#312 Fix handling of min value as token upper bound

Summary:
In Cassandra using min token value (INT64_MIN) as an upper bound is specially interpreted to
include all token hashes (rather than none).
This behavior is used, for instance, by Presto when splitting the entire token range into
partitions.

Test Plan: jenkins, ql-query-test.cc

Reviewers: pritam.damania, robert

Reviewed By: robert

Subscribers: yql

Differential Revision: https://phabricator.dev.yugabyte.com/D4911

src/yb/yql/cql/ql/exec/eval_where.cc

@@ -96,16 +96,24 @@ CHECKED_STATUS Executor::WhereClauseToPB(QLReadRequestPB *req,
         req->set_hash_code(hash_code);
         break;
       case QL_OP_LESS_THAN:
-        if (hash_code > YBPartition::kMinHashCode) {
-          req->set_max_hash_code(hash_code - 1);
-        } else {
-          // Token hash smaller than min implies no results.
-          *no_results = true;
-          return Status::OK();
+        // Cassandra treats INT64_MIN upper bound as special case that includes everything (i.e. it
+        // adds no real restriction). So we skip (do nothing) in that case.
+        if (result.int64_value() != INT64_MIN) {
+          if (hash_code > YBPartition::kMinHashCode) {
+            req->set_max_hash_code(hash_code - 1);
+          } else {
+            // Token hash smaller than min implies no results.
+            *no_results = true;
+            return Status::OK();
+          }
         }
         break;
       case QL_OP_LESS_THAN_EQUAL:
-        req->set_max_hash_code(hash_code);
+        // Cassandra treats INT64_MIN upper bound as special case that includes everything (i.e. it
+        // adds no real restriction). So we skip (do nothing) in that case.
+        if (result.int64_value() != INT64_MIN) {
+          req->set_max_hash_code(hash_code);
+        }
         break;
       case QL_OP_EQUAL:
         req->set_hash_code(hash_code);

src/yb/yql/cql/ql/test/ql-query-test.cc

@@ -1473,6 +1473,29 @@ TEST_F(TestQLQuery, TestScanWithBounds) {
       Substitute(select_stmt_template, "<=", std::get<0>(rows[9]), ">", INT64_MAX), processor, rows,
       0, 0);
 
+  //------------------------------------------------------------------------------------------------
+  // Testing Select with token range limits
+  //------------------------------------------------------------------------------------------------
+  // Entire range: [min, max].
+  TestSelectWithoutOrderBy(
+      Substitute(select_stmt_template, ">=", INT64_MIN, "<=", INT64_MAX), processor, rows, 0, 10);
+
+  // Entire range: [min, min] (upper bound min is treated as a special case in Cassandra).
+  TestSelectWithoutOrderBy(
+      Substitute(select_stmt_template, ">=", INT64_MIN, "<=", INT64_MIN), processor, rows, 0, 10);
+
+  // Entire range: [min, min). (upper bound min is treated as a special case in Cassandra).
+  TestSelectWithoutOrderBy(
+      Substitute(select_stmt_template, ">=", INT64_MIN, "<", INT64_MIN), processor, rows, 0, 10);
+
+  // Empty range: (max, max].
+  TestSelectWithoutOrderBy(
+      Substitute(select_stmt_template, ">", INT64_MAX, "<=", INT64_MAX), processor, rows, 0, 0);
+
+  // Empty range: (max, min] (max as strict lower bound already excludes all hashes).
+  TestSelectWithoutOrderBy(
+      Substitute(select_stmt_template, ">", INT64_MAX, "<=", INT64_MIN), processor, rows, 0, 0);
+
   //------------------------------------------------------------------------------------------------
   // Testing Select with exact partition key (equal condition with token)
   //------------------------------------------------------------------------------------------------