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From:Brian Aker Date:July 16 2009 5:06pm
Subject:Re: is MySQL bug #44373 really a bug?
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Hi!

On Jul 16, 2009, at 9:37 AM, Michael Widenius wrote:

> For example, MySQL may first do an ORDER by optimization and use a
> bitmap that only fetches the row id + what is in the ORDER BY part and
> then later it may fetch the whole rows.

I've been wondering for a while now if there wouldn't be a better way  
to handle this then swapping out the bitmap guts for different actions.

The bitmap system seems a little fragile in its current state (I had  
to fix a few bugs in it recently when we found corner cases where it  
was not always signaling usage correctly).

It also causes bad assert cases if an engine makes use of the Field  
objects in a way that is appropriate but not really thought out. There  
are a number of engines out there that have to disable them to avoid  
the asserts (which I think are aggressive and good).

Cheers,
	-Brian
Thread
is MySQL bug #44373 really a bug?Zardosht Kasheff14 Jul
  • Re: is MySQL bug #44373 really a bug?Sergei Golubchik18 Jul
Re: is MySQL bug #44373 really a bug?Zardosht Kasheff15 Jul
  • Re: is MySQL bug #44373 really a bug?Michael Widenius16 Jul
    • Re: is MySQL bug #44373 really a bug?Brian Aker16 Jul
    • Re: is MySQL bug #44373 really a bug?Sergei Golubchik18 Jul
      • Re: is MySQL bug #44373 really a bug?Michael Widenius19 Jul