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Sylvain Lebresne commented on CASSANDRA-4894: --------------------------------------------- Maybe it could use some explanation of what those number means? I had no clue whatsoever before looking at the source. > log number of combined/merged rows during a compaction > ------------------------------------------------------ > > Key: CASSANDRA-4894 > URL: https://issues.apache.org/jira/browse/CASSANDRA-4894 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Matthew F. Dennis > Assignee: Yuki Morishita > Priority: Minor > Fix For: 1.2.1 > > Attachments: 4894-1.2.txt > > > we already log some details about compactions but it would be useful to know > how many rows were merged (resulting in "useful" work) and how many were > unique (representing "wasted work"). > the simple approach requires two additional counters (one for unique rows, > one for merged rows). As the merge join is progressing if two or more rows > are combined, tick the joined counter. If a row is simply copied tick the > unique counter. > a more complete solution would be to keep a separate count for each number of > merges. This would require number_of_files_being_merged counters. If no > rows were merged, tick counters[0], if two rows were merged tick counters[1] > and so on -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira