I want to know whether we can create index on data ?
Your best bet to understanding how SciDB “indexes” data, is to read the architectural white paper.
But in a nut shell? SciDB organizes array data into “blocks” (that we call “chunks”) and then maps the chunks to instances in a way that lets the engine figure out, for a given cell in the array ( a ) which block contains the cell, ( b ) which instance contains that block, ( c ) where on that instance the physical block/chunk is located, and finally ( d ) where within the block/chunk a particular cell is located. And it does all of this with some relatively simple integer arithmetic.
SciDB doesn’t create “indices” in the usual, DBMS manner. There are no B-Trees, R-Trees, etc. We might add one in the future, but for now, queries that address the data by predicates over dimensions are really, really fast.