RE: [sqlalchemy] Storing Nested Lists
-Original Message- From: sqlalchemy@googlegroups.com [mailto:sqlalch...@googlegroups.com] On Behalf Of greg Sent: 25 April 2010 22:59 To: sqlalchemy Subject: [sqlalchemy] Storing Nested Lists Hi All, I'm new to sqlalchemy. I've been reading the documentation and group archives, but can't really find an answer to my question. I suspect it's a question of terminology, and that I don't really know the term for what I'm looking for. Can I map a nested list to one column, and have my nested list returned to me intact? A simple example is a list like: ['a','b','c', ['x','y','z',['m','n','o']]] If anyone can point me in the right direction, I'd much appreciate it. Thanks. If you make the column a PickleType: http://www.sqlalchemy.org/docs/reference/sqlalchemy/types.html#sqlalchem y.types.PickleType ...it should behave as you want. Simon -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Mapping dictionaries with string keys and record values
Hi Michael. On Sun, 2010-04-25 at 22:32 -0400, Michael Bayer wrote: You should be able to roll this yourself as a custom dictlike collection class . That's what I did :-) I wrote mostly to share my code and to suggest that this should be available out of the box. sorry, it seems you've done that already. I'm surprised the existing attribute_mapped_collection doesn't do this already ? I was surprised as well. well, it doesn't. It should, and maybe should raise an error if the two values don't match. It doesn't make much sense to add another collection class to do what the first one should. Agreed. I'm sure you noticed that you can remove the repetition by working the other way, i.e.: item.note.set(Note(key=color, value=blue, desc=This should be blue because)) item.note.set(Note(key=shape, value=rectangular)) Indeed, although I find it unintuitive that set actually does an append/insert/add operation. Apart from that, I try to keep the mapping code and the data objects (which carry application logic) separate in case we ever want to use a non-SQL data backend (NoSQL DB, ZODB, ...). So usually, there is no set method on item.notes and there is no key property in the Note class (it's added by the mapper as _key). also, never do this: class Note(object): def __init__(self, **args): self.__dict__.update(args) That's not production code. I just added it to get initialization in one line. you bypass all of SQLAlchemy's history tracking logic. do this instead: class Note(object): def __init__(self, **args): for k, v in args.items(): setattr(self, k, v) I usually name the possible keyword arguments explicitly as the output of help(Note) is otherwise quite unhelpful. Thanks for your reply and the remarks! Do you plan to extend attribute_mapped_collection to update the key like in my example? Be aware that this approach also has it's downside. For example, assigning item2 = Item() item2.notes['color'] = item.notes['color'] will not work contrary to what one might expect (it generated a conflict on the id column). The solution is to have the target collection copy the assigned object if it has a key already. But that might be too much magic to be easy to understand. So I think, the automatic key update should be an option. Greetings, Torsten -- DYNAmore Gesellschaft fuer Ingenieurdienstleistungen mbH Torsten Landschoff Office Dresden Tel: +49-(0)351-4519587 Fax: +49-(0)351-4519561 mailto:torsten.landsch...@dynamore.de http://www.dynamore.de Registration court: Mannheim, HRB: 109659, based in Karlsruhe, Managing director: Prof. Dr. K. Schweizerhof, Dipl.-Math. U. Franz -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: Storing Nested Lists
Excellent. Thanks very much. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] further restricting a query provided as raw sql
Michael Bayer wrote: Any serious ideas or should I just go sulk in the corner? you have to use IN, and you have to generate the SQL every time based on the number of values you'd like to put into the IN. Does SA have any helper code anywhere for this? Chris -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] correct way to handle 'MySQL server has gone away'?
Chris Withers wrote:
raise exc.InvalidRequestError(Can't reconnect until invalid
transaction is rolled back)
sqlalchemy.exc.InvalidRequestError: Can't reconnect until invalid
transaction is rolled back
Asking here as it sounds like it might be related.
