ืืื ืื Postgres ืืืขืื, ืื ืืขืงืกืื ืืขื ืขื ืงืจืืืืฉ ืฆื ืืคืืฉืึทื ืืื ื ืึทืืืึทืืืืืื ื ืื ืืึทืืึทืืืืก ืกืืึธืจืืืืฉ (ืืขืจืืคื ืื ืงืืคึผืข). Postgres ืฉืืืฆื ื ืืฉื ืงืืึทืกืืขืจืื ื ืคึฟืึทืจ ืขืก, ืืื ืื MVCC ืึทืจืงืึทืืขืงืืฉืขืจ ืืขืคึฟืืจื ืืืจ ืฆื ืขื ืืืงื ืืื ืคืืืข ืืืขืจืกืืขืก ืคืื ืืขืจ ืืขืืืืงืขืจ ืืืคึผืืข. ืืขืจืืืขืจ, ืขืก ืืื ืืืืขืจ ืืืืืืืง ืฆื ืงืขื ืขื ืฆื ืฉืึทืคึฟื ืืื ืืืึทื ืขื ืขืคืขืงืืืื ืื ืืขืงืกืื ืฆื ืฉืืืฆื ืึทืคึผืืึทืงืืืฉืึทื ื.
ืืื ืืจืขื ืืขื ืฆื ืืืื ืืคืืขืจืงืืึทืืงืืึทื ืขืืืขืืข ืขืฆืืช ืคึฟืึทืจ ืึธืคึผืืืืืืื ื ืืื ืืืคึผืจืืืืื ื ืื ื ืืฆื ืคืื ืื ืืขืงืกืื.
ืืึทืืขืจืงืื ื: ืื ืงืืืืจืื ืืขืืืืื ืืื ืื ืึทืจืืขื ืืืืฃ ืึทื ืืึธืืืคืืขื .
ื ืืฆื ืงืึทืืืขืจืื ื ืื ืืขืงืกืื
ืืื ืก ืงืืง ืืื ืึท ืืงืฉื ืฆื ืฆืืจืืงืงืจืืื E- ืืจืืื ืืืขื ืื ืคึฟืึทืจ ืื ืึทืงืืืื ืืืืขืจื. ืืื ืื ืืืฉ customer ืขืก ืืื ืึท ืืืึทื active, ืืื ืื ืึธื ืคึฟืจืขื ืืื ืคึผืฉืื:
pagila=# EXPLAIN SELECT email FROM customer WHERE active=0;
QUERY PLAN
-----------------------------------------------------------
Seq Scan on customer (cost=0.00..16.49 rows=15 width=32)
Filter: (active = 0)
(2 rows)
ืื ืึธื ืคึฟืจืขื ืจืืคื ืื ืืึทื ืฅ ืืืฉ ืืืขืจืงืืงื ืกืืงืืืึทื ืก customer. ืืึธืืืจ ืืึทืื ืึทื ืืื ืืขืงืก ืืืืฃ ืืขืจ ืืืึทื active:
pagila=# CREATE INDEX idx_cust1 ON customer(active);
CREATE INDEX
pagila=# EXPLAIN SELECT email FROM customer WHERE active=0;
QUERY PLAN
-----------------------------------------------------------------------------
Index Scan using idx_cust1 on customer (cost=0.28..12.29 rows=15 width=32)
Index Cond: (active = 0)
(2 rows)
ืืขืืึธืืคึฟื, ืกืึทืืกืึทืงืืืึทื ื ืืืขืจืงืืงื ืคืืจืงืขืจื ืืื "index scan". ืืึธืก ืืืื ื ืึทื Postgres ืืืขื ืงืจืืื ืืขื ืืื ืืขืงืก "idx_cust1", ืืื ืืึทื ืคืึธืจืืขืฆื ืืืื ืื ืืืฉ ืงืืคึผืข ืฆื ืืืืขื ืขื ืื ืืืึทืืืขืก ืคืื ืื ืืขืจืข ืฉืคืืืื (ืืื ืืขื ืคืึทื, ืื ืืืึทื email) ืึทื ืื ืืงืฉื ืืึทืจืฃ.
