Feature/239 request sequence generators

[Uday-Polineni]

Summary

This PR implements regional request ID sequence generators for Virginia and Ireland (#239). It introduces a band-from-sequence format REQ-{band}-XXX-XXX-XXX-XXX, with each region assigned a non-overlapping sequence range so IDs stay globally unique.

Problem

The existing generate_request_id() function had the following issues:

• Used INT for seq_id, limiting scale for Ireland’s trillion-scale range
• No sequence bounds (NO MINVALUE, NO MAXVALUE) — ranges were not partitioned per region
• Ireland used an unqualified nextval('request_id_seq') instead of the schema-qualified sequence name
• No way to assign ~1 trillion IDs per region without collisions across Virginia and Ireland

Approach

New ID format:
REQ-{band}-XXX-XXX-XXX-XXX (2-digit band + four 3-digit groups)

Sequence range partitioning:

Region	Band	Sequence range	Example first ID
Virginia	00	1 → 999,999,999,999	REQ-00-000-000-000-001
Ireland	01	1,000,000,000,000 → 1,999,999,999,999	REQ-01-000-000-000-000

Band-from-sequence (same function in both regions):

• Band is derived from the sequence value: FLOOR(seq_id / 1,000,000,000,000)
• Virginia seq_id = 1 → band 00; Ireland seq_id = 1T → band 01
• No region-specific branching in the function — only the sequence start/range differs per region

Future-proofing (new regions / exhausted ranges):

• Each band is a 1 trillion ID block: band NN maps to sequence values NN × 1T through (NN + 1) × 1T − 1
• Virginia uses band 00 (0 → 1T − 1); Ireland uses band 01 (1T → 2T − 1)
• If a new region is added, assign the next band — e.g. band 02 with sequence START 2,000,000,000,000, MAXVALUE 2,999,999,999,999 → IDs like REQ-02-...
• If an existing region exhausts its range, move it to the next free band using the same pattern (03 → 3T to 4T − 1, and so on)
• The same generate_request_id() logic applies everywhere — band is always derived from FLOOR(seq_id / 1T); only the sequence START / MINVALUE / MAXVALUE changes per region

Files changed

File	Purpose
ddl/Tables/ddl_request.sql	Virginia create script — sequence bounds + generate_request_id()
ddl/Tables/Scripts/ireland_dev_saayam_rdbms.sql	Ireland create script — sequence bounds + generate_request_id()
ddl/ddl_changes/ddl_alter_virginia_sequence_generator.sql	Virginia function change — CREATE OR REPLACE FUNCTION
ddl/ddl_changes/ddl_alter_ireland_sequence_generator.sql	Ireland function change — CREATE OR REPLACE FUNCTION
script-library/tests/test_virginia_generate_request_id.sql	Virginia smoke test (REQ-00-...)
script-library/tests/test_ireland_generate_request_id.sql	Ireland smoke test (REQ-01-...)

Test plan

• Deploy Virginia DDL on a test DB; run test_virginia_generate_request_id.sql — all checks return OK:
• Deploy Ireland DDL on a test DB; run test_ireland_generate_request_id.sql — all checks return OK:
• Smoke tests use BEGIN / ROLLBACK

Closes #239