It occurred transiently, though, and appears to have resolved itself
without any intervention. Where would I look to find out what caused the
invalid transaction and how it was rolled back?
We've had this occur again, wondered if anyone had any suggestions...
So, the first error is this:
return session.query(Feed).filter(Feed.enabled==True).all()
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1267, in all
return list(self)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1361, in __iter__
return self._execute_and_instances(context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1364, in _execute_and_instances
result = self.session.execute(querycontext.statement,
params=self._params, mapper=self._mapper_zero_or_none())
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/session.py,
line 753, in execute
clause, params or {})
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 824, in execute
return Connection.executors[c](self, object, multiparams, params)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 874, in _execute_clauseelement
return self.__execute_context(context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 896, in __execute_context
self._cursor_execute(context.cursor, context.statement,
context.parameters[0], context=context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 950, in _cursor_execute
self._handle_dbapi_exception(e, statement, parameters, cursor, context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 931, in _handle_dbapi_exception
raise exc.DBAPIError.instance(statement, parameters, e,
connection_invalidated=is_disconnect)
sqlalchemy.exc.OperationalError: (OperationalError) (2006, 'MySQL server
has gone away') u'SELECT ...
So, my guess is that we're not handling this error correctly.
How should we be handling it?
Anyway, subsequent to this, we got:
return session.query(Feed).filter(Feed.enabled==True).all()
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1267, in all
return list(self)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1361, in __iter__
return self._execute_and_instances(context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1364, in _execute_and_instances
result = self.session.execute(querycontext.statement,
params=self._params, mapper=self._mapper_zero_or_none())
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/session.py,
line 753, in execute
clause, params or {})
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 824, in execute
return Connection.executors[c](self, object, multiparams, params)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 872, in _execute_clauseelement
parameters=params
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 938, in __create_execution_context
return dialect.execution_ctx_cls(dialect, connection=self, **kwargs)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/default.py,
line 170, in __init__
self.cursor = self.create_cursor()
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/default.py,
line 258, in create_cursor
return self._connection.connection.cursor()
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 576, in connection
raise exc.InvalidRequestError(Can't reconnect until invalid
transaction is rolled back)
sqlalchemy.exc.InvalidRequestError: Can't reconnect until invalid
transaction is rolled back
...until the app was restarted.
Any ideas?
cheers,
Chris
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[sqlalchemy] Database locking
Hello, I am using multiple servers to access a sqlite db via sqlachemy. I am using the latest SQLAlchemy and pysqlite-2.6.0. I get permenant locking and it causes mayhem. I did rebuild sqlite to make it --enable-threadsafe. Whats the approach to handle this problem? Thanks, garyc -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Mapping dictionaries with string keys and record values
Torsten Landschoff wrote: Thanks for your reply and the remarks! Do you plan to extend attribute_mapped_collection to update the key like in my example? here's some things to note on that: 1. I'm not sure why it wasn't that way already, and I'd want to hear from Jason Kirtland, its author, on if we are missing something or otherwise whats up. I have a vague notion that there was a reason for this, or maybe not. 2. I wonder if there's a way to make this happen more deeply than within setattr(). Like the collection internals would include an event to operate upon the target object that includes the other args from the collection decorator. 3. corresponding delete() event. Set the attribute on the replaced object to None ? that seems potentially surprising ? Be aware that this approach also has it's downside. For example, assigning item2 = Item() item2.notes['color'] = item.notes['color'] will not work contrary to what one might expect (it generated a conflict on the id column). The solution is to have the target collection copy the assigned object if it has a key already. But that might be too much magic to be easy to understand. the target can only be in one collection at a time so I would think item2's id wins. its a primary key switch. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] correct way to handle 'MySQL server has gone away'?
