feat(ql3): establish 3.0 incubation baseline

back/migrations/postgresql/sqlMigration.ts

@@ -0,0 +1,34 @@
+import { createHash } from 'crypto';
+import type { MigrationStreamStep } from '../core/migrationStream';
+import type { PostgresMigrationContext } from '../adapters/postgresMigrationStreamStore';
+
+export interface PostgresSqlMigrationDefinition {
+  readonly id: string;
+  readonly statements: readonly string[];
+}
+
+export function checksumPostgresStatements(
+  statements: readonly string[],
+): string {
+  return createHash('sha256')
+    .update(
+      JSON.stringify({
+        format: 1,
+        statements,
+      }),
+    )
+    .digest('hex');
+}
+
+export function definePostgresSqlMigration(
+  definition: PostgresSqlMigrationDefinition,
+): MigrationStreamStep<PostgresMigrationContext> {
+  const statements = Object.freeze([...definition.statements]);
+  return Object.freeze({
+    id: definition.id,
+    checksum: checksumPostgresStatements(statements),
+    async up(context: PostgresMigrationContext) {
+      for (const statement of statements) await context.query(statement);
+    },
+  });
+}