Thanks for taking a look.
On 2018/01/19 14:39, Michael Paquier wrote:
> On Thu, Jan 18, 2018 at 06:54:18PM +0900, Amit Langote wrote:
>> I think having pg_partition_root() and pg_partition_parent() will give
>> users enough to get useful views as follows:
>
> So... pg_partition_root() gives you access to the highest relation in
> the hierarchy, and pg_partition_parent() gives you access to the direct
> parent.
Right.
>> drop table p;
>> create table p (a int) partition by list (a);
>> create table p123 partition of p for values in (1, 2, 3) partition by list
> (a);
>> create table p12 partition of p1 for values in (1, 2) partition by list (a);
>> create table p12 partition of p123 for values in (1, 2) partition by list
>> (a);
>> create table p1 partition of p12 for values in (1);
>> create table p2 partition of p12 for values in (2);
>> create table p3 partition of p123 for values in (3);
>
> You need to reorder those queries, the creation of the first p12 would
> fail as p1 does not exist at this point.
Oops. I had copy-pasted above commands from the psql's \s output and
ended up copying the command I didn't intend to. Here it is again, but
without the mistake I made in my last email:
drop table p;
create table p (a int) partition by list (a);
create table p123 partition of p for values in (1, 2, 3) partition by list
(a);
create table p12 partition of p123 for values in (1, 2) partition by list (a);
create table p1 partition of p12 for values in (1);
create table p2 partition of p12 for values in (2);
create table p3 partition of p123 for values in (3);
> Wouldn't also a
> pg_partition_tree() be useful? You could shape it as a function which
> returns all regclass partitions in the tree as unique entries. Combined
> with pg_partition_parent() it can be powerful as it returns NULL for the
> partition at the top of the tree. So I think that we could live without
> pg_partition_root(). At the end, let's design something which makes
> unnecessary the use of WITH RECURSIVE when looking at a full partition
> tree to ease the user's life.
Do you mean pg_partition_tree(regclass), that returns all partitions in
the partition tree whose root is passed as the parameter?
Perhaps, like the following (roughly implemented in the attached)?
select pg_partition_root(p) as root_parent,
pg_partition_parent(p) as parent,
p as relname,
pg_total_relation_size(p) as size
from pg_partition_tree_tables('p') p
order by 4;
root_parent | parent | relname | size
-------------+--------+---------+---------
p | | p | 0
p | p | p123 | 0
p | p123 | p12 | 0
p | p123 | p3 | 3653632
p | p12 | p1 | 3653632
p | p12 | p2 | 3653632
(6 rows)
> Documentation, as well as regression tests, would be welcome :)
OK, I will add those things in the next version.
Thanks,
Amit
>From 50dfb02bd3ea833d8b18fc5d3d54e863fbc223e4 Mon Sep 17 00:00:00 2001
From: amit <[email protected]>
Date: Tue, 16 Jan 2018 19:02:13 +0900
Subject: [PATCH] Add assorted partition reporting functions
---
src/backend/catalog/partition.c | 117 +++++++++++++++++++++++++++++++++++-
src/backend/utils/cache/lsyscache.c | 22 +++++++
src/include/catalog/partition.h | 1 +
src/include/catalog/pg_proc.h | 12 ++++
src/include/utils/lsyscache.h | 1 +
5 files changed, 152 insertions(+), 1 deletion(-)
diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index 8adc4ee977..ac92bbfa71 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -32,6 +32,7 @@
#include "catalog/pg_type.h"
#include "commands/tablecmds.h"
#include "executor/executor.h"
+#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
@@ -181,6 +182,7 @@ static int partition_bound_bsearch(PartitionKey key,
static int get_partition_bound_num_indexes(PartitionBoundInfo b);
static int get_greatest_modulus(PartitionBoundInfo b);
static uint64 compute_hash_value(PartitionKey key, Datum *values, bool
*isnull);
+static Oid get_partition_parent_internal(Oid relid, bool recurse_to_root);
/* SQL-callable function for use in hash partition CHECK constraints */
PG_FUNCTION_INFO_V1(satisfies_hash_partition);
@@ -1362,7 +1364,7 @@ check_default_allows_bound(Relation parent, Relation
default_rel,
/*
* get_partition_parent
*
- * Returns inheritance parent of a partition by scanning pg_inherits
+ * Returns inheritance parent of a partition.
