Re: Performance on Bulk Insert to Partitioned Table - Mailing list pgsql-performance

On Dec 24, 2012, at 9:07 PM, Charles Gomes <charlesrg@outlook.com> wrote:

> By the way, I've just re-wrote the code to target the partitions individually and I've got almost 4 times
improvement.
> Shouldn't it be faster to process the trigger, I would understand if there was no CPU left, but there is lots of cpu
tochew. 

I saw your 20% idle cpu and raise eyebrows.

> It seems that there will be no other way to speedup unless the insert code is partition aware.
>
> ----------------------------------------
>> From: charlesrg@outlook.com
>> To: jeff.janes@gmail.com
>> CC: ondrej.ivanic@gmail.com; pgsql-performance@postgresql.org
>> Subject: Re: [PERFORM] Performance on Bulk Insert to Partitioned Table
>> Date: Mon, 24 Dec 2012 10:51:12 -0500
>>
>> ________________________________
>>> Date: Sun, 23 Dec 2012 14:55:16 -0800
>>> Subject: Re: [PERFORM] Performance on Bulk Insert to Partitioned Table
>>> From: jeff.janes@gmail.com
>>> To: charlesrg@outlook.com
>>> CC: ondrej.ivanic@gmail.com; pgsql-performance@postgresql.org
>>>
>>> On Thursday, December 20, 2012, Charles Gomes wrote:
>>> True, that's the same I feel, I will be looking to translate the
>>> trigger to C if I can find good examples, that should accelerate.
>>>
>>> I think your performance bottleneck is almost certainly the dynamic
>>> SQL. Using C to generate that dynamic SQL isn't going to help much,
>>> because it is still the SQL engine that has to parse, plan, and execute
>>> it.
>>>
>>> Are the vast majority if your inserts done on any given day for records
>>> from that same day or the one before; or are they evenly spread over
>>> the preceding year? If the former, you could use static SQL in IF and
>>> ELSIF for those days, and fall back on the dynamic SQL for the
>>> exceptions in the ELSE block. Of course that means you have to update
>>> the trigger every day.
>>>
>>>
>>> Using rules would be totally bad as I'm partitioning daily and after
>>> one year having 365 lines of IF won't be fun to maintain.
>>>
>>> Maintaining 365 lines of IF is what Perl was invented for. That goes
>>> for triggers w/ static SQL as well as for rules.
>>>
>>> If you do the static SQL in a trigger and the dates of the records are
>>> evenly scattered over the preceding year, make sure your IFs are nested
>>> like a binary search, not a linear search. And if they are mostly for
>>> "today's" date, then make sure you search backwards.
>>>
>>> Cheers,
>>>
>>> Jeff
>>
>> Jeff, I've changed the code from dynamic to:
>>
>> CREATE OR REPLACE FUNCTION quotes_insert_trigger()
>> RETURNS trigger AS $$
>> DECLARE
>> r_date text;
>> BEGIN
>> r_date = to_char(new.received_time, 'YYYY_MM_DD');
>> case r_date
>>    when '2012_09_10' then
>>        insert into quotes_2012_09_10 values (NEW.*) using new;
>>        return;
>>    when '2012_09_11' then
>>        insert into quotes_2012_09_11 values (NEW.*) using new;
>>        return;
>>    when '2012_09_12' then
>>        insert into quotes_2012_09_12 values (NEW.*) using new;
>>        return;
>>    when '2012_09_13' then
>>        insert into quotes_2012_09_13 values (NEW.*) using new;
>>        return;
>>    when '2012_09_14' then
>>        insert into quotes_2012_09_14 values (NEW.*) using new;
>>        return;
>>    when '2012_09_15' then
>>        insert into quotes_2012_09_15 values (NEW.*) using new;
>>        return;
>>    when '2012_09_16' then
>>        insert into quotes_2012_09_16 values (NEW.*) using new;
>>        return;
>>    when '2012_09_17' then
>>        insert into quotes_2012_09_17 values (NEW.*) using new;
>>        return;
>>    when '2012_09_18' then
>>        insert into quotes_2012_09_18 values (NEW.*) using new;
>>        return;
>>    when '2012_09_19' then
>>        insert into quotes_2012_09_19 values (NEW.*) using new;
>>        return;
>>    when '2012_09_20' then
>>        insert into quotes_2012_09_20 values (NEW.*) using new;
>>        return;
>>    when '2012_09_21' then
>>        insert into quotes_2012_09_21 values (NEW.*) using new;
>>        return;
>>    when '2012_09_22' then
>>        insert into quotes_2012_09_22 values (NEW.*) using new;
>>        return;
>>    when '2012_09_23' then
>>        insert into quotes_2012_09_23 values (NEW.*) using new;
>>        return;
>>    when '2012_09_24' then
>>        insert into quotes_2012_09_24 values (NEW.*) using new;
>>        return;
>> end case
>> RETURN NULL;
>> END;
>> $$
>> LANGUAGE plpgsql;
>>
>>
>> However I've got no speed improvement.
>> I need to keep two weeks worth of partitions at a time, that's why all the WHEN statements.
>> Wish postgres could automate the partition process natively like the other sql db.
>>
>> Thank you guys for your help.
>>
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