MySQL Bugs: #70617: Default persistent stats can cause unexpected long query times

Bug #70617	Default persistent stats can cause unexpected long query times
Submitted:	14 Oct 2013 19:18	Modified:	27 May 2015 8:38
Reporter:	Justin Swanhart	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S2 (Serious)
Version:	5.6.13	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	analyze, Optimizer, regression, statistics

File:	Maximum allowed size is 50MB.
Description:
Privacy:

If the data you need to attach is more than 50MB, you should create a compressed archive of the data, split it to 50MB chunks, and upload each of them as a separate attachment.

To split a large file:

On *nix platforms use the split command e.g. split -b 50MB <my_large_archive> <my_split_archive_prefix>
On windows use WinZip or a similar utility to split the large file

sample testcase. Sometimes EXPLAIN will show table scan for a few seconds until stats are avail.. Is this what you're seeing ?

Attachment: bug70617_testcase1.sql (application/octet-stream, text), 1.05 KiB.

this testcase should take ~10 seconds to execute. it waits for stats...

Attachment: bug70617_testcase_poll.sql (application/octet-stream, text), 1.04 KiB.