Implement DB size estimation for DuckDB (#2742)

* added EstimateSize in OLAPStore

* review changes

runtime/drivers/druid/druid.go

@@ -73,3 +73,7 @@ func (c *connection) Migrate(ctx context.Context) (err error) {
 func (c *connection) MigrationStatus(ctx context.Context) (current, desired int, err error) {
 	return 0, 0, nil
 }
+
+func (c *connection) EstimateSize() (int64, bool) {
+	return 0, false
+}

runtime/drivers/duckdb/connectors.go

@@ -43,6 +43,19 @@ func (c *connection) Ingest(ctx context.Context, env *connectors.Env, source *co
 	return summary, err
 }
 
+func (c *connection) EstimateSize() (int64, bool) {
+	var paths []string
+	path := c.config.DBFilePath
+	if path == "" {
+		return 0, true
+	}
+
+	// Add .wal file path (e.g final size will be sum of *.db and *.db.wal)
+	dbWalPath := fmt.Sprintf("%s.wal", path)
+	paths = append(paths, path, dbWalPath)
+	return fileSize(paths), true
+}
+
 func (c *connection) ingest(ctx context.Context, env *connectors.Env, source *connectors.Source) (*drivers.IngestionSummary, error) {
 	// Driver-specific overrides
 	if source.Connector == "local_file" {

runtime/drivers/motherduck/connectors.go

@@ -43,6 +43,10 @@ func (c *connection) Ingest(ctx context.Context, env *connectors.Env, source *co
 	return summary, err
 }
 
+func (c *connection) EstimateSize() (int64, bool) {
+	return 0, false
+}
+
 func (c *connection) ingest(ctx context.Context, env *connectors.Env, source *connectors.Source) (*drivers.IngestionSummary, error) {
 	// Driver-specific overrides
 	if source.Connector == "local_file" {

runtime/drivers/olap.go

@@ -26,6 +26,7 @@ type OLAPStore interface {
 	Execute(ctx context.Context, stmt *Statement) (*Result, error)
 	Ingest(ctx context.Context, env *connectors.Env, source *connectors.Source) (*IngestionSummary, error)
 	InformationSchema() InformationSchema
+	EstimateSize() (int64, bool)
 }
 
 // Statement wraps a query to execute against an OLAP driver.