[Twisted-Python] ADBAPI and individual rows

[Tommi Virtanen]

On Fri, Aug 08, 2003 at 07:12:00PM -0400, Edmund Dengler wrote:
> Digging a bit more into the DB side, and I wonder a bit about the API for
> adbapi. From what I can tell, the runQuery() will return a Deferred for
> the whole result set (which implies the result set is in memory). Is there
> a method or style for running a query in which each row will be passed
> back through a Deferred one at a time? (Basically, each cycle through
> reactor.run() would be returning a single row).
> 
> What I am looking for is how to deal with a large result set without
> requiring the whole set be in memory. Should I be looking elsewhere within
> Twisted to do this?

	Here's what I did with Ldaptor (note how the callback and the
	returned Deferred play together):

    def search(self,
	       filterText=None,
	       filterObject=None,
	       attributes=(),
	       scope=pureldap.LDAP_SCOPE_wholeSubtree,
	       derefAliases=pureldap.LDAP_DEREF_neverDerefAliases,
	       sizeLimit=0,
	       timeLimit=0,
	       typesOnly=0,
	       callback=None):
	"""

	Perform an LDAP search with this object as the base.

	@param filterText: LDAP search filter as a string.

	@param filterObject: LDAP search filter as LDAPFilter.
	Note if both filterText and filterObject are given, they
	are combined with AND. If neither is given, the search is
	made with a filter that matches everything.

	@param attributes: List of attributes to retrieve for the
	result objects. An empty list and means all.

	@param scope: Whether to recurse into subtrees.

	@param derefAliases: Whether to deref LDAP aliases. TODO write
	better documentation.

	@param sizeLimit: At most how many entries to return. 0 means
	unlimited.

	@param timeLimit: At most how long to use for processing the
	search request. 0 means unlimited.

	@param typesOnly: Whether to return attribute types only, or
	also values.

	@param callback: Callback function to call for each resulting
	LDAPEntry. None means gather the results into a list and give
	that to the Deferred returned from here.

	@return: A Deferred that will complete when the search is
	done. The Deferred gives None if callback was given and a list
	of the search results if callback is not given or is None.

	"""

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