Chris Withers wrote:
Chris Withers wrote:
raise exc.InvalidRequestError(Can't reconnect until invalid
transaction is rolled back)
sqlalchemy.exc.InvalidRequestError: Can't reconnect until invalid
transaction is rolled back
Asking here as it sounds like it might be related.
It occurred transiently, though, and appears to have resolved itself
without any intervention. Where would I look to find out what caused the
invalid transaction and how it was rolled back?
We've had this occur again, wondered if anyone had any suggestions...
So, the first error is this:
return session.query(Feed).filter(Feed.enabled==True).all()
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1267, in all
return list(self)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1361, in __iter__
return self._execute_and_instances(context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/query.py,
line 1364, in _execute_and_instances
result = self.session.execute(querycontext.statement,
params=self._params, mapper=self._mapper_zero_or_none())
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/orm/session.py,
line 753, in execute
clause, params or {})
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 824, in execute
return Connection.executors[c](self, object, multiparams, params)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 874, in _execute_clauseelement
return self.__execute_context(context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 896, in __execute_context
self._cursor_execute(context.cursor, context.statement,
context.parameters[0], context=context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 950, in _cursor_execute
self._handle_dbapi_exception(e, statement, parameters, cursor,
context)
File
/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.8-py2.5.egg/sqlalchemy/engine/base.py,
line 931, in _handle_dbapi_exception
raise exc.DBAPIError.instance(statement, parameters, e,
connection_invalidated=is_disconnect)
sqlalchemy.exc.OperationalError: (OperationalError) (2006, 'MySQL server
has gone away') u'SELECT ...
So, my guess is that we're not handling this error correctly.
How should we be handling it?
you have to rollback the current transaction, and either throw an error or
try the whole transaction again.
line 576, in connection
raise exc.InvalidRequestError(Can't reconnect until invalid
transaction is rolled back)
sqlalchemy.exc.InvalidRequestError: Can't reconnect until invalid
transaction is rolled back
...until the app was restarted.
MySQL disconnected. your transaction was gone. SQLA will reconnect, but
not until you've let it know that you've agreed to chuck your current
transaction on the app side, since its gone on the DB side.
as always, none of these problems ever occur (well disconnects, but the
app will recover), if you ensure that you are doing:
try:
do_my_stuff()
except:
Session.rollback()
raise
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Re: [sqlalchemy] further restricting a query provided as raw sql
Chris Withers wrote:
Michael Bayer wrote:
Any serious ideas or should I just go sulk in the corner?
you have to use IN, and you have to generate the SQL every time based on
the number of values you'd like to put into the IN.
Does SA have any helper code anywhere for this?
we have the in_() construct. It should be in the ORM and SQL expression
tutorials:
t1 = Table('mytable', metadata, Column('foo', String))
select([t1]).where(t1.c.foo.in_(['a', 'b', 'c']))
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Re: [sqlalchemy] Database locking
gazza wrote: Hello, I am using multiple servers to access a sqlite db via sqlachemy. I am using the latest SQLAlchemy and pysqlite-2.6.0. I get permenant locking and it causes mayhem. I did rebuild sqlite to make it --enable-threadsafe. Whats the approach to handle this problem? one helpful thing is to disable connection pooling. see http://www.sqlalchemy.org/docs/reference/dialects/sqlite.html#threading-behavior . Thanks, garyc -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re-using labels
Let's say I write something like: fixed_column = cast(my_column.op(/)(2**32), Integer).label(fixed_column) print select([fixed_column]).where(fixed_column 100) I get: SELECT CAST(my_column / :my_columnn_1 AS INTEGER) AS fixed_column FROM table WHERE CAST(my_column / :my_column_1 AS INTEGER) :param_1 Is there any reason fixed_column is not re-used in the where statement? Is it possible to make this happen? It would make my statements much more readable. Thanks, - Peter -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Mapping dictionaries with string keys and record values
On Mon, Apr 26, 2010 at 8:24 AM, Michael Bayer mike...@zzzcomputing.com wrote:
Torsten Landschoff wrote:
Thanks for your reply and the remarks! Do you plan to extend
attribute_mapped_collection to update the key like in my example?
here's some things to note on that:
1. I'm not sure why it wasn't that way already, and I'd want to hear from
Jason Kirtland, its author, on if we are missing something or otherwise
whats up. I have a vague notion that there was a reason for this, or
maybe not.
