| From: | amul sul <sulamul(at)gmail(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Thom Brown <thom(at)linux(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Yugo Nagata <nagata(at)sraoss(dot)co(dot)jp>, David Steele <david(at)pgmasters(dot)net>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [POC] hash partitioning |
| Date: | 2017-11-02 08:15:22 |
| Message-ID: | CAAJ_b94cgSmxoywzvA7Nz0XxG821Fs+_2EW90fAss4WUNn_r5g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Nov 2, 2017 at 1:35 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, Nov 1, 2017 at 3:46 PM, amul sul <sulamul(at)gmail(dot)com> wrote:
>> Although partition constraints become more simple, there isn't any performance
>> gain with 0005 patch. Also I am little skeptic about logic in 0005 where we
>> copied extended hash function info from the partition key, what if parent is
>> changed while we are using it? Do we need to keep lock on parent until commit in
>> satisfies_hash_partition?
>
> I don't think it should be possible for the parent to be changed. I
> mean, the partition key is altogether immutable -- it can't be changed
> after creation time. The partition bounds can be changed for
> individual partitions but that would require a lock on the partition.
>
> Can you give an example of the kind of scenario about which you are concerned?
>
Yes, you are correct, column involved in the partitioning are immutable.
I was just worried about any change in the partition key column that
might change selected hash function.
Regards,
Amul
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