Different row estimations on base rels
От | Donald Dong |
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Тема | Different row estimations on base rels |
Дата | |
Msg-id | C48F353B-A15F-4A69-A49D-38ADA6B8F131@csumb.edu обсуждение исходный текст |
Ответы |
Re: Different row estimations on base rels
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Список | pgsql-hackers |
Hi, I noticed the estimated rows of the base relations during the join searching is *very* different from the estimations in the final plan. Join search (rows of the initial_rels): RELOPTINFO (ct): rows=1 width=4 RELOPTINFO (it): rows=1 width=4 RELOPTINFO (mc): rows=17567 width=32 RELOPTINFO (mi_idx): rows=1380035 width=8 RELOPTINFO (t): rows=2528356 width=25 The final plan: Seq Scan on company_type ct (cost=0.00..1.05 rows=1 width=4) Seq Scan on info_type it (cost=0.00..2.41 rows=1 width=4) Parallel Seq Scan on movie_companies mc (cost=0.00..37814.90 rows=7320 width=32) Parallel Seq Scan on movie_info_idx mi_idx (cost=0.00..13685.15 rows=575015 width=8) Index Scan using title_pkey on title t (cost=0.43..0.58 rows=1 width=25) By looking at the joinrel->rows, I would expect relation t to have the largest size, however, this is not true at all. I wonder what's causing this observation, and how to get estimations close to the final plan? Thank you, Donald Dong
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