From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Rui Zhong <reversezr33(at)gmail(dot)com> |
Cc: | pgsql-bugs(at)lists(dot)postgresql(dot)org |
Subject: | Re: [bug report] A sql statements make query hang |
Date: | 2020-01-06 06:50:33 |
Message-ID: | 4138.1578293433@sss.pgh.pa.us |
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Lists: | pgsql-bugs |
Rui Zhong <reversezr33(at)gmail(dot)com> writes:
> When we run follow statements make query hang and never return in
> PostgreSQL 13devel, we consider it might be a bug of PostgreSQL and report
> it.
> CREATE TEMPORARY TABLE v0 ( v1 INT UNIQUE ) ;
> WITH RECURSIVE v0 ( v1 ) AS ( SELECT -128 UNION SELECT v1 + 33 FROM v0 )
> SELECT 'x' from v0;
That's an infinite recursion, so I'm not sure why you think there's
a server bug here.
In practice, I think you'd get an integer overflow error after
awhile, where "awhile" is defined as INT_MAX/33 recursions.
It might take considerable patience to reach that point though.
(And when you did, it still wouldn't be a bug. The calculation
specified by this query must eventually overflow any finite
arithmetic.)
> When we run in mysql, it suddenly return an empty set.
Hardly requires commentary.
regards, tom lane
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