Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.sai.msu.su/~megera/postgres/talks/Everything-Indexes-v3.pdf Äàòà èçìåíåíèÿ: Fri Apr 25 15:16:07 2014 Äàòà èíäåêñèðîâàíèÿ: Mon Apr 11 08:08:19 2016 Êîäèðîâêà:

PostgreSQL (v3)
, ,

PostgreSQL Development Team


::Teodor Sigaev
· Locale support · Extendability (indexing)
· GiST, GIN, SP-GiST

· Extensions:
· · · · · intarray pg_trgm ltree hstore, hstore v2.0 jsonb plantuner
htps://www.facebook.com/oleg.bartunov obartunov@gmail.com

· Full Text Search (FTS)


Alexander Korotkov
· · · · · Indexed regexp search GIN compression & fast scan Fast GiST build Range types indexing Split for GiST

aekorotkov@gmail.com



« »
the only weapon that is effective against a werewolf, witch, or other monsters.


« »
· -- ( SQL) . · ! ·
· - (KNN !) · (exclusion contraint!) · ,,

·
· ,


« »
·
· SQL -- , , , , ,

·
· , , , , · , , .

· ! ·


PostgreSQL
· -- , . · TID (tuple id - #page: ofset) · , ( GIN) · MVCC: (), . · · , index bloat.



:
· - WHERE expr opr value · - ORDER BY expr [ASC|DESC] · knn - ORDER BY expr opr value [ASC]



· ( ) · (, concurrent index ) · ( GIN ) · -- ( ) ·


:
CREATE TABLE test3 AS (SELECT id, random() AS v, point(random(), random()) AS p FROM generate_series(1,1000000) id); ALTER TABLE test3 ADD PRIMARY KEY (id); CREATE INDEX test3_p_idx ON test3 USING gist (p); CREATE INDEX test3_v_id_idx ON test3 (v, id); SELECT * FROM test3 WHERE p <@ box(point(0.5, 0.5), point(0.51, 0.51)); Bitmap Heap Scan on test3 (cost=48.03..2805.08 rows=1000 width=28) (actual time=0.123..0.226 rows=98 loops=1) Recheck Cond: (p <@ '(0.51,0.51),(0.5,0.5)'::box) Heap Blocks: exact=95 -> Bitmap Index Scan on test3_p_idx (cost=0.00..47.78 rows=1000 width=0) (actual time=0.102..0.102 rows=98 loops=1) Index Cond: (p <@ '(0.51,0.51),(0.5,0.5)'::box) Planning time: 0.111 ms Execution time: 0.532 ms (7 rows)


:
1. pg_atribute 2. oid pg_operator 3. 4. oid pg_opclass 5. pg_amop oid oid 6., ( pg_amop) .


:
SELECT * FROM test3 WHERE p <@ box(point(0.5, 0.5), point(0.51, 0.51)); pg_operator oid oprname oprleft oprright 511 <@ 600 603 (box) 512 <@ 600 602 756 <@ 600 604 ... pg_amop amopfamilyamopopramopstrategy 1029 511 28 4015 511 8 4016 511 8 ... pg_attribute attrelid attname attnum atttypid 377315 id 1 23 377315 v 2 701 377315 p 3 600 ...

pg_index indrelid indkey indclass pg_opclass opcfamily opcname oid 377315 1 1978 377315 3 10068 1970float8_ops 3123 377315 2 1 3123 1978 1976int4_ops 1978 1029point_ops 10068 ... ...


«» ?
Seq Scan on tbl (cost=0.00..17.50 rows=700 width=8) Filter: (a > 30) Rows Removed by Filter: 300 Index Only Scan using ab_idx on tbl (cost=0.28..6.03 rows=100 width=8) Index Cond: (a > 90) Heap Fetches: 0 update tbl set a=18; Bitmap Heap Scan on tbl (cost=9.67..20.92 rows=180 width=8) Recheck Cond: (a > 90) -> Bitmap Index Scan on ab_idx (cost=0.00..9.63 rows=180 width=0) Index Cond: (a > 90) set enable_indexonlyscan to of; set enable_bitmapscan to of; Index Scan using ab_idx on tbl (cost=0.28..6.04 rows=1 width=8) Index Cond: (a > 90)


Sequental Scan
·
<10 A B C D E


(Index Scan)
· , ( ),
<10 C A B C D E


(Index-only Scan)
· , , Visibility Map -. <10
C A B C D E

Visibiliy Map


++
· -- , ORDER BY, .
<10 C A B C D E


B-tree
· --
<10 C A B C D E


GiST,GIN,SP-GiST
· -- API,
<10 C A B C D E


Bitmap index scan
· Index scan , bitmap . .
<10 C 1 0 A B C D E

1 1

1 1


Bitmap index scan
· Index scan , bitmap . . · bitmap (work_mem) (#page,#ofset) · work_mem , #page
· RECHECK -- , !



· Cost-based , :
· · «»
· ·

·
· EXPLAIN, explain.depesz.com · (generate_series()) · contrib/pgbench



· (postgresql.conf, SET)
· · · · enable_seqscan enable_indexscan enable_bitmapscan enable_indexonlyscan

· plantuner --
· htp://www.sigaev.ru/git/gitweb.cgi?p=plantuner.git;a=summary

· pg_hint_plan --
· htp://en.sourceforge.jp/projects/pghintplan/ · htp://habrahabr.ru/post/169751/



· (postgresql.conf, SET)
· efectve_cache_size (1/2, ¾ RAM) - planner · random_page_cost (4.0) -- . random_page_cost, . SSD 1.0. · maintenance_work_mem -- CREATE INDEX · work_mem -- BITMAP HEAP SCAN. RECHECK ( ).

· (analyze) .


