Release 0.70¶
Warning
This release contained a packaging error that resulted in an unusable server tarball. Do not use this release.
Views¶
We have added support for creating views within Presto. Views are defined using Presto syntax but are stored (as blobs) by connectors. Currently, views are supported by the Raptor and Hive connectors. For the Hive connector, views are stored within the Hive metastore as Hive views, but they cannot be queried by Hive, nor can Hive views be queried by Presto.
See CREATE VIEW and DROP VIEW for details and examples.
DUAL Table¶
The synthetic DUAL
table is no longer supported. As an alternative, please
write your queries without a FROM
clause or use the VALUES
syntax.
Presto Verifier¶
There is a new project, Presto Verifier, which can be used to verify a set of queries against two different clusters.
Connector Improvements¶
Connectors can now add hidden columns to a table. Hidden columns are not displayed in
DESCRIBE
orinformation_schema
, and are not considered forSELECT *
. As an example, we have added a hiddenrow_number
column to thetpch
connector.Presto contains an extensive test suite to verify the correctness. This test suite has been extracted into the
presto-test
module for use during connector development. For an example, seeTestRaptorDistributedQueries
.
Machine Learning Functions¶
We have added two new machine learning functions, which can be used
by advanced users familiar with LIBSVM. The functions are
learn_libsvm_classifier
and learn_libsvm_regressor
. Both take a
parameters string which has the form key=value,key=value
General Changes¶
New comparison functions:
greatest()
andleast()
New window functions:
first_value()
,last_value()
, andnth_value()
We have added a config option to disable falling back to the interpreter when expressions fail to be compiled to bytecode. To set this option, add
compiler.interpreter-enabled=false
toetc/config.properties
. This will force certain queries to fail rather than running slowly.DATE
values are now implicitly coerced toTIMESTAMP
andTIMESTAMP WITH TIME ZONE
by setting the hour/minute/seconds to0
with respect to the session timezone.Minor performance optimization when planning queries over tables with tens of thousands of partitions or more.
Fixed a bug when planning
ORDER BY ... LIMIT
queries which could result in duplicate and un-ordered results under rare conditions.Reduce the size of stats collected from tasks, which dramatically reduces garbage generation and improves coordinator stability.
Fix compiler cache for expressions.
Fix processing of empty or commented out statements in the CLI.
Hive Changes¶
There are two new configuration options for the Hive connector,
hive.max-initial-split-size
, which configures the size of the initial splits, andhive.max-initial-splits
, which configures the number of initial splits. This can be useful for speeding up small queries, which would otherwise have low parallelism.The Hive connector will now consider all tables with a non-empty value for the table property
presto_offline
to be offline. The value of the property will be used in the error message.We have added support for for
DROP TABLE
in the hive connector. By default, this feature is not enabled. To enable it, sethive.allow-drop-table=true
in your Hive catalog properties file.Ignore subdirectories when generating splits (this now matches the non-recursive behavior of Hive).
Fix handling of maps with null keys.