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Add pg_sequences view

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Like pg_tables, pg_views, and others, this view contains information
about sequences in a way that is independent of the system catalog
layout but more comprehensive than the information schema.

To help implement the view, add a new internal function
pg_sequence_last_value() to return the last value of a sequence.  This
is kept separate from pg_sequence_parameters() to separate querying
run-time state from catalog-like information.

Reviewed-by: Andreas Karlsson <andreas@proxel.se>
This commit is contained in:
Peter Eisentraut
2016-11-18 12:00:00 -05:00
parent 8f91f323b4
commit 67dc4ccbb2
10 changed files with 233 additions and 10 deletions
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17
src/backend/catalog/system_views.sql
View File

@ -158,6 +158,23 @@ CREATE VIEW pg_indexes AS
LEFT JOIN pg_tablespace T ON (T.oid = I.reltablespace)
WHERE C.relkind IN ('r', 'm') AND I.relkind = 'i';
CREATE OR REPLACE VIEW pg_sequences AS
SELECT
N.nspname AS schemaname,
C.relname AS sequencename,
pg_get_userbyid(C.relowner) AS sequenceowner,
p.start_value AS start_value,
p.minimum_value AS min_value,
p.maximum_value AS max_value,
p.increment AS increment_by,
p.cycle_option AS cycle,
p.cache_size AS cache_size,
pg_sequence_last_value(C.oid) AS last_value
FROM pg_class C LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace),
LATERAL pg_sequence_parameters(C.oid) p
WHERE NOT pg_is_other_temp_schema(N.oid)
AND relkind = 'S';
CREATE VIEW pg_stats WITH (security_barrier) AS
SELECT
nspname AS schemaname,

49
src/backend/commands/sequence.c
View File

@ -1534,8 +1534,8 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
TupleDesc tupdesc;
Datum values[5];
bool isnull[5];
Datum values[6];
bool isnull[6];
SeqTable elm;
Relation seqrel;
Buffer buf;
@ -1551,7 +1551,7 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
errmsg("permission denied for sequence %s",
RelationGetRelationName(seqrel))));
tupdesc = CreateTemplateTupleDesc(5, false);
tupdesc = CreateTemplateTupleDesc(6, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "start_value",
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "minimum_value",
@ -1562,6 +1562,8 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "cycle_option",
BOOLOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "cache_size",
INT8OID, -1, 0);
BlessTupleDesc(tupdesc);
@ -1574,6 +1576,7 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
values[2] = Int64GetDatum(seq->max_value);
values[3] = Int64GetDatum(seq->increment_by);
values[4] = BoolGetDatum(seq->is_cycled);
values[5] = Int64GetDatum(seq->cache_value);
UnlockReleaseBuffer(buf);
relation_close(seqrel, NoLock);
@ -1581,6 +1584,46 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
return HeapTupleGetDatum(heap_form_tuple(tupdesc, values, isnull));
}
/*
* Return the last value from the sequence
*
* Note: This has a completely different meaning than lastval().
*/
Datum
pg_sequence_last_value(PG_FUNCTION_ARGS)
{
Oid relid = PG_GETARG_OID(0);
SeqTable elm;
Relation seqrel;
Buffer buf;
HeapTupleData seqtuple;
Form_pg_sequence seq;
bool is_called;
int64 result;
/* open and AccessShareLock sequence */
init_sequence(relid, &elm, &seqrel);
if (pg_class_aclcheck(relid, GetUserId(), ACL_SELECT | ACL_USAGE) != ACLCHECK_OK)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied for sequence %s",
RelationGetRelationName(seqrel))));
seq = read_seq_tuple(elm, seqrel, &buf, &seqtuple);
is_called = seq->is_called;
result = seq->last_value;
UnlockReleaseBuffer(buf);
relation_close(seqrel, NoLock);
if (is_called)
PG_RETURN_INT64(result);
else
PG_RETURN_NULL();
}
void
seq_redo(XLogReaderState *record)

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

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 201611041
#define CATALOG_VERSION_NO 201611181
#endif