EXPLAIN
· · · · ANALYZE - COSTS ON|OFF, Syntax: EXPLAIN [ ( opton [, ...] ) ] BUFFERS ON|OFF - EXPLAIN [ ANALYZE ] [ VER
· SHARED READ,HIT -- ,

statement BOSE ] statement

· TIMING ON|OFF --

where opton can be one of: ANALYZE [ boolean ] VERBOSE [ boolean ] COSTS [ boolean ] BUFFERS [ boolean ] TIMING [ boolean ] FORMAT { TEXT | XML | JSON | YAML }


EXPLAIN
· ·
· Rows estmated actual rows -- (analyze table, ALTER TABLE ... ALTER COLUMN ... SET STATISTICS ...) · -- Shared hit · Recheck -- Heap Blocks: exact, lossy (work_mem) · costs · Planning tme , , prepared statements


EXPLAIN

explain(analyze,buffers, costs on) SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.6; QUERY PLAN -------------------------------------------------------------------------------------------Bitmap Heap Scan on test1 (cost=2149.53..9073.25 rows=101181 width=12) (actual time=12.384..51.759 rows=99831 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Heap Blocks: exact=5406 Buffers: shared hit=2155 read=3527 -> Bitmap Index Scan on test1_v_idx (cost=0.00..2124.24 rows=101181 width=0) (actual time=11.617..11.617 rows=99831 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Buffers: shared read=276 Planning time: 0.097 ms Execution time: 57.792 ms (9 rows)


EXPLAIN

explain(analyze,buffers, costs on) SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.6; QUERY PLAN -------------------------------------------------------------------------------------------Bitmap Heap Scan on test1 (cost=2149.53..9073.25 rows=101181 width=12) (actual time=10.894 Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Heap Blocks: exact=5406 Buffers: shared hit=5682 ­ Buffers: shared hit=2155 read=3527 -> Bitmap Index Scan on test1_v_idx (cost=0.00..2124.24 rows=101181 width=0) (actual ti Index Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Buffers: shared hit=276 Planning time: 0.092 ms Execution time: 38.000 ms (9 rows)


CREATE INDEX
CREATE ( [ [ [ [ [ UNIQUE ] INDEX [ CONCURRENTLY { column_name | ( expression ) } NULLS { FIRST | LAST } ] [, ...] WITH ( storage_parameter = value TABLESPACE tablespace_name ] WHERE predicate ] ] [ name ] ON table_name [ USING method ] [ COLLATE collation ] [ opclass ] [ ASC | DESC ] ) [, ... ] ) ]

Syntax: ALTER INDEX ALTER INDEX ALTER INDEX ALTER INDEX

[ [ [ [

IF IF IF IF

EXISTS EXISTS EXISTS EXISTS

] ] ] ]

name name name name

RENAME TO new_name SET TABLESPACE tablespace_name SET ( storage_parameter = value [, ... ] ) RESET ( storage_parameter [, ... ] )

DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ]


CREATE INDEX
CREATE ( [ [ [ [ [ UNIQUE ] INDEX [ CONCURRENTLY { column_name | ( expression ) } NULLS { FIRST | LAST } ] [, ...] WITH ( storage_parameter = value TABLESPACE tablespace_name ] WHERE predicate ] ] [ name ] ON table_name [ USING method ] [ COLLATE collation ] [ opclass ] [ ASC | DESC ] ) [, ... ] ) ]

=# \d pg_am Table "pg_catalog.pg_am" Column | Type | Modifiers -----------------+----------+----------amname | name | not null amstrategies | smallint | not null amsupport | smallint | not null amcanorder | boolean | not null ....................................... amcanunique | boolean | not null amoptions | regproc | not null

=# select amname from pg_am; amname -------btree ACCESS METHODS hash gist gin spgist (5 rows)


CREATE INDEX
CREATE ( [ [ [ [ [ UNIQUE ] INDEX [ CONCURRENTLY { column_name | ( expression ) } NULLS { FIRST | LAST } ] [, ...] WITH ( storage_parameter = value TABLESPACE tablespace_name ] WHERE predicate ] ] [ name ] ON table_name [ USING method ] [ COLLATE collation ] [ opclass ] [ ASC | DESC ] ) [, ... ] ) ]

· storage_parameter
· BTREE, GiST - FILLFACTOR · GIN -- FASTUPDATE

· TABLESPACE -- / · pclass -- ( ) · ASC|DESC -- ORDER BY


CREATE INDEX
CREATE ( [ [ [ [ [ UNIQUE ] INDEX [ CONCURRENTLY { column_name | ( expression ) } NULLS { FIRST | LAST } ] [, ...] WITH ( storage_parameter = value TABLESPACE tablespace_name ] WHERE predicate ] ] [ name ] ON table_name [ USING method ] [ COLLATE collation ] [ opclass ] [ ASC | DESC ] ) [, ... ] ) ]

· CONCURRENTLY --
· · «» · · · DROP INDEX CONCURRENTLY
postgres=# \d tt Table "public.tt" Column | Type | Modifiers --------+---------+----------i | integer | Indexes: "tt_idx" btree (i) INVALID


CREATE INDEX
CREATE ( [ [ [ [ [ UNIQUE ] INDEX [ CONCURRENTLY { column_name | ( expression ) } NULLS { FIRST | LAST } ] [, ...] WITH ( storage_parameter = value TABLESPACE tablespace_name ] WHERE predicate ] ] [ name ] ON table_name [ USING method ] [ COLLATE collation ] [ opclass ] [ ASC | DESC ] ) [, ... ] ) ]

·
· IMMUTABLE · «» · «» CREATE INDEX
create index sin_idx on foo(sin(id)); =# explain select 1 from foo where sin(id)=0; QUERY PLAN ------------------------------------------------------------------Index Scan using sin_idx on foo (cost=0.14..8.16 rows=1 width=0) Index Cond: (sin((id)::double precision) = 0::double precision) (2 rows)


CREATE INDEX
CREATE ( [ [ [ [ [ UNIQUE ] INDEX [ CONCURRENTLY { column_name | ( expression ) } NULLS { FIRST | LAST } ] [, ...] WITH ( storage_parameter = value TABLESPACE tablespace_name ] WHERE predicate ] ] [ name ] ON table_name [ USING method ] [ COLLATE collation ] [ opclass ] [ ASC | DESC ] ) [, ... ] ) ]

· COLLATE collaton ! tags text[] · CREATE INDEX tagidx ON t USING gin (tags collate "C") 11 10,000,000 CREATE INDEX tagidx ON t USING gin (tags collate «ru_RU.ut8»);


( )
CREATE TABLE test1 WITH (autovacuum_enabled = off) AS (SELECT id, random() v FROM generate_series(1,1000000) id); CREATE INDEX test1_v_idx ON test1 (v);

!

SELECT * FROM test1 WHERE v BETWEEN 0.1 AND 0.9 Bitmap Heap Scan on test1 (cost=107.67..5701.65 rows=5000 width=12) (actual time=82.343..155.903 rows=799793 loops=1) Recheck Cond: ((v >= 0.1::double precision) AND (v <= 0.9::double precision)) Heap Blocks: exact=5406 -> Bitmap Index Scan on test1_v_idx (cost=0.00..106.42 rows=5000 width=0) (actual time=81.576..81.576 rows=799793 loops=1) Index Cond: ((v >= 0.1::double precision) AND (v <= 0.9::double precision)) Planning time: 0.069 ms Execution time: 192.032 ms


( )
SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.500001; ! Bitmap Heap Scan on test1 (cost=107.67..5701.65 rows=5000 width=12) (actual time=0.022..0.022 rows=0 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.500001::double precision)) Heap Blocks: -> Bitmap Index Scan on test1_v_idx (cost=0.00..106.42 rows=5000 width=0) (actual time=0.021..0.021 rows=0 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.500001::double precision)) Planning time: 0.097 ms Execution time: 0.037 ms

SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.6; Bitmap Heap Scan on test1 (cost=107.67..5701.65 rows=5000 width=12) (actual time=11.256..31.522 rows=99831 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Heap Blocks: exact=5406 -> Bitmap Index Scan on test1_v_idx (cost=0.00..106.42 rows=5000 width=0) (actual time=10.559 Index Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Planning time: 0.086 ms Execution time: 36.370 ms

!


