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Posted to commits@cassandra.apache.org by "Benjamin Lerer (JIRA)" <ji...@apache.org> on 2018/06/25 07:08:00 UTC
[jira] [Updated] (CASSANDRA-14538) Add virtual table to view cache
information
[ https://issues.apache.org/jira/browse/CASSANDRA-14538?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Benjamin Lerer updated CASSANDRA-14538:
---------------------------------------
Reviewer: Benjamin Lerer
> 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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