Quick question about index key compression
c.f. Note 1109743
After applying index key compression to an index, are newly added or changed entries also compressed?
Or do you have to keep re-compressing the index as the index content changes.
Stefan Koehler replied
> After applying index key compression to an index, are newly added or changed entries also compressed?
Yes .. Oracle does a "live-compression", so every newly insert/changed on compressed key columns will be compressed.
I have also verified this with some block dumps on an oracle 10.2.0.4 database .. unfortunately i didn't extend my blog post with this. If you want to take a closer look by your own, just perform some index leaf block dumps.
The interpretation of block dumps can be viewed here: