user-query-optimizer 0.1.6

SQL query optimization hints

## Introduction This API will help you optimize your sql queries for better performance.

## How to use Create an optimizer object specific to a single (database, schema) pair e.g. optimizer = get_optimizer(“presto”, schema)

Get optimization hints using optimize_query(query) e.g. presto_op.optimize_query(query)

Initial Optimization Checks

• Using approximate algorithms (approx_distinct() instead of COUNT(DISTINCT …))

• Selecting the columns the user wants explicitly, rather than using (SELECT *)

• Filtering on partitioned columns

• Try to extract nested subqueries using a WITH clause.

• Suggest filtering on most effective columns, by parquet-file ordering

• Eliminate filtering overhead for partitioned columns

Other Stuff

• Replace UNION with UNION ALL if duplicates do not need to be removed

• Aggregate a series of LIKE clauses into one regexp_like expression

• Push down a complex join condition into a sub query

• Specify GROUP BY targets with numbers for expressions

### Testing To run unit tests, run py.test (or py.test -s to see stdout) in the tests directory.