- The functionality of result.rowcount is now disabled

by default, and can be re-enabled using the 'enable_rowcount'
flag with create_engine(), as well as the 'enable_rowcount'
execution context flag on a per-execute basis.  This because
cursor.rowcount requires cursor access (can't be evaluated
lazily since the result auto-closes) and also incurs an
expensive round-trip.

1 files changed, 34 insertions, 9 deletions

diff --git a/lib/sqlalchemy/dialects/firebird/kinterbasdb.py b/lib/sqlalchemy/dialects/firebird/kinterbasdb.py
index 9984d32a2..890ba83fe 100644
--- a/lib/sqlalchemy/dialects/firebird/kinterbasdb.py
+++ b/lib/sqlalchemy/dialects/firebird/kinterbasdb.py
@@ -13,21 +13,34 @@ The connection URL is of the form
 
 Kinterbasedb backend specific keyword arguments are:
 
-type_conv
-  select the kind of mapping done on the types: by default SQLAlchemy
+* type_conv - select the kind of mapping done on the types: by default SQLAlchemy
   uses 200 with Unicode, datetime and decimal support (see details__).
 
-concurrency_level
-  set the backend policy with regards to threading issues: by default
+* concurrency_level - set the backend policy with regards to threading issues: by default
   SQLAlchemy uses policy 1 (see details__).
 
+* enable_rowcount - False by default, this enables the usage of "cursor.rowcount" with the 
+  Kinterbasdb dialect.   When disabled, SQLAlchemy's ResultProxy will
+  return -1 for result.rowcount.   The rationale here is that Kinterbasdb
+  requires a second round trip to the database when .rowcount is called - 
+  since SQLA's resultproxy automatically closes the cursor after a 
+  non-result-returning statement, rowcount must be called, if at all,
+  before the result object is returned.   The behavior can also be 
+  controlled on a per-execution basis using the `enable_rowcount`
+  option with :meth:`execution_options()`::
+  
+      conn = engine.connect().execution_options(enable_rowcount=True)
+      r = conn.execute(stmt)
+      print r.rowcount
+  
 __ http://sourceforge.net/projects/kinterbasdb
 __ http://firebirdsql.org/index.php?op=devel&sub=python
 __ http://kinterbasdb.sourceforge.net/dist_docs/usage.html#adv_param_conv_dynamic_type_translation
 __ http://kinterbasdb.sourceforge.net/dist_docs/usage.html#special_issue_concurrency
 """
 
-from sqlalchemy.dialects.firebird.base import FBDialect, FBCompiler
+from sqlalchemy.dialects.firebird.base import FBDialect, \
+                                    FBCompiler, FBExecutionContext
 from sqlalchemy import util, types as sqltypes
 
 class _FBNumeric_kinterbasdb(sqltypes.Numeric):
@@ -38,11 +51,21 @@ class _FBNumeric_kinterbasdb(sqltypes.Numeric):
             else:
                 return value
         return process
-        
+
+class FBExecutionContext_kinterbasdb(FBExecutionContext):
+    @property
+    def rowcount(self):
+        if self.execution_options.get('enable_rowcount', 
+                                        self.dialect.enable_rowcount):
+            return self.cursor.rowcount
+        else:
+            return -1
+            
 class FBDialect_kinterbasdb(FBDialect):
     driver = 'kinterbasdb'
     supports_sane_rowcount = False
     supports_sane_multi_rowcount = False
+    execution_ctx_cls = FBExecutionContext_kinterbasdb
     
     supports_native_decimal = True
     
@@ -54,12 +77,14 @@ class FBDialect_kinterbasdb(FBDialect):
         
     )
     
-    def __init__(self, type_conv=200, concurrency_level=1, **kwargs):
+    def __init__(self, type_conv=200, concurrency_level=1, enable_rowcount=False, **kwargs):
         super(FBDialect_kinterbasdb, self).__init__(**kwargs)
-
+        self.enable_rowcount = enable_rowcount
         self.type_conv = type_conv
         self.concurrency_level = concurrency_level
-
+        if enable_rowcount:
+            self.supports_sane_rowcount = True
+        
     @classmethod
     def dbapi(cls):
         k = __import__('kinterbasdb')