4
src/include/catalog/pg_proc.h
View File

@ -1763,8 +1763,10 @@ DATA(insert OID = 1576 ( setval PGNSP PGUID 12 1 0 0 0 f f f f t f v u 2 0 20
DESCR("set sequence value");
DATA(insert OID = 1765 ( setval PGNSP PGUID 12 1 0 0 0 f f f f t f v u 3 0 20 "2205 20 16" _null_ _null_ _null_ _null_ _null_ setval3_oid _null_ _null_ _null_ ));
DESCR("set sequence value and is_called status");
DATA(insert OID = 3078 ( pg_sequence_parameters PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 2249 "26" "{26,20,20,20,20,16}" "{i,o,o,o,o,o}" "{sequence_oid,start_value,minimum_value,maximum_value,increment,cycle_option}" _null_ _null_ pg_sequence_parameters _null_ _null_ _null_));
DATA(insert OID = 3078 ( pg_sequence_parameters PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 2249 "26" "{26,20,20,20,20,16,20}" "{i,o,o,o,o,o,o}" "{sequence_oid,start_value,minimum_value,maximum_value,increment,cycle_option,cache_size}" _null_ _null_ pg_sequence_parameters _null_ _null_ _null_));
DESCR("sequence parameters, for use by information schema");
DATA(insert OID = 4032 ( pg_sequence_last_value PGNSP PGUID 12 1 0 0 0 f f f f t f v u 1 0 20 "2205" _null_ _null_ _null_ _null_ _null_ pg_sequence_last_value _null_ _null_ _null_ ));
DESCR("sequence last value");
DATA(insert OID = 1579 ( varbit_in PGNSP PGUID 12 1 0 0 0 f f f f t f i s 3 0 1562 "2275 26 23" _null_ _null_ _null_ _null_ _null_ varbit_in _null_ _null_ _null_ ));
DESCR("I/O");

1
src/include/commands/sequence.h
View File

@ -73,6 +73,7 @@ extern Datum setval3_oid(PG_FUNCTION_ARGS);
extern Datum lastval(PG_FUNCTION_ARGS);
extern Datum pg_sequence_parameters(PG_FUNCTION_ARGS);
extern Datum pg_sequence_last_value(PG_FUNCTION_ARGS);
extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
extern ObjectAddress AlterSequence(ParseState *pstate, AlterSeqStmt *stmt);

14
src/test/regress/expected/rules.out
View File

@ -1615,6 +1615,20 @@ UNION ALL
l.label
FROM (pg_shseclabel l
JOIN pg_authid rol ON (((l.classoid = rol.tableoid) AND (l.objoid = rol.oid))));
pg_sequences| SELECT n.nspname AS schemaname,
c.relname AS sequencename,
pg_get_userbyid(c.relowner) AS sequenceowner,
p.start_value,
p.minimum_value AS min_value,
p.maximum_value AS max_value,
p.increment AS increment_by,
p.cycle_option AS cycle,
p.cache_size,
pg_sequence_last_value((c.oid)::regclass) AS last_value
FROM (pg_class c
LEFT JOIN pg_namespace n ON ((n.oid = c.relnamespace))),
LATERAL pg_sequence_parameters(c.oid) p(start_value, minimum_value, maximum_value, increment, cycle_option, cache_size)
WHERE ((NOT pg_is_other_temp_schema(n.oid)) AND (c.relkind = 'S'::"char"));
pg_settings| SELECT a.name,
a.setting,
a.unit,

23
src/test/regress/expected/sequence.out
View File

@ -300,20 +300,39 @@ SELECT nextval('sequence_test2');
5
(1 row)
CREATE SEQUENCE sequence_test3; -- not read from, to test is_called
-- Information schema
SELECT * FROM information_schema.sequences WHERE sequence_name IN
('sequence_test2', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
('sequence_test2', 'sequence_test3', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
'serialtest2_f4_seq', 'serialtest2_f5_seq', 'serialtest2_f6_seq')
ORDER BY sequence_name ASC;
sequence_catalog | sequence_schema | sequence_name | data_type | numeric_precision | numeric_precision_radix | numeric_scale | start_value | minimum_value | maximum_value | increment | cycle_option
------------------+-----------------+--------------------+-----------+-------------------+-------------------------+---------------+-------------+---------------+---------------------+-----------+--------------
regression | public | sequence_test2 | bigint | 64 | 2 | 0 | 32 | 5 | 36 | 4 | YES
regression | public | sequence_test3 | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f2_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f3_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f4_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f5_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f6_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
(6 rows)
(7 rows)
SELECT schemaname, sequencename, start_value, min_value, max_value, increment_by, cycle, cache_size, last_value
FROM pg_sequences
WHERE sequencename IN
('sequence_test2', 'sequence_test3', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
'serialtest2_f4_seq', 'serialtest2_f5_seq', 'serialtest2_f6_seq')
ORDER BY sequencename ASC;
schemaname | sequencename | start_value | min_value | max_value | increment_by | cycle | cache_size | last_value
------------+--------------------+-------------+-----------+---------------------+--------------+-------+------------+------------
public | sequence_test2 | 32 | 5 | 36 | 4 | t | 1 | 5
public | sequence_test3 | 1 | 1 | 9223372036854775807 | 1 | f | 1 |
public | serialtest2_f2_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f3_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f4_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f5_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f6_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
(7 rows)
-- Test comments
COMMENT ON SEQUENCE asdf IS 'won''t work';