( )
VACUUM ANALYZE test1; SELECT * FROM test1 WHERE v BETWEEN 0.1 AND 0.9; Seq Scan on test1 (cost=0.00..20406.00 rows=800835 width=12) (actual time=0.008..144.527 rows=799793 loops=1) Filter: ((v >= 0.1::double precision) AND (v <= 0.9::double precision)) Rows Removed by Filter: 200207 Planning time: 0.095 ms Execution time: 180.556 ms SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.500001; Index Scan using test1_v_idx on test1 (cost=0.42..8.45 rows=1 width=12) (actual time=0.011..0.011 rows=0 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.500001::double precision)) Planning time: 0.104 ms Execution time: 0.025 ms


random_page_cost
SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.6; Bitmap Heap Scan on test1 (cost=2149.53..9073.25 rows=101181 width=12) (actual time=10.302..30.350 rows=99831 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Heap Blocks: exact=5406 -> Bitmap Index Scan on test1_v_idx (cost=0.00..2124.24 rows=101181 width=0) (actual time=9.556..9.556 rows=99831 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Planning time: 0.104 ms Execution time: 35.187 ms SET random_page_cost = 1; Index Scan using test1_v_idx on test1 (cost=0.42..7708.04 rows=101181 width=12) (actual time=0.016..54.971 rows=99831 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Planning time: 0.096 ms Execution time: 59.795 ms


work_mem
show work_mem; work_mem ---------4MB (1 row) SET work_mem = '128 kB'; Bitmap Heap Scan on test1 (cost=2149.53..9073.25 rows=101181 width=12) (actual time=8.527..104.225 rows=99831 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Rows Removed by Index Recheck: 687690 Heap Blocks: exact=1269 lossy=4137 -> Bitmap Index Scan on test1_v_idx (cost=0.00..2124.24 rows=101181 width=0) (actual time=8.386..8.386 rows=99831 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.6::double precision)) Planning time: 0.109 ms Execution time: 108.821 ms


maintenance_work_mem
· (BULK INDEX CREATION)
, ( )
SET maintenance_work_mem = '1 MB'; CREATE INDEX test1_v_idx ON test1 (v); Time: 1194,299 ms SET maintenance_work_mem = '128 MB'; CREATE INDEX test1_v_idx ON test1 (v); Time: 708,644 ms


CLUSTER
·
· · ACCESS EXCLUSIVE lock - :( · · FILLFACTOR < 100% CLUSTER [VERBOSE] table_name [ USING index_name ] CLUSTER [VERBOSE] ALTER TABLE ... CLUSTER ON index_name SET WITHOUT CLUSTER


CLUSTER
SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.6; Bitmap Heap Scan on test1 (actual time=20.269..51.084 rows=200321 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.7::double precision)) Heap Blocks: exact=5406 Buffers: shared hit=5956 -> Bitmap Index Scan on test1_v_idx (actual time=19.490..19.490 rows=200321 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.7::double precision)) Buffers: shared hit=550 Execution time: 62.382 ms CLUSTER test1 USING test1_v_idx; =# \d test1 Table "public.test1" Column | Type | Modifiers --------+------------------+----------id | integer | v | double precision | Indexes: "test1_v_idx" btree (v) CLUSTER


CLUSTER
SELECT * FROM test1 WHERE v BETWEEN 0.5 AND 0.6; Bitmap Heap Scan on test1 (actual time=15.824..34.043 rows=200321 loops=1) Recheck Cond: ((v >= 0.5::double precision) AND (v <= 0.7::double precision)) Heap Blocks: exact=1084 Buffers: shared hit=1634 -> Bitmap Index Scan on test1_v_idx (actual time=15.704..15.704 rows=200321 loops=1) Index Cond: ((v >= 0.5::double precision) AND (v <= 0.7::double precision)) Buffers: shared hit=550 Execution time: 44.517 ms

· ~ 5 , 5046 vs 1084 !


Tablespace
· tablespace ( ) IO
tablespace : CREATE INDEX test1_v1_idx ON test1(v1) TABLESPACE idx_tablespace; tablespace: ALTER INDEX test1_v1_idx SET TABLESPACE idx_tablespace; - ! CREATE INDEX CONCURRENTLY test1_v1_idx2 ON test1(v1) TABLESPACE idx_tablespace; BEGIN; DROP INDEX test1_v1_idx; - ! ALTER INDEX test1_v1_idx2 RENAME TO test1_v1_idx; COMMIT;


Unlogged tables
· · · · · WAL , UNLOGGED
CREATE INSERT INSERT Time: CREATE INSERT INSERT Time: TABLE test INTO test 0 1000000 3055.022 ms UNLOGGED INTO testU 0 1000000 572.509 ms (id integer, r float); SELECT id, random() FROM generate_series(1,1000000) id; TABLE testU (id integer, r float); SELECT id, random() FROM generate_series(1,1000000) id;


LIKE

# CREATE INDEX dblp_titles_idx ON dblp_titles(s); # EXPLAIN ANALYZE SELECT * FROM dblp_titles WHERE s LIKE 'Transaction%'; QUERY PLAN ------------------------------------------------------------------------------------------------Seq Scan on dblp_titles (cost=0.00..57433.89 rows=12634 width=36) (actual time=0.030..321.498 r Filter: (s ~~ 'Transaction%'::text) Rows Removed by Filter: 2526351 Total runtime: 321.652 ms (4 rows)

# CREATE INDEX dblp_titles_pattern_idx ON dblp_titles(s text_pattern_ops); # EXPLAIN ANALYZE SELECT * FROM dblp_titles WHERE s LIKE 'Transaction%'; QUERY PLAN ------------------------------------------------------------------------------------------------Index Scan using dblp_titles_pattern_idx on dblp_titles (cost=0.00..9.18 rows=159 width=52) (ac Index Cond: ((s ~>=~ 'Transaction'::text) AND (s ~<~ 'Transactioo'::text)) Filter: (s ~~ 'Transaction%'::text) Total runtime: 0.706 ms (4 rows)


ORDER BY
SELECT * FROM test1 ORDER BY v; Index Scan using test1_v_idx on test1 (cost=0.00..47604.02 rows=1000000 width=12) (actual time=0.018..145.569 rows=1000000 loops=1) Buffers: shared hit=8141 Total runtime: 188.832 ms SET enable_indexscan = off; SELECT * FROM test1 ORDER BY v; Sort (cost=132154.34..134654.34 rows=1000000 width=12) (actual time=636.567..752.384 rows=1000000 loops=1) Sort Key: v Sort Method: external sort Disk: 25424kB Buffers: shared hit=5406, temp read=3178 written=3178 -> Seq Scan on test1 (cost=0.00..15406.00 rows=1000000 width=12) (actual time=0.010..86.157 rows=1000000 loops=1) Buffers: shared hit=5406 Total runtime: 819.682 ms


, ORDER BY LIMIT
«»?

