EXPLAIN (PostgreSQL)

https://www.postgresql.org/docs/current/sql-explain.html

EXPLAIN show the execution plan of a statement

.../...
 ->  Index Scan using your_key on your_table your_table  (cost=0.43..8.39 rows=1 width=952) (actual time=1.030..1.030 rows=0 loops=39649)
       Index Cond: (id = your_id)
       Filter: (your_filter_id = ######)
       Rows Removed by Filter: 1
Planning Time: 0.441 ms
Execution Time: 50387.333 ms

Simple query on a table with a single integer column and 10000 rows

EXPLAIN SELECT * FROM foo; 

                       QUERY PLAN
---------------------------------------------------------
 Seq Scan on foo  (cost=0.00..155.00 rows=10000 width=4)
(1 row)

JSON formatting:

EXPLAIN (FORMAT JSON) SELECT * FROM foo;
           QUERY PLAN           
--------------------------------
 [                             +
   {                           +
     "Plan": {                 +
       "Node Type": "Seq Scan",+
       "Relation Name": "foo", +
       "Alias": "foo",         +
       "Startup Cost": 0.00,   +
       "Total Cost": 155.00,   +
       "Plan Rows": 10000,     +
       "Plan Width": 4         +
     }                         +
   }                           +
 ]
(1 row)

Related terms

• Bitmap scan
• EXPLAIN ANALYZE (MySQL)
• EXPLAIN ANALYZE (PostgreSQL)
• WAL
• pg_statistic
• PostgreSQL parallel query

Activities

• https://wiki.postgresql.org/wiki/Using_EXPLAIN

See also

• SQL, NewSQL: GraphQL (2015), SQLite, select, insert, select count, Distributed SQL, TablePlus, Cache hit ratio, pg_stat_user_tables, EXPLAIN, Index (PostgreSQL), DDL, SQL/MED, Group by, List users, SQL Injection, SQLAlchemy, CREATE USER, CREATE ROLE, EXPLAIN, ALTER DATABASE, REVOKE, NOLOCK, NOWAIT, EXISTS, Unique constraint
• PostgreSQL: pg_dump, pg_restore, pgAdmin, pg_config, psql, pg_ctl, pg_isready, initdb, Role, Schema, DBeaver, Navicat, DataGrip, OmniDB, Adminer, docker-compose.xml PostgreSQL, PostgreSQL version, PostgreSQL logs, postgresql.conf, pg_hba.conf, $HOME/.pg_service.conf, Create database (PostgreSQL), Create user, createdb, GRANT, pg_stat, PostgreSQL VACUUM, EXPLAIN, pg stat activity, Autovacuum, ALTER DATABASE, PostgreSQL statistics collector, Shared buffers, EXPLAIN (PostgreSQL), EXPLAIN ANALYZE, Bitmap scan, EXPLAIN VERBOSE, EXPLAIN VERBOSE (PostgresSQL), WAL, ALTER USER, CREATE ROLE, CREATE USER, \du, show users, \l, The Statistics Collector, pganalyze, cron.schedule, Master, pg_tables, PostgreSQL replication, CREATE, SET, TOAST, PgBouncer, Restore DB, Index, meta-commands, Table, foreign table, Schema, Sequence, Views, materialized view, Table Partitioning, monitoring, PostgreSQL System Administration Functions, PostgreSQL extension, privileges, logging, PGTune, PostgreSQL parameter tunning, PostgreSQL modules, pgbench, PostgreSQL users

https://www.postgresql.org/docs/9.1/sql-explain.html