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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-14538) Add virtual table to view cache information
Date Fri, 22 Jun 2018 15:13:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-14538?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16520483#comment-16520483
] 

ASF GitHub Bot commented on CASSANDRA-14538:
--------------------------------------------

GitHub user clohfink opened a pull request:

    https://github.com/apache/cassandra/pull/238

    Add virtual table to view cache information for CASSANDRA-14538

    

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/clohfink/cassandra caches_vtable

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/cassandra/pull/238.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #238
    
----
commit 80eba29a7653c9ca922511f76599de9080b93be7
Author: Chris Lohfink <clohfink@...>
Date:   2018-06-22T15:11:52Z

    Add virtual table to view cache information for CASSANDRA-14538

----


> Add virtual table to view cache information
> -------------------------------------------
>
>                 Key: CASSANDRA-14538
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14538
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Chris Lohfink
>            Assignee: Chris Lohfink
>            Priority: Minor
>              Labels: virtual-tables
>
>  Add a couple tables, one for displaying the general cache information (like in {{nodetool
info}}) and another to view the contents (ish) of keycache. This would be pretty useful in
tests to tell if things are in the cache and in finding wide partitions and performance issues.
> Possibility to discuss: DELETE on the key cache to evict specific records, I wrote the
code to do it but im not sure if its valuable or worth complexity. TRUNCATE support on virtual
tables might be nice as a way to clear the keycache as well. These can be followup tickets
though if it seems like a good idea as truncate and delete are currently disabled in virtual
tables and that behavior should maybe be its own ticket/discussion.
>  
> {code}
> cqlsh> SELECT * FROM system_views.caches;
>  name    | entries | hit_ratio | hits | recent_hits_per_sec | recent_requests_per_sec
| requests | size_max | size_used
> ---------+---------+-----------+------+---------------------+-------------------------+----------+----------+-----------
>  counter |       0 |       NaN |    0 |                   0 |                       0
|        0 | 12582912 |         0
>      key |      19 |  0.922509 |  250 |                  11 |                      13
|      271 | 25165824 |      1728
>      row |       0 |       NaN |    0 |                   0 |                       0
|        0 | 16777216 |         0
> (3 rows)
> cqlsh> SELECT * FROM system_views.key_cache;
>  keyspace_name | table_name       | key                 | sstable | size
> ---------------+------------------+---------------------+---------+------
>          basic |             wide |                row1 |       5 |   64
>          basic |             wide |                row1 |       6 |   64
>         system |            local |               local |      15 |   24
>         system |            local |               local |      16 |   24
>         system |            local |               local |      17 |   24
>         system | sstable_activity | system_auth:roles:1 |      13 |   24
>    system_auth |            roles |           cassandra |       1 |   24
>  system_schema |           tables |               basic |      13 |   24
>  system_schema |           tables |         system_auth |      13 |   24
>  system_schema |           tables |  system_distributed |      13 |   24
>  system_schema |           tables |       system_traces |      13 |   24
>  system_schema |          columns |               basic |      13 |   24
>  system_schema |          columns |         system_auth |      13 |   24
>  system_schema |          columns |  system_distributed |      13 |   24
>  system_schema |          columns |       system_traces |      13 |   24
>  system_schema |        keyspaces |               basic |      13 |   24
>  system_schema |        keyspaces |         system_auth |      13 |   24
>  system_schema |        keyspaces |  system_distributed |      13 |   24
>  system_schema |        keyspaces |       system_traces |      13 |   24
> (19 rows)
> {code}



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