Check if a schema already exists and not create it (#925)

For when we have permissions to check schema existance

flow/connectors/snowflake/snowflake.go

@@ -147,6 +147,7 @@ func NewSnowflakeConnector(ctx context.Context,
 	if snowflakeProtoConfig.MetadataSchema != nil {
 		metadataSchema = *snowflakeProtoConfig.MetadataSchema
 	}
+
 	flowName, _ := ctx.Value(shared.FlowNameKey).(string)
 	return &SnowflakeConnector{
 		ctx:                ctx,
@@ -1010,7 +1011,20 @@ func (c *SnowflakeConnector) updateNormalizeMetadata(flowJobName string, normali
 }
 
 func (c *SnowflakeConnector) createPeerDBInternalSchema(createSchemaTx *sql.Tx) error {
-	_, err := createSchemaTx.ExecContext(c.ctx, fmt.Sprintf(createSchemaSQL, c.metadataSchema))
+	// check if the internal schema exists
+	row := createSchemaTx.QueryRowContext(c.ctx, checkSchemaExistsSQL, c.metadataSchema)
+	var schemaExists pgtype.Bool
+	err := row.Scan(&schemaExists)
+	if err != nil {
+		return fmt.Errorf("error while reading result row: %w", err)
+	}
+
+	if schemaExists.Bool {
+		c.logger.Info(fmt.Sprintf("internal schema %s already exists", c.metadataSchema))
+		return nil
+	}
+
+	_, err = createSchemaTx.ExecContext(c.ctx, fmt.Sprintf(createSchemaSQL, c.metadataSchema))
 	if err != nil {
 		return fmt.Errorf("error while creating internal schema for PeerDB: %w", err)
 	}