Implement leader election over postgresql

[CookiePieWw]

What type of enhancement is this?

Other

What does the enhancement do?

• Candidate registration
  • Init feat: init PgElection with candidate registration #5209
  • Separate registration and keep alive logics refactor: split up candidate registration and keep alive #5320
• Leader election feat: add election logic for PgElection #5249
• Txn
  • Connection Pool feat: use connection pool for pg kv backend in preparation for txn #5260
  • Txn Impl feat: add Txn for pg kv backend #5266
• Config
  • Configurable pg kv backend table name feat(config): make table name of pg backend configurable #5244
  • Configurable advisory lock id feat(config): make table name of pg backend configurable #5244
  • Configurable isolation level for txn
• Tests
  • Unit test for Txn
    • Init feat: add Txn for pg kv backend #5266
    • Fix concurrent problem when multiple unit test are executed
      Hopefully we can get it done in feat: add Txn for pg kv backend #5266 too.
  • Sqlness refactor: refactor PgStore #5309
  • Integration test(integration): add pg kvbackend #5331