Hou-san, On Tue, Jun 1, 2021 at 5:43 PM houzj.f...@fujitsu.com <houzj.f...@fujitsu.com> wrote: > From: Amit Langote <amitlangot...@gmail.com> > > > > Where are you thinking to cache the partidx list? Inside > > > > PartitionDesc or some executor struct? > > > > > > I was thinking cache the partidx list in PartitionDescData which is in > > > relcache, if possible, we can use the cached partition between statements. > > > > Ah, okay. I thought you were talking about a different idea. > > How and where would you determine that a cached partidx value is indeed the > > correct one for > > a given row? > > Anyway, do you want to try writing a patch to see how it might work? > > Yeah, the different idea here is to see if it is possible to share the cached > partition info between statements efficiently. > > But, after some research, I found something not as expected:
Thanks for investigating this. > Currently, we tried to use ExecPartitionCheck to check the if the cached > partition is the correct one. And if we want to share the cached partition > between statements, we need to Invoke ExecPartitionCheck for single-row > INSERT, > but the first time ExecPartitionCheck call will need to build expression state > tree for the partition. From some simple performance tests, the cost to build > the state tree could be more than the cached partition saved which could bring > performance degradation. Yeah, using the executor in the lower layer will defeat the whole point of caching in that layer. > So, If we want to share the cached partition between statements, we seems > cannot > use ExecPartitionCheck. Instead, I tried directly invoke the partition support > function(partsupfunc) to check If the cached info is correct. In this > approach I > tried cache the *bound offset* in PartitionDescData, and we can use the bound > offset > to get the bound datum from PartitionBoundInfoData and invoke the partsupfunc > to do the CHECK. > > Attach a POC patch about it. Just to share an idea about sharing cached > partition info > between statements. I have not looked at your patch yet, but yeah that's what I would imagine doing it. -- Amit Langote EDB: http://www.enterprisedb.com
