From ef1472b3303ad22c3dc1aad2a7d63c229eb5d061 Mon Sep 17 00:00:00 2001
From: Adam Holmberg <Adam.Holmberg@datastax.com>
Date: Wed, 11 Feb 2015 11:46:26 -0600
Subject: [PATCH] Added some additional logging around connection setup and
 schema management.

---
 cassandra/cqlengine/connection.py | 15 +++++++++++++++
 cassandra/cqlengine/exceptions.py |  1 +
 cassandra/cqlengine/management.py | 14 ++++++++++++--
 cassandra/cqlengine/models.py     |  1 -
 4 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/cassandra/cqlengine/connection.py b/cassandra/cqlengine/connection.py
index 6c5d4152..253598c2 100644
--- a/cassandra/cqlengine/connection.py
+++ b/cassandra/cqlengine/connection.py
@@ -45,10 +45,16 @@ def default():
     (except for row_factory)
     """
     global cluster, session
+
+    if session:
+        log.warn("configuring new connection for cqlengine when one was already set")
+
     cluster = Cluster()
     session = cluster.connect()
     session.row_factory = dict_factory
 
+    log.debug("cqlengine connection initialized with default session to localhost")
+
 
 def set_session(s):
     """
@@ -58,11 +64,17 @@ def set_session(s):
     This may be relaxed in the future
     """
     global cluster, session
+
+    if session:
+        log.warn("configuring new connection for cqlengine when one was already set")
+
     if s.row_factory is not dict_factory:
         raise CQLEngineException("Failed to initialize: 'Session.row_factory' must be 'dict_factory'.")
     session = s
     cluster = s.cluster
 
+    log.debug("cqlengine connection initialized with %s", s)
+
 
 def setup(
         hosts,
@@ -104,8 +116,10 @@ def setup(
     cluster = Cluster(hosts, **kwargs)
     try:
         session = cluster.connect()
+        log.debug("cqlengine connection initialized with internally created session")
     except NoHostAvailable:
         if retry_connect:
+            log.warn("connect failed, setting up for re-attempt on first use")
             kwargs['default_keyspace'] = default_keyspace
             kwargs['consistency'] = consistency
             kwargs['lazy_connect'] = False
@@ -157,6 +171,7 @@ def get_cluster():
 def handle_lazy_connect():
     global lazy_connect_args
     if lazy_connect_args:
+        log.debug("lazy connect")
         hosts, kwargs = lazy_connect_args
         lazy_connect_args = None
         setup(hosts, **kwargs)
diff --git a/cassandra/cqlengine/exceptions.py b/cassandra/cqlengine/exceptions.py
index 09327687..6bc6e624 100644
--- a/cassandra/cqlengine/exceptions.py
+++ b/cassandra/cqlengine/exceptions.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+
 class CQLEngineException(Exception):
     pass
 
diff --git a/cassandra/cqlengine/management.py b/cassandra/cqlengine/management.py
index 7c7fcff4..958d252f 100644
--- a/cassandra/cqlengine/management.py
+++ b/cassandra/cqlengine/management.py
@@ -130,12 +130,14 @@ def _create_keyspace(name, durable_writes, strategy_class, strategy_options):
     else:
         log.info("Not creating keyspace %s because it already exists", name)
 
+
 def delete_keyspace(name):
     msg = "Deprecated. Use drop_keyspace instead"
     warnings.warn(msg, DeprecationWarning)
     log.warn(msg)
     drop_keyspace(name)
 
+
 def drop_keyspace(name):
     """
     Drops a keyspace, if it exists.
@@ -156,6 +158,8 @@ def sync_table(model):
     """
     Inspects the model and creates / updates the corresponding table and columns.
 
+    This function can only add fields that are not part of the primary key.
+
     Note that the attributes removed from the model are not deleted on the database.
     They become effectively ignored by (will not show up on) the model.
 
@@ -184,6 +188,7 @@ def sync_table(model):
 
     # check for an existing column family
     if raw_cf_name not in tables:
+        log.debug("sync_table creating new table %s", cf_name)
         qs = get_create_table(model)
 
         try:
@@ -194,20 +199,26 @@ def sync_table(model):
             if "Cannot add already existing column family" not in unicode(ex):
                 raise
     else:
+        log.debug("sync_table checking existing table %s", cf_name)
         # see if we're missing any columns
         fields = get_fields(model)
         field_names = [x.name for x in fields]
+        model_fields = set()
         for name, col in model._columns.items():
             if col.primary_key or col.partition_key:
                 continue  # we can't mess with the PK
+            model_fields.add(name)
             if col.db_field_name in field_names:
                 continue  # skip columns already defined
 
             # add missing column using the column def
             query = "ALTER TABLE {} add {}".format(cf_name, col.get_column_def())
-            log.debug(query)
             execute(query)
 
+        db_fields_not_in_model = model_fields.symmetric_difference(field_names)
+        if db_fields_not_in_model:
+            log.info("Table %s has fields not referenced by model: %s", cf_name, db_fields_not_in_model)
+
         update_compaction(model)
 
     table = cluster.metadata.keyspaces[ks_name].tables[raw_cf_name]
@@ -391,7 +402,6 @@ def update_compaction(model):
         options = json.dumps(options).replace('"', "'")
         cf_name = model.column_family_name()
         query = "ALTER TABLE {} with compaction = {}".format(cf_name, options)
-        log.debug(query)
         execute(query)
         return True
 
diff --git a/cassandra/cqlengine/models.py b/cassandra/cqlengine/models.py
index 85d432b8..980dffc5 100644
--- a/cassandra/cqlengine/models.py
+++ b/cassandra/cqlengine/models.py
@@ -42,7 +42,6 @@ class hybrid_classmethod(object):
     Allows a method to behave as both a class method and
     normal instance method depending on how it's called
     """
-
     def __init__(self, clsmethod, instmethod):
         self.clsmethod = clsmethod
         self.instmethod = instmethod