On 22/11/2024 22:53, Frédéric Yhuel wrote:
My colleague Christophe Courtois and I have been trying to fix a bad
plan for one of Dalibo's clients. It is a (probably well-known) problem
with skewed data and a parameterized Nested Loop with an underestimation
of the cardinality of the inner relati
On 11/21/24 13:13, James Pang wrote:
> experts,
> Postgresql v14.8, client app use Postgresql JDBC, it start a single
> query that return 470k rows totally in one time, but sometimes, database
> server side got error "could not send data to client: Connection reset
> by peer".
> any idea wh
My colleague Christophe Courtois and I have been trying to fix a bad
plan for one of Dalibo's clients. It is a (probably well-known) problem
with skewed data and a parameterized Nested Loop with an underestimation
of the cardinality of the inner relation.
Here is a test case (the script to cre
On 22/11/2024 18:12, Ba Jinsheng wrote:
I think the key difference is that the patch disables the usage of Hash
Join, which incurs a worse performance.
I see here a problem with a number of groups: when predicting it
incorrectly, Postgres doesn't use the Memoize node. Disabling HashJoin
puts Ne
