PostgreSQL

# Major enhancements include:
- Allow queries to retrieve data only from indexes, avoiding heap access (index-only scans)
- Allow the planner to generate custom plans for specific parameter values even when using prepared statements
- Improve the planner's ability to use nested loops with inner index scans
- Allow streaming replication slaves to forward data to other slaves (cascading replication)
- Allow pg_basebackup to make base backups from standby servers
- Add a pg_receivexlog tool to archive WAL file changes as they are written
- Add the SP-GiST (Space-Partitioned GiST) index access method
- Add support for range data types
- Add a JSON data type
- Add a security_barrier option for views
- Allow libpq connection strings to have the format of a URI
- Add a single-row processing mode to libpq for better handling of large result sets