Add pg_partition_root to display top-most parent of a partition tree

This is useful when looking at partition trees with multiple layers, and
combined with pg_partition_tree, it provides the possibility to show up
an entire tree by just knowing one member at any level.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera, Amit Langote
Discussion: https://postgr.es/m/[email protected]

1 files changed, 58 insertions, 0 deletions

diff --git a/src/test/regress/expected/partition_info.out b/src/test/regress/expected/partition_info.out
index 3e15e02f8da..a884df976fd 100644
--- a/src/test/regress/expected/partition_info.out
+++ b/src/test/regress/expected/partition_info.out
@@ -12,6 +12,18 @@ SELECT * FROM pg_partition_tree(0);
        |             |        |      
 (1 row)
 
+SELECT pg_partition_root(NULL);
+ pg_partition_root 
+-------------------
+ 
+(1 row)
+
+SELECT pg_partition_root(0);
+ pg_partition_root 
+-------------------
+ 
+(1 row)
+
 -- Test table partition trees
 CREATE TABLE ptif_test (a int, b int) PARTITION BY range (a);
 CREATE TABLE ptif_test0 PARTITION OF ptif_test
@@ -66,6 +78,20 @@ SELECT relid, parentrelid, level, isleaf
  ptif_test01 | ptif_test0  |     0 | t
 (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
+  JOIN pg_class c ON (p.relid = c.oid);
+    relid    | parentrelid | level | isleaf 
+-------------+-------------+-------+--------
+ ptif_test   |             |     0 | f
+ ptif_test0  | ptif_test   |     1 | f
+ ptif_test1  | ptif_test   |     1 | f
+ ptif_test2  | ptif_test   |     1 | t
+ ptif_test01 | ptif_test0  |     2 | t
+ ptif_test11 | ptif_test1  |     2 | t
+(6 rows)
+
 -- List all indexes members of the tree
 SELECT relid, parentrelid, level, isleaf
   FROM pg_partition_tree('ptif_test_index');
@@ -98,6 +124,20 @@ SELECT relid, parentrelid, level, isleaf
  ptif_test01_index | ptif_test0_index |     0 | t
 (1 row)
 
+-- List all members using pg_partition_root with leaf index reference
+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);
+       relid       |   parentrelid    | level | isleaf 
+-------------------+------------------+-------+--------
+ ptif_test_index   |                  |     0 | f
+ ptif_test0_index  | ptif_test_index  |     1 | f
+ ptif_test1_index  | ptif_test_index  |     1 | f
+ ptif_test2_index  | ptif_test_index  |     1 | t
+ ptif_test01_index | ptif_test0_index |     2 | t
+ ptif_test11_index | ptif_test1_index |     2 | t
+(6 rows)
+
 DROP TABLE ptif_test;
 -- Table that is not part of any partition tree is the only member listed.
 CREATE TABLE ptif_normal_table(a int);
@@ -108,6 +148,12 @@ SELECT relid, parentrelid, level, isleaf
  ptif_normal_table |             |     0 | t
 (1 row)
 
+SELECT pg_partition_root('ptif_normal_table');
+ pg_partition_root 
+-------------------
+ ptif_normal_table
+(1 row)
+
 DROP TABLE ptif_normal_table;
 -- Various partitioning-related functions return NULL if passed relations
 -- of types that cannot be part of a partition tree; for example, views,
@@ -126,5 +172,17 @@ SELECT * FROM pg_partition_tree('ptif_test_matview');
        |             |        |      
 (1 row)
 
+SELECT pg_partition_root('ptif_test_view');
+ pg_partition_root 
+-------------------
+ 
+(1 row)
+
+SELECT pg_partition_root('ptif_test_matview');
+ pg_partition_root 
+-------------------
+ 
+(1 row)
+
 DROP VIEW ptif_test_view;
 DROP MATERIALIZED VIEW ptif_test_matview;