11.184. Release 0.57

Distinct Aggregations

The DISTINCT argument qualifier for aggregation functions is nowfully supported. For example:

  1. SELECT country, count(DISTINCT city), count(DISTINCT age)
  2. FROM users
  3. GROUP BY country

Note

approx_distinct() should be used in preference to thiswhenever an approximate answer is allowable as it is substantiallyfaster and does not have any limits on the number of distinct items itcan process. COUNT(DISTINCT …) must transfer every item over thenetwork and keep each distinct item in memory.

Hadoop 2.x

Use the hive-hadoop2 connector to read Hive data from Hadoop 2.x.See Deploying Presto for details.

Amazon S3

All Hive connectors support reading data fromAmazon S3.This requires two additional catalog properties for the Hive connectorto specify your AWS Access Key ID and Secret Access Key:

  1. hive.s3.aws-access-key=AKIAIOSFODNN7EXAMPLE
  2. hive.s3.aws-secret-key=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY

Miscellaneous

  • Allow specifying catalog and schema in the JDBC Driver URL.
  • Implement more functionality in the JDBC driver.
  • Allow certain custom InputFormats to work by propagatingHive serialization properties to the RecordReader.
  • Many execution engine performance improvements.
  • Fix optimizer performance regression.
  • Fix weird MethodHandle exception.