| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: weird hash plan cost, starting with pg10 |
| Date: | 2020-03-23 17:00:59 |
| Message-ID: | 18131.1584982859@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> While messing with EXPLAIN on a query emitted by pg_dump, I noticed that
> current Postgres 10 emits weird bucket/batch/memory values for certain
> hash nodes:
> -> Hash (cost=0.11..0.11 rows=10 width=12) (actual time=0.002..0.002 rows=1 loops=8)
> Buckets: 2139062143 Batches: 2139062143 Memory Usage: 8971876904722400kB
> -> Function Scan on unnest init_1 (cost=0.01..0.11 rows=10 width=12) (actual time=0.001..0.001 rows=1 loops=8)
Looks suspiciously like uninitialized memory ...
> The complete query is:
Reproduces here, though oddly only a couple of the several hash subplans
are doing that.
I'm not planning to dig into it right this second either.
regards, tom lane
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