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Subject [GitHub] [trafodion] DaveBirdsall opened a new pull request #1821: [TRAFODION-3291] Fix core when multi-column stats are done on lots of columns
Date Tue, 02 Apr 2019 18:59:09 GMT
DaveBirdsall opened a new pull request #1821: [TRAFODION-3291] Fix core when multi-column stats
are done on lots of columns
URL: https://github.com/apache/trafodion/pull/1821
 
 
   The problem given in the JIRA is that creating a multi-column histogram on 500 columns
results in a tdm_arkcmp core.
   
   There are two changes in this change set:
   
   1. Fixes the core by addressing a buffer overrun problem. When we log messages, we use
a fixed size buffer for the message text. When a column list is long enough, we were overrunning
this buffer, causing the core. The fix truncates the column list text to avoid these overruns.
   
   2. Adds a limit on the number of columns in a multi-column histogram. As a practical matter,
they are not useful on large column sets. Too, the request could conceivably be a syntax mistake
by the user; it may be the user intended to specify a list of columns to create single column
histograms upon. The limit is set at 10 (we already have such a limit when automatically generating
multi-column histograms for key prefixes). It can be overridden using CQD USTAT_MULTI_COLUMN_LIMIT.

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