Re: negative bitmapset member not allowed Error with partition pruning - Mailing list pgsql-hackers

From David Rowley
Subject Re: negative bitmapset member not allowed Error with partition pruning
Date
Msg-id CAKJS1f-z_EZxLZeb7dbJ5G89O6c=7CBPr4Z4WHJiHnBHB+8R3Q@mail.gmail.com
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In response to Re: negative bitmapset member not allowed Error with partitionpruning  (Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>)
Responses Re: negative bitmapset member not allowed Error with partition pruning  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On 27 July 2018 at 13:35, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote:
> On 2018/07/27 1:28, Tom Lane wrote:
>> (BTW, I'm not sure that it was wise to design bms_add_range to fail for
>> empty ranges.  Maybe it'd be better to redefine it as a no-op for
>> upper < lower?)
>
> FWIW, I was thankful that David those left those checks there, because it
> helped expose quite a few bugs when writing this code or perhaps that was
> his intention to begin with, but maybe he thinks differently now (?).

I think it's more useful to keep as a bug catcher, although I do
understand the thinking behind just having it be a no-op.

Partition pruning is complex code so I think additional caution is
warranted. People are more likely to notice the error and complain.
It's likely especially useful with tools like sqlsmith, as I imagine
it does not validate the actual results of queries (does it?). but I'm
pretty sure that the ERROR would get flagged up.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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