Brian Aker wrote:
> Remove it++
++
> On Aug 16, 2009, at 9:53 AM, Padraig O'Sullivan wrote:
>
>> Hi!
>>
>> I have a quick question on some code I am thinking of removing that
>> I'd like to get some opinions on. At the moment, there are 2 functions
>> in the optimizer in Drizzle for searching for an optimal query plan:
>>
>> - find_best
>> - greedy_search
>>
>> The method that is used is determined by the optimizer_search_depth
>> parameter. We can see this from the following code:
>>
>> if (search_depth == MAX_TABLES+2)
>> { /*
>> TODO: 'MAX_TABLES+2' denotes the old implementation of find_best before
>> the greedy version. Will be removed when greedy_search is approved.
>> */
>> join->best_read= DBL_MAX;
>> if (find_best(join, join_tables, join->const_tables, 1.0, 0.0))
>> return(true);
>> }
>> else
>> {
>> if (search_depth == 0)
>> /* Automatically determine a reasonable value for 'search_depth' */
>> search_depth= determine_search_depth(join);
>> if (greedy_search(join, join_tables, search_depth, prune_level))
>> return(true);
>> }
>>
>> Currently, in drizzle, optimizer_search_depth is set to 62 by default
>> so we never actually use the find_best method for searching for an
>> optimal plan. Thus, I'm wondering if anyone has any objections to
>> removing the find_best method? That way, we only have 1 method for
>> searching through query plans.
>>
>> From looking at the comments in the optimizer source code, it seems
>> that find_best will be removed from the MySQL source in the future
>> also (if it has not already?)
>>
>> -Padraig
>>
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>
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