Re: BUG #15427: DROP INDEX did not free up disk space

Andres Freund <andres@anarazel.de> writes:
> On 2018-10-12 03:27:28 +0000, PG Bug reporting form wrote:
>> Performed a DROP INDEX to free up disk space but, whilst the command
>> succeeded the disk space was not freed up.

> The problem here is that even though we send a invalidation message to
> all backends, there's nothing to force backends to process invalidation
> messages in time if they're idle.

Uh, what's that got to do with it?

My recollection (though I've not looked at the code) is that we
truncate the file to ensure disk space is freed, whether or not
all backends have closed their FDs for the file.  This is quite
independent of the sinval mechanism.

I'm suspicious that this report reflects some weird behavior
of a non-mainline filesystem ...

            regards, tom lane