23
src/test/regress/expected/sequence_1.out
View File

@ -300,20 +300,39 @@ SELECT nextval('sequence_test2');
5
(1 row)
CREATE SEQUENCE sequence_test3; -- not read from, to test is_called
-- Information schema
SELECT * FROM information_schema.sequences WHERE sequence_name IN
('sequence_test2', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
('sequence_test2', 'sequence_test3', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
'serialtest2_f4_seq', 'serialtest2_f5_seq', 'serialtest2_f6_seq')
ORDER BY sequence_name ASC;
sequence_catalog | sequence_schema | sequence_name | data_type | numeric_precision | numeric_precision_radix | numeric_scale | start_value | minimum_value | maximum_value | increment | cycle_option
------------------+-----------------+--------------------+-----------+-------------------+-------------------------+---------------+-------------+---------------+---------------------+-----------+--------------
regression | public | sequence_test2 | bigint | 64 | 2 | 0 | 32 | 5 | 36 | 4 | YES
regression | public | sequence_test3 | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f2_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f3_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f4_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f5_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
regression | public | serialtest2_f6_seq | bigint | 64 | 2 | 0 | 1 | 1 | 9223372036854775807 | 1 | NO
(6 rows)
(7 rows)
SELECT schemaname, sequencename, start_value, min_value, max_value, increment_by, cycle, cache_size, last_value
FROM pg_sequences
WHERE sequencename IN
('sequence_test2', 'sequence_test3', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
'serialtest2_f4_seq', 'serialtest2_f5_seq', 'serialtest2_f6_seq')
ORDER BY sequencename ASC;
schemaname | sequencename | start_value | min_value | max_value | increment_by | cycle | cache_size | last_value
------------+--------------------+-------------+-----------+---------------------+--------------+-------+------------+------------
public | sequence_test2 | 32 | 5 | 36 | 4 | t | 1 | 5
public | sequence_test3 | 1 | 1 | 9223372036854775807 | 1 | f | 1 |
public | serialtest2_f2_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f3_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f4_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f5_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
public | serialtest2_f6_seq | 1 | 1 | 9223372036854775807 | 1 | f | 1 | 2
(7 rows)
-- Test comments
COMMENT ON SEQUENCE asdf IS 'won''t work';

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

@ -138,12 +138,23 @@ SELECT nextval('sequence_test2');
SELECT nextval('sequence_test2');
SELECT nextval('sequence_test2');
CREATE SEQUENCE sequence_test3; -- not read from, to test is_called
-- Information schema
SELECT * FROM information_schema.sequences WHERE sequence_name IN
('sequence_test2', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
('sequence_test2', 'sequence_test3', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
'serialtest2_f4_seq', 'serialtest2_f5_seq', 'serialtest2_f6_seq')
ORDER BY sequence_name ASC;
SELECT schemaname, sequencename, start_value, min_value, max_value, increment_by, cycle, cache_size, last_value
FROM pg_sequences
WHERE sequencename IN
('sequence_test2', 'sequence_test3', 'serialtest2_f2_seq', 'serialtest2_f3_seq',
'serialtest2_f4_seq', 'serialtest2_f5_seq', 'serialtest2_f6_seq')
ORDER BY sequencename ASC;
-- Test comments
COMMENT ON SEQUENCE asdf IS 'won''t work';
COMMENT ON SEQUENCE sequence_test2 IS 'will work';