Cassandra timeout during read query at consistency ONE

Question

I have a problem with the cassandra db and hope somebody can help me. I have a table “log”. In the log table, I have inserted about 10000 rows. Everything works fine. I can

Answer 1

That error message indicates a problem with the READ operation. Most likely it is a READ timeout. You may need to update your Cassandra.yaml with a larger read timeout time as described in this SO answer.

Example for 200 seconds:

read_request_timeout_in_ms: 200000

If updating that does not work you may need to tweak the JVM settings for Cassandra. See DataStax's "Tuning Java Ops" for more information

Answer 2

count() is a very costly operation, imagine Cassandra need to scan all the row from all the node just to give you the count. In small amount of rows if works, but on bigger data, you should use another approaches to avoid timeout.

• First of all, we have to retrieve row by row to count amount and forgot about count(*)
• We should make a several(dozens, hundreds?) queries with filtering by partition and clustering key and summ amount of rows retrieved by each query.
• Here is good explanation what is clustering and partition keys In your case day - is partition key, composite key consists from two columns: date and ip.
• It most likely impossible to do it with cqlsh commandline client, so you should write a script by yourself. Official drivers for popular programming languages: http://docs.datastax.com/en/developer/driver-matrix/doc/common/driverMatrix.html

Example of one of such queries:

select day, date, ip, iid, request, src, tid, txt from test.log where day='Saturday' and date='2017-08-12 00:00:00' and ip='127.0 0.1'

Remarks:

• If you need just to calculate count and nothing more, probably has a sense to google for tool like https://github.com/brianmhess/cassandra-count

• If Cassandra refuses to run your query without ALLOW FILTERING that mean query is not efficient https://stackoverflow.com/a/38350839/2900229