Re: Database config for large table

Hi Joel,

Could you give an example of the type of queries that are performing 
badly?  Also, are you keeping at least one connection open to the 
embedded database at all times?  If your application is running Mckoi in 
embedded mode and it creates only a single connection, performs a query, 
and then closes the connection, you are incurring the cost of starting 
and stopping the database together with the time it takes to perform the 
query.  In addition, each time you close the last connection to an 
embedded database, the cache is wiped so you lose the benefit of 
collecting cached data over a long session.

So I suggest you make sure to keep at least one connection open to the 
embedded database over the entire session of your application.  To 
increase the size of the cache, modify the 'data_cache_size' property in 
your .conf file.  For example, to set the cache size to 32MB;

data_cache_size=33554432

Hope this information help,
Toby.


Joel Garringer wrote:
> We have a table with a few hundred thousand records with a couple of 
> dozen columns. Most of the columns are type FLOAT or INT.
> 
> We have been having a really tough time with performance against this 
> table. Queries against the table can take several minutes to run, and I 
> really think that we are just missing something.
> 
> The table can easily grow to around 100 meg, and I wanted to make sure 
> there weren’t any easy changes we could make to the “.conf†file that 
> would help us. The database was very peppy when this table had less than 
> 50,000 records, so the performance problems have kind of taken us by 
> surprise.
> 
> We run the database in embedded mode and we could give the database 
> hundreds of meg of memory if we needed to, but I not sure if/how Mckoi 
> can use the extra memory.
> 
> I think that I can send a copy of the table if you want to look at it.
> 
> Thanks.
> Joel



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