Re: hash join error improvement (old)

On 2020-May-26, Tom Lane wrote:

> Are you sure you correctly identified the source of the bogus error
> report?

This version's better.  It doesn't touch the write side at all.
On the read side, only report a short read as such if errno's not set.

This error isn't frequently seen.  This page
https://blog.csdn.net/pg_hgdb/article/details/106279303
(A Postgres fork; blames the error on the temp hash files being encrypted,
suggests to increase temp_buffers) is the only one I found.

There are more uses of BufFileRead that don't bother to distinguish
these two cases apart, though -- logtape.c, tuplestore.c,
gistbuildbuffers.c all do the same.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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