Cassandra for Oracle DBA Part 17: Tracing Sessions

As like oracle 100046  , you can also trace the Cassandra Session and it provide you the following information , the highlighted blue parts are important to understand that data has been fetched from different nodes and how many undo it has to read and how many from cache and how many reads from tables, this is very useful to understand the data distribution and the times that taking to get data from distributed nodes.

cqlsh>tracing on

Tracing session: ad1bd5e0-47c9-11e6-a439-e7c99fc0dbe2

cqlsh> select * from "PortfolioDemo"."Portfolios" LIMIT 10000;

 activity                                                                                       | timestamp    | source    | source_elapsed

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

                                                                             execute_cql3_query | 10:43:39,968 | 127.0.0.1 |              0

                                Parsing select * from "PortfolioDemo"."Portfolios" LIMIT 10000; | 10:43:39,968 | 127.0.0.1 |            639

                                                                            Preparing statement | 10:43:39,969 | 127.0.0.1 |           1207

                                                                  Sending message to /127.0.0.2 | 10:43:39,971 | 127.0.0.1 |           3151

                                                      Executing single-partition query on users | 10:43:39,971 | 127.0.0.1 |           3455

                                                                   Acquiring sstable references | 10:43:39,971 | 127.0.0.1 |           3488

                                                                    Merging memtable tombstones | 10:43:39,971 | 127.0.0.1 |           3539

                                                                    Key cache hit for sstable 2 | 10:43:39,971 | 127.0.0.1 |           3649

                                                    Seeking to partition beginning in data file | 10:43:39,971 | 127.0.0.1 |           3660

                      Skipped 0/1 non-slice-intersecting sstables, included 0 due to tombstones | 10:43:39,972 | 127.0.0.1 |           4180

                                                               Message received from /127.0.0.1 | 10:43:39,972 | 127.0.0.2 |             88

                                                     Merging data from memtables and 1 sstables | 10:43:39,972 | 127.0.0.1 |           4195

                                                             Read 1 live and 0 tombstoned cells | 10:43:39,972 | 127.0.0.1 |           4251

                                                                  Sending message to /127.0.0.3 | 10:43:39,974 | 127.0.0.1 |           6523

                                                      Executing single-partition query on users | 10:43:39,974 | 127.0.0.2 |           1567

                                                                   Acquiring sstable references | 10:43:39,974 | 127.0.0.2 |           1653

                                                                    Merging memtable tombstones | 10:43:39,974 | 127.0.0.2 |           1767

                                                                    Key cache hit for sstable 2 | 10:43:39,974 | 127.0.0.2 |           1945

                                                    Seeking to partition beginning in data file | 10:43:39,974 | 127.0.0.2 |           1994

                      Skipped 0/1 non-slice-intersecting sstables, included 0 due to tombstones | 10:43:39,975 | 127.0.0.2 |           2654

                                                     Merging data from memtables and 1 sstables | 10:43:39,975 | 127.0.0.2 |           2677

-Thanks

GeekDBA