performance regression by pr/46504

[tiancaiamao]

Enhancement

Ref #25754
2023.9.5
See http://www.zenlife.tk:18081/alloc

cd session;
go test -tags intest  -bench BenchmarkIntegerIndexLookup -run XXX -benchmem;

Before vs After:

BenchmarkIntegerIndexLookup-16              3301            413728 ns/op          118861 B/op       969 allocs/op
BenchmarkIntegerIndexLookup-16              2366            523089 ns/op          154557 B/op       1564 allocs/op

[hawkingrei]

It is a sad story. We worry about OOM after enabling the planner cache. so we decided to disable the planner cache when to GA the planner cache.

[qw4990]

It's caused by #46504. But it's expected, we disable non-prepare plan cache to ensure stability.

[tiancaiamao]

From the picture, we can see the historial data.
I just wonder, why it regression so much when it's disable ... whereas no such obvious improvement when it's introduced.