Hi.
You may have guessed from $subject that the two don't work together.
create table p (a int) partition by list (a);
create table p1 partition of p for values in (1, 2) partition by list (a);
create table p11 partition of p1 for values in (1);
create table p12 partition of p1 for values in (2);
insert into p select i % 2 + 1 from generate_series(1, 1000) i;
On HEAD:
select pg_relation_size('p');
pg_relation_size
------------------
0
(1 row)
select pg_total_relation_size('p');
pg_total_relation_size
------------------------
0
(1 row)
After applying the attached patch:
select pg_relation_size('p');
pg_relation_size
------------------
49152
(1 row)
select pg_total_relation_size('p');
pg_total_relation_size
------------------------
98304
(1 row)
The patch basically accumulates and returns the sizes of all leaf
partitions when passed a partitioned table. Will add it to next CF.
Thanks,
Amit
From 4a5db12ad0155e043500d87caf2cc9438eb87e23 Mon Sep 17 00:00:00 2001
From: amit <amitlangot...@gmail.com>
Date: Thu, 14 Dec 2017 13:56:08 +0900
Subject: [PATCH] Teach dbsize.c functions about partitioned tables
---
src/backend/utils/adt/dbsize.c | 101 ++++++++++++++++++++++++++++++++++-------
1 file changed, 85 insertions(+), 16 deletions(-)
diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 58c0b01bdc..145f511c6c 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -17,6 +17,7 @@
#include "access/htup_details.h"
#include "catalog/catalog.h"
#include "catalog/namespace.h"
+#include "catalog/partition.h"
#include "catalog/pg_authid.h"
#include "catalog/pg_tablespace.h"
#include "commands/dbcommands.h"
@@ -307,13 +308,17 @@ calculate_relation_size(RelFileNode *rfn, BackendId
backend, ForkNumber forknum)
return totalsize;
}
-Datum
-pg_relation_size(PG_FUNCTION_ARGS)
+/*
+ * Computes and stores in *size the file size of the specified fork of the
+ * relation with OID relOid.
+
+ * Returns true if size was sucessfully calculated and stored in *size, false
+ * otherwise.
+ */
+static bool
+pg_relation_size_internal(Oid relOid, char *forkName, int64 *size)
{
- Oid relOid = PG_GETARG_OID(0);
- text *forkName = PG_GETARG_TEXT_PP(1);
Relation rel;
- int64 size;
rel = try_relation_open(relOid, AccessShareLock);
@@ -321,17 +326,52 @@ pg_relation_size(PG_FUNCTION_ARGS)
* Before 9.2, we used to throw an error if the relation didn't exist,
but
* that makes queries like "SELECT pg_relation_size(oid) FROM pg_class"
* less robust, because while we scan pg_class with an MVCC snapshot,
- * someone else might drop the table. It's better to return NULL for
- * already-dropped tables than throw an error and abort the whole query.
+ * someone else might drop the table. It's better to return that we
+ * couldn't get the size for already-dropped tables than throw an error
+ * and abort the whole query.
*/
if (rel == NULL)
- PG_RETURN_NULL();
+ return false;
+
+ /*
+ * For a partitioned table, get the size by accumulating that of its
+ * leaf partitions.
+ */
+ if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+ {
+ PartitionDesc partdesc = rel->rd_partdesc;
+ int i;
- size = calculate_relation_size(&(rel->rd_node), rel->rd_backend,
-
forkname_to_number(text_to_cstring(forkName)));
+ *size = 0;
+ for (i = 0; i < partdesc->nparts; i++)
+ {
+ int64 partsize;
+
+ if (pg_relation_size_internal(partdesc->oids[i],
forkName,
+
&partsize))
+ *size += partsize;
+ }
+ }
+ else
+ *size = calculate_relation_size(&(rel->rd_node),
rel->rd_backend,
+
forkname_to_number(forkName));
relation_close(rel, AccessShareLock);
+ return true;
+}
+
+Datum
+pg_relation_size(PG_FUNCTION_ARGS)
+{
+ Oid relOid = PG_GETARG_OID(0);
+ text *forkName = PG_GETARG_TEXT_PP(1);
+ int64 size;
+
+ if (!pg_relation_size_internal(relOid, text_to_cstring(forkName),
+ &size))
+ PG_RETURN_NULL();
+
PG_RETURN_INT64(size);
}
@@ -508,22 +548,51 @@ calculate_total_relation_size(Relation rel)
return size;
}
-Datum
-pg_total_relation_size(PG_FUNCTION_ARGS)
+static int64
+pg_total_relation_size_internal(Oid relOid, int64 *size)
{
- Oid relOid = PG_GETARG_OID(0);
Relation rel;
- int64 size;
rel = try_relation_open(relOid, AccessShareLock);
if (rel == NULL)
- PG_RETURN_NULL();
+ return false;
- size = calculate_total_relation_size(rel);
+ /*
+ * For a partitioned table, get the size by accumulating that of its
+ * leaf partitions.
+ */
+ if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+ {
+ PartitionDesc partdesc = rel->rd_partdesc;
+ int i;
+
+ *size = 0;
+ for (i = 0; i < partdesc->nparts; i++)
+ {
+ int64 partsize;
+
+ if (pg_total_relation_size_internal(partdesc->oids[i],
&partsize))
+ *size += partsize;
+ }
+ }
+ else
+ *size = calculate_total_relation_size(rel);
relation_close(rel, AccessShareLock);
+ return true;
+}
+
+Datum
+pg_total_relation_size(PG_FUNCTION_ARGS)
+{
+ Oid relOid = PG_GETARG_OID(0);
+ int64 size;
+
+ if (!pg_total_relation_size_internal(relOid, &size))
+ PG_RETURN_NULL();
+
PG_RETURN_INT64(size);
}
--
2.11.0
