Difference between revisions of "EXPLAIN (PostgreSQL)"

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Line 45: Line 45:
 
* [[EXPLAIN ANALYZE (PostgreSQL)]]
 
* [[EXPLAIN ANALYZE (PostgreSQL)]]
 
* [[WAL]]
 
* [[WAL]]
* [[pg_statistics]]
+
* [[pg_statistic]]
  
 
== Activities ==
 
== Activities ==

Revision as of 07:12, 6 August 2021

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

[1]

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

Activities

See also

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