backgound indexes • Secondary node In v2.1.0 – in background, for backgound indexes In v2.0.x and earlier – always in foreground • Recovering node Always in foreground
(options: “BasicCursor” and “BtreeCursor”) • “nscanned” - count of scanned items (for BasicCursor – documents, for BtreeCursor – index items) • “nscannedObjects” - number of documments scanned • “n” - count of matched documents
during query execution • “millis” - time of query execution • “scanAndOrder” - true, in case if in-memory sorting required • “indexOnly” - covered index is used • “isMultiKey” - index over array is used • “clauses” - used for iteration over more than one index
unique constraints in one collection – Ability to define scope of uniqueness • Solution: – Sparse and Unique index – List of unique tokens: _unique: [ "<scope1>$<value1>", "<scope2>$<value2>" ]