Re: Postgresql JDBC process consumes more memory than psql client

On Mon, Sep 05, 2022 at 12:40:46PM +0000, James Pang (chaolpan) wrote:
>   We run same update or delete SQL statement " DELETE FROM ... WHERE ... "  the table is a hash partition table (256 hash partitions). When run the sql from Postgresql JDBC driver, it soon increased to 150MB memory (RES filed from top command),       but when run the same SQL from psql , it only consumes about 10MB memory.  UPDATE statements is similar , need 100MB memory, even it delete or update 0 rows.  Any specific control about Postgresql JDBC driver ?

It sounds like JDBC is using prepared statements, and partitions maybe
weren't pruned by the server.  What is the query plan from psql vs from
jdbc ?

https://wiki.postgresql.org/wiki/Slow_Query_Questions

What version is the postgres server ?
That affects pruning as well as memory use.

https://www.postgresql.org/docs/14/release-14.html
Improve the performance of updates and deletes on partitioned tables
with many partitions (Amit Langote, Tom Lane)

This change greatly reduces the planner's overhead for such cases, and
also allows updates/deletes on partitioned tables to use execution-time
partition pruning.

Actually, this is about the same response as when you asked in June,
except that was about UPDATE.
https://www.postgresql.org/message-id/PH0PR11MB519134D4171A126776E3E063D6B89@PH0PR11MB5191.namprd11.prod.outlook.com

-- 
Justin