Hey list, first time posting here so apologies if this is the wrong forum for this but I'm really out of options on how to solve this problem!
*Short version:* 1. High concurrent reads, performing the same well-indexed query type to the same two tables. 2. No additional traffic at all--just reads from these two tables. No writes anywhere. 3. Very fast (sub-second) when server is only servicing one request at a time. 4. Very slow (30s+) when server is servicing 2-3 requests at a time. Questions: 1. What resource is under contention for servicing read-only queries if you have a large buffer pool and a plenty-big thread cache? 2. What parameters can I tune to increase concurrent reads to these two tables? *Long version:* I've got a MySQL server that has only about 50 connections open to it at any given time. It basically only has one OLAP query type being ran against it that amounts to something like this: SELECT (3 fields with 1 count) FROM (SELECT (3 fields with 1 aggregate) FROM table INNER JOIN ... WHERE ... GROUP BY ...) dt GROUP BY ...; These queries are well indexed and run very well individually--sub-second, usually even faster. When I run a few of these queries simultaneously (2-3 on my laptop, 6-7 on our production boxes) performance grinds to a halt: Consistently about 30 seconds to service a query. Ideally, I'd like to be able to run 50+ of these queries concurrently. I've tried MySQL 5.5.27 and MySQL 5.6.13 and get the same results on both machines. I've tried tweaking the following my.cnf parameters to be higher: thread_concurrency = 20 thread_cache_size = 340 innodb_buffer_pool_size=2G A few other my.cnf parameters that I have set: innodb_file_format=Barracuda innodb_file_format_max=Barracuda innodb_file_per_table=1 skip-external-locking innodb_log_files_in_group=2 innodb_log_file_size=2000M max_allowed_packet=64M Thanks in advance, Brad Heller
