From 577982b7782aceaa0782ef4295663d72d39b09aa Mon Sep 17 00:00:00 2001
From: John Spray <john@neon.tech>
Date: Tue, 30 Apr 2024 11:04:54 +0100
Subject: [PATCH] pageserver: remove workarounds from #7454 (#7550)

PR #7454 included a workaround that let any existing bugged databases
start up. Having used that already, we may now

Closes: https://github.com/neondatabase/neon/issues/7480
---
 libs/pageserver_api/src/shard.rs | 18 ------------------
 pageserver/src/basebackup.rs     | 17 ++---------------
 2 files changed, 2 insertions(+), 33 deletions(-)

diff --git a/libs/pageserver_api/src/shard.rs b/libs/pageserver_api/src/shard.rs
index 2d7f6772b2..d769b2fd2f 100644
--- a/libs/pageserver_api/src/shard.rs
+++ b/libs/pageserver_api/src/shard.rs
@@ -538,24 +538,6 @@ impl ShardIdentity {
         }
     }
 
-    /// Special case for issue `<https://github.com/neondatabase/neon/issues/7451>`
-    ///
-    /// When we fail to read a forknum block, this function tells us whether we may ignore the error
-    /// as a symptom of that issue.
-    pub fn is_key_buggy_forknum(&self, key: &Key) -> bool {
-        if !is_rel_block_key(key) || key.field5 != INIT_FORKNUM {
-            return false;
-        }
-
-        let mut hash = murmurhash32(key.field4);
-        hash = hash_combine(hash, murmurhash32(key.field6 / self.stripe_size.0));
-        let mapped_shard = ShardNumber((hash % self.count.0 as u32) as u8);
-
-        // The key may be affected by issue #7454: it is an initfork and it would not
-        // have mapped to shard 0 until we fixed that issue.
-        mapped_shard != ShardNumber(0)
-    }
-
     /// Return true if the key should be discarded if found in this shard's
     /// data store, e.g. during compaction after a split.
     ///
diff --git a/pageserver/src/basebackup.rs b/pageserver/src/basebackup.rs
index 8c51e93643..53abd8bfb9 100644
--- a/pageserver/src/basebackup.rs
+++ b/pageserver/src/basebackup.rs
@@ -13,7 +13,7 @@
 use anyhow::{anyhow, bail, ensure, Context};
 use bytes::{BufMut, Bytes, BytesMut};
 use fail::fail_point;
-use pageserver_api::key::{key_to_slru_block, rel_block_to_key, Key};
+use pageserver_api::key::{key_to_slru_block, Key};
 use postgres_ffi::pg_constants;
 use std::fmt::Write as FmtWrite;
 use std::time::SystemTime;
@@ -300,20 +300,7 @@ where
                 if rel.forknum == INIT_FORKNUM {
                     // I doubt we need _init fork itself, but having it at least
                     // serves as a marker relation is unlogged.
-                    if let Err(_e) = self.add_rel(rel, rel).await {
-                        if self
-                            .timeline
-                            .get_shard_identity()
-                            .is_key_buggy_forknum(&rel_block_to_key(rel, 0x0))
-                        {
-                            // Workaround https://github.com/neondatabase/neon/issues/7451 -- if we have an unlogged relation
-                            // whose INIT_FORKNUM is not correctly on shard zero, then omit it in the basebackup.  This allows
-                            // postgres to start up.  The relation won't work, but it will be possible to DROP TABLE on it and
-                            // recreate.
-                            tracing::warn!("Omitting relation {rel} for issue #7451: drop and recreate this unlogged relation");
-                            continue;
-                        }
-                    };
+                    self.add_rel(rel, rel).await?;
                     self.add_rel(rel, rel.with_forknum(MAIN_FORKNUM)).await?;
                     continue;
                 }