Mysql benchmarking
From wikinotes
Traps
The Query Cache
Benchmarking is difficult, since MySQL is often configured to use a query cache.
This is similar to a key-value store of cacheable-queries, and their result.
This interferes with benchmarking, since repeat queries may be much faster to lookup.To avoid the query cache:
- Add a function to your selected rows - since they are not cacheable ex. 'SELECT ..., NOW() FROM ...' # TODO: validate - Use 'SQL_NO_CACHE' in your query ex. 'SELECT SQL_NO_CACHE ... FROM ...' (This often has not worked for me)The OS Cache
TODO:
research
Tools
Status
SHOW STATUS SHOW SESSION STATUS # low-level info about temp-tables, reads, sorting, etc.Query Processes
processes in
SHOW FULL PROCESSLIST
describe a query's currentstate
.
profiling in mysql shows the time spent in each state of a query.Profiler
# enable profiling in current session SET profiling = 1 SELECT SQL_NO_CACHE * FROM footable; SHOW PROFILES; # list profiled queries, by ID SHOW PROFILE; SHOW PROFILE FOR QUERY 1; # show profile for a specific query-id