[postgis-users] diffrent execution plan on Postgres 9.5 and Postgres 11 for ST_union and performance problem Postgres 11

Raúl Marín Rodríguez rmrodriguez at carto.com
Thu Apr 11 03:51:57 PDT 2019


I'm talking from memory so I might be wrong, but I recall that
Postgres 11 introduced some improvements to respect the memory limits
under certain queries / plans, so one thing that could be happening is
that PG 9.5 was using more memory than what work_mem actually should
have allowed. I'd try increasing `work_mem` and see if that changes
plans and you regain back the old performance.

Raúl Marín Rodríguez

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