*
* Note: Because this function assumes that the relation whose OID is passed
* as an argument will have precisely one parent, it should only be called
@@ -1371,6 +1373,37 @@ check_default_allows_bound(Relation parent, Relation
default_rel,
Oid
get_partition_parent(Oid relid)
{
+ if (!get_rel_relispartition(relid))
+ return InvalidOid;
+
+ return get_partition_parent_internal(relid, false);
+}
+
+/*
+ * get_partition_root_parent
+ *
+ * Returns root inheritance ancestor of a partition.
+ */
+Oid
+get_partition_root_parent(Oid relid)
+{
+ if (!get_rel_relispartition(relid))
+ return InvalidOid;
+
+ return get_partition_parent_internal(relid, true);
+}
+
+/*
+ * get_partition_parent_internal
+ *
+ * Returns inheritance parent of a partition by scanning pg_inherits.
+ * If recurse_to_root, it will check if the parent itself is a partition and
+ * if so, it will recurse to find its parent and so on until root parent is
+ * found.
+ */
+static Oid
+get_partition_parent_internal(Oid relid, bool recurse_to_root)
+{
Form_pg_inherits form;
Relation catalogRelation;
SysScanDesc scan;
@@ -1402,6 +1435,9 @@ get_partition_parent(Oid relid)
systable_endscan(scan);
heap_close(catalogRelation, AccessShareLock);
+ if (recurse_to_root && get_rel_relispartition(result))
+ result = get_partition_parent_internal(result, recurse_to_root);
+
return result;
}
@@ -3396,3 +3432,82 @@ satisfies_hash_partition(PG_FUNCTION_ARGS)
PG_RETURN_BOOL(rowHash % modulus == remainder);
}
+
+/*
+ * SQL wrapper around get_partition_root_parent() in
+ * src/backend/catalog/partition.c.
+ */
+Datum
+pg_partition_root(PG_FUNCTION_ARGS)
+{
+ Oid reloid = PG_GETARG_OID(0);
+ Oid rootoid;
+
+ rootoid = get_partition_root_parent(reloid);
+ if (OidIsValid(rootoid))
+ PG_RETURN_OID(rootoid);
+ else
+ PG_RETURN_OID(reloid);
+}
+
+/*
+ * SQL wrapper around get_partition_parent() in
+ * src/backend/catalog/partition.c.
+ */
+Datum
+pg_partition_parent(PG_FUNCTION_ARGS)
+{
+ Oid reloid = PG_GETARG_OID(0);
+ Oid parentoid;
+
+ parentoid = get_partition_parent(reloid);
+ if (OidIsValid(parentoid))
+ PG_RETURN_OID(parentoid);
+ else
+ PG_RETURN_NULL();
+}
+
+/*
+ * Returns Oids of tables in a publication.
+ */
+Datum
+pg_partition_tree_tables(PG_FUNCTION_ARGS)
+{
+ FuncCallContext *funcctx;
+ Oid reloid = PG_GETARG_OID(0);
+ List *partoids;
+ ListCell **lc;
+
+ /* stuff done only on the first call of the function */
+ if (SRF_IS_FIRSTCALL())
+ {
+ MemoryContext oldcontext;
+
+ /* create a function context for cross-call persistence */
+ funcctx = SRF_FIRSTCALL_INIT();
+
+ /* switch to memory context appropriate for multiple function
calls */
+ oldcontext =
MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+ partoids = find_all_inheritors(reloid, NoLock, NULL);
+ lc = (ListCell **) palloc(sizeof(ListCell *));
+ *lc = list_head(partoids);
+ funcctx->user_fctx = (void *) lc;
+
+ MemoryContextSwitchTo(oldcontext);
+ }
+
+ /* stuff done on every call of the function */
+ funcctx = SRF_PERCALL_SETUP();
+ lc = (ListCell **) funcctx->user_fctx;
+
+ while (*lc != NULL)
+ {
+ Oid partoid = lfirst_oid(*lc);
+
+ *lc = lnext(*lc);
+ SRF_RETURN_NEXT(funcctx, ObjectIdGetDatum(partoid));
+ }
+
+ SRF_RETURN_DONE(funcctx);
+}
diff --git a/src/backend/utils/cache/lsyscache.c
b/src/backend/utils/cache/lsyscache.c
index e8aa179347..92353a6004 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1836,6 +1836,28 @@ get_rel_relkind(Oid relid)
}
/*
+ * get_rel_relispartition
+ *
+ * Returns the value of pg_class.relispartition for a given
relation.
