gocql | Package gocql implements a fast and robust Cassandra client

If you look into documentation for Gocql package, then you will see that the decimal is mapped to the Go's infDec data type (see its doc) so you need to use it instead of Float64.

no EC2 IMDS role found, operation error ec2imds: GetMetadata, exceeded maximum number of attempts, 3, request send failed, Get \"http://169.254.169.254/latest/meta-data/iam/security-credentials/\": dial tcp 169.254.169.254:80: connect: host is down

Your snippet of code is attempting to use the EC2 instance meta-data service to read an IAM role to use. For that to work, you need to be able to communicate with it, and the role must be attached to the instance.

Is your Go service running on an EC2 instance? If not, that would explain your error. If it is, make sure the process or container has appropriate network access (eg: network namespace) to communicate with 169.254.169.254.

How can a client driver know, which tablet server to send the request?

The driver periodically queries this table:

Specify the tserver addresses with their headless service dns names like below and it should work:

I found that gocqltable does the trick for what I want. gocqltable has a mapper built in to convert Go types to Cassandra types, so I copied the type.go file into my project (since the original is unexported) and used it as specified in table.go.

You can find the stringTypeOf method I used here, and the usage of it here.

All those queries are coming from your application. They are not done by Cassandra.

Those messages from MonitoringTask are logged by a feature in Cassandra 3.10+ called slow query logging (CASSANDRA-12403). I've previously explained it in this post -- https://community.datastax.com/questions/7835/.

The slow query logging aggregates queries which took longer than slow_query_log_timeout_in_ms (default is 500ms) into groups of 5-second "windows". As part of the aggregation, columns are not enumerated in the logging and are instead replaced with an asterisk (*) so they can be easily grouped.

In addition, drivers have paging enabled. When your application does not set a page size, the drivers default to a page size of 5000 (LIMIT 5000). This is the limit which gets logged in the slow query message you posted. Cheers!

Cassandra takes a few seconds to startup and begin accepting connections; backend is attempting to connect before it is ready. Your configuration works OK (for me) if you start up backend after a small delay (using docker-compose start backend). Modifying backend to retry the connection works reliably for me i.e.

Try defining your struct like this (use cql instead of json in your struct definition)

Toggle the network connection of a node off, and it will appear momentarily down. Any request that needed that node to satisfy the consistency level, or if that node was the co-ordinator of the query will need to retry.