Backport to branch(3.15) : Fix for admin.getNamespaceNames() when used with DynamoDB with the namespace prefix setting (#2658)

Co-authored-by: Vincent Guilpain <[email protected]>

Author: feeblefakie

core/src/main/java/com/scalar/db/storage/dynamo/DynamoAdmin.java

@@ -1278,8 +1278,9 @@ private Set<String> getNamespacesOfExistingTables() throws ExecutionException {
 
       for (Map<String, AttributeValue> tableMetadata : scanResponse.items()) {
         String fullTableName = tableMetadata.get(METADATA_ATTR_TABLE).s();
-        String namespaceName = fullTableName.substring(0, fullTableName.indexOf('.'));
-        nonPrefixedNamespaceNames.add(namespaceName);
+        String prefixedNamespaceName = fullTableName.substring(0, fullTableName.indexOf('.'));
+        String nonPrefixedNamespaceName = prefixedNamespaceName.substring(namespacePrefix.length());
+        nonPrefixedNamespaceNames.add(nonPrefixedNamespaceName);
       }
     } while (!lastEvaluatedKey.isEmpty());
 

core/src/test/java/com/scalar/db/storage/dynamo/DynamoAdminTestBase.java

@@ -1243,20 +1243,23 @@ public void getNamespaceNames_WithExistingTables_ShouldWorkProperly() throws Exe
     when(scanResponse.lastEvaluatedKey())
         .thenReturn(lastEvaluatedKeyFirstIteration)
         .thenReturn(lastEvaluatedKeySecondIteration);
+    String ns1 = getNamespacePrefixConfig().orElse("") + "ns1";
+    String ns2 = getNamespacePrefixConfig().orElse("") + "ns2";
+    when(scanResponse.count()).thenReturn(2);
     when(scanResponse.items())
         .thenReturn(
             ImmutableList.of(
                 ImmutableMap.of(
                     DynamoAdmin.METADATA_ATTR_TABLE,
-                    AttributeValue.builder().s("ns1.tbl1").build())))
+                    AttributeValue.builder().s(ns1 + ".tbl1").build())))
         .thenReturn(
             ImmutableList.of(
                 ImmutableMap.of(
                     DynamoAdmin.METADATA_ATTR_TABLE,
-                    AttributeValue.builder().s("ns1.tbl2").build()),
+                    AttributeValue.builder().s(ns1 + ".tbl2").build()),
                 ImmutableMap.of(
                     DynamoAdmin.METADATA_ATTR_TABLE,
-                    AttributeValue.builder().s("ns2.tbl3").build())));
+                    AttributeValue.builder().s(ns2 + ".tbl3").build())));
 
     // Act
     Set<String> actual = admin.getNamespaceNames();