ] <replaceable class="parameter">target_alias</replaceable> ]
 USING <replaceable class="parameter">data_source</replaceable> ON <replaceable class="parameter">join_condition</replaceable>
 <replaceable class="parameter">when_clause</replaceable> [...]
 
 <phrase>where <replaceable class="parameter">data_source</replaceable> is:</phrase>
 
-{ <replaceable class="parameter">source_table_name</replaceable> | ( <replaceable class="parameter">source_query</replaceable> ) } [ [ AS ] <replaceable class="parameter">source_alias</replaceable> ]
+{ [ ONLY ] <replaceable class="parameter">source_table_name</replaceable> [ * ] | ( <replaceable class="parameter">source_query</replaceable> ) } [ [ AS ] <replaceable class="parameter">source_alias</replaceable> ]
 
 <phrase>and <replaceable class="parameter">when_clause</replaceable> is:</phrase>
 
@@ -129,6 +129,14 @@ DELETE
     <listitem>
      <para>
       The name (optionally schema-qualified) of the target table to merge into.
+      If <literal>ONLY</literal> is specified before the table name, matching
+      rows are updated or deleted in the named table only.  If
+      <literal>ONLY</literal> is not specified, matching rows are also updated
+      or deleted in any tables inheriting from the named table.  Optionally,
+      <literal>*</literal> can be specified after the table name to explicitly
+      indicate that descendant tables are included.  The
+      <literal>ONLY</literal> keyword and <literal>*</literal> option do not
+      affect insert actions, which always insert into the named table only.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +159,12 @@ DELETE
     <listitem>
      <para>
       The name (optionally schema-qualified) of the source table, view, or
-      transition table.
+      transition table.  If <literal>ONLY</literal> is specified before the
+      table name, matching rows are included from the named table only.  If
+      <literal>ONLY</literal> is not specified, matching rows are also included
+      from any tables inheriting from the named table.  Optionally,
+      <literal>*</literal> can be specified after the table name to explicitly
+      indicate that descendant tables are included.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/test/regress/expected/merge.out b/src/test/regress/expected/merge.out
index 9d4d0febeec..6c8a18f7b54 100644
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -1886,6 +1886,7 @@ CREATE TABLE measurement_y2007m01 (
 ) WITH (autovacuum_enabled=off);
 ALTER TABLE measurement_y2007m01 DROP COLUMN filler;
 ALTER TABLE measurement_y2007m01 INHERIT measurement;
+INSERT INTO measurement VALUES (0, '2005-07-21', 5, 15);
 CREATE OR REPLACE FUNCTION measurement_insert_trigger()
 RETURNS TRIGGER AS $$
 BEGIN
@@ -1917,15 +1918,17 @@ INSERT INTO measurement VALUES (1, '2007-01-17', 10, 10);
 SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
        tableoid       | city_id |  logdate   | peaktemp | unitsales 
 ----------------------+---------+------------+----------+-----------
+ measurement          |       0 | 07-21-2005 |        5 |        15
  measurement_y2006m02 |       1 | 02-10-2006 |       35 |        10
  measurement_y2006m02 |       1 | 02-16-2006 |       45 |        20
  measurement_y2006m03 |       1 | 03-17-2006 |       25 |        10
  measurement_y2006m03 |       1 | 03-27-2006 |       15 |        40
  measurement_y2007m01 |       1 | 01-15-2007 |       10 |        10
  measurement_y2007m01 |       1 | 01-17-2007 |       10 |        10
-(6 rows)
+(7 rows)
 
