SQL Where Expressions

An SQL Where expression is a standard SQL Value Expression, and is coerced to a boolean type after evaluation. The SQL WHERE clause is used to select a subset of rows to process. Only rows which are true are kept; rows that evaluate to null or false are discarded.

Optimization of Where Expressions over datasets using indexes

The following patterns in a Where expression will be optimized against a dataset by using the column index for the given column:

This can considerably speed up a lot of MLDB queries.