From c3c13db346749c3dfe45e167db2129c645377e9e Mon Sep 17 00:00:00 2001
From: Haobo Xu <haobo@fb.com>
Date: Mon, 20 May 2013 21:28:09 -0700
Subject: [PATCH] [RocksDB] [Performance Bug] MemTable::Get Slow

Summary:
The merge operator diff introduced a performance problem in MemTable::Get.
An exit condition is missed when the current key does not match the user key.
This could lead to full memtable scan if the user key is not found.

Test Plan: make check; db_bench

Reviewers: dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10851
---
 db/memtable.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/db/memtable.cc b/db/memtable.cc
index 097b60ff5..7a7c6bb7a 100644
--- a/db/memtable.cc
+++ b/db/memtable.cc
@@ -185,6 +185,9 @@ bool MemTable::Get(const LookupKey& key, std::string* value, Status* s,
           return true;
         }
       }
+    } else {
+      // exit loop if user key does not match
+      break;
     }
   }