Github user DaveBirdsall commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/505#discussion_r64837288
--- Diff: core/sql/ustat/hs_globals.cpp ---
@@ -546,10 +557,11 @@ NABoolean HSGlobalsClass::setHBaseCacheSize(double
sampleRatio)
Int64 workableCacheSize = (Int64)(sampleRatio * calibrationFactor);
if (workableCacheSize < 1)
workableCacheSize = 1; // can't go below 1 unfortunately
+ else if (workableCacheSize > 50)
+ workableCacheSize = 50;
- Int32 max = getDefaultAsLong(HBASE_NUM_CACHE_ROWS_MAX);
- if ((workableCacheSize < 10000) && // don't bother if 10000 works
- (max == 10000)) // don't do it if user has already set this CQD
+ Int32 maxDefault = getDefaultAsLong(HBASE_NUM_CACHE_ROWS_MAX);
+ if (maxDefault == 10000) // don't do it if user has already set this CQD
--- End diff --
Thanks for the suggestion for NADefaults::getProvenance(). I'll make this
change.
In the case that the user sets the CQD him/herself, I wanted to give them
complete freedom to experiment as they please. Higher values may make UPDATE
STATS run faster (though experiements suggest not by much). The trade-off in
using higher values is an increased risk of failure.
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