pg_partition_ancestors

Adds another introspection feature for partitioning, necessary for
further psql patches.

Reviewed-by: Michaël Paquier
Discussion: https://postgr.es/m/20190226222757.GA31622@alvherre.pgsql

doc/src/sgml/func.sgml

@@ -20274,6 +20274,17 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
         their partitions, and so on.
        </entry>
       </row>
+      <row>
+       <entry>
+        <indexterm><primary>pg_partition_ancestors</primary></indexterm>
+        <literal><function>pg_partition_ancestors(<type>regclass</type>)</function></literal>
+       </entry>
+       <entry><type>setof regclass</type></entry>
+       <entry>
+        List the ancestor relations of the given partition,
+        including the partition itself.
+       </entry>
+      </row>
       <row>
        <entry>
         <indexterm><primary>pg_partition_root</primary></indexterm>

src/backend/utils/adt/partitionfuncs.c

@@ -201,3 +201,52 @@ pg_partition_root(PG_FUNCTION_ARGS)
 	Assert(OidIsValid(rootrelid));
 	PG_RETURN_OID(rootrelid);
 }
+
+/*
+ * pg_partition_ancestors
+ *
+ * Produces a view with one row per ancestor of the given partition,
+ * including the input relation itself.
+ */
+Datum
+pg_partition_ancestors(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+	FuncCallContext *funcctx;
+	ListCell  **next;
+
+	if (SRF_IS_FIRSTCALL())
+	{
+		MemoryContext oldcxt;
+		List	   *ancestors;
+
+		funcctx = SRF_FIRSTCALL_INIT();
+
+		if (!check_rel_can_be_partition(relid))
+			SRF_RETURN_DONE(funcctx);
+
+		oldcxt = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		ancestors = get_partition_ancestors(relid);
+		ancestors = lcons_oid(relid, ancestors);
+
+		next = (ListCell **) palloc(sizeof(ListCell *));
+		*next = list_head(ancestors);
+		funcctx->user_fctx = (void *) next;
+
+		MemoryContextSwitchTo(oldcxt);
+	}
+
+	funcctx = SRF_PERCALL_SETUP();
+	next = (ListCell **) funcctx->user_fctx;
+
+	if (*next != NULL)
+	{
+		Oid			relid = lfirst_oid(*next);
+
+		*next = lnext(*next);
+		SRF_RETURN_NEXT(funcctx, ObjectIdGetDatum(relid));
+	}
+
+	SRF_RETURN_DONE(funcctx);
+}

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201902161
+#define CATALOG_VERSION_NO	201903041
 
 #endif

src/include/catalog/pg_proc.dat

@@ -10528,6 +10528,11 @@
   proargmodes => '{i,o,o,o,o}',
   proargnames => '{rootrelid,relid,parentrelid,isleaf,level}',
   prosrc => 'pg_partition_tree' },
+{ oid => '3425', descr => 'view ancestors of the partition',
+  proname => 'pg_partition_ancestors', prorows => '10', proretset => 't',
+  provolatile => 'v', prorettype => 'regclass', proargtypes => 'regclass',
+  proallargtypes => '{regclass,regclass}', proargmodes => '{i,o}',
+  proargnames => '{partitionid,relid}', prosrc => 'pg_partition_ancestors' },
 
 # function to get the top-most partition root parent
 { oid => '3424', descr => 'get top-most partition root parent',

src/test/regress/expected/partition_info.out

@@ -11,6 +11,16 @@ SELECT * FROM pg_partition_tree(0);
 -------+-------------+--------+-------
 (0 rows)
 
+SELECT * FROM pg_partition_ancestors(NULL);
+ relid 
+-------
+(0 rows)
+
+SELECT * FROM pg_partition_ancestors(0);
+ relid 
+-------
+(0 rows)
+
 SELECT pg_partition_root(NULL);
  pg_partition_root 
 -------------------
@@ -92,6 +102,21 @@ SELECT relid, parentrelid, level, isleaf
  ptif_test3 | ptif_test   |     0 | f
 (1 row)
 
+-- List all ancestors of root and leaf tables
+SELECT * FROM pg_partition_ancestors('ptif_test01');
+    relid    
+-------------
+ ptif_test01
+ ptif_test0
+ ptif_test
+(3 rows)
+
+SELECT * FROM pg_partition_ancestors('ptif_test');
+   relid   
+-----------
+ ptif_test
+(1 row)
+
 -- List all members using pg_partition_root with leaf table reference
 SELECT relid, parentrelid, level, isleaf
   FROM pg_partition_tree(pg_partition_root('ptif_test01')) p
@@ -164,6 +189,21 @@ SELECT relid, parentrelid, level, isleaf
  ptif_test11_index | ptif_test1_index |     2 | t
 (7 rows)
 