It's not something that can be easily solved in the general case with
the current API. The mapped collections use a 'keyfunc' to figure out
the dictionary key for loaded instances, for example
'operator.attrgetter(name)' for attribute_mapped_collection(name).
Mechanically reversing that logic in a setting operation sounds
pretty hard to me, but perhaps if we allowed an 'assignfunc' function
to be supplied that would do the trick. Internally, the collection
code would call it during a dict['key'] = instance assignment
operation, maybe passing just the key value and the instance:
def assignfunc(key, instance):
instance.name = key
For highly constrained types like the attribute- and column-mapped
collections, these functions would be easy to generate.
A good test for the feature would be a mapped collection that maps a
tuple of attributes, such as one created by
attribute_mapped_collection(('x', 'y')). Assigning collection[1,
2] = instance should assign both instance.x and instance.y in that
case.
2. I wonder if there's a way to make this happen more deeply than within
setattr(). Like the collection internals would include an event to
operate upon the target object that includes the other args from the
collection decorator.
I have a hunch this is only meaningful for mapped collections-
mutations like list_collection[2:5] would be difficult to translate
and I'm not sure what information one would want to capture there.
Worth a look though.
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Re: [sqlalchemy] Mapping dictionaries with string keys and record values
On Mon, 2010-04-26 at 11:24 -0400, Michael Bayer wrote: 2. I wonder if there's a way to make this happen more deeply than within setattr(). Like the collection internals would include an event to operate upon the target object that includes the other args from the collection decorator. Sorry, I was unable to follow you here. You think there should be an event generated to be handled by the collection internals? What arguments of the decorator are you talking about? 3. corresponding delete() event. Set the attribute on the replaced object to None ? that seems potentially surprising ? In my case it did not matter much since the object is owned by the mapped collection. So after the delete, it is garbage collected anyway. As the client code does not know about the key attribute, it would not notice the change anyway even if it still has a pointer. For me this is the same as some code still having a reference to a value that was stored in a dict. If you remove it from the dictionary, you may still keep a reference but it is not reachable anymore from the dict. To make this match with the database, I am using cascade=delete-orphan. item2 = Item() item2.notes['color'] = item.notes['color'] will not work contrary to what one might expect (it generated a conflict on the id column). The solution is to have the target collection copy the assigned object if it has a key already. But that might be too much magic to be easy to understand. the target can only be in one collection at a time so I would think item2's id wins. its a primary key switch. Can't it belong to two collections if there is a secondary join? In plain Python code, both mappings would have a reference to the same object. Greetings, Torsten -- DYNAmore Gesellschaft fuer Ingenieurdienstleistungen mbH Torsten Landschoff Office Dresden Tel: +49-(0)351-4519587 Fax: +49-(0)351-4519561 mailto:torsten.landsch...@dynamore.de http://www.dynamore.de Registration court: Mannheim, HRB: 109659, based in Karlsruhe, Managing director: Prof. Dr. K. Schweizerhof, Dipl.-Math. U. Franz -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Mapping dictionaries with string keys and record values
