Chris Lohfink created CASSANDRA-14538:
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Summary: 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
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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