I've been reading the documentation and this list in order to evaluate the
adoption of elasticsearch in a project.
I've got a few open questions I'd like to see clarified.
- number of indexes in a cluster
What are the effects of the number of different indexes managed by a single
cluster, what are the parameters and factors in play on using multiple
indexes and which kind of overheads occur when the number of managed
What would be the effect of having a high number of indexes say 10000 of
which only 1000 or so are actually actively used (indexing and querying)
with the remaining 9000 being used very infrequently (say few times per
- Indexes and mappings
On the mapping documentation is stated  "Mapping types are a way to try
and divide the documents indexed into the same index into logical groups.
Think of it as tables in a database".
I understand that mapping can't be updated  but a full index rebuild is
needed if the mapping definition needs changes.
Is this still the case if the mapping change is only the addition of a new
If adding a new field to a mapping is possible, where do I find an example
of how to do it?
- Document storage
By default elasticsearch stores the indexed document, only one post on the
mailing list  states how to turn off this feature, are there any
consequences to turning documet storage off?
What's the overhead in terms of storage, memory usage and indexing speed of
having document storage turned off or on?
Will the update  script work with document storage turned off (it's my
understanding that because of lucene internals updating a document actually
means deleting the old document from the index and adding the new one)