PostgreSQL 11 ืื ืืจืึธืืืืกื ืงืึทืืืขืจืื ื ืื ืืขืงืกืื. ืืื ืืึธืื ืืืจ ืฆื ืึทืจืืึทื ื ืขืืขื ืืืื ืขืจ ืึธืืขืจ ืืขืจ ื ืึธื ืฉืคืืืื ืืื ืืขืจ ืืื ืืขืงืก ืืื - ืืืืขืจ ืืืึทืืืขืก ืืขื ืขื ืกืืึธืจื ืืื ืื ืืื ืืขืงืก ืืึทืื ืงืจืึธื.
ืืืื ืืืจ ืืขืืืืื ื ืืขื ืฉืืจืื ืืื ืฆืืืขืืขืื ืื E- ืืจืืื ืืืขืจื ืื ืืขืจ ืืื ืืขืงืก, Postgres ืืืึธืื ื ืืฉื ืืึทืจืคึฟื ืฆื ืงืืงื ืืื ืื ืืืฉ ืงืืคึผืข ืคึฟืึทืจ ืื ืืืขืจื email. ืืื ืก ืืขื ืืืื ืืึธืก ืึทืจืืขื:
pagila=# CREATE INDEX idx_cust2 ON customer(active) INCLUDE (email);
CREATE INDEX
pagila=# EXPLAIN SELECT email FROM customer WHERE active=0;
QUERY PLAN
----------------------------------------------------------------------------------
Index Only Scan using idx_cust2 on customer (cost=0.28..12.29 rows=15 width=32)
Index Cond: (active = 0)
(2 rows)
ยซIndex Only Scan" ืืขืจืฆืืืื ืืื ืื ืึทื ืื ืึธื ืคึฟืจืขื ืืืฆื ืืึทืจืฃ ืืืืื ืื ืืื ืืขืงืก, ืืืึธืก ืืขืืคึผืก ืืืกืืืืื ืึทืืข ืื ืืืกืง I/O ืฆื ืืืืขื ืขื ืื ืงืืคึผืข ืคืื โโืื ืืืฉ.
ืืืึทื ื, ืงืึทืืืขืจืื ื ืื ืืขืงืกืื ืืขื ืขื ืืืืื ืื ืืืฆื ืคึฟืึทืจ ื-ืืืืืขืจ. ืึธืืขืจ, ืืื ืืขื ืคืึทื, ืื ืืืฉืึทืื ืื ืืืขื ืืืื ืืขืืขืจ.
ื ืืฆื ืคึผืึทืจืืืืืฉ ืื ืืขืงืกืื
ืืืื ืื ืืขืงืกืื ืืื ืืขืงืก ืืืืื ืึท ืกืึทืืกืขื ืคืื ืื ืจืึธืื ืคืื ืื ืืืฉ. ืืึธืก ืึทืืึทืื ืืืจ ืฆื ืจืึทืืขืืืขื ืื ืืื ืืขืงืก ืืจืืืก ืืื ืืืจืืคืืจื ืกืงืึทื ื ืคืึทืกืืขืจ.
