New answers tagged optimizer
7
The recent 5.6 version has added this feature.
See: MySQL Internals Manual ::chapter 9. Tracing the Optimizer
Typical Usage:
# Turn tracing on (it's off by default):
SET optimizer_trace="enabled=on";
SELECT ...; # your query here
SELECT * FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;
# possibly more queries...
# When done with tracing, disable it:
SET ...
1
The best I can immediately mention is to simply run EXPLAIN on a query.
There is a graphical way to do this
pt-visual-explain
mk-visual-explain (Source Code)
As for steps to optimizing a query, a parse tree is created. Rather than explaining the parser here, please read my post from Mar 11, 2013 (Is there an execution difference between a JOIN condition ...
4
You can get some of that information by turning on the configuration parameter log_planner_stats. Most of that information, however, doesn't really exist, because the planner does not fully compute all alternative plans and their costs. It only explores an alternative plan until it can determine that it is slower than the current best plan. So alternative ...
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