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

[Raúl Marín Rodríguez]

Hi,

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
carto.com