OK, I took a look at the source code and for now it seems to me that we
both are partially right ( ;-) ), but changing index_interval does NOT
require rebuilding SSTables:
Yes, index sample file can be persisted (see
io/sstable/IndexSummary.java, serialize/deserialize methods +
io/sstable/SSTableReader.java, loadSummary() method)
BUT
It will be rebuilt on startup if index_interval has changed
(io/sstable/SSTableReader.java, loadSummary(), lines 422+ and load()
method, line 371).
:-)
M.
it is ( very ) safe to assume the row index is re-built/updated when new
sstables are built.
Obviously the sample of this index will have to follow this process very
closely.
It is possible however that the sample itself is not persisted and is
built at startup as opposed to *only* when the index changes.( which is
what I thought was happening )
It shouldn't be too difficult to verify this, but I'd appreciate if
someone who looked at this before could confirm if this is the case.