On Mon, 2010-04-26 at 11:08 -0700, jason kirtland wrote: 1. I'm not sure why it wasn't that way already, and I'd want to hear from Jason Kirtland, its author, on if we are missing something or otherwise whats up. I have a vague notion that there was a reason for this, or maybe not. It's not something that can be easily solved in the general case with the current API. The mapped collections use a 'keyfunc' to figure out the dictionary key for loaded instances, for example 'operator.attrgetter(name)' for attribute_mapped_collection(name). Mechanically reversing that logic in a setting operation sounds pretty hard to me, but perhaps if we allowed an 'assignfunc' function to be supplied that would do the trick. Internally, the collection I agree. The idea of an assignfunc crossed my mind as well. Greetings, Torsten -- DYNAmore Gesellschaft fuer Ingenieurdienstleistungen mbH Torsten Landschoff Office Dresden Tel: +49-(0)351-4519587 Fax: +49-(0)351-4519561 mailto:torsten.landsch...@dynamore.de http://www.dynamore.de Registration court: Mannheim, HRB: 109659, based in Karlsruhe, Managing director: Prof. Dr. K. Schweizerhof, Dipl.-Math. U. Franz -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: Database locking
Thanks Michael. Not sure if this is the only thing I need to do. Why disable connection pooling? Thanks, Garyc On Apr 26, 10:32 am, Michael Bayer mike...@zzzcomputing.com wrote: gazza wrote: Hello, I am using multiple servers to access a sqlite db via sqlachemy. I am using the latest SQLAlchemy and pysqlite-2.6.0. I get permenant locking and it causes mayhem. I did rebuild sqlite to make it --enable-threadsafe. Whats the approach to handle this problem? one helpful thing is to disable connection pooling. seehttp://www.sqlalchemy.org/docs/reference/dialects/sqlite.html#threadi... . Thanks, garyc -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Re: Database locking
gazza wrote: Thanks Michael. Not sure if this is the only thing I need to do. Why disable connection pooling? it means the app will release filehandles completely when a connection is released, and also that individual threads in your app will use distinct connections. The QueuePool implementation, not the default for SQLite, will also provide the latter, but I've observed that QueuePool doesn't really provide much if any performance gain over straight file open/close per connection. SQLite really doesn't like multithreaded access on a single connection. Thanks, Garyc On Apr 26, 10:32 am, Michael Bayer mike...@zzzcomputing.com wrote: gazza wrote: Hello, I am using multiple servers to access a sqlite db via sqlachemy. I am using the latest SQLAlchemy and pysqlite-2.6.0. I get permenant locking and it causes mayhem. I did rebuild sqlite to make it --enable-threadsafe. Whats the approach to handle this problem? one helpful thing is to disable connection pooling. seehttp://www.sqlalchemy.org/docs/reference/dialects/sqlite.html#threadi... . Thanks, garyc -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Re: Database locking
Thanks Michael. I am going to do some more research on SQLAlchemy and how it handles locks and its interaction with sqlite. I will try and post my findings next week. Thanks, Garyc --- On Mon, 4/26/10, Michael Bayer mike...@zzzcomputing.com wrote: From: Michael Bayer mike...@zzzcomputing.com Subject: Re: [sqlalchemy] Re: Database locking To: sqlalchemy@googlegroups.com Date: Monday, April 26, 2010, 4:39 PM gazza wrote: Thanks Michael. Not sure if this is the only thing I need to do. Why disable connection pooling? it means the app will release filehandles completely when a connection is released, and also that individual threads in your app will use distinct connections. The QueuePool implementation, not the default for SQLite, will also provide the latter, but I've observed that QueuePool doesn't really provide much if any performance gain over straight file open/close per connection. SQLite really doesn't like multithreaded access on a single connection. Thanks, Garyc On Apr 26, 10:32 am, Michael Bayer mike...@zzzcomputing.com wrote: gazza wrote: Hello, I am using multiple servers to access a sqlite db via sqlachemy. I am using the latest SQLAlchemy and pysqlite-2.6.0. I get permenant locking and it causes mayhem. I did rebuild sqlite to make it --enable-threadsafe. Whats the approach to handle this problem? one helpful thing is to disable connection pooling. seehttp://www.sqlalchemy.org/docs/reference/dialects/sqlite.html#threadi... . Thanks, garyc -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
