Avoid reading PrimaryKey from disk by using PrimaryKeyWithSource

     [java] Result "org.apache.cassandra.test.microbench.index.sai.NEQQueryBench.queryNEQ":
     [java]   17761666.739 ±(99.9%) 260418.205 ns/op [Average]
     [java]   (min, avg, max) = (17644295.340, 17761666.739, 18241636.689), stdev = 172250.519
     [java]   CI (99.9%): [17501248.533, 18022084.944] (assumes normal distribution)
     [java]
     [java]
     [java] # Run complete. Total time: 00:07:36
     [java]
     [java] REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
     [java] why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
     [java] experiments, perform baseline and negative tests that provide experimental control, make sure
     [java] the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
     [java] Do not assume the numbers tell you what you want them to tell.
     [java]
     [java] Benchmark               (numRowsWithinPartition)  Mode  Cnt         Score        Error  Units
     [java] NEQQueryBench.queryNEQ                      1000  avgt   10   2169861.695 ±  11355.830  ns/op
     [java] NEQQueryBench.queryNEQ                     10000  avgt   10  17761666.739 ± 260418.205  ns/op

Author: michaeljmarshall

src/java/org/apache/cassandra/index/sai/disk/PrimaryKeyMapIterator.java

@@ -110,7 +110,7 @@ protected PrimaryKey computeNext()
     {
         while (currentRowId >= 0 && currentRowId < keys.count())
         {
-            PrimaryKey key = keys.primaryKeyFromRowId(currentRowId++);
+            PrimaryKey key = keys.primaryKeyFromRowId(currentRowId++, getMinimum(), getMaximum());
             if (filter == KeyFilter.KEYS_WITH_CLUSTERING && key.hasEmptyClustering())
                 continue;
             return key;