Partial/selective indexes

[ddorian]

What:
Like postgresql has: https://www.postgresql.org/docs/current/static/indexes-partial.html
Why:
To create smaller/specialiazed/faster indexes (or just index subset of table).
Example:
Move heavy-user's items to it's own index. Create a small index for "last hour" data (will require deleting of old indexes).
How:
By using the current partition-index http://doc.elassandra.io/en/latest/mapping.html#partitioned-index. Modifying it so if the function returns Null or empty-string, no indexing is done into es.

Makes sense ?

[vroyer]

Yes, in elassandra, if a partition function return an index name unavailable (does not exist, is closed or not writable), data is not indexed (for this partition function, but you can set many partition functions with different names).

If you don't want to delete old indices but continue to search in it, you can also set a index.block.write=true (a dynamic index setting), and new data won't be indexed in that index (but still in some other if there is....)

index partition function works fine for time-frame indices, its easy to delete later on, but also for any other split rule, like per-user index or per-country index with any dedicated mapping or access rules...

[ddorian]

Hmm, I thought the partition function also created the index if it didn't exist. Wouldn't it make more sense to automatically create the index if it doesn't exist ?
And not create an index when it returns Null/empty-string ?

[vroyer]

Keep in mind that creating an index involve a PAXOS transaction to update the mapping, so you cannot afford this from many indexing threads.