ืืื ืก ืืึธืื ืืืจ ืืึทืจืคึฟื ืฆื ืืึทืงืืืขื ืึท ืจืฉืืื ืคืื E- ืืจืืื ืึทืืจืขืกืขืก ืคึฟืึทืจ ืืื ืืืขืจ ืงืึทืกืืึทืืขืจื ืืื ืงืึทืืืคืึธืจื ืืึท. ืื ืืงืฉื ืืืขื ืืืื ืืื ืืึธืก:
SELECT c.email FROM customer c
JOIN address a ON c.address_id = a.address_id
WHERE a.district = 'California';
which has a query plan that involves scanning both the tables that are joined:
pagila=# EXPLAIN SELECT c.email FROM customer c
pagila-# JOIN address a ON c.address_id = a.address_id
pagila-# WHERE a.district = 'California';
QUERY PLAN
----------------------------------------------------------------------
Hash Join (cost=15.65..32.22 rows=9 width=32)
Hash Cond: (c.address_id = a.address_id)
-> Seq Scan on customer c (cost=0.00..14.99 rows=599 width=34)
-> Hash (cost=15.54..15.54 rows=9 width=4)
-> Seq Scan on address a (cost=0.00..15.54 rows=9 width=4)
Filter: (district = 'California'::text)
(6 rows)ืืืึธืก ืจืขืืืืขืจ ืื ืืขืงืกืื ืืืขื ืืขืื ืืื ืื:
pagila=# CREATE INDEX idx_address1 ON address(district);
CREATE INDEX
pagila=# EXPLAIN SELECT c.email FROM customer c
pagila-# JOIN address a ON c.address_id = a.address_id
pagila-# WHERE a.district = 'California';
QUERY PLAN
---------------------------------------------------------------------------------------
Hash Join (cost=12.98..29.55 rows=9 width=32)
Hash Cond: (c.address_id = a.address_id)
-> Seq Scan on customer c (cost=0.00..14.99 rows=599 width=34)
-> Hash (cost=12.87..12.87 rows=9 width=4)
-> Bitmap Heap Scan on address a (cost=4.34..12.87 rows=9 width=4)
Recheck Cond: (district = 'California'::text)
-> Bitmap Index Scan on idx_address1 (cost=0.00..4.34 rows=9 width=0)
Index Cond: (district = 'California'::text)
(8 rows)
ืืืขืจืงืืงื address ืืื ืจืืคึผืืืืกื ืืืจื ืืื ืืขืงืก ืกืงืึทื ืื ื idx_address1, ืืื ืืขืืึธืื ืืขืจ ืงืืคึผืข ืืื ืกืงืึทื ื address.
ืืื ื ืืึธืก ืืื ืึท ืึธืคื ืึธื ืคึฟืจืขื ืืื ืืึทืจืฃ ืืืื ืึธืคึผืืืืืืขื, ืืืจ ืงืขื ืขื ื ืืฆื ืึท ืคึผืึทืจืืืืืฉ ืืื ืืขืงืก, ืืืึธืก ืื ืืขืงืกืื ืืืืื ืื ืจืึธืื ืืื ืึทืืจืขืกืขืก ืืื ืืืึธืก ืื ืืขืื ื โCaliforniaโ:
pagila=# CREATE INDEX idx_address2 ON address(address_id) WHERE district='California';
CREATE INDEX
pagila=# EXPLAIN SELECT c.email FROM customer c
pagila-# JOIN address a ON c.address_id = a.address_id
pagila-# WHERE a.district = 'California';
QUERY PLAN
------------------------------------------------------------------------------------------------
Hash Join (cost=12.38..28.96 rows=9 width=32)
Hash Cond: (c.address_id = a.address_id)
-> Seq Scan on customer c (cost=0.00..14.99 rows=599 width=34)
-> Hash (cost=12.27..12.27 rows=9 width=4)
-> Index Only Scan using idx_address2 on address a (cost=0.14..12.27 rows=9 width=4)
(5 rows)
ืืืฆื ืื ืืงืฉื ืืืืื ืืืืขื ื idx_address2 ืืื ื ืื ืึธื ืจืืจื ืืขื ืืืฉ address.
ื ืืฆื ืืืืื-ืืืขืจื ืื ืืขืงืกืื
ืขืืืขืืข ืฉืคืืืื ืืืึธืก ืืึทืจืคึฟื ืฆื ืืืื ืื ืืขืงืกื ืงืขื ื ืืฉื ืึทื ืืืึทืืื ืึท ืกืงืึทืืึทืจ ืืึทืื ืืืคึผ. ืืืึทื ืืืืคึผืก ืืื jsonb, arrays ะธ tsvector ืึทื ืืืึทืืื ืงืึทืืคึผืึทืื ื ืึธืืขืจ ืงืืืคื ืืื ืื ืื. ืืืื ืืืจ ืืึทืจืคึฟื ืฆื ืืื ืืขืงืก ืึทืืึท ืฉืคืืืื, ืืืจ ืืืืฉืึทืืืึทืื ืืึทืจืคึฟื ืฆื ืืืื ืคึฟืึทืจ ืึทืืข ืื ืืืื ืืืึทืืืขืก ืืื ืื ืฉืคืืืื.
