From f8bdce101542ace882cf891f001f53c702a9685b Mon Sep 17 00:00:00 2001
From: John Spray <john@neon.tech>
Date: Fri, 1 Mar 2024 13:26:45 +0000
Subject: [PATCH] pageserver: fix duplicate shard_id in span (#6981)

## Problem

shard_id in span is repeated:
- https://github.com/neondatabase/neon/issues/6723

Closes: #6723

## Summary of changes

- Only add shard_id to the span when fetching a cached timeline, as it
is already added when loading an uncached timeline.
---
 pageserver/src/page_service.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/pageserver/src/page_service.rs b/pageserver/src/page_service.rs
index 11eb512750..cd9c48f9af 100644
--- a/pageserver/src/page_service.rs
+++ b/pageserver/src/page_service.rs
@@ -1115,7 +1115,10 @@ impl PageServerHandler {
         ctx: &RequestContext,
     ) -> Result<PagestreamBeMessage, PageStreamError> {
         let timeline = match self.get_cached_timeline_for_page(req) {
-            Ok(tl) => tl,
+            Ok(tl) => {
+                set_tracing_field_shard_id(tl);
+                tl
+            }
             Err(key) => {
                 match self
                     .load_timeline_for_page(tenant_id, timeline_id, key)
@@ -1140,9 +1143,6 @@ impl PageServerHandler {
             }
         };
 
-        // load_timeline_for_page sets shard_id, but get_cached_timeline_for_page doesn't
-        set_tracing_field_shard_id(timeline);
-
         let _timer = timeline
             .query_metrics
             .start_timer(metrics::SmgrQueryType::GetPageAtLsn);