Re: BUG #15609: synchronous_commit=off insert performance regressionwith secondary indexes - Mailing list pgsql-bugs

From Saul, Jean Paolo
Subject Re: BUG #15609: synchronous_commit=off insert performance regressionwith secondary indexes
Date
Msg-id CA+73ANffu7xZDPOAtH5=jNsN2eyOWx8Dw0R4Hi_92pxqm4=1Ag@mail.gmail.com
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In response to Re: BUG #15609: synchronous_commit=off insert performance regressionwith secondary indexes  ("Saul, Jean Paolo" <paolo.saul@verizonconnect.com>)
Responses Re: BUG #15609: synchronous_commit=off insert performance regressionwith secondary indexes  (Peter Geoghegan <pg@bowt.ie>)
List pgsql-bugs
Hi All,


I have found a short term workaround for this. You recreate the index with an added second column with high-cardinality.
ex. CREATE INDEX ON test_indexes USING BTREE (low_cardinality_column, primary_key_id);

We have around 1,500 tables with low-cardinality indexes, so its not the best workaround but one that restores the performance bump for PG11.

Can anyone please shed some light as to why this works?
The only thing I could think of is a locking issue with the leaf nodes.

How much testing is required for this to be considered a proper bug?


Cheers,

Paolo



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