Got a big concern on PMM QAN Analytics, on our actual scenario we’re currently using PMM2 QAN on Mariadb Instance where there is a really demanding throughput of different queries.
We are on PMM 2.12.0 server and client.
We were able to config pmm-client to extract QAN --query-source=perfschema as we would love to get full stats on all queries and slowlog with a value of long_query_time=0 would have a big performance impact on server side.
The issue now is that performance digesting is constantly losing digest info as follow:
mysqladmin ext -ri1 -udba -p | grep -i digest
| Performance_schema_digest_lost | 120 |
| Performance_schema_digest_lost | 900 |
| Performance_schema_digest_lost | 977 |
| Performance_schema_digest_lost | 422 |
| Performance_schema_digest_lost | 928 |
And we also configured performance_schema_digests_size=-1 and performance_schema_events_stages_history_long_size=-1 and still at their highest values possible and digest_lost is always present.
The pseudo solution we’ve found its to periodically truncate performance_schema.events_statements_summary_by_digest and performane_schema.events_statements_history_long, in order to let pmm2-client to re-fetch newest digest .
Is there any pmm2-client configuration recommended on this high load scenarios to reduce data lost? We are constantly getting a small partial queries on QAN side, not showing all queries.
Is there any configuration to indicate pmm2-client to “clean” already fetched data from perfschema??, for example, this truncate perfschema tables operation after fetching last digests??
Thanks you in advance for any help