Re: Berkeley DB...

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> > > And, while we are on heap subject - using index (RECNO) for heap
> > > means that all our secondary-index scans will performe TWO
> > > index scans - first, to find recno in secondary-index, and
> > > second, to find heap tuple using recno (now indices give us
> > > TID, which is physical address).
> > 
> > Yes, that was one of my questions.  Why use recno at all?  We already
> > have heap access which is very fast.  Why switch to SDB which gives us
> > a recno ordering of heap that doesn't do us any real good, except to
> > allow tuple update without changing indexes.
> 
> But if we'll use our heap AM, then we'll have to implement redo/undo
> for it... no sence to switch to SDB for btree/hash WAL support -:)

Yes, SDB would give us redo/undo in heap, and that would make things
easier.  However, if there is the overhead of a double-index lookup when
using indexes, it seems like a very high cost.

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