config/database: update queries to improve reads/writes (#19975)

* config/database: update queries to improve reads/writes

* reflect review comments

* move tx initialization

* add comments and fix psql migration

* fix spelling

* refactor

* add more descriptive comment

config/migrations/postgres/000003_update_configurations_sha.down.sql

@@ -0,0 +1 @@
+ALTER TABLE Configurations DROP COLUMN IF EXISTS SHA;

config/migrations/postgres/000003_update_configurations_sha.up.sql

@@ -0,0 +1 @@
+ALTER TABLE Configurations ADD COLUMN IF NOT EXISTS SHA CHAR(64) DEFAULT '';