On my phone now, but it smells of file-based sorting, making disk access the bottleneck.
Can you provide the explain?
Brad Heller <brad@stripped> wrote:
>Hey list, first time posting here so apologies if this is the wrong
>for this but I'm really out of options on how to solve this problem!
>1. High concurrent reads, performing the same well-indexed query type
>the same two tables.
>2. No additional traffic at all--just reads from these two tables. No
>3. Very fast (sub-second) when server is only servicing one request at
>4. Very slow (30s+) when server is servicing 2-3 requests at a time.
>1. What resource is under contention for servicing read-only queries if
>have a large buffer pool and a plenty-big thread cache?
>2. What parameters can I tune to increase concurrent reads to these two
>I've got a MySQL server that has only about 50 connections open to it
>any given time. It basically only has one OLAP query type being ran
>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
>usually even faster. When I run a few of these queries simultaneously
>on my laptop, 6-7 on our production boxes) performance grinds to a
>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
>machines. I've tried tweaking the following my.cnf parameters to be
>thread_concurrency = 20
>thread_cache_size = 340
>A few other my.cnf parameters that I have set:
>Thanks in advance,
Sent from Kaiten Mail. Please excuse my brevity.