Multivariate MCV list vs. statistics target
От | Tomas Vondra |
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Тема | Multivariate MCV list vs. statistics target |
Дата | |
Msg-id | 20190618213357.vli3i23vpkset2xd@development обсуждение исходный текст |
Ответы |
Re: Multivariate MCV list vs. statistics target
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Список | pgsql-hackers |
Hi, One slightly inconvenient thing I realized while playing with the address data set is that it's somewhat difficult to set the desired size of the multi-column MCV list. At the moment, we simply use the maximum statistic target for attributes the MCV list is built on. But that does not allow keeping default size for per-column stats, and only increase size of multi-column MCV lists. So I'm thinking we should allow tweaking the statistics for extended stats, and serialize it in the pg_statistic_ext catalog. Any opinions why that would be a bad idea? I suppose it should be part of the CREATE STATISTICS command, but I'm not sure what'd be the best syntax. We might also have something more similar to ALTER COLUMNT, but perhaps ALTER STATISTICS s SET STATISTICS 1000; looks a bit too weird. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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