SELECT * FROM test1 ORDER BY v LIMIT 20; Limit (cost=0.00..0.95 rows=20 width=12) (actual time=0.014..0.021 rows=20 loops=1) Buffers: shared hit=4 -> Index Scan using test1_v_idx on test1 (cost=0.00..47604.02 rows=1000000 width=12) (actual Buffers: shared hit=4 Total runtime: 0.033 ms

SELECT * FROM test1 ORDER BY v LIMIT 20 OFFSET 900000; Limit (cost=42843.62..42844.57 rows=20 width=12) (actual time=178.863..178.868 rows=20 loops=1) Buffers: shared hit=7327 -> Index Scan using test1_v_idx on test1 (cost=0.00..47604.02 rows=1000000 width=12) (actual Buffers: shared hit=7327 Total runtime: 178.887 ms



SELECT * FROM test1 WHERE v >= 0.9 ORDER BY v LIMIT 20; Limit (cost=0.00..4.85 rows=20 width=12) (actual time=0.050..0.058 rows=20 loops=1) Buffers: shared hit=3 read=1 -> Index Scan using test1_v_idx on test1 (cost=0.00..24503.79 rows=101021 width=12) (actual Index Cond: (v >= 0.9::double precision) Buffers: shared hit=3 read=1 Total runtime: 0.075 ms


, ORDER BY LIMIT
CREATE TABLE test4 AS (SELECT id, (random()*20::int) AS v1, random() AS v2 FROM generate_series(1,1000000) id); CREATE INDEX test4_v1_v2_idx ON test4 (v1, v2);

SELECT * FROM test4 ORDER BY v1, v2 LIMIT 20; Limit (cost=0.00..1.12 rows=20 width=20) (actual time=0.012..0.097 rows=20 loops=1) -> Index Scan using test4_v1_v2_idx on test4 (cost=0.00..55892.40 rows=1000000 width=20) (ac Total runtime: 0.110 ms

SELECT * FROM test4 WHERE (v1, v2) > (9,0.5) ORDER BY v1, v2 LIMIT 20; Limit (cost=0.00..1.58 rows=20 width=20) (actual time=0.025..0.088 rows=20 loops=1) -> Index Scan using test4_v1_v2_idx on test4 (cost=0.00..43628.52 rows=551512 width=20) (act Index Cond: (ROW(v1, v2) > ROW(9::double precision, 0.5::double precision)) Total runtime: 0.111 ms


, ORDER BY LIMIT
· !
SELECT * FROM test4 ORDER BY v1 LIMIT 20; Limit (cost=0.00..1.12 rows=20 width=20) (actual time=0.016..0.042 rows=20 loops=1) -> Index Scan using test4_v1_v2_idx on test4 (cost=0.00..55889.49 rows=1000000 width=20) (actual time=0.016..0.042 rows=20 loops=1) Total runtime: 0.060 ms

SELECT * FROM test4 ORDER BY v2 LIMIT 20; Limit (cost=42979.64..42979.69 rows=20 width=20) (actual time=161.618..161.620 rows=20 loops=1) -> Sort (cost=42979.64..45479.64 rows=1000000 width=20) (actual time=161.616..161.618 rows=20 loops=1) Sort Key: v2 Sort Method: top-N heapsort Memory: 26kB -> Seq Scan on test4 (cost=0.00..16370.00 rows=1000000 width=20) (actual time=0.036..83.817 rows=1000000 loops=1) Total runtime: 161.645 ms


Index-only scan (9.2+)
· Index Scan -, .
· (xmin, xmax). .

· Crash-safe Visibility Map ( ) , «» .
· Index-Only Scan Visibility Map ·


Index-only scan
\d test4 Table "public.test4" Column | Type | Modifiers --------+------------------+----------id | integer | v1 | double precision | v2 | double precision | Indexes: "test4_v1_v2_idx" btree (v1) ANALYZE test4; SELECT v1, v2 FROM test4 WHERE v1 < 0.5; Bitmap Heap Scan on test4 (actual time=5.618..16.428 rows=24617 loops=1) Recheck Cond: (v1 < 0.5::double precision) Heap Blocks: exact=6238 -> Bitmap Index Scan on test4_v1_v2_idx (actual time=4.030..4.030 rows=24617 loops=1) Index Cond: (v1 < 0.5::double precision) Execution time: 17.835 ms


Index-only scan
· Index-only Scan , !
SET enable_bitmapscan = OFF; SET enable_seqscan = OFF; v1,v2 SELECT v1,v2 FROM test4 WHERE v1 Index Scan using test4_v1_v2_idx Index Cond: (v1 < 0.5::double Execution time: 18.381 ms (v1) < 0.5; on test4 (actual time=0.028..16.846 rows=24617 loops=1) precision)

· v1 , Heap Fetches ?
SELECT v1 FROM test4 WHERE v1 < 0.5; Index Only Scan using test4_v1_v2_idx on test4 (actual time=0.038..13.890 rows=24617 loops=1) Index Cond: (v1 < 0.5::double precision) Heap Fetches: 24617 Execution time: 15.172 ms


Index-only scan
· v1 , Heap Fetches ?
· Visibility Map !
select relname,100*relallvisible/(relpages+1) as allvisible from pg_class where relname='test4'; relname | allvisible ---------+-----------test4 | 0 vacuum test4; select relname,100*relallvisible/(relpages+1) as allvisible from pg_class where relname='test4'; relname | allvisible ---------+-----------test4 | 99 Index Only Scan using test4_v1_v2_idx on test4 (actual time=0.021..2.762 rows=24617 loops=1) Index Cond: (v1 < 0.5::double precision) Heap Fetches: 0 Execution time: 3.878 ms

