On May 27, 2008, at 3:21 PM, Waldemar Osuch wrote:
> Quote:
>
> Up to this point the default arraysize is 1 meaning that a single row
> is internally fetched at a time. This has nothing to do with
> fetchone(), fetchmany() or fetchall(). Regardless of which of those
> methods is used, internally cx_Oracle fetches one row at a time. If
> you change the arraysize to 50, internally cx_Oracle will fetch 50
> rows at a time. Again, this is regardless of whether you use
> fetchone(), fetchmany() or fetchall(). Some of the confusion may lie
> in the fact that the default value for rows to fetch in fetchmany() is
> the arraysize -- but that is all it is, a default value!
see, that's a really unfortunate decision on his part to reuse
"arraysize" in such an arbitrary way like that, while *not* using it
at the point at which it is entirely reasonable, that is when you have
already stated you want to fetchmany(n) or fetchall(). This is
totally a bug in cx_oracle.
>
> class MyConnection(cx_Oracle.Connection):
>
> def cursor(self):
> cursor = cx_Oracle.Cursor(self)
> cursor.arraysize = 50
> return cursor
>
> What this does is automatically set the arraysize to 50 every time a
> cursor is created. This can be done to transparently set the arraysize
> and should allow you to proceed with whatever code needs to assume an
> arraysize of that value. Otherwise you can feel free to change it
> yourself after creating the cursor.
>
> And as has already been noted, in the next release of cx_Oracle, the
> default arraysize will be 50 in order to resolve this problem
> "permanently". :-)
that workaround works, and also implementing "default_arraysize"
within OracleDialect as follows is acceptable. If someone can test
this and post a trac ticket I can commit this to 0.4/0.5:
Index: lib/sqlalchemy/databases/oracle.py
===================================================================
--- lib/sqlalchemy/databases/oracle.py (revision 4819)
+++ lib/sqlalchemy/databases/oracle.py (working copy)
@@ -213,6 +213,12 @@
self.out_parameters[name] =
self.cursor.var(dbtype)
self.parameters[0][name] =
self.out_parameters[name]
+ def create_cursor(self):
+ cursor = self._connection.connection.cursor()
+ if self.dialect.default_arraysize:
+ cursor.arraysize = self.dialect.default_arraysize
+ return cursor
+
def get_result_proxy(self):
if hasattr(self, 'out_parameters'):
if self.compiled_parameters is not None and
len(self.compiled_parameters) == 1:
@@ -242,8 +248,9 @@
supports_pk_autoincrement = False
default_paramstyle = 'named'
- def __init__(self, use_ansi=True, auto_setinputsizes=True,
auto_convert_lobs=True, threaded=True, allow_twophase=True, **kwargs):
+ def __init__(self, use_ansi=True, auto_setinputsizes=True,
auto_convert_lobs=True, threaded=True, allow_twophase=True,
default_arraysize=None, **kwargs):
default.DefaultDialect.__init__(self, **kwargs)
+ self.default_arraysize = default_arraysize
self.use_ansi = use_ansi
self.threaded = threaded
self.allow_twophase = allow_twophase
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