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Re: Optimizer executes inperformant subquery first
Posted by: Øystein Grøvlen
Date: December 19, 2013 02:45AM

Hi Martin,

Thanks for filing a bug and uploading a test case. I will take a look at it.

As you observed the trace is truncated, and it does not include the interesting part. To see the whole trace, you will need to increase the value of optimizer_trace_max_mem_size session variable. There is a column in the trace table called MISSING_BYTES_BEYOND_MAX_MEM_SIZE that will tell you how much you need. I usually set it to 1MB. That seems to be sufficient in most cases:
set optimizer_trace_max_mem_size=1024*1024;

Since the trace will be large, it is probably better to upload it to the bug report instead of posting it here.

Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway

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