11.125. Release 0.93

ORC Memory Usage

This release changes the Presto ORC reader to favor small buffers when readingvarchar and varbinary data. Some ORC files contain columns of data that arehundreds of megabytes when decompressed. In the previous Presto ORC reader, wewould allocate a single large shared buffer for all values in the column. Thiswould cause heap fragmentation in CMS and G1, and it would cause OOMs sinceeach value of the column retains a reference to the shared buffer. In thisrelease the ORC reader uses a separate buffer for each value in the column.This reduces heap fragmentation and excessive memory retention at the expenseof object creation.

Verifier

  • Add support for setting username and password per query
    If you’re upgrading from 0.92, you need to alter your verifier_queries table
  1. ALTER TABLE verifier_queries add test_username VARCHAR(256) NOT NULL default 'verifier-test';
  2. ALTER TABLE verifier_queries add test_password VARCHAR(256);
  3. ALTER TABLE verifier_queries add control_username VARCHAR(256) NOT NULL default 'verifier-test';
  4. ALTER TABLE verifier_queries add control_password VARCHAR(256);

General Changes

  • Add optimizer for LIMIT 0
  • Fix incorrect check to disable string statistics in ORC
  • Ignore hidden columns in INSERT and CREATE TABLE AS queries
  • Add SOCKS support to CLI
  • Improve CLI output for update queries
  • Disable pushdown for non-deterministic predicates

原文: https://prestodb.io/docs/current/release/release-0.93.html