Major enhancements in PostgreSQL 11 include:
- Improvements to partitioning functionality, including:
- Add support for partitioning by a hash key
- Add support for PRIMARY KEY, FOREIGN KEY, indexes, and triggers on partitioned tables
- Allow creation of a "default" partition for storing data that does not match any of the remaining partitions
- UPDATE statements that change a partition key column now cause affected rows to be moved to the appropriate partitions
- Improve SELECT performance through enhanced partition elimination strategies during query planning and execution
- Improvements to parallelism, including:
- CREATE INDEX can now use parallel processing while building a B-tree index
- Parallelization is now possible in CREATE TABLE ... AS, CREATE MATERIALIZED VIEW, and certain queries using UNION
- Parallelized hash joins and parallelized sequential scans now perform better
- SQL stored procedures that support embedded transactions
- Optional Just-in-Time (JIT) compilation for some SQL code, speeding evaluation of expressions
- Window functions now support all framing options shown in the SQL:2011 standard, including RANGE distance PRECEDING/FOLLOWING, GROUPS mode, and frame exclusion options
- Covering indexes can now be created, using the INCLUDE clause of CREATE INDEX
- Many other useful performance improvements, including the ability to avoid a table rewrite for ALTER TABLE ... ADD COLUMN with a non-null column default
https://www.postgresql.org/docs/11/static/release-11.html
https://news.ycombinator.com/item?id=18248422