diff --git a/asterix-app/src/test/resources/optimizerts/results/consolidate-selects-complex.plan b/asterix-app/src/test/resources/optimizerts/results/consolidate-selects-complex.plan
index f8bd22d..3abde90 100644
--- a/asterix-app/src/test/resources/optimizerts/results/consolidate-selects-complex.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/consolidate-selects-complex.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_01.plan b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_01.plan
index 9d2d60b..3fbd339 100644
--- a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_01.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_01.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_02.plan b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_02.plan
index 8cad02f..e3baddf 100644
--- a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_02.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive-open_02.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_01.plan b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_01.plan
index 9d2d60b..3fbd339 100644
--- a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_01.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_01.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_02.plan b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_02.plan
index 8cad02f..e3baddf 100644
--- a/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_02.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/orders-index-search-conjunctive_02.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/q01_pricing_summary_report_nt.plan b/asterix-app/src/test/resources/optimizerts/results/q01_pricing_summary_report_nt.plan
index 97c7b80..fb35c0c 100644
--- a/asterix-app/src/test/resources/optimizerts/results/q01_pricing_summary_report_nt.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/q01_pricing_summary_report_nt.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC), $$2(ASC)] HASH:[$$1, $$2]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC), $$3(ASC)] HASH:[$$2, $$3]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index-open.plan b/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index-open.plan
index d86e4f5..f77dc35 100644
--- a/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index-open.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index-open.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index.plan b/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index.plan
index d86e4f5..f77dc35 100644
--- a/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/rtree-secondary-index.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan b/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan
index 83a29cc..2d3d8fc 100644
--- a/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- COMMIT  |PARTITIONED|
   -- STREAM_PROJECT  |PARTITIONED|
     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/skip-index/skip-rtree-secondary-index.plan b/asterix-app/src/test/resources/optimizerts/results/skip-index/skip-rtree-secondary-index.plan
index 25b65de..1534f6c 100644
--- a/asterix-app/src/test/resources/optimizerts/results/skip-index/skip-rtree-secondary-index.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/skip-index/skip-rtree-secondary-index.plan
@@ -3,10 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
         -- BULKLOAD  |PARTITIONED|
-          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$1(ASC)] HASH:[$$1]  |PARTITIONED|
-            -- DATASOURCE_SCAN  |PARTITIONED|
+          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$2(ASC)] HASH:[$$2]  |PARTITIONED|
+            -- ASSIGN  |PARTITIONED|
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                -- DATASOURCE_SCAN  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
 -- DISTRIBUTE_RESULT  |PARTITIONED|
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|