Grigory Smolkin <g.smolkin@postgrespro.ru> writes:
> I`ve noticed interesting aspect in temp tables working. It appears
> postgres is trying to reserve space on disk for temp tables even before
> temp_buffers overflow.
Sure. Just like it reserves space for ordinary tables right away,
long before there's any need to push the data out of shared_buffers.
Otherwise, you might find yourself having to throw an "out of disk
space" error after having already committed the relevant INSERTs.
regards, tom lane
