Re: Re: patch submission: truncate trailing nulls from heap rows to reduce the size of the null bitmap [Review]

On 13 October 2012 08:54, Amit kapila <amit(dot)kapila(at)huawei(dot)com> wrote:

> As per the last discussion for this patch, performance data needs to be
> provided before this patch's Review can proceed further.
>
> So as per your suggestion and from the discussions about this patch, I have
> collected the performance data as below:
>
>
>
> Results are taken with following configuration.
> 1. Schema - UNLOGGED TABLE with 2,000,000 records having all columns are INT
> type.
> 2. shared_buffers = 10GB
> 3. All the performance result are taken with single connection.
> 4. Performance is collected for INSERT operation (insert into temptable
> select * from inittable)
>
> Platform details:
> Operating System: Suse-Linux 10.2 x86_64
> Hardware : 4 core (Intel(R) Xeon(R) CPU L5408 @ 2.13GHz)
> RAM : 24GB
>
> Documents Attached:
> init.sh : Which will create the schema
> sql_used.sql : sql's used for taking results
>
> Trim_Nulls_Perf_Report.html : Performance data
>
>
> Observations from Performance Results
>
> ------------------------------------------------
>
> 1. There is no performance change for cloumns that have all valid
> values(non- NULLs).
>
> 2. There is a visible performance increase when number of columns containing
> NULLS are more than > 60~70% in table have large number of columns.
>
> 3. There are visible space savings when number of columns containing NULLS
> are more than > 60~70% in table have large number of columns.
>
>
> Let me know if there is more performance data needs to be collected for this
> patch?

I can't make sense of your performance report. Because of that I can't
derive the same conclusions from it you do.

Can you explain the performance results in more detail, so we can see
what they mean? Like which are the patched, which are the unpatched
results? Which results are comparable, what the percentages mean etc..

We might then move quickly towards commit, or at least more tests.

--
Simon Riggs http://www.2ndQuadrant.com/
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