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Re: Proposals for improving BKA/MRR visibility in EXPLAIN anddiagnostics



>>>>> "Philip" == Philip Stoev <pstoev@xxxxxxxxxxxx> writes:


>> If Handler_mrr_key_sort_count == Handler_multi_range_read_init_count then 
>> we've
>> had enough buffer space. If key_sort_count is two times greater than the 
>> number
>> of init operations, then one could conclude that on average two buffer 
>> refills
>> were needed and increasing buffer size up to 2x would be beneficial.

Philip> I would say that instead there must be a variable that shows the number of 
Philip> buffer refills. This way the user gets a single variable to monitor, without 
Philip> having to do any math. Then, the performance advice becomes "watch this 
Philip> variable and try to minimize it by using a larger buffer", the way we 
Philip> currently say "watch the .ee.g threads created variable and try to minimize 
Philip> it by using a larger thread pool".

Agree that having a variable (maybe even in addition to the other
suggested one) for buffer refills would be a good thing!