Re: [ZODB-Dev] Any risk about foreign zodb references
Le 18/07/2011 18:16, David Glick a écrit : > On 7/18/11 9:08 AM, Alexandre Garel wrote: >> Hello, >> >> We are building up an application where we use multiple zodb instances. >> Indexation is done using solr. >> zodb are served through zc.zodbwsgi. ZODB connections are set only >> on-demand, upon traversal. Each zodb has its intid local utility. Each >> object also has a uuid. >> >> I have a zodb with global parameters objects on /params and distinct >> zodb as /foo /bar /baz and so on. >> Objects in a zodb may reference objects of the same zodb or of /params. >> >> I have two possible strategies : >> >> - either store uuid of referenced objects and retrieve objects from solr >> (which will give me a zodb name + intid of object) >> - either directly reference the objects of /params >> >> Of course second option seems better and more natural. >> >> I read >> http://svn.zope.org/ZODB/trunk/src/ZODB/tests/multidb.txt?rev=99605&view=markup >> and using pdb on databases = request.environ['zodb.connection'] I can >> see the zodb.databases map >> which is ok. I also know that _p_oid is unique and _p_jar handled for >> each object so I feel confident on this side. >> >> So before I dive into this, is this kind of cross-database reference >> used on production applications. Is there any-risk or any trick to be >> aware ? > Using cross-database references can be treacherous, because the garbage > collection that occurs when packing a ZODB the typical way is not aware > of the cross-db references. So if there's an object in one db that is > only referenced from a different db, it will get garbage-collected > during packing. You can probably use > http://pypi.python.org/pypi/zc.zodbdgc instead of standard packing to > avoid that problem. Thanks for the advice. I normally won't fall in this case as my params objects are contained in parents and must exists even when all other zodb would not. Thanks for your feedback. -- Alex Garel ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
Re: [ZODB-Dev] Any risk about foreign zodb references
On 7/18/11 9:08 AM, Alexandre Garel wrote: > Hello, > > We are building up an application where we use multiple zodb instances. > Indexation is done using solr. > zodb are served through zc.zodbwsgi. ZODB connections are set only > on-demand, upon traversal. Each zodb has its intid local utility. Each > object also has a uuid. > > I have a zodb with global parameters objects on /params and distinct > zodb as /foo /bar /baz and so on. > Objects in a zodb may reference objects of the same zodb or of /params. > > I have two possible strategies : > > - either store uuid of referenced objects and retrieve objects from solr > (which will give me a zodb name + intid of object) > - either directly reference the objects of /params > > Of course second option seems better and more natural. > > I read > http://svn.zope.org/ZODB/trunk/src/ZODB/tests/multidb.txt?rev=99605&view=markup > and using pdb on databases = request.environ['zodb.connection'] I can > see the zodb.databases map > which is ok. I also know that _p_oid is unique and _p_jar handled for > each object so I feel confident on this side. > > So before I dive into this, is this kind of cross-database reference > used on production applications. Is there any-risk or any trick to be > aware ? Using cross-database references can be treacherous, because the garbage collection that occurs when packing a ZODB the typical way is not aware of the cross-db references. So if there's an object in one db that is only referenced from a different db, it will get garbage-collected during packing. You can probably use http://pypi.python.org/pypi/zc.zodbdgc instead of standard packing to avoid that problem. -- David Glick Web Developer davidgl...@groundwire.org 206.286.1235x32 Online tools and strategies for the environmental movement. Sign up for our newsletter: http://www.groundwire.org/email-capture ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
[ZODB-Dev] Any risk about foreign zodb references
Hello, We are building up an application where we use multiple zodb instances. Indexation is done using solr. zodb are served through zc.zodbwsgi. ZODB connections are set only on-demand, upon traversal. Each zodb has its intid local utility. Each object also has a uuid. I have a zodb with global parameters objects on /params and distinct zodb as /foo /bar /baz and so on. Objects in a zodb may reference objects of the same zodb or of /params. I have two possible strategies : - either store uuid of referenced objects and retrieve objects from solr (which will give me a zodb name + intid of object) - either directly reference the objects of /params Of course second option seems better and more natural. I read http://svn.zope.org/ZODB/trunk/src/ZODB/tests/multidb.txt?rev=99605&view=markup and using pdb on databases = request.environ['zodb.connection'] I can see the zodb.databases map which is ok. I also know that _p_oid is unique and _p_jar handled for each object so I feel confident on this side. So before I dive into this, is this kind of cross-database reference used on production applications. Is there any-risk or any trick to be aware ? Thanks in advance for any comment :-) Alex ___ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev
