Use MDB_PREV_MULTIPLE

in get_global_output_indices

src/blockchain_db/lmdb/db_lmdb.cpp

@@ -2475,6 +2475,34 @@ void BlockchainLMDB::get_output_global_indices(const uint64_t& amount, const std
         LOG_PRINT_L1("Index: " << index << " Elems: " << num_elems << " partial results found for get_output_tx_and_index");
         break;
       }
+      if (!curcount && index > num_elems/2)
+      {
+        mdb_cursor_get(cur, &k, &v, MDB_LAST_DUP);
+        mdb_cursor_get(cur, &k, &v, MDB_PREV);    /* kludge to unset C_EOF */
+        mdb_cursor_get(cur, &k, &v, MDB_NEXT);
+        mdb_cursor_get(cur, &k, &v, MDB_GET_MULTIPLE);
+
+        curcount = num_elems;
+        while(1)
+        {
+          TIME_MEASURE_START(db1);
+          int count = v.mv_size / sizeof(uint64_t);
+          curcount -= count;
+          if (curcount > index)
+          {
+            mdb_cursor_get(cur, &k, &v, MDB_PREV_MULTIPLE);
+          } else
+          {
+            blockstart = curcount;
+            curcount += count;
+            break;
+          }
+          TIME_MEASURE_FINISH(db1);
+          t_dbmul += db1;
+        }
+
+      } else
+      {
         while (index >= curcount)
         {
           TIME_MEASURE_START(db1);
@@ -2492,6 +2520,7 @@ void BlockchainLMDB::get_output_global_indices(const uint64_t& amount, const std
           TIME_MEASURE_FINISH(db1);
           t_dbmul += db1;
         }
+      }
 
       LOG_PRINT_L3("Records returned: " << curcount << " Index: " << index);
       TIME_MEASURE_START(db2);