[GitHub] incubator-trafodion pull request #1232: [TRAFODION-2738] Rowset buffer size ...

[asfgit]

Github user asfgit closed the pull request at:

https://github.com/apache/incubator-trafodion/pull/1232


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[GitHub] incubator-trafodion pull request #1232: [TRAFODION-2738] Rowset buffer size ...

[selvaganesang]

Github user selvaganesang commented on a diff in the pull request:


https://github.com/apache/incubator-trafodion/pull/1232#discussion_r139270056
  
--- Diff: core/sql/sqlcomp/nadefaults.cpp ---
@@ -1336,6 +1336,8 @@ SDDkwd__(EXE_DIAGNOSTIC_EVENTS,   "OFF"),
 
  SDDui___(EXE_MEMORY_FOR_PROBE_CACHE_IN_MB,"100"),
 
+ SDDui___(EXE_MEMORY_FOR_UNPACK_ROWS_IN_MB,"100"),
--- End diff --

Because there is an easy way to change the memory size, we can determine 
the optimal default at a later date.  I believe the current default of 100 MB 
should be good enough for most of the use cases.


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[GitHub] incubator-trafodion pull request #1232: [TRAFODION-2738] Rowset buffer size ...

[sureshsubbiah]

Github user sureshsubbiah commented on a diff in the pull request:


https://github.com/apache/incubator-trafodion/pull/1232#discussion_r139228319
  
--- Diff: core/sql/sqlcomp/nadefaults.cpp ---
@@ -1336,6 +1336,8 @@ SDDkwd__(EXE_DIAGNOSTIC_EVENTS,   "OFF"),
 
  SDDui___(EXE_MEMORY_FOR_PROBE_CACHE_IN_MB,"100"),
 
+ SDDui___(EXE_MEMORY_FOR_UNPACK_ROWS_IN_MB,"100"),
--- End diff --

A default value of 100 MB maybe too small. I understand that this is good 
for mixed workloads, but do consider than plans with Unpack, especially when 
used for insert/upsert are simple. Unpack is always serial and part of master 
exe. Often there is only one in a query.  The cost of having a low value here 
seems to be that queue length from unpack could be limited by this when we are 
loading a table with wide rows (even if actual data in row is not wide). We 
know from performance runs that queue length is critical to upsert load 
performance. This is a hunch on my part and could be misguided. It will be good 
to performance test for upsert of table with wide rows, if you think that is 
worthwhile.


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