I tried to reproduce the problem with your table structures populated with synthetic data, and I am getting the same exact execution plan as you quoted, but the query itself only takes a fraction of second (0.01 sec with 600K records in `humans` and 40K records in `towncities`).
If it's still repeatable on your data, would it be possible for you to upload your data dumps to our FTP server (ftp://ftp.askmonty.org/)? If you could do that, please also include your cnf/ini file.
Note that condition only occurs with the limit condition in place ie
LIMIT 275 , 25
just running the query without it returns the data fine
files uploaded to private dir elena.tar.gz
Thank you for the data, it helped to reproduce the problem.
I filed a bug on your behalf on launchpad: https://bugs.launchpad.net/maria/+bug/1000051
You can track further progress there.
Thank you :-)
all the best, John
FYI: The problem has been fixed, the fix will be included in the next 5.3 release, and in the 5.5 series release that is after the next one (5.5.23 was already building, so the fix didn't make it into 5.5.23)
s/5.5.23/5.5.24/. The fix will be in the release next after 5.5.24.
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