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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/20181207014015.GP2407@paquier.xyz
This commit is contained in:
Michael Paquier 2019-02-08 08:56:14 +09:00
parent 34ea1ab7fd
commit 3677a0b26b
6 changed files with 153 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
doc/src/sgml/func.sgml
View File

@ -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_root</primary></indexterm>
<literal><function>pg_partition_root(<type>regclass</type>)</function></literal>
</entry>
<entry><type>regclass</type></entry>
<entry>
Return the top-most parent of a partition tree to which the given
relation belongs.
</entry>
</row>
</tbody>
</tgroup>
</table>

75
src/backend/utils/adt/partitionfuncs.c
View File

@ -25,6 +25,33 @@
#include "utils/lsyscache.h"
#include "utils/syscache.h"
/*
* Checks if a given relation can be part of a partition tree. Returns
* false if the relation cannot be processed, in which case it is up to
* the caller to decide what to do, by either raising an error or doing
* something else.
*/
static bool
check_rel_can_be_partition(Oid relid)
{
char relkind;
/* Check if relation exists */
if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relid)))
return false;
relkind = get_rel_relkind(relid);
/* Only allow relation types that can appear in partition trees. */
if (relkind != RELKIND_RELATION &&
relkind != RELKIND_FOREIGN_TABLE &&
relkind != RELKIND_INDEX &&
relkind != RELKIND_PARTITIONED_TABLE &&
relkind != RELKIND_PARTITIONED_INDEX)
return false;
return true;
}
/*
* pg_partition_tree
@ -39,19 +66,10 @@ pg_partition_tree(PG_FUNCTION_ARGS)
{
#define PG_PARTITION_TREE_COLS 4
Oid rootrelid = PG_GETARG_OID(0);
char relkind = get_rel_relkind(rootrelid);
FuncCallContext *funcctx;
ListCell **next;
if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(rootrelid)))
PG_RETURN_NULL();
/* Return NULL for relation types that cannot appear in partition trees */
if (relkind != RELKIND_RELATION &&
relkind != RELKIND_FOREIGN_TABLE &&
relkind != RELKIND_INDEX &&
relkind != RELKIND_PARTITIONED_TABLE &&
relkind != RELKIND_PARTITIONED_INDEX)
if (!check_rel_can_be_partition(rootrelid))
PG_RETURN_NULL();
/* stuff done only on the first call of the function */
@ -153,3 +171,40 @@ pg_partition_tree(PG_FUNCTION_ARGS)
/* done when there are no more elements left */
SRF_RETURN_DONE(funcctx);
}
/*
* pg_partition_root
*
* Returns the top-most parent of the partition tree to which a given
* relation belongs, or NULL if it's not (or cannot be) part of any
* partition tree.
*/
Datum
pg_partition_root(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
Oid rootrelid;
List *ancestors;
if (!check_rel_can_be_partition(relid))
PG_RETURN_NULL();
/*
* If the relation is not a partition (it may be the partition parent),
* return itself as a result.
*/
if (!get_rel_relispartition(relid))
PG_RETURN_OID(relid);
/* Fetch the top-most parent */
ancestors = get_partition_ancestors(relid);
rootrelid = llast_oid(ancestors);
list_free(ancestors);
/*
* "rootrelid" must contain a valid OID, given that the input relation is
* a valid partition tree member as checked above.
*/
Assert(OidIsValid(rootrelid));
PG_RETURN_OID(rootrelid);
}

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 201902071
#define CATALOG_VERSION_NO 201902081
#endif

5
src/include/catalog/pg_proc.dat
View File

@ -10509,4 +10509,9 @@
proargnames => '{rootrelid,relid,parentrelid,isleaf,level}',
prosrc => 'pg_partition_tree' },
# function to get the top-most partition root parent
{ oid => '3424', descr => 'get top-most partition root parent',
proname => 'pg_partition_root', prorettype => 'regclass',
proargtypes => 'regclass', prosrc => 'pg_partition_root' },
]

58
src/test/regress/expected/partition_info.out
View File

@ -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;

13
src/test/regress/sql/partition_info.sql
View File

@ -3,6 +3,8 @@
--
SELECT * FROM pg_partition_tree(NULL);
SELECT * FROM pg_partition_tree(0);
SELECT pg_partition_root(NULL);
SELECT pg_partition_root(0);
-- Test table partition trees
CREATE TABLE ptif_test (a int, b int) PARTITION BY range (a);
@ -39,6 +41,10 @@ SELECT relid, parentrelid, level, isleaf
SELECT relid, parentrelid, level, isleaf
FROM pg_partition_tree('ptif_test01') p
JOIN pg_class c ON (p.relid = c.oid);
-- 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);
-- List all indexes members of the tree
SELECT relid, parentrelid, level, isleaf
@ -51,6 +57,10 @@ SELECT relid, parentrelid, level, isleaf
SELECT relid, parentrelid, level, isleaf
FROM pg_partition_tree('ptif_test01_index') p
JOIN pg_class c ON (p.relid = c.oid);
-- 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);
DROP TABLE ptif_test;
@ -58,6 +68,7 @@ DROP TABLE ptif_test;
CREATE TABLE ptif_normal_table(a int);
SELECT relid, parentrelid, level, isleaf
FROM pg_partition_tree('ptif_normal_table');
SELECT pg_partition_root('ptif_normal_table');
DROP TABLE ptif_normal_table;
-- Various partitioning-related functions return NULL if passed relations
@ -67,5 +78,7 @@ CREATE VIEW ptif_test_view AS SELECT 1;
CREATE MATERIALIZED VIEW ptif_test_matview AS SELECT 1;
SELECT * FROM pg_partition_tree('ptif_test_view');
SELECT * FROM pg_partition_tree('ptif_test_matview');
SELECT pg_partition_root('ptif_test_view');
SELECT pg_partition_root('ptif_test_matview');
DROP VIEW ptif_test_view;
DROP MATERIALIZED VIEW ptif_test_matview;