Turn on random access for Syzygy files in Windows (#1840)

[stockfish] / src / syzygy / tbprobe.cpp

diff --git a/src/syzygy/tbprobe.cpp b/src/syzygy/tbprobe.cpp
index 60979a5687409a41001e93332f0019ffcae3e330..57c7d872e1b496a104774582de1a07838b4587af 100644 (file)
--- a/src/syzygy/tbprobe.cpp
+++ b/src/syzygy/tbprobe.cpp
@@ -224,8 +224,9 @@ public:
             exit(1);
         }
 #else
+        // Note FILE_FLAG_RANDOM_ACCESS is only a hint to Windows and as such may get ignored.
         HANDLE fd = CreateFile(fname.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr,
-                               OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+                               OPEN_EXISTING, FILE_FLAG_RANDOM_ACCESS, nullptr);
 
         if (fd == INVALID_HANDLE_VALUE)
             return *baseAddress = nullptr, nullptr;