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replace_hash_partition() function
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8 files changed

+288
-23
lines changed

8 files changed

+288
-23
lines changed

‎expected/pathman_basic.out‎

Lines changed: 46 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -885,14 +885,58 @@ SELECT * FROM test.hash_rel WHERE id = 123;
885885
123 | 456 | 789
886886
(1 row)
887887

888+
/* Test replacing hash partition */
889+
CREATE TABLE test.hash_rel_extern (LIKE test.hash_rel INCLUDING ALL);
890+
SELECT pathman.replace_hash_partition('test.hash_rel_0', 'test.hash_rel_extern');
891+
replace_hash_partition
892+
------------------------
893+
test.hash_rel_extern
894+
(1 row)
895+
896+
\d+ test.hash_rel_0
897+
Table "test.hash_rel_0"
898+
Column | Type | Modifiers | Storage | Stats target | Description
899+
--------+---------+------------------------------------------------------------+---------+--------------+-------------
900+
id | integer | not null default nextval('test.hash_rel_id_seq'::regclass) | plain | |
901+
value | integer | not null | plain | |
902+
abc | integer | | plain | |
903+
Indexes:
904+
"hash_rel_0_pkey" PRIMARY KEY, btree (id)
905+
Triggers:
906+
hash_rel_upd_trig BEFORE UPDATE ON test.hash_rel_0 FOR EACH ROW EXECUTE PROCEDURE test.hash_rel_upd_trig_func()
907+
908+
\d+ test.hash_rel_extern
909+
Table "test.hash_rel_extern"
910+
Column | Type | Modifiers | Storage | Stats target | Description
911+
--------+---------+------------------------------------------------------------+---------+--------------+-------------
912+
id | integer | not null default nextval('test.hash_rel_id_seq'::regclass) | plain | |
913+
value | integer | not null | plain | |
914+
abc | integer | | plain | |
915+
Indexes:
916+
"hash_rel_extern_pkey" PRIMARY KEY, btree (id)
917+
Check constraints:
918+
"pathman_hash_rel_extern_2_check" CHECK (pathman.get_hash_part_idx(hashint4(value), 3) = 0)
919+
Inherits: test.hash_rel
920+
921+
INSERT INTO test.hash_rel SELECT * FROM test.hash_rel_0;
922+
DROP TABLE test.hash_rel_0;
923+
EXPLAIN SELECT * FROM test.hash_rel;
924+
QUERY PLAN
925+
---------------------------------------------------------------------------------------------
926+
Append (cost=10000000000.00..30000000032.44 rows=2044 width=12)
927+
-> Seq Scan on hash_rel_extern (cost=10000000000.00..10000000030.40 rows=2040 width=12)
928+
-> Seq Scan on hash_rel_1 (cost=10000000000.00..10000000001.02 rows=2 width=12)
929+
-> Seq Scan on hash_rel_2 (cost=10000000000.00..10000000001.02 rows=2 width=12)
930+
(4 rows)
931+
888932
/*
889933
* Clean up
890934
*/
891935
SELECT pathman.drop_partitions('test.hash_rel');
892-
NOTICE: drop cascades to 3 other objects
893-
NOTICE: 2 rows copied from test.hash_rel_0
936+
NOTICE: drop cascades to 2 other objects
894937
NOTICE: 3 rows copied from test.hash_rel_1
895938
NOTICE: 2 rows copied from test.hash_rel_2
939+
NOTICE: 2 rows copied from test.hash_rel_extern
896940
drop_partitions
897941
-----------------
898942
3

‎hash.sql‎

Lines changed: 107 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -22,8 +22,8 @@ DECLARE
2222
v_child_relname TEXT;
2323
v_plain_schema TEXT;
2424
v_plain_relname TEXT;
25-
v_atttype REGTYPE;
26-
v_hashfunc REGPROC;
25+
-- v_atttype REGTYPE;
26+
-- v_hashfunc REGPROC;
2727
v_init_callback REGPROCEDURE;
2828

2929
BEGIN
@@ -41,8 +41,8 @@ BEGIN
4141
PERFORM @extschema@.common_relation_checks(parent_relid, attribute);
4242

4343
/* Fetch atttype and its hash function */
44-
v_atttype := @extschema@.get_attribute_type(parent_relid, attribute);
45-
v_hashfunc := @extschema@.get_type_hash_func(v_atttype);
44+
-- v_atttype := @extschema@.get_attribute_type(parent_relid, attribute);
45+
-- v_hashfunc := @extschema@.get_type_hash_func(v_atttype);
4646

4747
SELECT * INTO v_plain_schema, v_plain_relname
4848
FROM @extschema@.get_plain_schema_and_relname(parent_relid);
@@ -64,15 +64,23 @@ BEGIN
6464
parent_relid::TEXT,
6565
@extschema@.get_rel_tablespace_name(parent_relid));
6666

67-
EXECUTE format('ALTER TABLE %s ADD CONSTRAINT %s
68-
CHECK (@extschema@.get_hash_part_idx(%s(%s), %s) = %s)',
67+
-- EXECUTE format('ALTER TABLE %s ADD CONSTRAINT %s
68+
-- CHECK (@extschema@.get_hash_part_idx(%s(%s), %s) = %s)',
69+
-- v_child_relname,
70+
-- @extschema@.build_check_constraint_name(v_child_relname::REGCLASS,
71+
-- attribute),
72+
-- v_hashfunc::TEXT,
73+
-- attribute,
74+
-- partitions_count,
75+
-- partnum);
76+
EXECUTE format('ALTER TABLE %s ADD CONSTRAINT %s CHECK (%s)',
6977
v_child_relname,
70-
@extschema@.build_check_constraint_name(v_child_relname::REGCLASS,
78+
@extschema@.build_check_constraint_name(v_child_relname,
7179
attribute),
72-
v_hashfunc::TEXT,
73-
attribute,
74-
partitions_count,
75-
partnum);
80+
@extschema@.build_hash_condition(v_child_relname,
81+
attribute,
82+
partitions_count,
83+
partnum));
7684

7785
PERFORM @extschema@.copy_foreign_keys(parent_relid, v_child_relname::REGCLASS);
7886

@@ -105,6 +113,94 @@ END
105113
$$ LANGUAGE plpgsql
106114
SET client_min_messages = WARNING;
107115

116+
/*
117+
* Replace hash partition with another one. It could be useful in case when
118+
* someone wants to attach foreign table as a partition
119+
*/
120+
CREATE OR REPLACE FUNCTION @extschema@.replace_hash_partition(
121+
old_partition REGCLASS,
122+
new_partition REGCLASS)
123+
RETURNS REGCLASS AS
124+
$$
125+
DECLARE
126+
v_attname TEXT;
127+
rel_persistence CHAR;
128+
v_init_callback REGPROCEDURE;
129+
v_parent_relid REGCLASS;
130+
v_part_count INT;
131+
v_part_num INT;
132+
BEGIN
133+
PERFORM @extschema@.validate_relname(old_partition);
134+
PERFORM @extschema@.validate_relname(new_partition);
135+
136+
/* Parent relation */
137+
v_parent_relid := @extschema@.get_parent_of_partition(old_partition);
138+
139+
/* Acquire lock on parent */
140+
PERFORM @extschema@.lock_partitioned_relation(v_parent_relid);
141+
142+
/* Ignore temporary tables */
143+
SELECT relpersistence FROM pg_catalog.pg_class
144+
WHERE oid = new_partition INTO rel_persistence;
145+
146+
IF rel_persistence = 't'::CHAR THEN
147+
RAISE EXCEPTION 'temporary table "%" cannot be used as a partition',
148+
new_partition::TEXT;
149+
END IF;
150+
151+
/* Check that new partition has an equal structure as parent does */
152+
IF NOT @extschema@.validate_relations_equality(v_parent_relid, new_partition) THEN
153+
RAISE EXCEPTION 'partition must have the exact same structure as parent';
154+
END IF;
155+
156+
/* Get partitioning key */
157+
v_attname := attname FROM @extschema@.pathman_config WHERE partrel = v_parent_relid;
158+
IF v_attname IS NULL THEN
159+
RAISE EXCEPTION 'table "%" is not partitioned', v_parent_relid::TEXT;
160+
END IF;
161+
162+
/* Calculate partitions count and old partition's number */
163+
v_part_count := count(*) FROM @extschema@.pathman_partition_list WHERE parent = v_parent_relid;
164+
v_part_num := @extschema@.get_partition_hash(v_parent_relid, old_partition);
165+
166+
/* Detach old partition */
167+
EXECUTE format('ALTER TABLE %s NO INHERIT %s', old_partition, v_parent_relid);
168+
EXECUTE format('ALTER TABLE %s DROP CONSTRAINT IF EXISTS %s',
169+
old_partition,
170+
@extschema@.build_check_constraint_name(old_partition::REGCLASS,
171+
v_attname));
172+
173+
/* Attach new one */
174+
EXECUTE format('ALTER TABLE %s INHERIT %s', new_partition, v_parent_relid);
175+
EXECUTE format('ALTER TABLE %s ADD CONSTRAINT %s CHECK (%s)',
176+
new_partition,
177+
@extschema@.build_check_constraint_name(new_partition::regclass,
178+
v_attname),
179+
@extschema@.build_hash_condition(new_partition::regclass,
180+
v_attname,
181+
v_part_count,
182+
v_part_num));
183+
184+
/* Fetch init_callback from 'params' table */
185+
WITH stub_callback(stub) as (values (0))
186+
SELECT coalesce(init_callback, 0::REGPROCEDURE)
187+
FROM stub_callback
188+
LEFT JOIN @extschema@.pathman_config_params AS params
189+
ON params.partrel = v_parent_relid
190+
INTO v_init_callback;
191+
192+
PERFORM @extschema@.invoke_on_partition_created_callback(v_parent_relid,
193+
new_partition,
194+
v_init_callback);
195+
196+
/* Invalidate cache */
197+
PERFORM @extschema@.on_update_partitions(v_parent_relid);
198+
199+
RETURN new_partition;
200+
END
201+
$$
202+
LANGUAGE plpgsql;
203+
108204
/*
109205
* Creates an update trigger
110206
*/

