Re: [Postgres-xc-developers] hash by UUID

[Ashutosh B. <ash...@en...>]

On Tue, Sep 10, 2013 at 5:37 PM, Mason Sharp <ma...@st...> wrote:

>
>
>
> On Tue, Sep 10, 2013 at 4:20 AM, Ashutosh Bapat <
> ash...@en...> wrote:
>
>> Unrelated to your patch, I think, we should now change the way we are
>> handling hash distribution. Instead of having switch cases to get the hash
>> functions, to decide whether a certain column is distributable, we should
>> really be looking up the pg_type catalogs. This has following advantages
>> 1. hashing for distribution would be inline with rest of the hashing
>> (hash joins for example), in the server
>> 2. We don't need to keep adding datatypes to switch cases. Any data type
>> with a hash function would be hash-distributable. Only thing is we
>> shouldn't allow the hash function of a data type to be changed if there is
>> a distributed table based on this hash function.
>> 3. Tables can be distributed by user defined types which have hash
>> functions.
>>
>> This was serious flaw in the previous design, which needs to be corrected
>> before we can add new types to distribution.
>>
>
> I would put other things at a higher priority right now to help increase
> the user base rather than redesigning this.  Some past reworking of
> portions of the code broke things or disabled optimizations that were
> previously working that took a long time before they were working again, so
> I think we should be careful before undertaking changes.
>

The more code we add over badly designed code, we will have more of those
instances and in later versions of Postgres-XC, which means harder it
becomes to fix things.


> In particular, if newly proposed changes increase the diff and complexity
> for merging with vanilla PostgreSQL, we should be cautious.
>
>
This change will be only in the XC specific code, so there won't be
conflicts with PG merge.


> Anyway, this is needed by a StormDB support customer who is using
> Postgres-XC (not StormDB). We are hoping to keep them as close to the
> REL1_1_STABLE branch as possible.  For 1.0, we have had to maintain a
> specially patched version for customers to ensure a stable version and
> still merge in important bug fixes.
>
> Regards,
>
> Mason
>
>
>
>> Same would, then be applicable for modulo distribution where existence of
>> % operator with integer input and integer output can be used.
>>
>>
>
>
>
>
>>
>> On Tue, Sep 10, 2013 at 1:00 PM, Andrei Martsinchyk <
>> and...@gm...> wrote:
>>
>>>  Hello,
>>>
>>> PostgresXC does not support hash distribution by UUID data type.
>>> Attached a small patch that enables the feature.
>>>
>>> --
>>> Andrei Martsinchyk
>>>
>>> StormDB - http://www.stormdb.com
>>> The Database Cloud
>>>
>>>
>>>
>>> ------------------------------------------------------------------------------
>>> How ServiceNow helps IT people transform IT departments:
>>> 1. Consolidate legacy IT systems to a single system of record for IT
>>> 2. Standardize and globalize service processes across IT
>>> 3. Implement zero-touch automation to replace manual, redundant tasks
>>>
>>> http://pubads.g.doubleclick.net/gampad/clk?id=51271111&iu=/4140/ostg.clktrk
>>> _______________________________________________
>>> Postgres-xc-developers mailing list
>>> Pos...@li...
>>> https://lists.sourceforge.net/lists/listinfo/postgres-xc-developers
>>>
>>>
>>
>>
>> --
>> Best Wishes,
>> Ashutosh Bapat
>> EnterpriseDB Corporation
>> The Postgres Database Company
>>
>>
>> ------------------------------------------------------------------------------
>> How ServiceNow helps IT people transform IT departments:
>> 1. Consolidate legacy IT systems to a single system of record for IT
>> 2. Standardize and globalize service processes across IT
>> 3. Implement zero-touch automation to replace manual, redundant tasks
>>
>> http://pubads.g.doubleclick.net/gampad/clk?id=51271111&iu=/4140/ostg.clktrk
>> _______________________________________________
>> Postgres-xc-developers mailing list
>> Pos...@li...
>> https://lists.sourceforge.net/lists/listinfo/postgres-xc-developers
>>
>>
>
>
> --
> Mason Sharp
>
>
> StormDB - http://www.stormdb.com
> The Database Cloud
> Postgres-XC Support and Services
>



-- 
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company