test/cluster/dtest: wide_rows_test.py: fix key_appearance accumulation

In validate_entities_recognized_as_large(), key_appearance was
overwritten on each loop iteration instead of being accumulated.
This meant that for entity_type == "cell" in multi-node clusters,
entities_count only reflected the last node's count rather than
the total across all nodes. Fix by using += to accumulate.

Update expected_entity_number in test_large_cell_in_materialized_view
to account for RF=3 replication (each cell appears on all 3 nodes).

Bug inherited from scylla-dtest.

SCYLLA-VERSION-GEN

@@ -78,7 +78,7 @@ fi
 
 # Default scylla product/version tags
 PRODUCT=scylla
-VERSION=2026.2.0-rc0
+VERSION=2026.3.0-dev
 
 if test -f version
 then

test/cluster/dtest/ccmlib/scylla_cluster.py

@@ -227,6 +227,11 @@ class ScyllaCluster:
     def flush(self) -> None:
         self.nodetool("flush")
 
+    def compact(self, keyspace: str = "", tables: list[str] | None = None) -> None:
+        for node in self.nodelist():
+            if node.is_running():
+                node.compact(keyspace=keyspace, tables=tables)
+
     @staticmethod
     def debug(message: str) -> None:
         logger.debug(message)

test/cluster/dtest/ccmlib/scylla_node.py

@@ -111,6 +111,7 @@ class ScyllaNode:
         self.data_center = server.datacenter
         self.rack = server.rack
 
+        self._hostid = None
         self._smp_set_during_test = None
         self._smp = None
         self._memory = None
@@ -465,6 +466,9 @@ class ScyllaNode:
         if wait_for_binary_proto:
             self.wait_for_binary_interface(from_mark=self.mark)
 
+        if not self._hostid:
+            self.hostid()
+
         if wait_other_notice:
             timeout = self.cluster.default_wait_other_notice_timeout
             for node, mark in marks:
@@ -647,11 +651,12 @@ class ScyllaNode:
             cmd.append(table)
         self.nodetool(" ".join(cmd), **kwargs)
 
-    def compact(self, keyspace: str = "", tables: str | None = ()) -> None:
+    def compact(self, keyspace: str = "", tables: list[str] | None = None) -> None:
         compact_cmd = ["compact"]
         if keyspace:
             compact_cmd.append(keyspace)
-        compact_cmd += tables
+        if tables:
+            compact_cmd.extend(tables)
         self.nodetool(" ".join(compact_cmd))
 
     def drain(self, block_on_log: bool = False) -> None:
@@ -824,10 +829,13 @@ class ScyllaNode:
         assert timeout is None, "argument `timeout` is not supported"  # not used in scylla-dtest
         assert force_refresh is None, "argument `force_refresh` is not supported"  # not used in scylla-dtest
 
-        try:
-            return self.cluster.manager.get_host_id(server_id=self.server_id)
-        except Exception as exc:
-            self.error(f"Failed to get hostid: {exc}")
+        if not self._hostid:
+            try:
+                self._hostid = self.cluster.manager.get_host_id(server_id=self.server_id)
+            except Exception as exc:
+                self.error(f"Failed to get hostid: {exc}")
+
+        return self._hostid
 
     def rmtree(self, path: str | Path) -> None:
         """Delete a directory content without removing the directory.

test/cluster/dtest/tools/assertions.py

@@ -263,3 +263,25 @@ def assert_lists_equal_ignoring_order(list1, list2, sort_key=None):
         sorted_list2 = sorted(normalized_list2, key=lambda elm: str(elm[sort_key]))
 
     assert sorted_list1 == sorted_list2
+
+
+def assert_equal_more_with_deviation(actual, expect, deviation_perc):
+    """
+    Assert actual is within inclusive interval [expected...expected+deviation_perc]
+    @param actual Value inspected
+    @param expect Beginning of expected interval
+    @param deviation_perc allowed percent increase
+    """
+    deviation_high = (expect * (100 + deviation_perc)) / 100
+    assert expect <= actual <= deviation_high, f"Expect result interval  {expect}..{deviation_high}, received {actual}"
+
+
+def assert_less_equal_lists(actual_list, expected_list, msg=None):
+    """
+    Assert actual_list is a subset of the expected list, prints hardcoded or parameterized error message
+    @param actual_list Inspected list
+    @param expected_list List that supposed to include actual_list
+    @param msg Configured message default None.
+    """
+    standardMsg = msg or f"{actual_list} not less than or equal to {expected_list}"
+    assert set(actual_list) <= set(expected_list), standardMsg