 CREATE TABLE new_measurement (LIKE measurement) WITH (autovacuum_enabled=off);
+INSERT INTO new_measurement VALUES (0, '2005-07-21', 25, 20);
 INSERT INTO new_measurement VALUES (1, '2006-03-01', 20, 10);
 INSERT INTO new_measurement VALUES (1, '2006-02-16', 50, 10);
 INSERT INTO new_measurement VALUES (2, '2006-02-10', 20, 20);
@@ -1933,6 +1936,37 @@ INSERT INTO new_measurement VALUES (1, '2006-03-27', NULL, NULL);
 INSERT INTO new_measurement VALUES (1, '2007-01-17', NULL, NULL);
 INSERT INTO new_measurement VALUES (1, '2007-01-15', 5, NULL);
 INSERT INTO new_measurement VALUES (1, '2007-01-16', 10, 10);
+BEGIN;
+MERGE INTO ONLY measurement m
+ USING new_measurement nm ON
+      (m.city_id = nm.city_id and m.logdate=nm.logdate)
+WHEN MATCHED AND nm.peaktemp IS NULL THEN DELETE
+WHEN MATCHED THEN UPDATE
+     SET peaktemp = greatest(m.peaktemp, nm.peaktemp),
+        unitsales = m.unitsales + coalesce(nm.unitsales, 0)
+WHEN NOT MATCHED THEN INSERT
+     (city_id, logdate, peaktemp, unitsales)
+   VALUES (city_id, logdate, peaktemp, unitsales);
+SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate, peaktemp;
+       tableoid       | city_id |  logdate   | peaktemp | unitsales 
+----------------------+---------+------------+----------+-----------
+ measurement          |       0 | 07-21-2005 |       25 |        35
+ measurement_y2006m02 |       1 | 02-10-2006 |       35 |        10
+ measurement_y2006m02 |       1 | 02-16-2006 |       45 |        20
+ measurement_y2006m02 |       1 | 02-16-2006 |       50 |        10
+ measurement_y2006m03 |       1 | 03-01-2006 |       20 |        10
+ measurement_y2006m03 |       1 | 03-17-2006 |       25 |        10
+ measurement_y2006m03 |       1 | 03-27-2006 |       15 |        40
+ measurement_y2006m03 |       1 | 03-27-2006 |          |          
+ measurement_y2007m01 |       1 | 01-15-2007 |        5 |          
+ measurement_y2007m01 |       1 | 01-15-2007 |       10 |        10
+ measurement_y2007m01 |       1 | 01-16-2007 |       10 |        10
+ measurement_y2007m01 |       1 | 01-17-2007 |       10 |        10
+ measurement_y2007m01 |       1 | 01-17-2007 |          |          
+ measurement_y2006m02 |       2 | 02-10-2006 |       20 |        20
+(14 rows)
+
+ROLLBACK;
 MERGE into measurement m
  USING new_measurement nm ON
       (m.city_id = nm.city_id and m.logdate=nm.logdate)
@@ -1946,6 +1980,7 @@ WHEN NOT MATCHED THEN INSERT
 SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
        tableoid       | city_id |  logdate   | peaktemp | unitsales 
 ----------------------+---------+------------+----------+-----------
+ measurement          |       0 | 07-21-2005 |       25 |        35
  measurement_y2006m02 |       1 | 02-10-2006 |       35 |        10
  measurement_y2006m02 |       1 | 02-16-2006 |       50 |        30
  measurement_y2006m03 |       1 | 03-01-2006 |       20 |        10
@@ -1953,8 +1988,37 @@ SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
  measurement_y2007m01 |       1 | 01-15-2007 |       10 |        10
  measurement_y2007m01 |       1 | 01-16-2007 |       10 |        10
  measurement_y2006m02 |       2 | 02-10-2006 |       20 |        20
+(8 rows)
+
+BEGIN;
+MERGE INTO new_measurement nm
+ USING ONLY measurement m ON
+      (nm.city_id = m.city_id and nm.logdate=m.logdate)
+WHEN MATCHED THEN DELETE;
+SELECT * FROM new_measurement ORDER BY city_id, logdate;
+ city_id |  logdate   | peaktemp | unitsales 
+---------+------------+----------+-----------
+       1 | 02-16-2006 |       50 |        10
+       1 | 03-01-2006 |       20 |        10
+       1 | 03-27-2006 |          |          
+       1 | 01-15-2007 |        5 |          
+       1 | 01-16-2007 |       10 |        10
+       1 | 01-17-2007 |          |          
+       2 | 02-10-2006 |       20 |        20
 (7 rows)
 
