: Column Performance in a query - Mailing list pgsql-performance

From Venkat Balaji
Subject : Column Performance in a query
Date
Msg-id CAFrxt0hs1D0oedyE8vtQH=CD6_K=0X-2k2JrwOZDPb=ub+7OEg@mail.gmail.com
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Responses Re: : Column Performance in a query
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Hello Everyone,

Generally when it comes to query performance, I check how the vacuuming and statistics collection is performed on Tables and Indexes hit by the query.

Apart from the above i check the code logic ( for any bad joins ) and column statistics as well.

I got hold of two catalog tables "pg_stats" and "pg_class".

Column "avg_width" and "distinct" in pg_stats gets me lot of sensible information regarding, column values and size of the column.

Can someone help me know when the values in these columns are bound to change ? Is it only when ANALYZE runs ?

I am about to calculate lot of metrics depending on above values. Please help !

Thanks
Venkat


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