ืืึธืืืจ ืคึผืจืืืืจื ืฆื ืืขืคึฟืื ืขื ืื ืืืืืขื ืคืื ืึทืืข ืคืืืืก ืืื ืงืืืคึผืก ืคืื ื ืื ืืขืจืึธืื ื ืขืืขื. ืืื ืื ืืืฉ film ืขืก ืืื ืึท ืืขืงืกื ืืืึทื ืืขืจืืคื special_features. ืืืื ืึท ืคึฟืืื ืืื ืืขื "ืกืคึผืขืฆืืขื ืคืึทืจืืึธื", ืืขืจ ืืืึทื ืึผืืื ืึทื ืขืืขืืขื ื ืืื ืื ืคืึธืจืขื ืคืื ืึท ืืขืงืกื ืืขื ืืข Behind The Scenes. ืฆื ืืืื ืคึฟืึทืจ ืึทืืข ืึทืืึท ืคืืืืก, ืืืจ ืืึทืจืคึฟื ืฆื ืืืืกืงืืืึทืื ืึทืืข ืจืึธืื ืืื "ืืื ืืขืจ ืื ืกืื ื" ืืืึท ืงืืื ืืขื ืืข ืืืึทืืืขืก special_features:
SELECT title FROM film WHERE special_features @> '{"Behind The Scenes"}';
ืงืึทื ืืืื ืืึทื ื ืึธืคึผืขืจืึทืืึธืจ @> ืืฉืขืง ืฆื ืื ืจืขืื ืืืึทื ืืื ืึท ืกืึทืืกืขื ืคืื ืื ืืื ืงืก ืืืึทื.
ืึธื ืคึฟืจืขื ืคึผืืึทื:
pagila=# EXPLAIN SELECT title FROM film
pagila-# WHERE special_features @> '{"Behind The Scenes"}';
QUERY PLAN
-----------------------------------------------------------------
Seq Scan on film (cost=0.00..67.50 rows=5 width=15)
Filter: (special_features @> '{"Behind The Scenes"}'::text[])
(2 rows)ืืืึธืก ืจืืงืืืขืก ืึท ืืึทื ืฅ ืงืืคึผืข ืืืขืจืงืืงื ืืื ืึท ืคึผืจืืึทื ืคืื 67.
ืืึธืืืจ ืืขื ืืืื ืึท ืจืขืืืืขืจ ื-ืืืื ืืื ืืขืงืก ืืืขื ืืขืืคึฟื ืืื ืื:
pagila=# CREATE INDEX idx_film1 ON film(special_features);
CREATE INDEX
pagila=# EXPLAIN SELECT title FROM film
pagila-# WHERE special_features @> '{"Behind The Scenes"}';
QUERY PLAN
-----------------------------------------------------------------
Seq Scan on film (cost=0.00..67.50 rows=5 width=15)
Filter: (special_features @> '{"Behind The Scenes"}'::text[])
(2 rows)ืืขืจ ืืื ืืขืงืก ืืื ืืคืืื ื ืืฉื ืืืืจืืื ืืขืืืืจื. ืื ื-ืืืื ืืื ืืขืงืก ืืื ืงืืื ืืขืืึทื ืง ืืืขืื ืื ืขืงืืืกืืขื ืฅ ืคืื ืืืื ืขืืขืืขื ืื ืืื ืื ืืืึทืืืขืก ืขืก ืื ืืขืงืกืื.
ืืืจ ืืึทืจืคึฟื ืึท GIN ืืื ืืขืงืก.
pagila=# CREATE INDEX idx_film2 ON film USING GIN(special_features);
CREATE INDEX
pagila=# EXPLAIN SELECT title FROM film
pagila-# WHERE special_features @> '{"Behind The Scenes"}';
QUERY PLAN
---------------------------------------------------------------------------
Bitmap Heap Scan on film (cost=8.04..23.58 rows=5 width=15)
Recheck Cond: (special_features @> '{"Behind The Scenes"}'::text[])
-> Bitmap Index Scan on idx_film2 (cost=0.00..8.04 rows=5 width=0)
Index Cond: (special_features @> '{"Behind The Scenes"}'::text[])
(4 rows)ืื GIN ืืื ืืขืงืก ืฉืืืฆื ืืึทืคึผืื ื ืืืื ืืืึทืืืขืก ืฆื ืื ืืขืงืกื ืงืึทืืคึผืึทืืึทื ืืืึทืืืขืก, ืจืืืึทืืืื ื ืืื ืืขืจ ืืื ืืึทืื ืื ืคึผืจืืึทื ืคืื ืื ืึธื ืคึฟืจืขื ืคึผืืึทื.
