how small to split a table?

[Vivek Khera <vivek(at)khera(dot)org>]

I've got one logging table that is over 330 million rows to store 6  
months' worth of data.  It consists of two integers and a 4-character  
long string.  I have one primary key which is the two integers, and  
an additional index on the second integer.

I'm planning to use inheritance to split the table into a bunch of  
smaller ones by using a modulo function on one of the integers on  
which we scan often.

My question is how small to make each inherited piece?  If I do  
modulo 10, then each sub-table will be between 32 and 34 million rows  
today based on current distribution.

If I expect to increase traffic 2 times over the next year (thus  
doubling my logs) what would you recommend?

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