Re: Hashtable faster than SQL ?!!

Hi Dmytro,

without taking care about the network-time, namepiping etc., ms-sql/indexes
never get such results as the hashtable do.. i saw better results on
PostgreSQL...

are you sure the indexes are stored on the harddisk? i thought they were in
the RAM..

i am curious if sql server 2005 will conquer the speed as the hashtable do...

steven




"Dmytro Lapshyn [MVP]" wrote:

> Hi Steven,
>
> There's nothing surprising. The Hashtable is (well, let's assume so) in the
> RAM, and its searching algorithm is optimized for performance. The SQL
> Server keeps indexes on disk, so even if the algorithm is similar, loading
> the indexes from disk takes time (as well as transmitting the result set
> over the network or over a named pipe).
>
> --
> Sincerely,
> Dmytro Lapshyn [Visual Developer - Visual C# MVP]
>
>
> "Steven Wolf" <apoc69@xxxxxxx> wrote in message
> news:5167D5D4-DDA4-4B9A-8419-8066DBE78C47@xxxxxxxxxxxxxxxx
> > Hi guys,
> >
> > can a hashtable be faster than a sql server??
> > i made my own O/R mapping with an "entity cache" (caching all mapped
> > objects). So, when i get some data from my sql server, i map that data to
> > an
> > entity-object and i leave a copy of it in the entity cache.
> >
> > the entity cache is a simple hashtable, which stores as key:
> > the ID of the entity ( the same id as the primary key of the sql-table )
> > and
> > the entity type.. and as value: the object itself.
> >
> > so, when i access the cache, i say: Contact contact = EntityCache.Get(
> > 5109,
> > typeof( Contact ) )
> >
> > i just made some tests and i filled the cache with 1 mio. contacts.
> > the result: searching the hashtable for one value, costs mostly ~0.000.007
> > sec! (nanoseconds).. thats amazing!! my sql server can never reach such
> > values! my dev. machine is just an amd 2 ghz with 1 gb ram.
> >
> > of course i can search in the cache only by id, but it is the same way as
> > the sql server would search for an index, isn'it? i thought about, to
> > setup
> > an extra caching-server... just read a big sql-table and store everything
> > in
> > the entity-cache..(updating/inserting/deleting or searching by other
> > values
> > is another topic).
> >
> >
> > i cant believe it!
> >
> > steven.
>
>
.

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