feat: make empty parent_span_id null for v1 (#5690)

src/servers/src/otlp/trace/span.rs

@@ -32,22 +32,22 @@ pub struct TraceSpan {
     pub service_name: Option<String>,
     pub trace_id: String,
     pub span_id: String,
-    pub parent_span_id: String,
+    pub parent_span_id: Option<String>,
 
     // the following are fields
-    pub resource_attributes: Attributes, // TODO(yuanbohan): Map in the future
+    pub resource_attributes: Attributes,
     pub scope_name: String,
     pub scope_version: String,
-    pub scope_attributes: Attributes, // TODO(yuanbohan): Map in the future
+    pub scope_attributes: Attributes,
     pub trace_state: String,
     pub span_name: String,
     pub span_kind: String,
     pub span_status_code: String,
     pub span_status_message: String,
-    pub span_attributes: Attributes, // TODO(yuanbohan): Map in the future
-    pub span_events: SpanEvents,     // TODO(yuanbohan): List in the future
-    pub span_links: SpanLinks,       // TODO(yuanbohan): List in the future
-    pub start_in_nanosecond: u64,    // this is also the Timestamp Index
+    pub span_attributes: Attributes,
+    pub span_events: SpanEvents,  // TODO(yuanbohan): List in the future
+    pub span_links: SpanLinks,    // TODO(yuanbohan): List in the future
+    pub start_in_nanosecond: u64, // this is also the Timestamp Index
     pub end_in_nanosecond: u64,
 }
 
@@ -203,7 +203,11 @@ pub fn parse_span(
         service_name,
         trace_id: bytes_to_hex_string(&span.trace_id),
         span_id: bytes_to_hex_string(&span.span_id),
-        parent_span_id: bytes_to_hex_string(&span.parent_span_id),
+        parent_span_id: if span.parent_span_id.is_empty() {
+            None
+        } else {
+            Some(bytes_to_hex_string(&span.parent_span_id))
+        },
 
         resource_attributes: Attributes::from(resource_attrs),
         trace_state: span.trace_state,

src/servers/src/otlp/trace/v0.rs

@@ -91,7 +91,10 @@ pub fn write_span_to_row(writer: &mut TableData, span: TraceSpan) -> Result<()>
     let iter = vec![
         (TRACE_ID_COLUMN, span.trace_id),
         (SPAN_ID_COLUMN, span.span_id),
-        (PARENT_SPAN_ID_COLUMN, span.parent_span_id),
+        (
+            PARENT_SPAN_ID_COLUMN,
+            span.parent_span_id.unwrap_or_default(),
+        ),
     ]
     .into_iter()
     .map(|(col, val)| (col.to_string(), val));

src/servers/src/otlp/trace/v1.rs

@@ -103,8 +103,18 @@ pub fn write_span_to_row(writer: &mut TableData, span: TraceSpan) -> Result<()>
     row_writer::write_tags(writer, tags.into_iter(), &mut row)?;
 
     // write fields
+    if let Some(parent_span_id) = span.parent_span_id {
+        row_writer::write_fields(
+            writer,
+            std::iter::once(make_string_column_data(
+                PARENT_SPAN_ID_COLUMN,
+                parent_span_id,
+            )),
+            &mut row,
+        )?;
+    }
+
     let fields = vec![
-        make_string_column_data(PARENT_SPAN_ID_COLUMN, span.parent_span_id),
         make_string_column_data(SPAN_KIND_COLUMN, span.span_kind),
         make_string_column_data(SPAN_NAME_COLUMN, span.span_name),
         make_string_column_data("span_status_code", span.span_status_code),