trace_log/query_log from performance tests shows (for
cases when prewarm query fails with timeout, 15sec) excessive
writeTraceInfo() in trace_log and QueryProfilerRuns in query_log, but
this is not the root cause of the timeout, but consequence.
Also query_log shows that on failures the following profile events has
significantly higher values:
- PerfLocalMemoryMisses (6.3x more)
- PerfLocalMemoryReferences (7x more)
- PerfDataTLBMisses (6.9x more)
- PerfInstructionTLBMisses (6.4x more)
During looking at performance tests logs I noticed that once the prewarm
query fails other server (left/right) was merging (MergeTree) something
in *_log tables.
But, using MergeTree for *_log in performance tests is useless, since
anyway environment for performance tests uses ramdrive.
And so MergeTree merges just increase overhead.
Eventually I expect that this should decrease extra memory referencing
and so this should decrease cache/TLB misses.
CI: https://clickhouse-test-reports.s3.yandex.net/30886/c504e0c08df7a926bb479a1d297f326f5c48a32f/performance_comparison/report.html#fail1
v2: <partition_by remove="remove"/>
