feat(db): adding relational instance table (#10007)

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# Which Problems Are Solved

Implementing Instance table to new relational database schema

# How the Problems Are Solved


The following fields must be managed in this table:

- `id`
- `name`
- `default_org_id`
- `zitadel_project_id`
- `console_client_id`
- `console_app_id`
- `default_language`
- `created_at`
- `updated_at`
- `deleted_at`

The repository must provide the following functions:

Manipulations:
- create
  - `name`
  - `default_org_id`
  - `zitadel_project_id`
  - `console_client_id`
  - `console_app_id`
  - `default_language`
- update
  - `name`
  - `default_language`
- delete

Queries:
- get returns single instance matching the criteria and pagination,
should return error if multiple instances were found
- list returns list of instances matching the criteria, pagination

Criteria are the following:
- by id

pagination:
- by created_at
- by updated_at
- by name

### instance events

The following events must be applied on the table using a projection
(`internal/query/projection`)

- `instance.added` results in create
- `instance.changed` changes the `name` field
- `instance.removed` sets the the `deleted_at` field
- `instance.default.org.set` sets the `default_org_id` field
- `instance.iam.project.set` sets the `zitadel_project_id` field
- `instance.iam.console.set` sets the `console_client_id` and
`console_app_id` fields
- `instance.default.language.set` sets the `default_language` field
- if answer is yes to discussion: `instance.domain.primary.set` sets the
`primary_domain` field

### acceptance criteria

- [x] migration is implemented and gets executed
- [x] domain interfaces are implemented and documented for service layer
- [x] repository is implemented and implements domain interface
- [x] testing
  - [x] the repository methods
  - [x] events get reduced correctly
  - [x] unique constraints

# Additional Context

- Closes https://github.com/zitadel/zitadel/issues/9935

backend/v3/storage/database/dialect/postgres/conn.go

@@ -13,9 +13,7 @@ type pgxConn struct {
 	*pgxpool.Conn
 }
 
-var (
-	_ database.Client = (*pgxConn)(nil)
-)
+var _ database.Client = (*pgxConn)(nil)
 
 // Release implements [database.Client].
 func (c *pgxConn) Release(_ context.Context) error {
@@ -47,9 +45,9 @@ func (c *pgxConn) QueryRow(ctx context.Context, sql string, args ...any) databas
 
 // Exec implements [database.Pool].
 // Subtle: this method shadows the method (Pool).Exec of pgxPool.Pool.
-func (c *pgxConn) Exec(ctx context.Context, sql string, args ...any) error {
-	_, err := c.Conn.Exec(ctx, sql, args...)
-	return err
+func (c *pgxConn) Exec(ctx context.Context, sql string, args ...any) (int64, error) {
+	res, err := c.Conn.Exec(ctx, sql, args...)
+	return res.RowsAffected(), err
 }
 
 // Migrate implements [database.Migrator].

backend/v3/storage/database/dialect/postgres/migration/001_instance_table/up.sql

@@ -1,6 +1,26 @@
 CREATE TABLE IF NOT EXISTS zitadel.instances(
-    id VARCHAR(100) NOT NULL
-    , PRIMARY KEY (id)
+  id TEXT NOT NULL CHECK (id <> '') PRIMARY KEY,
+  name TEXT NOT NULL CHECK (name <> ''),
+  default_org_id TEXT, -- NOT NULL,
+  iam_project_id TEXT, -- NOT NULL,
+  console_client_id TEXT, -- NOT NULL,
+  console_app_id TEXT, -- NOT NULL,
+  default_language TEXT, -- NOT NULL,
+  created_at TIMESTAMPTZ DEFAULT NOW(),
+  updated_at TIMESTAMPTZ DEFAULT NOW(),
+  deleted_at TIMESTAMPTZ DEFAULT NULL
+);
 
-    , name VARCHAR(100) NOT NULL
-);
+CREATE OR REPLACE FUNCTION zitadel.set_updated_at()
+RETURNS TRIGGER AS $$
+BEGIN
+  NEW.updated_at := NOW();
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER trigger_set_updated_at
+BEFORE UPDATE ON zitadel.instances
+FOR EACH ROW
+WHEN (OLD.updated_at IS NOT DISTINCT FROM NEW.updated_at)
+EXECUTE FUNCTION zitadel.set_updated_at();

backend/v3/storage/database/dialect/postgres/pool.go

@@ -13,9 +13,13 @@ type pgxPool struct {
 	*pgxpool.Pool
 }
 
-var (
-	_ database.Pool = (*pgxPool)(nil)
-)
+var _ database.Pool = (*pgxPool)(nil)
+
+func PGxPool(pool *pgxpool.Pool) *pgxPool {
+	return &pgxPool{
+		Pool: pool,
+	}
+}
 
 // Acquire implements [database.Pool].
 func (c *pgxPool) Acquire(ctx context.Context) (database.Client, error) {
@@ -41,9 +45,9 @@ func (c *pgxPool) QueryRow(ctx context.Context, sql string, args ...any) databas
 
 // Exec implements [database.Pool].
 // Subtle: this method shadows the method (Pool).Exec of pgxPool.Pool.
-func (c *pgxPool) Exec(ctx context.Context, sql string, args ...any) error {
-	_, err := c.Pool.Exec(ctx, sql, args...)
-	return err
+func (c *pgxPool) Exec(ctx context.Context, sql string, args ...any) (int64, error) {
+	res, err := c.Pool.Exec(ctx, sql, args...)
+	return res.RowsAffected(), err
 }
 
 // Begin implements [database.Pool].
@@ -76,3 +80,15 @@ func (c *pgxPool) Migrate(ctx context.Context) error {
 	isMigrated = err == nil
 	return err
 }
+
+// Migrate implements [database.PoolTest].
+func (c *pgxPool) MigrateTest(ctx context.Context) error {
+	client, err := c.Pool.Acquire(ctx)
+	if err != nil {
+		return err
+	}
+
+	err = migration.Migrate(ctx, client.Conn())
+	isMigrated = err == nil
+	return err
+}

backend/v3/storage/database/dialect/postgres/tx.go

@@ -50,9 +50,9 @@ func (tx *pgxTx) QueryRow(ctx context.Context, sql string, args ...any) database
 
 // Exec implements [database.Transaction].
 // Subtle: this method shadows the method (Pool).Exec of pgxPool.Pool.
-func (tx *pgxTx) Exec(ctx context.Context, sql string, args ...any) error {
-	_, err := tx.Tx.Exec(ctx, sql, args...)
-	return err
+func (tx *pgxTx) Exec(ctx context.Context, sql string, args ...any) (int64, error) {
+	res, err := tx.Tx.Exec(ctx, sql, args...)
+	return res.RowsAffected(), err
 }
 
 // Begin implements [database.Transaction].