On Wed, Apr 03, 2019 at 11:40:57AM +0530, Pavan Deolasee wrote: > On Wed, Apr 3, 2019 at 10:19 AM Michael Paquier <mich...@paquier.xyz> wrote: >> - The comments in tuptoaster.h need to be updated to outline the >> difference between the compression invocation and the toast invocation >> thresholds. The wording could be better though. > > I see that you've done this already. But please let me if more is needed.
If you have a better idea of wording for that part... Please feel free. > Yeah, this is an issue with the existing code. Even though we allow setting > toast_tuple_target to a value less than compile-time TOAST_TUPLE_THRESHOLD, > the code doesn't really honour a value less than TOAST_TUPLE_THRESHOLD. In > other words, setting toast_tuple_target lesser than TOAST_TUPLE_THRESHOLD > doesn't have any effect. We don't even create a toast table if the > estimated length of tuple is not greater than TOAST_TUPLE_THRESHOLD. > > The change introduced by this patch will now trigger the tuptoaster code > when the compression or toast threshold is set to a value lower than > TOAST_TUPLE_THRESHOLD. But as far as I can see, that doesn't have any bad > effect on the toasting since toast_insert_or_update() is capable of > handling the case when the toast table is missing. There will be a > behavioural change though. e.g. It seems to me that c251336 should have done all those things from the start... In other terms, isn't that a bug and something that we should fix and back-patch? I'll begin a new thread about that to catch more attention, with Simon and Andrew in CC. -- Michael
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