Argthtjtr

Row caching only works if the table has a single column primary key otherwise if you add a clustering key to the table then row caching no longer works. The Cassandra version I've tested this against is 3.11.0 but the issue is also evident in 3.11.3 which is the latest one at the time of writing this.

I am using the default Cassandra configs plus:

key_cache_size_in_mb:

key_cache_save_period: 14400

row_cache_size_in_mb: 128

row_cache_save_period: 14400

It looks like a very fundamental feature so I am not quite sure whether this is a bug or something that I am missing:

cqlsh> CREATE TABLE test.table1 (k text, v text, PRIMARY KEY (k)) WITH caching = {'keys': 'ALL', 'rows_per_partition': '100'};

cqlsh> CREATE TABLE test.table2 (k text, v text, PRIMARY KEY (k, v)) WITH caching = {'keys': 'ALL', 'rows_per_partition': '100'};

cqlsh> insert into test.table1 (k,v) values('k1', 'v1');

cqlsh> insert into test.table2 (k,v) values('k1', 'v1');

cqlsh> tracing on;

Now Tracing is enabled

cqlsh> select * from test.table1 where k='k1';



 k  | v

----+----

 k1 | v1



(1 rows)



Tracing session: e81f1640-ebcb-11e8-b19a-8f0e04450cb9



 activity                                                                                | timestamp                  | source    | source_elapsed | client

-----------------------------------------------------------------------------------------+----------------------------+-----------+----------------+-----------

                                                                      Execute CQL3 query | 2018-11-19 07:22:44.004000 | 127.0.0.1 |              0 | 127.0.0.1

            Parsing select * from test.table1 where k='k1'; [Native-Transport-Requests-1] | 2018-11-19 07:22:44.005000 | 127.0.0.1 |            225 | 127.0.0.1

                                       Preparing statement [Native-Transport-Requests-1] | 2018-11-19 07:22:44.005000 | 127.0.0.1 |            395 | 127.0.0.1

                                                            Row cache miss [ReadStage-3] | 2018-11-19 07:22:44.005000 | 127.0.0.1 |            930 | 127.0.0.1

                                Executing single-partition query on table1 [ReadStage-3] | 2018-11-19 07:22:44.005000 | 127.0.0.1 |           1047 | 127.0.0.1

                                              Acquiring sstable references [ReadStage-3] | 2018-11-19 07:22:44.006000 | 127.0.0.1 |           1106 | 127.0.0.1

 Skipped 0/0 non-slice-intersecting sstables, included 0 due to tombstones [ReadStage-3] | 2018-11-19 07:22:44.006000 | 127.0.0.1 |           1180 | 127.0.0.1

                                                            Caching 1 rows [ReadStage-3] | 2018-11-19 07:22:44.006000 | 127.0.0.1 |           1282 | 127.0.0.1

                                 Merged data from memtables and 0 sstables [ReadStage-3] | 2018-11-19 07:22:44.006001 | 127.0.0.1 |           1529 | 127.0.0.1

                                         Read 1 live and 0 tombstone cells [ReadStage-3] | 2018-11-19 07:22:44.006001 | 127.0.0.1 |           1670 | 127.0.0.1

                                                                        Request complete | 2018-11-19 07:22:44.005903 | 127.0.0.1 |           1903 | 127.0.0.1





cqlsh> select * from test.table1 where k='k1';



 k  | v

----+----

 k1 | v1



(1 rows)



Tracing session: edf0cd70-ebcb-11e8-b19a-8f0e04450cb9



 activity                                                                     | timestamp                  | source    | source_elapsed | client

------------------------------------------------------------------------------+----------------------------+-----------+----------------+-----------

                                                           Execute CQL3 query | 2018-11-19 07:22:53.767000 | 127.0.0.1 |              0 | 127.0.0.1

 Parsing select * from test.table1 where k='k1'; [Native-Transport-Requests-1] | 2018-11-19 07:22:53.767000 | 127.0.0.1 |            160 | 127.0.0.1

                            Preparing statement [Native-Transport-Requests-1] | 2018-11-19 07:22:53.767000 | 127.0.0.1 |            335 | 127.0.0.1

                                                  Row cache hit [ReadStage-3] | 2018-11-19 07:22:53.768000 | 127.0.0.1 |            915 | 127.0.0.1

                              Read 1 live and 0 tombstone cells [ReadStage-3] | 2018-11-19 07:22:53.768000 | 127.0.0.1 |           1066 | 127.0.0.1

                                                             Request complete | 2018-11-19 07:22:53.768255 | 127.0.0.1 |           1255 | 127.0.0.1





cqlsh> select * from test.table2 where k='k1' and v='v1';



 k  | v

----+----

 k1 | v1



(1 rows)



Tracing session: f7c26200-ebcb-11e8-b19a-8f0e04450cb9



 activity                                                                                                     | timestamp                  | source    | source_elapsed | client

--------------------------------------------------------------------------------------------------------------+----------------------------+-----------+----------------+-----------

                                                                                           Execute CQL3 query | 2018-11-19 07:23:10.240000 | 127.0.0.1 |              0 | 127.0.0.1

                      Parsing select * from test.table2 where k='k1' and v='v1'; [Native-Transport-Requests-1] | 2018-11-19 07:23:10.240000 | 127.0.0.1 |            168 | 127.0.0.1

                                                            Preparing statement [Native-Transport-Requests-1] | 2018-11-19 07:23:10.240000 | 127.0.0.1 |            343 | 127.0.0.1

                                                                                 Row cache miss [ReadStage-2] | 2018-11-19 07:23:10.241000 | 127.0.0.1 |            824 | 127.0.0.1

 Fetching data but not populating cache as query does not query from the start of the partition [ReadStage-2] | 2018-11-19 07:23:10.241000 | 127.0.0.1 |            891 | 127.0.0.1

                                                     Executing single-partition query on table2 [ReadStage-2] | 2018-11-19 07:23:10.241000 | 127.0.0.1 |            923 | 127.0.0.1

                                                                   Acquiring sstable references [ReadStage-2] | 2018-11-19 07:23:10.241000 | 127.0.0.1 |            949 | 127.0.0.1

                                                                      Merging memtable contents [ReadStage-2] | 2018-11-19 07:23:10.241000 | 127.0.0.1 |            978 | 127.0.0.1

                                                              Read 1 live and 0 tombstone cells [ReadStage-2] | 2018-11-19 07:23:10.241000 | 127.0.0.1 |           1132 | 127.0.0.1

                                                                                             Request complete | 2018-11-19 07:23:10.241338 | 127.0.0.1 |           1338 | 127.0.0.1





cqlsh> select * from test.table2 where k='k1' and v='v1';



 k  | v

----+----

 k1 | v1



(1 rows)



Tracing session: f9d6c310-ebcb-11e8-b19a-8f0e04450cb9



 activity                                                                                                     | timestamp                  | source    | source_elapsed | client

--------------------------------------------------------------------------------------------------------------+----------------------------+-----------+----------------+-----------

                                                                                           Execute CQL3 query | 2018-11-19 07:23:13.729000 | 127.0.0.1 |              0 | 127.0.0.1

                      Parsing select * from test.table2 where k='k1' and v='v1'; [Native-Transport-Requests-2] | 2018-11-19 07:23:13.729000 | 127.0.0.1 |            182 | 127.0.0.1

                                                            Preparing statement [Native-Transport-Requests-2] | 2018-11-19 07:23:13.729000 | 127.0.0.1 |            355 | 127.0.0.1

                                                                                 Row cache miss [ReadStage-3] | 2018-11-19 07:23:13.730000 | 127.0.0.1 |            839 | 127.0.0.1

 Fetching data but not populating cache as query does not query from the start of the partition [ReadStage-3] | 2018-11-19 07:23:13.730000 | 127.0.0.1 |            902 | 127.0.0.1

                                                     Executing single-partition query on table2 [ReadStage-3] | 2018-11-19 07:23:13.730000 | 127.0.0.1 |            942 | 127.0.0.1

                                                                   Acquiring sstable references [ReadStage-3] | 2018-11-19 07:23:13.730000 | 127.0.0.1 |            967 | 127.0.0.1

                                                                      Merging memtable contents [ReadStage-3] | 2018-11-19 07:23:13.730000 | 127.0.0.1 |            992 | 127.0.0.1

                                                              Read 1 live and 0 tombstone cells [ReadStage-3] | 2018-11-19 07:23:13.730000 | 127.0.0.1 |           1116 | 127.0.0.1

                                                                                             Request complete | 2018-11-19 07:23:13.730307 | 127.0.0.1 |           1307 | 127.0.0.1

Looking at the tracing log it seems that rows with clustering keys might not be cachable - Fetching data but not populating cache as query does not query from the start of the partition?