Feature: Import PostgreSQL 19 new parser.

Hi,

I have updated the Pgpool-II parser to PostgreSQL 19.

Major parser changes in PostgreSQL 19 include:

- Add support for SQL Property Graph Queries (SQL/PGQ).
- Add FOR PORTION OF clauses to UPDATE and DELETE.
- Allow GROUP BY to process target-list subqueries containing
references to non-subquery columns.
- Allow window functions to use IGNORE NULLS and RESPECT NULLS.
- Add support for INSERT ... ON CONFLICT DO SELECT ... RETURNING.
- Add the REPACK command, which replaces VACUUM FULL and CLUSTER.
- Allow REPACK to rebuild tables without access-exclusive locking.
- Allow partitions to be merged and split using ALTER TABLE ...
MERGE/SPLIT PARTITIONS.
- Allow GRANT and REVOKE to specify the effective role.
- Allow CREATE SCHEMA to create more types of objects.
- Allow CHECKPOINT to accept a list of options.
- Add the CONNECTION clause to CREATE FOREIGN DATA WRAPPER.
- Add memory usage and parallelism reporting to VACUUM (VERBOSE).
etc.

Please review the attached patch.

Best regards,

Taiki Koshino<koshino(at)sraoss(dot)co(dot)jp>
SRA OSS K.K.
TEL: 03-5979-2701 FAX: 03-5979-2702
URL: https://www.sraoss.co.jp/