[Monetdb-developers] MAPI protocol suggestion

Martin Kersten Martin.Kersten at cwi.nl
Sat Nov 22 15:14:52 CET 2008


Stefan de Konink wrote:
> Martin Kersten wrote:
>> Consequently, moving to a binary protocol is not
>> warranted by comparison, nor effective in terms
>> of performance improvement. 50% of the cost in
>> MonetDB for these queries are the SQL parser and
>> query cache matching.
>>
>> Given the focus of MonetDB on datawarehousing,
>> rather then high volume web-interactions, there
>> has been no steps taken to improve the protocol.
>
> You only mention here the performance gain within MonetDB, as opposed 
> to the performance gain that could be generated if the client doesn't 
> need to parse integers from strings to work on them but only make an 
> in memory reference to the current row, and threating it as a c-struct.
Indeed. Even in an application it becomes relevant to know
how much time is actually spent at the interface. My conjuncture is
that it is a few percent only, contrived cases excluded.
Fastly outnumbered by even the network delays.

Measuring applications and studying there behavior using
e.g. Callgrind gives you a reasonable insight in the performance
bottlenecks. Eg. in your recent callgrind file there was about
a 10% cpu cycles loss due to virtualization it seemed.
>
>
> Stefan





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