+-- List all ancestors of root and leaf indexes
+SELECT * FROM pg_partition_ancestors('ptif_test01_index');
+       relid       
+-------------------
+ ptif_test01_index
+ ptif_test0_index
+ ptif_test_index
+(3 rows)
+
+SELECT * FROM pg_partition_ancestors('ptif_test_index');
+      relid      
+-----------------
+ ptif_test_index
+(1 row)
+
 DROP TABLE ptif_test;
 -- Table that is not part of any partition tree is not listed.
 CREATE TABLE ptif_normal_table(a int);
@@ -173,6 +213,11 @@ SELECT relid, parentrelid, level, isleaf
 -------+-------------+-------+--------
 (0 rows)
 
+SELECT * FROM pg_partition_ancestors('ptif_normal_table');
+ relid 
+-------
+(0 rows)
+
 SELECT pg_partition_root('ptif_normal_table');
  pg_partition_root 
 -------------------
@@ -207,6 +252,26 @@ SELECT * FROM pg_partition_tree('ptif_li_child');
 -------+-------------+--------+-------
 (0 rows)
 
+SELECT * FROM pg_partition_ancestors('ptif_test_view');
+ relid 
+-------
+(0 rows)
+
+SELECT * FROM pg_partition_ancestors('ptif_test_matview');
+ relid 
+-------
+(0 rows)
+
+SELECT * FROM pg_partition_ancestors('ptif_li_parent');
+ relid 
+-------
+(0 rows)
+
+SELECT * FROM pg_partition_ancestors('ptif_li_child');
+ relid 
+-------
+(0 rows)
+
 SELECT pg_partition_root('ptif_test_view');
  pg_partition_root 
 -------------------

src/test/regress/sql/partition_info.sql

@@ -3,6 +3,8 @@
 --
 SELECT * FROM pg_partition_tree(NULL);
 SELECT * FROM pg_partition_tree(0);
+SELECT * FROM pg_partition_ancestors(NULL);
+SELECT * FROM pg_partition_ancestors(0);
 SELECT pg_partition_root(NULL);
 SELECT pg_partition_root(0);
 
@@ -50,6 +52,9 @@ SELECT relid, parentrelid, level, isleaf
 SELECT relid, parentrelid, level, isleaf
   FROM pg_partition_tree('ptif_test3') p
   JOIN pg_class c ON (p.relid = c.oid);
+-- List all ancestors of root and leaf tables
+SELECT * FROM pg_partition_ancestors('ptif_test01');
+SELECT * FROM pg_partition_ancestors('ptif_test');
 -- List all members using pg_partition_root with leaf table reference
 SELECT relid, parentrelid, level, isleaf
   FROM pg_partition_tree(pg_partition_root('ptif_test01')) p
@@ -74,6 +79,9 @@ SELECT relid, parentrelid, level, isleaf
 SELECT relid, parentrelid, level, isleaf
   FROM pg_partition_tree(pg_partition_root('ptif_test01_index')) p
   JOIN pg_class c ON (p.relid = c.oid);
+-- List all ancestors of root and leaf indexes
+SELECT * FROM pg_partition_ancestors('ptif_test01_index');
+SELECT * FROM pg_partition_ancestors('ptif_test_index');
 
 DROP TABLE ptif_test;
 
@@ -81,6 +89,7 @@ DROP TABLE ptif_test;
 CREATE TABLE ptif_normal_table(a int);
 SELECT relid, parentrelid, level, isleaf
   FROM pg_partition_tree('ptif_normal_table');
+SELECT * FROM pg_partition_ancestors('ptif_normal_table');
 SELECT pg_partition_root('ptif_normal_table');
 DROP TABLE ptif_normal_table;
 
@@ -95,6 +104,10 @@ SELECT * FROM pg_partition_tree('ptif_test_view');
 SELECT * FROM pg_partition_tree('ptif_test_matview');
 SELECT * FROM pg_partition_tree('ptif_li_parent');
 SELECT * FROM pg_partition_tree('ptif_li_child');
+SELECT * FROM pg_partition_ancestors('ptif_test_view');
+SELECT * FROM pg_partition_ancestors('ptif_test_matview');
+SELECT * FROM pg_partition_ancestors('ptif_li_parent');
+SELECT * FROM pg_partition_ancestors('ptif_li_child');
 SELECT pg_partition_root('ptif_test_view');
 SELECT pg_partition_root('ptif_test_matview');
 SELECT pg_partition_root('ptif_li_parent');