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PostgreSQL 10 Administration Cookbook - Fourth Edition
book

PostgreSQL 10 Administration Cookbook - Fourth Edition

by Simon Riggs, Gianni Ciolli
May 2018
Intermediate to advanced content levelIntermediate to advanced
576 pages
30h 25m
English
Packt Publishing
Content preview from PostgreSQL 10 Administration Cookbook - Fourth Edition

How to do it…

Force index usage and compare plan costs with an index and without, as follows:

postgres=# EXPLAIN ANALYZE SELECT count(*) FROM itable WHERE id > 500;                         QUERY PLAN---------------------------------------------------------------------  Aggregate  (cost=188.75..188.76 rows=1 width=0)            (actual time=37.958..37.959 rows=1 loops=1)    ->  Seq Scan on itable  (cost=0.00..165.00 rows=9500 width=0)            (actual time=0.290..18.792 rows=9500 loops=1)         Filter: (id > 500) Total runtime: 38.027 ms(4 rows)postgres=# SET enable_seqscan TO false;SETpostgres=# EXPLAIN ANALYZE SELECT count(*) FROM itable WHERE id > 500;                         QUERY PLAN---------------------------------------------------------------------  Aggregate  (cost=323.25..323.26 rows=1 width=0) (actual time=44.467..44.469 ...
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Publisher Resources

ISBN: 9781788474924Supplemental Content