+ROLLBACK;
+MERGE INTO new_measurement nm
+ USING measurement m ON
+      (nm.city_id = m.city_id and nm.logdate=m.logdate)
+WHEN MATCHED THEN DELETE;
+SELECT * FROM new_measurement ORDER BY city_id, logdate;
+ city_id |  logdate   | peaktemp | unitsales 
+---------+------------+----------+-----------
+       1 | 03-27-2006 |          |          
+       1 | 01-17-2007 |          |          
+(2 rows)
+
 DROP TABLE measurement, new_measurement CASCADE;
 NOTICE:  drop cascades to 3 other objects
 DETAIL:  drop cascades to table measurement_y2006m02
diff --git a/src/test/regress/sql/merge.sql b/src/test/regress/sql/merge.sql
index e5754f3cd9c..98fe1040bd4 100644
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -1231,6 +1231,7 @@ CREATE TABLE measurement_y2007m01 (
 ) WITH (autovacuum_enabled=off);
 ALTER TABLE measurement_y2007m01 DROP COLUMN filler;
 ALTER TABLE measurement_y2007m01 INHERIT measurement;
+INSERT INTO measurement VALUES (0, '2005-07-21', 5, 15);
 
 CREATE OR REPLACE FUNCTION measurement_insert_trigger()
 RETURNS TRIGGER AS $$
@@ -1264,6 +1265,7 @@ INSERT INTO measurement VALUES (1, '2007-01-17', 10, 10);
 SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
 
 CREATE TABLE new_measurement (LIKE measurement) WITH (autovacuum_enabled=off);
+INSERT INTO new_measurement VALUES (0, '2005-07-21', 25, 20);
 INSERT INTO new_measurement VALUES (1, '2006-03-01', 20, 10);
 INSERT INTO new_measurement VALUES (1, '2006-02-16', 50, 10);
 INSERT INTO new_measurement VALUES (2, '2006-02-10', 20, 20);
@@ -1272,6 +1274,21 @@ INSERT INTO new_measurement VALUES (1, '2007-01-17', NULL, NULL);
 INSERT INTO new_measurement VALUES (1, '2007-01-15', 5, NULL);
 INSERT INTO new_measurement VALUES (1, '2007-01-16', 10, 10);
 
+BEGIN;
+MERGE INTO ONLY measurement m
+ USING new_measurement nm ON
+      (m.city_id = nm.city_id and m.logdate=nm.logdate)
+WHEN MATCHED AND nm.peaktemp IS NULL THEN DELETE
+WHEN MATCHED THEN UPDATE
+     SET peaktemp = greatest(m.peaktemp, nm.peaktemp),
+        unitsales = m.unitsales + coalesce(nm.unitsales, 0)
+WHEN NOT MATCHED THEN INSERT
+     (city_id, logdate, peaktemp, unitsales)
+   VALUES (city_id, logdate, peaktemp, unitsales);
+
+SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate, peaktemp;
+ROLLBACK;
+
 MERGE into measurement m
  USING new_measurement nm ON
       (m.city_id = nm.city_id and m.logdate=nm.logdate)
@@ -1284,6 +1301,23 @@ WHEN NOT MATCHED THEN INSERT
    VALUES (city_id, logdate, peaktemp, unitsales);
 
 SELECT tableoid::regclass, * FROM measurement ORDER BY city_id, logdate;
+
+BEGIN;
+MERGE INTO new_measurement nm
+ USING ONLY measurement m ON
+      (nm.city_id = m.city_id and nm.logdate=m.logdate)
+WHEN MATCHED THEN DELETE;
+
+SELECT * FROM new_measurement ORDER BY city_id, logdate;
+ROLLBACK;
+
+MERGE INTO new_measurement nm
+ USING measurement m ON
+      (nm.city_id = m.city_id and nm.logdate=m.logdate)
+WHEN MATCHED THEN DELETE;
+
+SELECT * FROM new_measurement ORDER BY city_id, logdate;
+
 DROP TABLE measurement, new_measurement CASCADE;
 DROP FUNCTION measurement_insert_trigger();