‎init.sql‎

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -803,3 +803,23 @@ CREATE OR REPLACE FUNCTION @extschema@.invoke_on_partition_created_callback(
803803
init_callback REGPROCEDURE)
804804
RETURNS VOID AS 'pg_pathman', 'invoke_on_partition_created_callback'
805805
LANGUAGE C;
806+
807+
/*
808+
* Build hash condition for a CHECK CONSTRAINT
809+
*/
810+
CREATE OR REPLACE FUNCTION @extschema@.build_hash_condition(
811+
parent_relid REGCLASS,
812+
attname TEXT,
813+
partitions_count INT,
814+
partition_number INT)
815+
RETURNS TEXT AS 'pg_pathman', 'build_hash_condition'
816+
LANGUAGE C;
817+
818+
/*
819+
* Returns hash value for specified partition (0..N)
820+
*/
821+
CREATE OR REPLACE FUNCTION @extschema@.get_partition_hash(
822+
parent_relid REGCLASS,
823+
partition REGCLASS)
824+
RETURNS INT AS 'pg_pathman', 'get_partition_hash'
825+
LANGUAGE C;

‎sql/pathman_basic.sql‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -236,6 +236,15 @@ ALTER TABLE test.hash_rel ADD COLUMN abc int;
236236
INSERT INTO test.hash_rel (id, value, abc) VALUES (123, 456, 789);
237237
SELECT * FROM test.hash_rel WHERE id = 123;
238238

239+
/* Test replacing hash partition */
240+
CREATE TABLE test.hash_rel_extern (LIKE test.hash_rel INCLUDING ALL);
241+
SELECT pathman.replace_hash_partition('test.hash_rel_0', 'test.hash_rel_extern');
242+
\d+ test.hash_rel_0
243+
\d+ test.hash_rel_extern
244+
INSERT INTO test.hash_rel SELECT * FROM test.hash_rel_0;
245+
DROP TABLE test.hash_rel_0;
246+
EXPLAIN SELECT * FROM test.hash_rel;
247+
239248
/*
240249
* Clean up
241250
*/

‎src/pl_funcs.c‎

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -201,24 +201,19 @@ Datum
201201
get_attribute_type_pl(PG_FUNCTION_ARGS)
202202
{
203203
Oid relid = PG_GETARG_OID(0);
204-
text *attname = PG_GETARG_TEXT_P(1);
204+
char *attname = text_to_cstring(PG_GETARG_TEXT_P(1));
205205
Oid result;
206-
HeapTuple tp;
207206

