From 54be6c478eea0eb6f5a808cb82b4e45c14a0802f Mon Sep 17 00:00:00 2001
From: Vlad Lazar <vlalazar.vlad@gmail.com>
Date: Tue, 1 Oct 2024 14:20:43 +0100
Subject: [PATCH] pageserver: exclude unbounded keys from size warning

---
 libs/pageserver_api/src/key.rs                | 10 +++++++
 .../src/tenant/storage_layer/delta_layer.rs   | 26 ++++++++++++++-----
 .../src/tenant/storage_layer/image_layer.rs   | 26 ++++++++++++++-----
 3 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/libs/pageserver_api/src/key.rs b/libs/pageserver_api/src/key.rs
index 4a776709c953..b3fcaae62f3f 100644
--- a/libs/pageserver_api/src/key.rs
+++ b/libs/pageserver_api/src/key.rs
@@ -748,6 +748,16 @@ impl Key {
         self.field1 == 0x00 && self.field4 != 0 && self.field6 != 0xffffffff
     }
 
+    #[inline(always)]
+    pub fn is_rel_dir_key(&self) -> bool {
+        self.field1 == 0x00
+            && self.field2 != 0
+            && self.field3 != 0
+            && self.field4 == 0
+            && self.field5 == 0
+            && self.field6 == 1
+    }
+
     /// Guaranteed to return `Ok()` if [`Self::is_rel_block_key`] returns `true` for `key`.
     #[inline(always)]
     pub fn to_rel_block(self) -> anyhow::Result<(RelTag, BlockNumber)> {
diff --git a/pageserver/src/tenant/storage_layer/delta_layer.rs b/pageserver/src/tenant/storage_layer/delta_layer.rs
index 6f9eda85f57b..2acad666b8d0 100644
--- a/pageserver/src/tenant/storage_layer/delta_layer.rs
+++ b/pageserver/src/tenant/storage_layer/delta_layer.rs
@@ -53,6 +53,7 @@ use camino::{Utf8Path, Utf8PathBuf};
 use futures::StreamExt;
 use itertools::Itertools;
 use pageserver_api::config::MaxVectoredReadBytes;
+use pageserver_api::key::DBDIR_KEY;
 use pageserver_api::keyspace::KeySpace;
 use pageserver_api::models::ImageCompressionAlgorithm;
 use pageserver_api::shard::TenantShardId;
@@ -963,14 +964,25 @@ impl DeltaLayerInner {
                 .blobs_at
                 .as_slice()
                 .iter()
-                .map(|(_, blob_meta)| format!("{}@{}", blob_meta.key, blob_meta.lsn))
+                .filter_map(|(_, blob_meta)| {
+                    if blob_meta.key.is_rel_dir_key() || blob_meta.key == DBDIR_KEY {
+                        // The size of values for these keys is unbounded and can
+                        // grow very large in pathological cases.
+                        None
+                    } else {
+                        Some(format!("{}@{}", blob_meta.key, blob_meta.lsn))
+                    }
+                })
                 .join(", ");
-            tracing::warn!(
-                "Oversized vectored read ({} > {}) for keys {}",
-                largest_read_size,
-                read_size_soft_max,
-                offenders
-            );
+
+            if !offenders.is_empty() {
+                tracing::warn!(
+                    "Oversized vectored read ({} > {}) for keys {}",
+                    largest_read_size,
+                    read_size_soft_max,
+                    offenders
+                );
+            }
         }
 
         largest_read_size
diff --git a/pageserver/src/tenant/storage_layer/image_layer.rs b/pageserver/src/tenant/storage_layer/image_layer.rs
index 3dcd7bc96271..9b53fa9e18cd 100644
--- a/pageserver/src/tenant/storage_layer/image_layer.rs
+++ b/pageserver/src/tenant/storage_layer/image_layer.rs
@@ -49,6 +49,7 @@ use camino::{Utf8Path, Utf8PathBuf};
 use hex;
 use itertools::Itertools;
 use pageserver_api::config::MaxVectoredReadBytes;
+use pageserver_api::key::DBDIR_KEY;
 use pageserver_api::keyspace::KeySpace;
 use pageserver_api::shard::{ShardIdentity, TenantShardId};
 use rand::{distributions::Alphanumeric, Rng};
@@ -587,14 +588,25 @@ impl ImageLayerInner {
                     .blobs_at
                     .as_slice()
                     .iter()
-                    .map(|(_, blob_meta)| format!("{}@{}", blob_meta.key, blob_meta.lsn))
+                    .filter_map(|(_, blob_meta)| {
+                        if blob_meta.key.is_rel_dir_key() || blob_meta.key == DBDIR_KEY {
+                            // The size of values for these keys is unbounded and can
+                            // grow very large in pathological cases.
+                            None
+                        } else {
+                            Some(format!("{}@{}", blob_meta.key, blob_meta.lsn))
+                        }
+                    })
                     .join(", ");
-                tracing::warn!(
-                    "Oversized vectored read ({} > {}) for keys {}",
-                    buf_size,
-                    max_vectored_read_bytes,
-                    offenders
-                );
+
+                if !offenders.is_empty() {
+                    tracing::warn!(
+                        "Oversized vectored read ({} > {}) for keys {}",
+                        buf_size,
+                        max_vectored_read_bytes,
+                        offenders
+                    );
+                }
             }
 
             let buf = BytesMut::with_capacity(buf_size);