· Index-only scan : 3.9 ms vs 18 ms


Loose Indexscan -- CTE
· MySQL -- distnct values. Loose indexscan distnct values.
\d t Table "public.t" Column | Type | Modifers --------+---------+----------id | integer | Indexes: "t_idx" btree (id) select distnct(id) from t; id ---0 1 (2 rows) Time: 279.461 ms =# with recursive t as (select min(id) as id from t union all select (select min(id) from t where id > t.id) from t where t.id is not null ) select id from t where id is not null union all select null where exists (select * from t where id is null); id ---0 1 (2 rows) Time: 0.895 ms




CREATE TABLE test2 AS (SELECT id, polygon(20,circle(point(random(), random()),0.01)) AS p FROM generate_series(1,50000) id); ALTER TABLE test2 ADD PRIMARY KEY (id); CREATE INDEX test2_box_idx ON test2 USING gist (p); SELECT * FROM test2 t1 JOIN test2 t2 ON t2.id > t1.id AND t1.p && t2.p; Nested Loop (cost=196.89..15740565.92 rows=4166667 width=72) (actual time=9.464..93463.065 rows=15742 loops=1) -> Seq Scan on test2 t1 (cost=0.00..13000.00 rows=50000 width=36) (actual time=0.027..54.015 rows=50000 loops=1) -> Bitmap Heap Scan on test2 t2 (cost=196.89..313.72 rows=83 width=36) (actual time=1.845..1.866 rows=0 loops=50000) Recheck Cond: ((t1.p && p) AND (id > t1.id)) Rows Removed by Index Recheck: 0 -> BitmapAnd (cost=196.89..196.89 rows=83 width=0) (actual time=1.751..1.751 rows=0 loo -> Bitmap Index Scan on test2_box_idx (cost=0.00..6.41 rows=250 width=0) (actual time=0.015..0.015 rows=2 loops=50000) Index Cond: (t1.p && p) -> Bitmap Index Scan on test2_pkey (cost=0.00..190.18 rows=16667 width=0) (actual time=1.733..1.733 rows=25000 loops=50000) Index Cond: (id > t1.id) Total runtime: 93465.872 ms



Nested (actual -> (actual -> (actual Loop (cost=0.28..320195.00 rows=4166667 width=72) time=0.117..50501.640 rows=1523159 loops=1) Seq Scan on test2 t1 (cost=0.00..3000.00 rows=50000 width=36) time=0.005..8.904 rows=50000 loops=1) Index Scan using test2_box_idx on test2 t2 (cost=0.28..5.51 rows=83 width=36) time=0.272..1.005 rows=30 loops=50000) Index Cond: (t1.p && p) Rows Removed by Index Recheck: 18 Filter: (id > t1.id) Rows Removed by Filter: 31 Planning time: 0.530 ms Execution time: 50574.670 ms (9 rows)


?
pg_operator oprname oprrest oprjoin oprleft oprright && areasel areajoinsel 604 604 (polygon) src/backend/utils/adt/geo_selfuncs.c Datum areasel(PG_FUNCTION_ARGS) { PG_RETURN_FLOAT8(0.005); } Datum areajoinsel(PG_FUNCTION_ARGS) { PG_RETURN_FLOAT8(0.005); }



SET enable_bitmapscan = OFF; SELECT * FROM test2 t1 JOIN test2 t2 ON t2.id > t1.id AND t1.p && t2.p; Nested Loop (cost=0.00..18358598.00 rows=4166667 width=72) (actual time=2.458..11824.565 rows=15742 loops=1) -> Seq Scan on test2 t1 (cost=0.00..13000.00 rows=50000 width=36) (actual time=0.005..20.801 rows=50000 loops=1) -> Index Scan using test2_box_idx on test2 t2 (cost=0.00..366.08 rows=83 width=36) (actual time=0.215..0.236 rows=0 loops=50000) Index Cond: (t1.p && p) Rows Removed by Index Recheck: 0 Filter: (id > t1.id) Rows Removed by Filter: 1 Total runtime: 11826.029 ms


plantuner
LOAD 'plantuner'; SET plantuner.forbid_index='test2_pkey'; SELECT Nested -> ->

* FROM test2 t1 JOIN test2 t2 ON t2.id > t1.id AND t1.p && t2.p; Loop (cost=6.43..17418092.51 rows=4166667 width=72) (actual time=1.547..12355.722 rows=15 Seq Scan on test2 t1 (cost=0.00..13000.00 rows=50000 width=36) (actual time=0.004..22.919 Bitmap Heap Scan on test2 t2 (cost=6.43..347.27 rows=83 width=36) (actual time=0.224..0.24 Recheck Cond: (t1.p && p) Rows Removed by Index Recheck: 0 Filter: (id > t1.id) Rows Removed by Filter: 1 -> Bitmap Index Scan on test2_box_idx (cost=0.00..6.41 rows=250 width=0) (actual time=0.014..0.014 rows=2 loops=50000) Index Cond: (t1.p && p) Total runtime: 12357.238 ms

plantuner: htp://www.sai.msu.su/~megera/wiki/plantuner


pg_hint_plan
LOAD 'pg_hint_plan';

/*+ IndexScan(test2 test2_box_idx) */ SELECT * FROM test2 t1 JOIN test2 t2 ON t2.id > t1.id AND t1.p && t2.p; Nested Loop (cost=0.00..18358598.00 rows=4166667 width=72) (actual time=2.457..11912.368 rows=15 -> Seq Scan on test2 t1 (cost=0.00..13000.00 rows=50000 width=36) (actual time=0.005..21.094 -> Index Scan using test2_box_idx on test2 t2 (cost=0.00..366.08 rows=83 width=36) (actual ti Index Cond: (t1.p && p) Rows Removed by Index Recheck: 0 Filter: (id > t1.id) Rows Removed by Filter: 1 Total runtime: 11913.821 ms

pg_hint_plan: htp://habrahabr.ru/post/169751/


?
CREATE Time: CREATE Time: INSERT Time: Total: CREATE Time: INSERT Time: ALTER Time: CREATE Time: Total: TABLE test5 (id integer PRIMARY KEY, v float8); 1,991 ms INDEX test5_v_idx ON test5(v); 0,506 ms INTO test5 (SELECT id, random() FROM generate_series(1,1000000) id); 4909,127 ms 4911 ms TABLE test5 (id integer, v float8); 0,763 ms INTO test5 (SELECT id, random() FROM generate_series(1,1000000) id); 938,852 ms TABLE test5 ADD PRIMARY KEY (id); 779,618 ms INDEX test5_v_idx ON test5(v); 1195,492 ms 2915 ms



CREATE TABLE test6 AS ( SELECT id, (random()*20::int) AS v1, random() AS v2 FROM generate_series(1,1000000) id); CREATE INDEX test6_v1_0_v2_idx ON test6 (v2) WHERE v1 = 0; ­ index size 8Kb vs 21 Mb (full)