208-
/* NOTE: for now it's the most efficient way */
209-
tp = SearchSysCacheAttName(relid, text_to_cstring(attname));
210-
if (HeapTupleIsValid(tp))
207+
if ((result = get_attribute_type(relid, attname)) != InvalidOid)
211208
{
212-
Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
213-
result = att_tup->atttypid;
214-
ReleaseSysCache(tp);
215-
216209
PG_RETURN_OID(result);
217210
}
218211
else
212+
{
219213
elog(ERROR, "Cannot find type name for attribute \"%s\" "
220214
"of relation \"%s\"",
221-
text_to_cstring(attname), get_rel_name_or_relid(relid));
215+
attname, get_rel_name_or_relid(relid));
216+
}
222217

223218
PG_RETURN_NULL(); /* keep compiler happy */
224219
}

‎src/pl_hash_funcs.c‎

Lines changed: 77 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -9,14 +9,19 @@
99
*/
1010

1111
#include "pathman.h"
12+
#include "utils.h"
1213

1314
#include "utils/typcache.h"
15+
#include "utils/lsyscache.h"
16+
#include "utils/builtins.h"
1417

1518

1619
/* Function declarations */
1720

1821
PG_FUNCTION_INFO_V1( get_type_hash_func );
1922
PG_FUNCTION_INFO_V1( get_hash_part_idx );
23+
PG_FUNCTION_INFO_V1( build_hash_condition );
24+
PG_FUNCTION_INFO_V1( get_partition_hash );
2025

2126

2227
/*
@@ -44,3 +49,75 @@ get_hash_part_idx(PG_FUNCTION_ARGS)
4449

4550
PG_RETURN_UINT32(hash_to_part_index(value, part_count));
4651
}
52+
53+
/*
54+
* Build hash condition for a CHECK CONSTRAINT
55+
*/
56+
Datum
57+
build_hash_condition(PG_FUNCTION_ARGS)
58+
{
59+
TypeCacheEntry *tce;
60+
61+
Oid parent = PG_GETARG_OID(0);
62+
text *attname = PG_GETARG_TEXT_P(1);
63+
uint32 partitions_count = PG_GETARG_UINT32(2);
64+
uint32 partition_number = PG_GETARG_UINT32(3);
65+
Oid attyp;
66+
char *result;
67+
68+
if (partition_number >= partitions_count)
69+
elog(ERROR,
70+
"Partition number cannot exceed partitions count");
71+
72+
/* Get attribute type and its hash function oid */
73+
attyp = get_attribute_type(parent, text_to_cstring(attname));
74+
if (attyp == InvalidOid)
75+
elog(ERROR,
76+
"Relation '%s' has no attribute '%s'",
77+
get_rel_name(parent),
78+
text_to_cstring(attname));
79+
80+
tce = lookup_type_cache(attyp, TYPECACHE_HASH_PROC);
81+
82+
/* Create hash condition CSTRING */
83+
result = psprintf("%s.get_hash_part_idx(%s(%s), %u) = %u",
84+
get_namespace_name(get_pathman_schema()),
85+
get_func_name(tce->hash_proc),
86+
text_to_cstring(attname),
87+
partitions_count,
88+
partition_number);
89+
90+
PG_RETURN_TEXT_P(cstring_to_text(result));
91+
}
92+
93+
/*
94+
* Returns hash value for specified partition (0..N)
95+
*/
96+
Datum
97+
get_partition_hash(PG_FUNCTION_ARGS)
98+
{
99+
const PartRelationInfo *prel;
100+
Oid parent = PG_GETARG_OID(0);
101+
Oid partition = PG_GETARG_OID(1);
102+
Oid *children;
103+
int i;
104+
105+
/* Validate partition type */
106+
prel = get_pathman_relation_info(parent);
107+
if (!prel || prel->parttype != PT_HASH)
108+
elog(ERROR,
109+
"Relation '%s' isn't partitioned by hash",
110+
get_rel_name(parent));
111+
112+
/* Searching for partition */
113+
children = PrelGetChildrenArray(prel);
114+
for (i=0; i<prel->children_count; i++)
115+
if (children[i] == partition)
116+
PG_RETURN_UINT32(i);
117+
118+
/* If we get here then there is no such partition for specified parent */
119+
elog(ERROR,
120+
"Relation '%s' isn't a part of partitioned table '%s'",
121+
get_rel_name(parent),
122+
get_rel_name(partition));
123+
}

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