2018-06-19 15:05 GMT-03:00 Robert Haas <robertmhaas@gmail.com>:
> Yeah, I agree that a GUC seems more powerful and easier to roll out.
> A downside is that there could be cached plans still using that old
> index. If we did DDL on the index we could be sure they all got
> invalidated, but otherwise how do we know?
>
If we want to test the effect of disabling an index, we could set GUC
only on the current session. DDL will make the index invisible
immediately. Things can go worse after that. I prefer the former. It
is more conservative but could confuse users if the effect is not
immediate (few words could explain cached plans x invisible indexes).
> BTW, like you, I seem to remember somebody writing an extension that
> did added a GUC that did exactly this, and demoing it at a conference.
> Maybe Oleg or Teodor?
>
https://github.com/postgrespro/plantuner
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