Re: Possible hang in 10.1 with JSON query over partially indexed partitions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Paul Jones <admin(at)cmicdo(dot)com>
Cc: Pgsql-general General <pgsql-general(at)postgresql(dot)org>
Subject: Re: Possible hang in 10.1 with JSON query over partially indexed partitions
Date: 2018-01-19 01:07:18
Message-ID: 7994.1516324038@sss.pgh.pa.us
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Paul Jones <admin(at)cmicdo(dot)com> writes:
> I may have discovered a situation in 10.1 where EXECUTEing a PREPARED
> statement acting on JSON data in partitioned tables hangs in an
> infinite loop for a particular set of data. Unfortunately, the data is
> proprietary, so I did the best I could below to describe what happened.

You haven't provided any real reason to think that this represents an
infinite loop and not just a really slow query. The query's filter
conditions are complex enough to render the planner's estimates basically
works of fiction :-(, so I have no faith in the estimates suggesting that
only a relatively small number of rows will get processed. It's
definitely making some progress, because your successive backtraces
show different blocks getting read.

regards, tom lane

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