+ */
+char
+get_rel_relispartition(Oid relid)
+{
+ HeapTuple tp;
+ Form_pg_class reltup;
+ bool result;
+
+ tp = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+ if (!HeapTupleIsValid(tp))
+ elog(ERROR, "cache lookup failed for relation %u", relid);
+ reltup = (Form_pg_class) GETSTRUCT(tp);
+ result = reltup->relispartition;
+ ReleaseSysCache(tp);
+
+ return result;
+}
+
+/*
* get_rel_tablespace
*
* Returns the pg_tablespace OID associated with a given relation.
diff --git a/src/include/catalog/partition.h b/src/include/catalog/partition.h
index 2faf0ca26e..287642b01b 100644
--- a/src/include/catalog/partition.h
+++ b/src/include/catalog/partition.h
@@ -52,6 +52,7 @@ extern PartitionBoundInfo
partition_bounds_copy(PartitionBoundInfo src,
extern void check_new_partition_bound(char *relname, Relation parent,
PartitionBoundSpec *spec);
extern Oid get_partition_parent(Oid relid);
+extern Oid get_partition_root_parent(Oid relid);
extern List *get_qual_from_partbound(Relation rel, Relation parent,
PartitionBoundSpec *spec);
extern List *map_partition_varattnos(List *expr, int fromrel_varno,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index f01648c961..64942b310c 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -5533,6 +5533,18 @@ DESCR("list of files in the WAL directory");
DATA(insert OID = 5028 ( satisfies_hash_partition PGNSP PGUID 12 1 0 2276 0 f
f f f f f i s 4 0 16 "26 23 23 2276" _null_ "{i,i,i,v}" _null_ _null_ _null_
satisfies_hash_partition _null_ _null_ _null_ ));
DESCR("hash partition CHECK constraint");
+/* function to get the root partition parent */
+DATA(insert OID = 3281 ( pg_partition_root PGNSP PGUID 12 10 0 0 0 f f f f t
f s s 1 0 2205 "2205" _null_ _null_ _null_ _null_ _null_ pg_partition_root
_null_ _null_ _null_ ));
+DESCR("oid of the partition root parent");
+
+/* function to get the partition parent */
+DATA(insert OID = 3556 ( pg_partition_parent PGNSP PGUID 12 10 0 0 0 f f f f
t f s s 1 0 2205 "2205" _null_ _null_ _null_ _null_ _null_ pg_partition_parent
_null_ _null_ _null_ ));
+DESCR("oid of the partition immediate parent");
+
+/* function to get OIDs of all tables in a given partition tree */
+DATA(insert OID = 3696 ( pg_partition_tree_tables PGNSP PGUID 12 1 1000 0
0 f f f f t t s s 1 0 2205 "2205" "{2205,2205}" "{i,o}" "{relid,relid}" _null_
_null_ pg_partition_tree_tables _null_ _null_ _null_ ));
+DESCR("get OIDs of tables in a partition tree");
+
/*
* Symbolic values for provolatile column: these indicate whether the result
* of a function is dependent *only* on the values of its explicit arguments,
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 9731e6f7ae..1000d9fd13 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -127,6 +127,7 @@ extern char *get_rel_name(Oid relid);
extern Oid get_rel_namespace(Oid relid);
extern Oid get_rel_type_id(Oid relid);
extern char get_rel_relkind(Oid relid);
+extern char get_rel_relispartition(Oid relid);
extern Oid get_rel_tablespace(Oid relid);
extern char get_rel_persistence(Oid relid);
extern Oid get_transform_fromsql(Oid typid, Oid langid, List *trftypes);
--
2.11.0
