Re> Re: ACEDB main memory requirements

Cyrus Harmon sly at FLY2.BERKELEY.EDU
Mon Jun 26 13:58:41 EST 1995

Jean says:

>ACEDB does NOT loads the full database in ram
>The amount of required memory is:
>size of cache 1 (configurable but at elast as big as the biggest
>object in the database, typically 2 or 4 Megs)
>size of cache 2 (typically 2 to 4 megs, however from 2-0 to 3-7
>there was a wrong aasumption in the cache management which caused the
>cache 2 to grow larger in some cases. This is fixed in 4.0)
>size of the dictionaries: around 40 bytes per object, reduced to around 20
>in 4.0 (however this is the theory and measurments in aquilla seem to indicate
>that the gain is not large, so there may be a bug in the newer system)
>Typically, acedb handles around 100k objs, hence this amounts to another 4Megs

Memory usage has long been a concern in the Macintosh version of ACeDB. Mac programs are given a set memory partition size on startup. We have found that 24 MB is usually adequate in light of what Jean says about cache1 and cache2. 

However, it isn't quite this simple. The lexiques get brought into the cache but are never flushed. If you have large lexiques, the size of cache2 will grow larger than the limit specifed in cachesize.wrm.

I have also noticed problems when attempting to add large quantities of data in a single session. This requires memory far in excess of the cache1 and cache2 limits. The workaround I use is to save after each large .ace file. This seems to alleviate the problem somewhat.


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