Approximate Aggregation Queries in Presto

We have added experimental support for aggregate queries that return approximate results with error bounds. This feature is designed to be used with sampled tables generated using the TABLESAMPLE POISSONIZED RESCALED. For example, the following query will create a 1% sample:

CREATE TABLE lineitems_sample AS
SELECT *
FROM tpch.sf10.lineitems TABLESAMPLE POISSONIZED (1) RESCALED

Then, to run an approximate query:

SELECT COUNT(*)
FROM lineitems_sample
APPROXIMATE AT 95.0 CONFIDENCE

           _col0
----------------------------
 5.991790345E7 +/- 14835.75
(1 row)

To enable this feature you must add analyzer.experimental-syntax-enabled=true to your config.