SELECT * FROM test6 WHERE v1 = 0 AND v2 BETWEEN 0.1 AND 0.4; Index Scan using test6_v1_0_v2_idx on test6 (cost=0.00..8.27 rows=1 width=20) (actual time=0.008 Index Cond: ((v2 >= 0.1::double precision) AND (v2 <= 0.4::double precision)) Total runtime: 0.037 ms SELECT * FROM test6 WHERE v1 = 0; Index Scan using test6_v1_0_v2_idx on test6 Total runtime: 0.021 ms

(cost=0.00..8.27 rows=1 width=20) (actual time=0.007

SELECT * FROM test6 WHERE v2 BETWEEN 0.1 AND 0.2; Seq Scan on test6 (cost=0.00..21370.00 rows=99962 width=20) (actual time=0.044..157.861 rows=100 Filter: ((v2 >= 0.1::double precision) AND (v2 <= 0.2::double precision)) Rows Removed by Filter: 899919 Total runtime: 162.312 ms



CREATE TABLE test7 AS ( SELECT id, random() AS v1, random() AS v2 FROM generate_series(1,1000000) id); CREATE INDEX test7_v1_plus_v2_idx ON test7((v1 + v2)); SELECT * FROM test7 WHERE v1 + v2 > 1.9; Bitmap Heap Scan on test7 (actual time=1.229..4.534 rows=4897 loops=1) Recheck Cond: ((v1 + v2) > 1.9::double precision) Heap Blocks: exact=3439 Buffers: shared hit=3456 -> Bitmap Index Scan on test7_v1_plus_v2_idx (actual time=0.656..0.656 rows=4897 loops=1) Index Cond: ((v1 + v2) > 1.9::double precision) Buffers: shared hit=17 Execution time: 4.921 ms



· CREATE INDEX !
SELECT * FROM test7 WHERE v2 + v1 > 1.9; QUERY PLAN -----------------------------------------------------------------Seq Scan on test7 (actual time=0.020..118.885 rows=4897 loops=1) Filter: ((v2 + v1) > 1.9::double precision) Rows Removed by Filter: 995103 Buffers: shared hit=4388 read=1982 Execution time: 119.202 ms (5 rows)


Heap-Only Tuples (HOT)
· -- delete, insert (MVCC) · 8.2: · 8.3+: , (Heap-Only Tuples, HOT) · :
CREATE TABLE test8 AS (SELECT id, random() AS v1, random() AS v2, random() AS v3 FROM generate_series(1,1000000) id); CREATE INDEX test8_v1_idx ON test8(v1); CREATE INDEX test8_v2_idx ON test8(v2); CREATE INDEX test8_v3_idx ON test8(v3);


Head Only Tuples (HOT)
test8_v1_idx - 21 MB test8_v2_idx - 21 MB test8_v3_idx - 21 MB UPDATE test8 SET v1 = v1 + 1 WHERE id % 20 = 0; test8_v1_idx - 23 MB test8_v2_idx - 21 MB test8_v3_idx - 21 MB VACUUM test8; UPDATE test8 SET v2 = v2 + 1 WHERE id % 20 = 0; test8_v1_idx - 23 MB test8_v2_idx - 23 MB test8_v3_idx - 21 MB
=# select n_tup_upd, n_tup_hot_upd from pg_stat_user_tables; n_tup_upd | n_tup_hot_upd -----------+--------------0| 0 0| 0 0| 0 50000 | 0

=# select n_tup_upd, n_tup_hot_upd from pg_stat_user_tables; n_tup_upd | n_tup_hot_upd -----------+--------------0| 0 0| 0 0| 0 100000 | 0


KNN-GiST
· KNN -- K (K- nearest neighbourhood) ·
· , · full table scan, · «» - range search, ?

· KNN-GiST
· (GiST) Priority Queue DFS (BFS) · K- · , KNN-GiST


KNN-GiST: ?



KNN-search: Examples
· Synthetc data ­ 1,000,000 randomly distributed points
create table qq ( id serial, p point, s int4); insert into qq (p,s) select point( p.lat, p.long), (random()*1000)::int from ( select (0.5-random())*180 as lat, random()*360 as long from ( select generate_series(1,1000000) ) as t ) as p; create index qq_p_s_idx on qq using gist(p); analyze qq;

· Query ­ find k-closest points to (0,0)
set enable_indexscan=on|off; explain (analyze on, buffers on) SELECT * FROM qq ORDER BY (p <-> '(0,0)') ASC LIMIT 10; · <-> - distance operator, provided by data type


KNN-search: Examples
· 1700 K=10 !
Limit (actual time=327.674..327.675 rows=10 loops=1) Buffers: shared hit=7353 -> Sort (actual time=327.673..327.674 rows=10 loops=1) Sort Key: ((p <-> '(0,0)'::point)) Sort Method: top-N heapsort Memory: 25kB Buffers: shared hit=7353 -> Seq Scan on qq (actual time=0.009..180.513 rows=1000000 loops=1) Buffers: shared hit=7353 Execution time: 327.698 ms -------------------------Limit (actual time=0.116..0.160 rows=10 loops=1) Buffers: shared hit=14 -> Index Scan using qq_p_s_idx on qq (actual time=0.116..0.156 rows=10 loops=1) Order By: (p <-> '(0,0)'::point) Buffers: shared hit=14 Execution time: 0.183 ms


KNN-search: Examples
· 220 K=1000 !
Limit (actual time=314.262..314.471 rows=1000 loops=1) Buffers: shared hit=7353 -> Sort (actual time=314.261..314.365 rows=1000 loops=1) Sort Key: ((p <-> '(0,0)'::point)) Sort Method: top-N heapsort Memory: 127kB Buffers: shared hit=7353 -> Seq Scan on qq (actual time=0.008..172.222 rows=1000000 loops=1) Buffers: shared hit=7353 Execution time: 314.599 ms -------------------------Limit (actual time=0.073..1.334 rows=1000 loops=1) Buffers: shared hit=1016 -> Index Scan using qq_p_s_idx on qq (actual time=0.072..1.225 rows=1000 loops=1) Order By: (p <-> '(0,0)'::point) Buffers: shared hit=1016 Execution time: 1.429 ms1


