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https://issues.apache.org/jira/browse/TRAFODION-2282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15589329#comment-15589329
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ASF GitHub Bot commented on TRAFODION-2282:
-------------------------------------------
Github user robertamarton commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/766#discussion_r84124281
--- Diff: core/sql/optimizer/opt.cpp ---
@@ -5034,6 +5029,20 @@ void OptDefaults::initialize(RelExpr* rootExpr)
preFetchHistograms_ = FALSE;
}
+ // Find out what the RMS security key invalidation garbage collection
+ // interval is (this mirrors the logic in runtimestats/ssmpipc.cpp), so
+ // we can fail-safe the histogram cache.
+
+ char *sct = getenv("RMS_SIK_GC_INTERVAL_SECONDS"); // in seconds
+ if (sct)
+ {
+ siKeyGCinterval_ = ((Int64) str_atoi(sct, str_len(sct)));
+ if (siKeyGCinterval_ < 10)
+ siKeyGCinterval_ = 10;
+ }
+ else
+ siKeyGCinterval_ = (Int64)24 * 60 * 60; // 24 hours
+
--- End diff --
The sik key interval is being stored as a class member. Could someone
change the envvar between the time you set the variable and the time it is
used? Would it be better to calculate it on the fly?
> Optimizer histogram cache is sometimes never refreshed
> ------------------------------------------------------
>
> Key: TRAFODION-2282
> URL: https://issues.apache.org/jira/browse/TRAFODION-2282
> Project: Apache Trafodion
> Issue Type: Bug
> Components: sql-cmp
> Affects Versions: 2.1-incubating
> Environment: All
> Reporter: David Wayne Birdsall
> Assignee: David Wayne Birdsall
> Fix For: 2.1-incubating
>
>
> Here's the scenario:
> In session 1, create a table T1 and populate it with, say, 200000 or more
> rows.
> In session 2, prepare a query that selects from T1. For example, select
> A,COUNT(*) FROM T1 GROUP BY A. The query should compile fine, but you should
> see missing statistics warning messages (warning codes 6007 and 6008).
> In session 1, do "update statistics for table t1 on every column"
> In session 2, prepare other queries over a period of time. What should happen
> is that after about an hour, the Optimizer decides to refresh the histograms.
> However, due to a bug, it might never do so. So, the missing statistics
> warnings (6007, 6008) never go away. Worse, the prepares never benefit from
> the statistics so plan choice may be poor.
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