Re: More stable query plans via more predictable column statistics

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От Robert Haas
Тема Re: More stable query plans via more predictable column statistics
Дата
Msg-id CA+TgmoZrcTZPJEaSHriSbEsJkB7pO=46fXoKVK1bQY6=KLqZsQ@mail.gmail.com
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Ответ на Re: More stable query plans via more predictable column statistics  ("Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de>)
Ответы Re: More stable query plans via more predictable column statistics  ("Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de>)
Список pgsql-hackers
On Thu, Mar 3, 2016 at 2:48 AM, Shulgin, Oleksandr
<oleksandr.shulgin@zalando.de> wrote:
> On Wed, Mar 2, 2016 at 7:33 PM, Alvaro Herrera <alvherre@2ndquadrant.com>
> wrote:
>> Shulgin, Oleksandr wrote:
>>
>> > Alright.  I'm attaching the latest version of this patch split in two
>> > parts: the first one is NULLs-related bugfix and the second is the
>> > "improvement" part, which applies on top of the first one.
>>
>> So is this null-related bugfix supposed to be backpatched?  (I assume
>> it's not because it's very likely to change existing plans).
>
> For the good, because cardinality estimations will be more accurate in these
> cases, so yes I would expect it to be back-patchable.

-1.  I think the cost of changing existing query plans in back
branches is too high.  The people who get a better plan never thank
us, but the people who (by bad luck) get a worse plan always complain.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



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