Drop connections before drop database (#14)

* test

* testing

* testing

* testing

* support for other psql versions

* Update postgresql/resource_postgresql_database.go

Co-authored-by: Cyril Gaudin <[email protected]>

* Update postgresql/resource_postgresql_database.go

* Update postgresql/resource_postgresql_database.go

* fixup! Update postgresql/resource_postgresql_database.go

Co-authored-by: Cyril Gaudin <[email protected]>

Author: p4cket

postgresql/config.go

@@ -25,6 +25,8 @@ const (
 	featureReplication
 	featureExtension
 	featurePrivileges
+	featureForceDropDatabase
+	featurePid
 )
 
 type dbRegistryEntry struct {
@@ -65,6 +67,14 @@ var (
 		// We do not support postgresql_grant and postgresql_default_privileges
 		// for Postgresql < 9.
 		featurePrivileges: semver.MustParseRange(">=9.0.0"),
+
+		// DROP DATABASE WITH FORCE
+		// for Postgresql >= 13
+		featureForceDropDatabase: semver.MustParseRange(">=13.0.0"),
+
+		// Column procpid was replaced by pid in pg_stat_activity
+		// for Postgresql >= 9.2 and above
+		featurePid: semver.MustParseRange(">=9.2.0"),
 	}
 )
 

postgresql/resource_postgresql_database.go

@@ -233,6 +233,7 @@ func resourcePostgreSQLDatabaseDelete(d *schema.ResourceData, meta interface{})
 	currentUser := c.config.getDatabaseUsername()
 	owner := d.Get(dbOwnerAttr).(string)
 
+	var dropWithForce string
 	var err error
 	if owner != "" {
 		// Needed in order to set the owner of the db if the connection user is not a
@@ -263,7 +264,18 @@ func resourcePostgreSQLDatabaseDelete(d *schema.ResourceData, meta interface{})
 		return err
 	}
 
-	sql := fmt.Sprintf("DROP DATABASE %s", pq.QuoteIdentifier(dbName))
+	// Terminate all active connections and block new one
+	if err := terminateBConnections(c, dbName); err != nil {
+		return err
+	}
+
+	// Drop with force only for psql 13+
+	if c.featureSupported(featureForceDropDatabase) {
+		dropWithForce = "WITH ( FORCE )"
+	}
+
+	sql := fmt.Sprintf("DROP DATABASE %s %s", pq.QuoteIdentifier(dbName), dropWithForce)
+
 	if _, err := c.DB().Exec(sql); err != nil {
 		return fmt.Errorf("Error dropping database: %w", err)
 	}
@@ -548,3 +560,25 @@ func doSetDBIsTemplate(c *Client, dbName string, isTemplate bool) error {
 
 	return nil
 }
+
+func terminateBConnections(c *Client, dbName string) error {
+	var terminateSql string
+
+	if c.featureSupported(featureDBAllowConnections) {
+		alterSql := fmt.Sprintf("ALTER DATABASE %s ALLOW_CONNECTIONS false", pq.QuoteIdentifier(dbName))
+
+		if _, err := c.DB().Exec(alterSql); err != nil {
+			return fmt.Errorf("Error blocking connections to database: %w", err)
+		}
+	}
+	pid := "procpid"
+	if c.featureSupported(featurePid) {
+		pid = "pid"
+	}
+	terminateSql = fmt.Sprintf("SELECT pg_terminate_backend(%s) FROM pg_stat_activity WHERE datname = '%s' AND %s <> pg_backend_pid()", pid, dbName, pid)
+	if _, err := c.DB().Exec(terminateSql); err != nil {
+		return fmt.Errorf("Error terminating database connections: %w", err)
+	}
+
+	return nil
+}