KNN-search: Examples
· 15600 K=10 N=10,000,000 !
Limit (actual time=3212.470..3212.473 rows=10 loops=1) Buffers: shared hit=96 read=73434 -> Sort (actual time=3212.469..3212.470 rows=10 loops=1) Sort Key: ((p <-> '(0,0)'::point)) Sort Method: top-N heapsort Memory: 25kB Buffers: shared hit=96 read=73434 -> Seq Scan on qq (actual time=0.009..1827.449 rows=10000000 loops=1) Buffers: shared hit=96 read=73434 Execution time: 3212.492 ms -------------------------Limit (actual time=0.143..0.184 rows=10 loops=1) Buffers: shared read=14 -> Index Scan using qq_p_s_idx on qq (actual time=0.143..0.182 rows=10 loops=1) Order By: (p <-> '(0,0)'::point) Buffers: shared read=14 Execution time: 0.205 ms


KNN-search:
· ( : '__', '_', '', '', '', '') · () S (W1, W2)
· N
union

/max(N1, N2)
CREATE EXTENSION pg_trgm; =# \d words Table "public.words" Column | Type | Modifiers --------+------+----------w | text | Indexes: "words_w_idx" gist (w gist_trgm_ops)

· 2 * Nunion/(N1 + N2) · Nunion/(N1 + N2 - Nunion)

· D (W1,W2):
· 1­S · 1/S


KNN-search:
select w from words order by w <-> 'risource' limit 5; w ---------resource rice rivets ridden rivalled (5 rows) Limit (actual time=0.333..0.345 rows=5 loops=1) -> Index Scan using words_w_idx on words (actual time=0.333..0.344 rows=5 loops=1) Order By: (w <-> 'risource'::text) Execution time: 0.366 ms


KNN-search: (Lateral Query)
SELECT w.w, s.w as similar FROM words w CROSS JOIN LATERAL (SELECT w FROM words ORDER BY w.w <-> w limit 2) s WHERE w.w LIKE 'ar%' AND w.w <> s.w; w | similar --------------+------------archiver | anniversary armadillos | armchairs artillery | distillery arithmetized | authorized armchairs | airspeed (5 rows) Nested Loop (actual time=0.727..2.592 rows=5 loops=1) -> Index Scan using words_w_idx on words w (actual time=0.127..0.165 rows=5 loops=1) Index Cond: (w ~~ 'ar%'::text) -> Subquery Scan on s (actual time=0.483..0.483 rows=1 loops=5) Filter: (w.w <> s.w) Rows Removed by Filter: 1 -> Limit (actual time=0.321..0.481 rows=2 loops=5) -> Index Scan using words_w_idx on words (actual time=0.318..0.477 rows=2 loops=5) Order By: (w <-> w.w) Execution time: 2.633 ms


KNN-search:
=# select w from words order by w <-> '%isourc%' limit 5; w ---------resource iron into idles injure (5 rows) Limit (actual time=0.251..0.261 rows=5 loops=1) -> Index Scan using words_w_idx on words (actual time=0.251..0.260 rows=5 loops=1) Order By: (w <-> '%isourc%'::text) Execution time: 0.282 ms


Indexing regular expressions (9.3+)
· contrib/pg_trgm supports indexing of regular-expression searches
select w from words where w ~ '.*sourc.*'; Index Scan using words_w_idx on words (cost=0.14..8.16 rows=1 width=9) (actual time=0.165..0.263 rows=1 loops=1) Index Cond: (w ~ '.*sourc.*'::text) Planning time: 0.150 ms Execution time: 0.279 ms (4 rows) explain analyze select w from words where w ~ '^r.*sour.*e$'; Index Scan using words_w_idx on words (cost=0.14..8.16 rows=1 width=9) (actual time=0.209..0.375 rows=1 loops=1) Index Cond: (w ~ '^r.*sour.*e$'::text) Planning time: 0.168 ms Execution time: 0.399 ms (4 rows)


Indexing regular expressions (9.3+)
· contrib/pg_trgm supports indexing of regular-expression searches
select * from man_lines where man_line ~* '(?:(?:p(?:ostgres(?:ql)?|g?sql)|sql)) (?:(?:(?:mak|us)e|do|is))';

Bitmap Heap Scan on man_lines (cost=285.32..930.42 rows=170 width=79) (actual time=579.765..592.435 rows=123 loops=1) Recheck Cond: (man_line ~* '(?:(?:p(?:ostgres(?:ql)?|g?sql)|sql)) (?:(?:(?:mak|us) Rows Removed by Index Recheck: 1909 -> Bitmap Index Scan on trgm_idx (cost=0.00..285.28 rows=170 width=0) (actual time=578.780..578.780 rows=2032 loops=1) Index Cond: (man_line ~* '(?:(?:p(?:ostgres(?:ql)?|g?sql)|sql)) (?:(?:(?:mak Total runtime: 592.474 ms (6 rows)



· CONSTRAINTS: PRIMARY KEY, UNIQUE (DEFERRABLE) · EXCLUSION CONSTRAINTS (9.0, Jef Davis)
· UNIQUE '=' BTREE · , , ? -- . · EXCLUSION CONSTRAINTS (x*y=y*x)

«

Add exclusion constraints, which generalize the concept of uniqueness to support any indexable commutatve operator, not just equality. Two rows violate the exclusion constraint if "row1.col OP row2.col" is TRUE for each of the columns in the constraint. »


EXCLUSION CONSTRAINTS: Example
·
CREATE EXTENSION btree_gist; CREATE TABLE reservation ( room TEXT, professor TEXT, during tstzrange, EXCLUDE USING gist (room WITH =, during WITH &&) );


EXCLUSION CONSTRAINTS: Example
· UNIQUE -- BTREE '='
=# CREATE TABLE test (i INT4, EXCLUDE (i WITH =)); CREATE TABLE =# \d test Table "public.test" Column | Type | Modifiers --------+---------+----------i | integer | Indexes: "test_i_excl" EXCLUDE USING btree (i WITH =)


EXCLUSION CONSTRAINTS: Example
· (unUnique)
CREATE TABLE reservation ( room TEXT, professor TEXT, during tstzrange, EXCLUDE USING gist (room );

WITH <>


EXCLUSION CONSTRAINTS: Example
·
CREATE TABLE boxes_unique ( id integer, box box, EXCLUDE USING btree (id WITH = ), EXCLUDE USING gist (box WITH &&) );
=# \d boxes_unique Table "public.boxes_unique" Column | Type | Modifiers --------+---------+----------id | integer | box | box | Indexes: "boxes_unique_box_excl" EXCLUDE USING gist (box WITH &&) "boxes_unique_id_excl" EXCLUDE USING btree (id WITH =)


EXCLUSION CONSTRAINTS: Example
· .

ins INS ins ERR DET ins ERR DET



ert into boxes_unique values(1, '((0,0),(2,2))'); ERT 0 1 ert into boxes_unique values(1, '((0,0),(1,1))'); OR: conflicting key value violates exclusion constraint "boxes_unique_id_excl" AIL: Key (id)=(1) conflicts with existing key (id)=(1). ert into boxes_unique values(2, '((0,0),(1,1))'); OR: conflicting key value violates exclusion constraint "boxes_unique_ box_excl" AIL: Key (box)=((1,1),(0,0)) conflicts with existing key (box)=((2,2),(0,0)).