ืืึทืงืืืขื ืืึทืคืจืืึทืขื ืคืื ืืืคึผืืืงืึทื ืื ืืขืงืกืื
ืื ืืขืงืกืื ืึทืงืืืืืึทืืืื ืืื ืฆืืึทื, ืืื ืืื ืึท ื ืืึท ืืื ืืขืงืก ืงืขื ืึทื ืืืึทืืื ืื ืืขืืืข ืืขืคึฟืื ืืฆืืข ืืื ืืืื ืขืจ ืคืื ืื ืคืจืืขืจืืืงืข ืึธื ืขืก. ืืืจ ืงืขื ืขื ื ืืฆื ืื ืงืึทืืึทืืึธื ืืืื ืื ื ืฆื ืงืจืืื ืืขื ืืฉ-ืืืื ืขืืืืืง ืกืงื ืืื ืืขืงืก ืืื pg_indexes. ืืืจ ืงืขื ื ืืืื ืืขืคึฟืื ืขื ืื ืืขืืืข ืืขืคึฟืื ืืฆืืข:
SELECT array_agg(indexname) AS indexes, replace(indexdef, indexname, '') AS defn
FROM pg_indexes
GROUP BY defn
HAVING count(*) > 1;
And hereโs the result when run on the stock pagila database:
pagila=# SELECT array_agg(indexname) AS indexes, replace(indexdef, indexname, '') AS defn
pagila-# FROM pg_indexes
pagila-# GROUP BY defn
pagila-# HAVING count(*) > 1;
indexes | defn
------------------------------------------------------------------------+------------------------------------------------------------------
{payment_p2017_01_customer_id_idx,idx_fk_payment_p2017_01_customer_id} | CREATE INDEX ON public.payment_p2017_01 USING btree (customer_id
{payment_p2017_02_customer_id_idx,idx_fk_payment_p2017_02_customer_id} | CREATE INDEX ON public.payment_p2017_02 USING btree (customer_id
{payment_p2017_03_customer_id_idx,idx_fk_payment_p2017_03_customer_id} | CREATE INDEX ON public.payment_p2017_03 USING btree (customer_id
{idx_fk_payment_p2017_04_customer_id,payment_p2017_04_customer_id_idx} | CREATE INDEX ON public.payment_p2017_04 USING btree (customer_id
{payment_p2017_05_customer_id_idx,idx_fk_payment_p2017_05_customer_id} | CREATE INDEX ON public.payment_p2017_05 USING btree (customer_id
{idx_fk_payment_p2017_06_customer_id,payment_p2017_06_customer_id_idx} | CREATE INDEX ON public.payment_p2017_06 USING btree (customer_id
(6 rows)
ืกืืคึผืขืจืกืขื ืื ืืขืงืกืื
ืขืก ืงืขื ืคึผืึทืกืืจื ืึทื ืืืจ ืึธื ืงืืืึทืื ืคืืืข ืื ืืขืงืกืื, ืืืื ืขืจ ืคืื ืืืึธืก ืื ืืขืงืกืื ืึท ืกืืคึผืขืจืกืขื ืคืื ืฉืคืืืื ืืืึธืก ืื ืืขืจืข ืื ืืขืงืกืื. ืืึธืก ืงืขื ืึธืืขืจ ืงืขื ื ืืฉื ืืืื ืืืืืืขืจืึทืืึทื - ืึท ืกืืคึผืขืจืกืขื ืงืขื ืจืขืืืืืึทื ืืื ืึทื ืืื ืืขืงืก-ืืืืื ืืืขืจืงืืงื, ืืืึธืก ืืื ืืื, ืึธืืขืจ ืขืก ืงืขื ื ืขืืขื ืฆื ืคืื ืคึผืืึทืฅ, ืึธืืขืจ ืื ืึธื ืคึฟืจืขื ืืืึธืก ืื ืกืืคึผืขืจืกืขื ืืื ืืืขื ืฆื ืึทืคึผืืึทืืืื ืืื ื ืื ืืขืจ ืืื ื ืืฆื.
