From: Roy Lyseng
Date: June 16 2011 8:48am
Subject: Re: bzr commit into mysql-trunk branch (roy.lyseng:3385) Bug#12603200
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On 16.06.11 10.03, Øystein Grøvlen wrote:
> On 15/06/2011 15:57, Roy Lyseng wrote:
>> #At file:///home/rl136806/mysql/repo/mysql-work0/ based on
>> revid:jorgen.loland@stripped
>>
>> 3385 Roy Lyseng 2011-06-15
>> Bug#12603200: Assert in QUICK_INDEX_MERGE_SELECT::need_sorted_output
>>
>> The problematic query is semi-join transformed and a LooseScan
>> strategy is selected. setup_semijoin_dups_elimination() inspects
>> the provided quick select object and attempts to set it to require
>> ordering of output rows. However, the quick select object was not
>> selected in the first place (see
>> Loose_scan_opt::check_ref_access_part1()), hence there is a missing
>> check that the index covered by the quick select matches the index
>> selected for the loose scan access.
>>
>> Fixed by adding this check, and also deleting the quick select object
>> if it was not chosen for accessing this table.
>
> Hi,
>
> Did you consider deleting the quick select object at the point where it is
> decided to not use it?

IMHO this is the place where the decision is taken. Do you have another view?

Thanks,
Roy