From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | David Osborne <david(at)qcode(dot)co(dot)uk> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Slow performance after restoring a dump |
Date: | 2018-03-19 16:22:00 |
Message-ID: | 1565.1521476520@sss.pgh.pa.us |
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Lists: | pgsql-performance |
David Osborne <david(at)qcode(dot)co(dot)uk> writes:
> Hi, yes I've run "analyse" against the newly restored database. Should that
> be enough?
My apologies, you did say that further down in the original message.
It looks like the core of the problem is the poor rowcount estimation
here:
-> Bitmap Index Scan on stock_trans_product_idx (cost=0.00..31.42 rows=1465 width=0) (actual time=0.009..0.009 rows=0 loops=1)
Index Cond: (product_id = 2466420)
Buffers: shared hit=3
You might be able to improve that by raising the statistics target
for stock_trans.product_id. I'm not sure why you weren't getting
bitten by the same issue in 9.1; but the cost estimates aren't
that far apart for the two plans, so maybe you were just lucky ...
regards, tom lane
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