ืืืื ืืืจ ืืึทืจืคึฟื ืฆื ืึธืืึทืืืื ืื ืืขืคึฟืื ืืฆืืข ืคืื โโืึทืืึท ืื ืืขืงืกืื, ืืืจ ืงืขื ืขื ืึธื ืืืืื ืืื ืคืื ืืืฉ pg_catalog.
ืึทื ืืืื ืื ืืขืงืกืื
ืืื ืึทืคึผืืึทืงืืืฉืึทื ื ืืืึธืก ื ืืฆื ืืึทืืึทืืืืกืื ืืืืึทืืื, ืึทืืื ืืึธื ืื ืคึฟืจืืื ืืืึธืก ืืื ื ืืฆื. ืืื ืึทืืขืจ ืฆืืืขืืืืื ืื ืืขืงืกืื ืงืขื ื ืื ืืขืจ ืืืื ืืขืืืืื ื ืืืจื ืงืืื ืงืืืืจืื. ืืขืืขืจ ืืึธื ืึท ืืื ืืขืงืก ืืื ืกืงืึทื ื, ืขืก ืืื ืืืืขืจืงื ืืืจื ืื ืกืืึทืืืกืืืง ืคืึทืจืืืึทืืืขืจ ืืื ืืื ืื ืกืืกืืขื ืงืึทืืึทืืึธื ืืืื ืื ื pg_stat_user_indexes ืืืจ ืงืขื ืขื ืืขื ืื ืืืขืจื idx_scan, ืืืึธืก ืืื ืึท ืงืืืืืึทืืึทืืืื ืืึธืืืึทื ืง. ืืจืึทืงืื ื ืืขื ืืืขืจื ืืืืขืจ ืึท ืฆืืื (ืืึธืื ืึท ืืืืฉ) ืืืขื ืืขืื ืึท ืืืืข ืืขืืึทื ืง ืคืื ืืืึธืก ืื ืืขืงืกืื ืืขื ืขื ื ืืฉื ืืขืืืืื ื ืืื ืงืขื ืืืื ืืจืึทืคึผื.
ืืึธ ืืื ืึท ืืงืฉื ืฆื ืืึทืงืืืขื ืื ืงืจืึทื ื ืืืขืจืงืืงื ืงืึทืื ืฅ ืคืื ืึทืืข ืื ืืขืงืกืื ืืื ืื ืกืืฉืขืืึท โpublicโ:
SELECT relname, indexrelname, idx_scan
FROM pg_catalog.pg_stat_user_indexes
WHERE schemaname = 'public';
with output like this:
pagila=# SELECT relname, indexrelname, idx_scan
pagila-# FROM pg_catalog.pg_stat_user_indexes
pagila-# WHERE schemaname = 'public'
pagila-# LIMIT 10;
relname | indexrelname | idx_scan
---------------+--------------------+----------
customer | customer_pkey | 32093
actor | actor_pkey | 5462
address | address_pkey | 660
category | category_pkey | 1000
city | city_pkey | 609
country | country_pkey | 604
film_actor | film_actor_pkey | 0
film_category | film_category_pkey | 0
film | film_pkey | 11043
inventory | inventory_pkey | 16048
(10 rows)ืจืืืืืืื ื ืื ืืขืงืกืื ืืื ืืืืื ืืงืขืจืข ืืึทืงืก
ืื ืืขืงืกืื ืึธืคื ืืึทืจืคึฟื ืฆื ืืืื ืฉืืึทืขื-ืืืฉืืคื, ืคึฟืึทืจ ืืืึทืฉืคึผืื ืืืขื ืืื ืืืขืจื ืืืึธืืืื, ืืื ืจื-ืฉืึทืคืื ื ืงืขื ืขื ืคืึทืจืืืืขืจื ืกืงืึทื ืื ื. ืื ืืขืงืกืื ืงืขื ืขื ืืืื ืืืขืจื ืคืืจืืืจืื. ืืฉืึทื ืืื ื ืืื ืืขืงืก ืคึผืึทืจืึทืืขืืขืจืก ืงืขื ืืืื ืืึทืจืคื ืืืื ืฉืืึทืขื-ืฉืึทืคืื ื.
