Re: [Maria-developers] Rev 4234: Fixed bug mdev-6071
Hi, Igor! On Jun 09, Igor Babaev wrote:
It's an improvement over the old behavior - as EXPLAIN shows correctly whether BKA is used. But I think there's still not enough diagnostics. In the bug report Sergey wrote that " I think it's a big gotcha that @join_buffer_size must be lower than @@join_buffer_space_limit when optimizer_space_limit optimization is off. " So, I'd believe users will be very confused that in some cases BKA is suddenly turned off, when they expect it to be used. Of course, without this bugfix they would've not even noticed that, which is even worse. So, this bugfix is good. But it would be nice to have some kind of an explanation of why BKA is not used. At the very least in the manual. Better - here as a warning, like if (for_explain) push_warning("BKA was not used because ..."; goto fail;
MY_TEST here (and in other similar places) is redundant, you could've simply written !tab->cache->init(options & SELECT_DESCRIBE))
and while it wasn't part of your bug fix, I cannot help but noticing that MY_TEST() is redundant here too. !prev_cache is boolean, it's always 0 or 1. Regards, Sergei
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Sergei Golubchik