Difference between revisions of "EXPLAIN (PostgreSQL)"

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==Simple query on a table with a single integer column and 10000 rows==
 
==Simple query on a table with a single integer column and 10000 rows==
<pre>EXPLAIN SELECT * FROM foo;
+
 
 +
<pre>EXPLAIN SELECT * FROM foo; <ref>https://www.postgresql.org/docs/9.1/sql-explain.html</ref>
  
 
                       QUERY PLAN
 
                       QUERY PLAN

Revision as of 06:50, 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

EXPLAIN SELECT * FROM foo; <ref>https://www.postgresql.org/docs/9.1/sql-explain.html</ref>

                       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)

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