Re: Identity projection

Hello, This is new version of identity projection patch.

Reverted projectionInfo and ExecBuildProjectionInfo. Identity
projection is recognized directly in ExecGroup, ExecResult, and
ExecWindowAgg. nodeAgg is reverted because I couldn't make it
sane..

The following is the result of performance test posted before in
order to show the source of the gain.

regards,

-- 
-- 
Kyotaro Horiguchi
NTT Open Source Software Center



At Fri, 05 Oct 2012 16:04:16 +0900, Kyotaro HORIGUCHI wrote in <20121005.160416.256387378.horiguchi.kyotaro@lab.ntt.co.jp>
> > Although I said as following, the gain seems a bit larger... I'll
> > recheck the testing conditions...
> 
> I had inspected more precisely on two aspects maginifying the
> effect of this patch by putting 300 columns into table.
> 
> 
> First, explain analyze says the difference caused by this patch
> is only in the actual time of Result node.
> 
> orig$ psql -c 'explain analyze select * from parenta'
>                           QUERY PLAN
> --------------------------------------------------------------------------
>  Result  (cost=0.00..176667.00 rows=1000001 width=1202)
>          (actual time=0.013.. *2406.792* rows=1000000 loops=1)
>    ->  Append  (cost=0.00..176667.00 rows=1000001 width=1202)
>                (actual time=0.011..412.749 rows=1000000 loops=1)
>          ->  Seq Scan on parenta  (cost=0.00..0.00 rows=1 width=1228)
>                                   (actual time=0.001..0.001 rows=0 loops=1)
>          ->  Seq Scan on childa000 parenta
>                             (cost=0.00..176667.00 rows=1000000 width=1202)
>                             (actual time=0.009..334.633 rows=1000000 loops=1)
>  Total runtime: 2446.474 ms
> (5 rows)
> 
> patched$ psql -c 'explain analyze select * from parenta'
>                           QUERY PLAN
> --------------------------------------------------------------------------
>  Result  (cost=0.00..176667.00 rows=1000001 width=1202)
>          (actual time=0.011.. *507.239* rows=1000000 loops=1)
>    ->  Append  (cost=0.00..176667.00 rows=1000001 width=1202)
>                (actual time=0.011..419.420 rows=1000000 loops=1)
>          ->  Seq Scan on parenta  (cost=0.00..0.00 rows=1 width=1228)
>                                   (actual time=0.000..0.000 rows=0 loops=1)
>          ->  Seq Scan on childa000 parenta
>                             (cost=0.00..176667.00 rows=1000000 width=1202)
>                             (actual time=0.010..335.721 rows=1000000 loops=1)
>  Total runtime: 545.879 ms
> (5 rows)
> 
> 
>  Second, the results of configure --enable-profiling shows that
> the exectime of ExecProject chages greately. This is consistent
> with what explain showed.
> 
> orig:
>  >  %   cumulative   self              self     total           
>  > time   seconds   seconds    calls   s/call   s/call  name    
>  > 60.29      1.26     1.26  1000005     0.00     0.00  slot_deform_tuple
> !> 30.14      1.89     0.63  1000000     0.00     0.00  ExecProject
>  >  3.35      1.96     0.07  3000004     0.00     0.00  ExecProcNode
>  >  0.96      1.98     0.02  1000002     0.00     0.00  ExecScan
>  >  0.96      2.00     0.02   166379     0.00     0.00  TerminateBufferIO
>  >  0.48      2.01     0.01  3000004     0.00     0.00  InstrStartNode
>  >  0.48      2.02     0.01  3000004     0.00     0.00  InstrStopNode
> !>  0.48      2.03     0.01  1000001     0.00     0.00  ExecResult
>  >  0.48      2.04     0.01   830718     0.00     0.00  LWLockAcquire
>  >  0.48      2.05     0.01   506834     0.00     0.00  hash_search_with_hash_value
>  >  0.48      2.06     0.01   341656     0.00     0.00  LockBuffer
>  >  0.48      2.07     0.01   168383     0.00     0.00  ReadBuffer_common
>  >  0.48      2.08     0.01        4     0.00     0.00  InstrEndLoop
>  >  0.48      2.09     0.01                             ExecCleanTargetListLength
>  >  0.00      2.09     0.00  2000005     0.00     0.00  MemoryContextReset
> 
> patched:
>  >   %   cumulative   self              self     total           
>  >  time   seconds   seconds    calls  ms/call  ms/call  name    
>  >  23.08      0.03     0.03  3000004     0.00     0.00  ExecProcNode
>  >  15.38      0.05     0.02  1000002     0.00     0.00  heapgettup_pagemode
>  >  15.38      0.07     0.02   830718     0.00     0.00  LWLockAcquire
>  >   7.69      0.08     0.01  2000005     0.00     0.00  MemoryContextReset
>  >   7.69      0.09     0.01  1000002     0.00     0.00  ExecScan
>  >   7.69      0.10     0.01  1000000     0.00     0.00  ExecStoreTuple
>  >   7.69      0.11     0.01   841135     0.00     0.00  LWLockRelease
>  >   7.69      0.12     0.01   168383     0.00     0.00  ReadBuffer_common
>  >   7.69      0.13     0.01   168383     0.00     0.00  UnpinBuffer
>  >   0.00      0.13     0.00  3000004     0.00     0.00  InstrStartNode
>  ...
> !>   0.00      0.13     0.00  1000001     0.00     0.00  ExecResult
> !>   0.00      0.13     0.00  1000000     0.00     0.00  ExecProject
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