[Egothor-tech] Question on merging barrels

[Leo Galambos]

shef wrote:
> Thanks. I'm guessing that the algorithm is implemented
> in the optimize() method, or maybe the add() method,
> but I can't make heads or tails of it. Can you
> describe  it in a few words?
>   

The algorithm tries to point the optimization step to barrels which
contain most outdated values. This strategy gives you: (I do not
remember my latest results, so read the numbers [+/-] several percents)
1) an index might be up to 20% larger than fully optimized index
2) searching is about 20-30% faster (comparing to fully optimized
index), but you pay with (up to) 10% higher peeks on a disk bus
3) updating: number of I/O operations is proportional to size of the update

As a side effect, the algorithm uses less barrels (aka index parts or
segments) and it also implies less file handles.

The basic algorithm is described here:
http://www.enformatika.org/ijcs/v1/v1-2-20.pdf

LG