ืืขืื ืคึผืึทืจืึทืืขื ืืื ืืขืงืก ืฉืึทืคืื ื
ืืื PostgreSQL 11, B-Tree ืืื ืืขืงืก ืฉืึทืคืื ื ืืื ืงืึทื ืงืขืจืึทื ื. ืฆื ืคืึทืจืืืืขืจื ืื ืฉืึทืคืื ื ืคึผืจืึธืฆืขืก, ืขืืืขืืข ืคึผืึทืจืึทืืขื ืืืขืจืก ืงืขื ืขื ืืืื ืืขืืืืื ื. ืึธืืขืจ, ืืึทืื ืืืืขืจ ืึทื ืื ืงืึทื ืคืืืืขืจืืืฉืึทื ืกืขืืืื ืืก ืืขื ืขื ืจืืืืืง:
SET max_parallel_workers = 32;
SET max_parallel_maintenance_workers = 16;ืื ืคืขืืืงืืึทื ืืืึทืืืขืก ืืขื ืขื ืฆื ืงืืืื. ืืืขืึทืืื, ืื ื ืืืขืจื ืืึธื ืคืึทืจืืจืขืกืขืจื ืืื ืื ื ืืืขืจ ืคืื ืคึผืจืึทืกืขืกืขืจ ืงืึธืจืขืก. ืืืืขื ืขื ืืขืจ ืืื .
ืืื ืืขืจืืจืื ื ืืื ืืขืงืก ืฉืึทืคืื ื
ืืืจ ืงืขื ืขื ืืึทืื ืืขื ืืื ืืขืงืก ืืื ืืขืจ ืืื ืืขืจืืจืื ื ื ืืฆื ืื ืึธืคึผืฆืืข CONCURRENTLY ืืืื CREATE INDEX:
pagila=# CREATE INDEX CONCURRENTLY idx_address1 ON address(district);
CREATE INDEXืืขื ืืื ืืขืงืก ืฉืึทืคืื ื ืคึผืจืึธืฆืขืืืจ ืืื ืึทื ืืขืจืฉ ืคืื ืื ืืขืืืืื ืืืขื ืืื ืึทื ืขืก ืืื ื ืืฉื ืืึทืจืคื ืืึทืงืื ื ืื ืืืฉ, ืืื ืืขืจืืืขืจ ืืื ื ืืฉื ืคืึทืจืฉืคึผืึทืจื ืฉืจืืึทืื ืึทืคึผืขืจืืืฉืึทื ื. ืืืืฃ ืื ืื ืืขืจืข ืืึทื ื, ืขืก ื ืขืื ืืขืจ ืืื ืงืึทื ืกืืื ืืขืจ ืจืขืกืืจืกื.
Postgres ืืื ืคืืืข ืคืืขืงืกืึทืืึทื ืึธืคึผืฆืืขืก ืคึฟืึทืจ ืงืจืืืืืื ื ืื ืืขืงืกืื ืืื ืกืึทืืืฉืึทื ื ืฆื ืงืืื ืกืคึผืขืฆืืขื ืงืึทืกืขืก, ืืื ืืืื ืืื ืืืขืื ืฆื ืคืืจื ืื ืืึทืืึทืืืืก ืืืื ืืืื ืึทืคึผืืึทืงืืืฉืึทื ืืืึทืงืกื ืืงืกืคึผืืึธืืกืืื. ืืืจ ืืึธืคื ืึทื ืื ืขืฆืืช ืืืขื ืืขืืคึฟื ืืืจ ืืึทืื ืืืื ืคึฟืจืืื ืฉื ืขื ืืื ืืืื ืืึทืืึทืืืืก ืืจืืื ืฆื ืืืึธื.
ืืงืืจ: www.habr.com