On Sat, Aug 10, 2019 at 3:27 AM Jim Finnerty <jfinnert@amazon.com> wrote:
>
> I missed this thread. I'd be happy to post the code for what we use as the
> stable query identifier, but we could definitely come up with a more
> efficient algorithm if we're willing to assume that the sql statements are
> the same if and only if the parse tree structure is the same.
>
> Currently what we do for the sql hash is to simply replace all the literals
> and then hash the resulting SQL string
Isn't that what pg_store_plan is already doing? Except that it
removes extraneous whitespaces and put identifiers in uppercase so
that you get a reasonable query identifier.
> you could define a stable identifier for each node type, ignore literal
> constants, and hash fully-qualified object names instead of OIDs. That
> should be pretty fast.
This has been discussed already, and resolving all object names and
qualifier names will add a dramatic overhead for many workloads.