From a31bba19b04d0cb3346ded88b21c72b1d9e3c146 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Mon, 28 Jun 2021 15:14:49 +0300
Subject: [PATCH] Compact RocksDB database after garbage collection.

Without this step, the page versions won't actually be removed, they're
just marked for deletion on the next RocksDB "merge" or "compact"
operation.

Author: Konstantin Knizhnik
---
 pageserver/src/object_repository.rs | 1 +
 pageserver/src/object_store.rs      | 3 +++
 pageserver/src/rocksdb_storage.rs   | 4 ++++
 3 files changed, 8 insertions(+)

diff --git a/pageserver/src/object_repository.rs b/pageserver/src/object_repository.rs
index 70b804cc26..1a8af822bb 100644
--- a/pageserver/src/object_repository.rs
+++ b/pageserver/src/object_repository.rs
@@ -623,6 +623,7 @@ impl ObjectTimeline {
             result.elapsed = now.elapsed();
             info!("Garbage collection completed in {:?}: {} relations inspected, {} version histories truncated, {} versions deleted, {} relations dropped",
                   result.elapsed, &result.n_relations, &result.truncated, &result.deleted, &result.dropped);
+            self.obj_store.compact();
         }
         Ok(())
     }
diff --git a/pageserver/src/object_store.rs b/pageserver/src/object_store.rs
index 56d1392ab8..d1c2b5a09d 100644
--- a/pageserver/src/object_store.rs
+++ b/pageserver/src/object_store.rs
@@ -68,4 +68,7 @@ pub trait ObjectStore: Send + Sync {
 
     /// Unlink object (used by GC). This mehod may actually delete object or just mark it for deletion.
     fn unlink(&self, key: &ObjectKey, lsn: Lsn) -> Result<()>;
+
+    // Compact storage and remove versions marged for deletion
+    fn compact(&self);
 }
diff --git a/pageserver/src/rocksdb_storage.rs b/pageserver/src/rocksdb_storage.rs
index bbf484a06e..6e4c2e31e5 100644
--- a/pageserver/src/rocksdb_storage.rs
+++ b/pageserver/src/rocksdb_storage.rs
@@ -207,6 +207,10 @@ impl ObjectStore for RocksObjectStore {
             lsn,
         }))
     }
+
+    fn compact(&self) {
+        self.db.compact_range::<&[u8], &[u8]>(None, None);
+    }
 }
 
 impl RocksObjectStore {