[
https://issues.apache.org/jira/browse/CASSANDRA-4894?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Matthew F. Dennis updated CASSANDRA-4894:
-----------------------------------------
Description:
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
was:
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 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
> 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
>
>
> 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
