Query tracing in Cassandra - cassandra

Question

Since, I could not find a query explain type of feature, I wrote the below python program to list the different phases the query is going through. While I am able to get the various phases and steps, it is not giving me the time spent in each phase/step. Is there a way to print the time as well
qlist = qf.read_query_file("query.txt")
for query in qlist:
rows = session.execute(query, trace=True)
trace = rows.get_query_trace()
duration = rows.get_query_trace().duration.total_seconds()
print('----------------------------------------')
print("Query Name:{query}, Duration:{duration}".format(query=query,duration=duration))
for event in trace.events:
print(event)
print('------------------------------------------')
The output is as shown below
Query Name:select * from iris_with_id, Duration:0.006939
Parsing select * from iris_with_id on xx.xxx.xxx.x[Native-Transport-Requests-1] at 2022-01-13 03:05:34.544000
Preparing statement on xx.xxx.xxx.x[Native-Transport-Requests-1] at 2022-01-13 03:05:34.544000
reading digest from /xx.xxx.xxx.x on xx.xxx.xxx.x[Native-Transport-Requests-1] at 2022-01-13 03:05:34.544000
Executing single-partition query on roles on xx.xxx.xxx.x[ReadStage-2] at 2022-01-13 03:05:34.545000

Answer 1

A Python app is probably a little overkill.
You can trace a query in cqlsh using the TRACING command:
cqlsh> TRACING ON;
You can then see all the stages of the execution including the elapsed time for each stage:
cqlsh> SELECT * FROM community.users_by_email WHERE email = 'alice#getvaccinated.now';
email | colour | name
-------------------------+--------+-------
alice#getvaccinated.now | red | Alice
(1 rows)
Tracing session: 4ed2b930-74dd-11ec-afd3-85873f459502
activity | timestamp | source | source_elapsed | client
--------------------------------------------------------------------------------------------------------------------------------------------+----------------------------+--------------+----------------+-----------------------------------------
Execute CQL3 query | 2022-01-14 01:57:20.068000 | 172.28.223.3 | 0 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Parsing SELECT * FROM users_by_email WHERE email = 'alice#getvaccinated.now'; [CoreThread-9] | 2022-01-14 01:57:20.070000 | 172.28.223.3 | 1831 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Preparing statement [CoreThread-9] | 2022-01-14 01:57:20.071000 | 172.28.223.3 | 2656 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Reading data from [/172.28.128.3] [CoreThread-11] | 2022-01-14 01:57:20.071000 | 172.28.223.3 | 3526 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Reading digests from [/172.28.237.4] [CoreThread-11] | 2022-01-14 01:57:20.072000 | 172.28.223.3 | 3887 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Sending READS.SINGLE_READ message to /172.28.128.3, size=190 bytes [CoreThread-4] | 2022-01-14 01:57:20.072000 | 172.28.223.3 | 4235 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Sending READS.SINGLE_READ message to /172.28.237.4, size=191 bytes [CoreThread-2] | 2022-01-14 01:57:20.072000 | 172.28.223.3 | 4340 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
READS.SINGLE_READ message received from /172.28.223.3 [CoreThread-4] | 2022-01-14 01:57:20.076000 | 172.28.128.3 | 434 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Merged data from memtables and 3 sstables during single-partition query on users_by_email for key 'alice#getvaccinated.now' [CoreThread-4] | 2022-01-14 01:57:20.077000 | 172.28.128.3 | 3167 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
READS.SINGLE_READ message received from /172.28.223.3 [CoreThread-5] | 2022-01-14 01:57:20.077000 | 172.28.237.4 | 461 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Read 1 live rows and 0 tombstone ones [CoreThread-4] | 2022-01-14 01:57:20.078000 | 172.28.128.3 | 3354 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Merged data from memtables and 3 sstables during single-partition query on users_by_email for key 'alice#getvaccinated.now' [CoreThread-5] | 2022-01-14 01:57:20.078000 | 172.28.237.4 | 3322 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Enqueuing READS.SINGLE_READ response to /172.28.128.3 [CoreThread-4] | 2022-01-14 01:57:20.078000 | 172.28.128.3 | 3487 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Read 1 live rows and 0 tombstone ones [CoreThread-5] | 2022-01-14 01:57:20.078000 | 172.28.237.4 | 3510 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Sending READS.SINGLE_READ message to /172.28.223.3, size=169 bytes [CoreThread-7] | 2022-01-14 01:57:20.078000 | 172.28.128.3 | 3846 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Enqueuing READS.SINGLE_READ response to /172.28.237.4 [CoreThread-5] | 2022-01-14 01:57:20.078000 | 172.28.237.4 | 3634 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Sending READS.SINGLE_READ message to /172.28.223.3, size=131 bytes [CoreThread-0] | 2022-01-14 01:57:20.078000 | 172.28.237.4 | 4012 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
READS.SINGLE_READ message received from /172.28.128.3 [CoreThread-7] | 2022-01-14 01:57:20.082000 | 172.28.223.3 | 14426 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Processing response from /172.28.128.3 [CoreThread-11] | 2022-01-14 01:57:20.082000 | 172.28.223.3 | 14792 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
READS.SINGLE_READ message received from /172.28.237.4 [CoreThread-8] | 2022-01-14 01:57:20.082000 | 172.28.223.3 | 14914 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Processing response from /172.28.237.4 [CoreThread-11] | 2022-01-14 01:57:20.083000 | 172.28.223.3 | 15165 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd
Request complete | 2022-01-14 01:57:20.085874 | 172.28.223.3 | 17874 | fa5f:ba11:8ac8:4fe7:a863:8df7:5cf2:7efd