Add missing Cassandra decimal data type mappings
fix NPE in CassandraColumnHandle toString()
Parallelize test queries in presto-main

Make all unit tests in presto-main run in parallel by default, and
annotate non-threadsafe tests with singleThreaded=true
Fix bugs of upper case Cassandra schema, table, column names
Add backpressure to InMemoryExchange
Run all tests in parallel by default

Annotate all tests that use @BeforeMethod with singleThreaded=true
Fix planning issue when using DISTICT aggregations in HAVING clause

Planning fails with a "Multiple entries with same key" error
Add test for HAVING with DISTINCT aggregations
Fix division by zero in some aggregations

Fix both VarianceAggregation and ApproximateAverageAggregation
Remove potential deadlock with broken connectors

Replace synchronized lock with a custom lock with timeout support

For close and updateSource stage change and then attempt to acquire
lock.  If lock is acquired, process change; otherwise lock holder
will process change before releasing lock.

For close, if lock can not be acquired, interrupt lock holder.
Remove obsolete test logging configuration
Fix logging for S3 tests
Support write and retry in PrestoS3FileSystem
Add tests for S3 table creation
Allow using IterableTransformer on arrays
Add error codes to categorize failures
Add error codes for Hive
Remove unused property
Global split assignment
Fix null values for DatabaseMetaData.getColumns