On Monday 19 May 2008 15:24, Matthew Toseland wrote: > On Monday 19 May 2008 14:47, Matthew Toseland wrote: > > On Monday 19 May 2008 11:34, Matthew Toseland wrote: > > > On Sunday 18 May 2008 19:44, Ian Clarke wrote: > > > > > > > > Looking at the manual, it looks like Perst operates at a lower level > > > > than db4o - you need to manually create and maintain indexes. This is > > > > closer to the Java collections API, which could be good because its > > > > more familiar, but it leaves more opportunities for the programmer to > > > > screw up, which is bad. > > > > > > IMHO we will get better performance and fewer screwups from a more > familiar > > > API. > > > > > > > > My preference for db4o is based mainly on my familiarity with it, the > > > > fact that it is more widely used, and the fact that it superficially > > > > appears to have a more credible company behind it. > > > > > > > > None of these is a solid justification for choosing one option over > > > > the other, but they all suggest that db4o is the way to go. > > > > > > We should, as bback suggests, test Perst, see what happens when it runs > out > > of > > > disk space. I will look into it soon. > > > > Completed testing. Perst fails gracefully on running out of disk space in > > between writes. The database is readable after the failed commit, and if I > > take away the bigfile occupying all the disk space, we can even write to it. > > > > How about we go with Perst? > > One big disadvantage for Perst: no online backup! No transactions may execute > while backup is in progress. :( > > Generally speaking Perst is significantly lower level than db4o. This isn't > necessarily a bad thing, it allows fine control and possibly better > performance... For example, all persistent objects in Perst must extend > Persistent (1 pointer 2 ints overhead), or implement IPersistent (which > involves copying code from Persistent)... or implement IValue, which allows > an inline value to be stored with the parent object, or java serialization > (but in that case the object must not refer to any persistent objects).
Actually, Perst is significantly higher level than db4o in one important respect: it has garbage collection. In db4o you have to explicitly delete everything.
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