EXCLUSION CONSTRAINTS: Example
· (partal) .
· .
create table boxes_unique ( id integer, box box, exclude using btree (id with =), exclude using gist (box with &&) WHERE (box <@ '((0,0),(5,5))') );
inse INSE inse INSE inse ERRO DETA rt into RT 0 1 rt into RT 0 1 rt into R: conf IL: Key boxes_unique values(1, '((0,0),(1,1))'); boxes_unique values(2, ' ((0,0),(10,10))'); boxes_unique values(3, '((0,0),(4,4))'); licting key value violates exclusion constraint "boxes_unique_box_excl" (box)=((4,4),(0,0)) conflicts with existing key (box)=((1,1),(0,0)).



· -
· · · · /

· DBA · htp://wiki.postgresql.org /wiki/Index_Maintenance


::



SELECT schemaname || '.' || relname AS table, indexrelname AS index, pg_size_pretty(pg_relation_size(i.indexrelid)) AS index_size, idx_scan as index_scans FROM pg_stat_user_indexes ui JOIN pg_index i ON ui.indexrelid = i.indexrelid WHERE NOT indisunique AND idx_scan < 50 AND pg_relation_size(relid) > 5 * 819 ORDER BY pg_relation_size(i.indexrelid) / nullif(idx_scan, 0) DESC NULLS FIRS pg_relation_size(i.indexrelid) DESC; table | index | index_size | index_scans ----------------+------------------+------------+------------public.apod | gin_apod_fts_idx | 1616 kB | 0 public.tbl | ab1_idx | 40 kB | 0 public.tbl | a_idx | 40 kB | 0 public.tbl | ba_idx | 40 kB | 0 public.reviews | reviews_gin_idx | 160 MB | 9 public.events | e_date_id | 3352 kB | 4 public.tbl | ab_idx | 88 kB | 28 (7 rows)



· -
·

=# \d tbl Table "public.tbl" Column | Type | Modifiers --------+---------+----------a | integer | b | integer | Indexes: "a_idx" btree (a) "ab1_idx" btree (a, b) "ab_idx" btree (a, b) "ba_idx" btree (a, b)

SELECT a.indrelid::regclass, a.indexrelid::regclass, b.indexrelid::regclass FROM (SELECT *,array_to_string(indkey,' ') AS cols FROM pg_index) a JOIN (SELECT *,array_to_string(indkey,' ') AS cols FROM pg_index) b ON ( a.indrelid=b.indrelid AND a.indexrelid > b.indexrelid AND ( (a.cols LIKE b.cols||'%' AND coalesce(substr(a.cols,length(b.cols)+1,1),' ')=' ' ) OR (b.cols LIKE a.cols||'%' AND coalesce(substr(b.cols,length(a.cols)+1,1),' ')=' ') ) ) ORDER BY indrelid; indrelid | indexrelid | indexrelid ----------+------------+-----------tbl | a_idx | ab1_idx tbl | a_idx | ba_idx tbl | a_idx | ab_idx (3 rows)


:: V2

SELECT idstat.relname AS tname,indexrelname AS iname, idstat.idx_scan AS used, pg_size_pretty(pg_relation_size(idstat.relid)) AS tsize, pg_size_pretty(pg_relation_size(indexrelid)) AS isize, n_tup_upd + n_tup_ins + n_tup_del as writes, indexdef AS create FROM pg_stat_user_indexes AS idstat JOIN pg_indexes ON (indexrelname = indexname AND idstat.schemaname = pg_indexes.schemaname) JOIN pg_stat_user_tables AS tabstat ON idstat.relid = tabstat.relid WHERE idstat.idx_scan < 200 AND indexdef !~* 'unique' ORDER BY idstat.relname, indexrelname; tname | iname | used | tsize | isize | writes | creat ---------+------------------+------+---------+---------+--------+-------------------------------apod | gin_apod_fts_idx | 0 | 2712 kB | 1616 kB | 1754 | CREATE INDEX gin_apod_fts_idx O events | e_date_id | 4 | 14 MB | 3352 kB | 151643 | CREATE INDEX e_date_id ON event reviews | reviews_gin_idx | 9 | 270 MB | 160 MB | 589859 | CREATE INDEX reviews_gin_idx ON tbl | a_idx | 0 | 72 kB | 40 kB | 2000 | CREATE INDEX a_idx ON tbl USING tbl | ab1_idx | 0 | 72 kB | 40 kB | 2000 | CREATE INDEX ab1_idx ON tbl USI tbl | ab_idx | 28 | 72 kB | 88 kB | 2000 | CREATE INDEX ab_idx ON tbl USIN tbl | ba_idx | 0 | 72 kB | 40 kB | 2000 | CREATE INDEX ba_idx ON tbl USIN (7 rows)


-
\d+ document; Table "public.document" Column | Type | Modifiers | Storage | Stats target | Description ------------------+--------------------------------+-----------+----------+--------------+------------id | integer | not null | plain | | kind | character varying(255) | not null | extended | | uid | character varying(255) | not null | extended | | sentenceId | character varying(255) | not null | extended | | text | text | not null | extended | | hepval | double precision | | plain | | created | timestamp(0) without time zone | not null | plain | | updated | timestamp(0) without time zone | | plain | | cardval | double precision | | plain | | nephval | double precision | | plain | | phosval | double precision | | plain | | patternCount | double precision | | plain | | ruleScore | double precision | | plain | | hepTermNormScore | double precision | | plain | | hepTermVarScore | double precision | | plain | | svm | double precision | | plain | | svmConfidence | double precision | | plain | | Indexes: "DocumentOLD_pkey" PRIMARY KEY, btree (id) "document_cardval_index" btree (cardval) "document_heptermnorm_index" btree ("hepTermNormScore" DESC NULLS LAST) "document_heptermvar_index" btree ("hepTermVarScore" DESC NULLS LAST) "document_hepval_index" btree (hepval DESC NULLS LAST) "document_kind_index" btree (kind) "document_nephval_index" btree (nephval DESC NULLS LAST) "document_patterncount_index" btree ("patternCount" DESC NULLS LAST) "document_phosval_index" btree (phosval DESC NULLS LAST) "document_rulescore_index" btree ("ruleScore" DESC NULLS LAST) "document_sentenceid_index" btree ("sentenceId") "document_svm_index" btree (svm) "document_uid_index" btree (uid)


! !