On Wed, Oct 14, 2020 at 10:09 PM Bruce Momjian <br...@momjian.us> wrote: > > On Wed, Oct 14, 2020 at 05:43:33PM +0800, Julien Rouhaud wrote: > > On Tue, Oct 13, 2020 at 4:53 AM Bruce Momjian <br...@momjian.us> wrote: > > > > > > On Mon, Oct 12, 2020 at 04:07:30PM -0400, Tom Lane wrote: > > > > Bruce Momjian <br...@momjian.us> writes: > > > > > On Mon, Oct 12, 2020 at 02:26:15PM -0400, Tom Lane wrote: > > > > >> Yeah, I agree --- a version number is the wrong way to think about > > > > >> this. > > > > > > > > > The version number was to invalidate _all_ query hashes if the > > > > > algorithm is slightly modified, rather than invalidating just some of > > > > > them, which could lead to confusion. > > > > > > > > Color me skeptical as to the use-case for that. From users' > > > > standpoints, > > > > the hash is mainly going to change when we change the set of parse node > > > > fields that get hashed. Which is going to happen at every major release > > > > and no (or at least epsilon) minor releases. So I do not see a point in > > > > tracking an algorithm version number as such. Seems like make-work. > > > > > > OK, I came up with the hash idea only to address one of your concerns > > > about mismatched hashes for algorithm improvements/changes. Seems we > > > might as well just document that cross-version hashes are different. > > > > Ok, so I tried to implement what seems to be the consensus. First > > attached patch moves the current pgss queryid computation in core, > > with a new compute_queryid GUC (on/off). One thing I don't really > > Why would someone turn compute_queryid off? Overhead?
Yes, or possibly to use a different algorithm.
