diff --git a/src/overpass_api/core/basic_types.h b/src/overpass_api/core/basic_types.h
index be44195d2..48c865ac3 100644
--- a/src/overpass_api/core/basic_types.h
+++ b/src/overpass_api/core/basic_types.h
@@ -48,20 +48,10 @@ struct Uint32_Index
   bool leq(void* rhs) const { return value <= *(uint32*)rhs; }
   bool equal(void* rhs) const { return value == *(uint32*)rhs; }
 
-  uint32 size_of() const
-  {
-    return 4;
-  }
-
-  static uint32 max_size_of()
-  {
-    return 4;
-  }
-
-  static uint32 size_of(void* data)
-  {
-    return 4;
-  }
+  uint32 size_of() const { return 4; }
+  static constexpr uint32 const_size() { return 4; }
+  static uint32 max_size_of() { return 4; }
+  static uint32 size_of(void* data) { return 4; }
 
   void to_data(void* data) const
   {
@@ -187,6 +177,7 @@ struct Uint64
   bool equal(void* rhs) const { return value == *(uint32*)rhs; }
 
   uint32 size_of() const { return 8; }
+  static constexpr uint32 const_size() { return 8; }
   static uint32 max_size_of() { return 8; }
   static uint32 size_of(void* data) { return 8; }
 
diff --git a/src/overpass_api/core/datatypes.h b/src/overpass_api/core/datatypes.h
index 9bbd794ec..0b44ecc73 100644
--- a/src/overpass_api/core/datatypes.h
+++ b/src/overpass_api/core/datatypes.h
@@ -693,15 +693,9 @@ struct Timestamp
   bool equal(void* rhs) const
   { return (timestamp>>32) == *(((uint8*)rhs) + 4) && (timestamp & 0xffffffffull) == *(uint32*)rhs; }
 
-  uint32 size_of() const
-  {
-    return 5;
-  }
-
-  static uint32 size_of(void* data)
-  {
-    return 5;
-  }
+  uint32 size_of() const { return 5; }
+  static constexpr uint32 const_size() { return 5; }
+  static uint32 size_of(void* data) { return 5; }
 
   void to_data(void* data) const
   {
diff --git a/src/overpass_api/core/type_tags.h b/src/overpass_api/core/type_tags.h
index f033ac246..a4d6b4d0f 100644
--- a/src/overpass_api/core/type_tags.h
+++ b/src/overpass_api/core/type_tags.h
@@ -125,6 +125,8 @@ struct Tag_Index_Local
     return 7 + key.length() + value.length();
   }
 
+  static constexpr uint32 const_size() { return 0; }
+
   static uint32 size_of(void* data)
   {
     return (*((uint16*)data) + *((uint16*)data + 1) + 7);
@@ -303,6 +305,8 @@ struct Tag_Index_Global
     return 4 + key.length() + value.length();
   }
 
+  static constexpr uint32 const_size() { return 0; }
+
   static uint32 size_of(void* data)
   {
     return (*((uint16*)data) + *((uint16*)data + 1) + 4);
diff --git a/src/template_db/block_backend.test.cc b/src/template_db/block_backend.test.cc
index 93b315a4d..d171004e8 100644
--- a/src/template_db/block_backend.test.cc
+++ b/src/template_db/block_backend.test.cc
@@ -46,15 +46,9 @@ struct IntIndex
   bool leq(void* rhs) const { return value <= *(uint32*)rhs; }
   bool equal(void* rhs) const { return value == *(uint32*)rhs; }
 
-  uint32 size_of() const
-  {
-    return 4;
-  }
-
-  static uint32 size_of(void* data)
-  {
-    return 4;
-  }
+  uint32 size_of() const { return 4; }
+  static constexpr uint32 const_size() { return 4; }
+  static uint32 size_of(void* data) { return 4; }
 
   void to_data(void* data) const
   {
diff --git a/src/template_db/dispatcher.test.cc b/src/template_db/dispatcher.test.cc
index 078c64565..4ac471ed8 100644
--- a/src/template_db/dispatcher.test.cc
+++ b/src/template_db/dispatcher.test.cc
@@ -44,20 +44,10 @@ struct IntIndex
   bool leq(void* rhs) const { return value <= *(uint32*)rhs; }
   bool equal(void* rhs) const { return value == *(uint32*)rhs; }
 
-  uint32 size_of() const
-  {
-    return 4;
-  }
-
-  static uint32 size_of(void* data)
-  {
-    return 4;
-  }
-
-  static uint32 max_size_of()
-  {
-    return 4;
-  }
+  uint32 size_of() const { return 4; }
+  static constexpr uint32 const_size() { return 4; }
+  static uint32 size_of(void* data) { return 4; }
+  static uint32 max_size_of() { return 4; }
 
   void to_data(void* data) const
   {
diff --git a/src/template_db/file_blocks.test.cc b/src/template_db/file_blocks.test.cc
index e56de219e..415a65b4e 100644
--- a/src/template_db/file_blocks.test.cc
+++ b/src/template_db/file_blocks.test.cc
@@ -43,6 +43,7 @@ struct IntIndex
   bool equal(void* rhs) const { return value == *(uint32*)rhs; }
   
   uint32 size_of() const { return (value < 24 ? 12 : value-12); }
+  static constexpr uint32 const_size() { return 0; }
   static uint32 size_of(void* data) { return ((*(uint32*)data) < 24 ? 12 : (*(uint32*)data)-12); }
 
   void to_data(void* data) const
diff --git a/src/template_db/file_blocks_index.h b/src/template_db/file_blocks_index.h
index a5beda9bf..4ef279203 100644
--- a/src/template_db/file_blocks_index.h
+++ b/src/template_db/file_blocks_index.h
@@ -325,11 +325,39 @@ inline uint64 file_size_of(const std::string& data_file_name)
 }
 
 
+template< typename Index >
+const uint8* binary_seek(const uint8* begin, const uint8* end, const Index& target)
+{
+  auto min = begin;
+  auto max = end;
+  while (max - min > 2*(Index::const_size() + 12))
+  {
+    auto middle = min + ((max - min)/(Index::const_size() + 12)/2*(Index::const_size() + 12));
+    if (target.less((void*)(middle+12)))
+      max = middle;
+    else
+      min = middle;
+  }
+  return min;
+}
+
+
 template< typename Index >
 void File_Blocks_Index_Iterator< Index >::seek(const Index& target)
 {
   if (ptr == end || target.less((void*)(ptr+12)))
     return;
+  if (Index::const_size() && ((end - ptr) > 32*(Index::const_size() + 12))
+      && !target.less((void*)(ptr + 32*(Index::const_size() + 12) + 12)))
+  {
+    decltype(ptr) next = binary_seek(ptr, end, target);
+    if (next != end)
+    {
+      while (ptr < next && target.equal((void*)(next+12)))
+        next -= (Index::const_size() + 12);
+    }
+    ptr = next;
+  }
   while (!target.equal((void*)(ptr+12)))
   {
     decltype(ptr) next = ptr+12;