Kwon, Chan Young wrote: > Hi, > > Let me describe more... > 1. My suggestion of LOB object is kind of Locator object. It does not contain > whole massive data. It just passes small piece of data when its methods are > called. > 2. buffer object is not enough to handle various kinds of LOB types. For > example, character LOB, binary LOB and unicode character LOB. > > In my company, this LOB class is already used as extension of DBAPI spec 2.0. > All colleagues like LOB class because it is very simple and easy to use. > So I sent this for your information.
There are various ways large binary/text objects are handled by databases at the API level. Some databases provide APIs which allow reading/writing such data in chunks, others provide file descriptors which can be use used for this, yet others maintain the files outside the database and provide "locator" objects for these. Since all of these approaches use a file-like interface in one way or another, perhaps we could agree on a common DB-API extension that defines the minimum interface of such objects and a constructor that turns an existing file into an object which can then be passed to the database (much like the Binary() constructor we have for binary data). Do you have documentation for the LOB object you are using available on the web ? Regards, -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, May 02 2011) >>> Python/Zope Consulting and Support ... http://www.egenix.com/ >>> mxODBC.Zope.Database.Adapter ... http://zope.egenix.com/ >>> mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/ ________________________________________________________________________ 2011-06-20: EuroPython 2011, Florence, Italy 49 days to go ::: Try our new mxODBC.Connect Python Database Interface for free ! :::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 http://www.egenix.com/company/contact/ > Best wishes, > Chanyoung Kwon > > SAP R&D Center Korea > > > > -----Original Message----- > From: Chris Clark [mailto:chris.cl...@ingres.com] > Sent: Thursday, April 28, 2011 2:05 AM > To: Kwon, Chan Young > Cc: db-sig@python.org > Subject: Re: [DB-SIG] About LOB > > Kwon, Chan Young wrote: >> I am implementing new DB API for new Database according to DB API 2.0. (as >> C-Extension) >> There is no specification about LOB in DB API 2.0 >> Especially, I need LOB object for piecewise LOB writing/reading after query >> execution. >> So I defined my own LOB object. >> I tried to make simple and easy interface for LOB. >> > > > BLarge OBject's (BLOBs) are alluded to in pep 249 BUT they really are > not detailed so I think you have spotted a weakness in the spec. CLOBs > (Character Large OBjects) are not covered at all. Locators are not > discussed but implied by references to bufferobjects. > > For BLOBs as input bind parameters check out the Binary() constructor > (case sensitive) at http://www.python.org/dev/peps/pep-0249/. > For BLOB results look for bufferobject in > http://www.python.org/dev/peps/pep-0249/ > > The spec (as I read it) really expects LOBs to be handled as one massive > block. However implementators can choose to implement locators behind > the scene so that data isn't sent across the wire unless the buffer > object is read from. > > So, model your LOB access methods on bufferobjects and you should be all > set! Marc-Andre reads/responds to the list regularly so take note of any > suggestions he has :-) > > Hope that helps get you started. > > Chris > > _______________________________________________ > DB-SIG maillist - DB-SIG@python.org > http://mail.python.org/mailman/listinfo/db-sig _______________________________________________ DB-SIG maillist - DB-SIG@python.org http://mail.python.org/mailman/listinfo/db-sig
