What is the best practise for updating a 'live' environment?
More specifically: suppose I have a database that is accessed by several instances of an application (say, a load-balanced Seaside app), but need to change the objects comprising the database in any of the following ways:
(1) Add/remove instance variables to/from a class that is persisted in a MagmaCollection; (2) Add/remove indexes to/from a particular MagmaCollection (perhaps after the changes in (1)); (3) Re-factor some of the classes, thus making minor changes to the schema
... how could the database be updated? Is there also some way to update all the existing objects in the database to reflect the new changes?
Amir
Hi Amir, for inst-vars of a class persisted in Magma, it just works like standard Smalltalk, please see:
http://wiki.squeak.org/squeak/5602
Indexes on MagmaCollections may be removed with the #removeIndex message (within a commit, of course).
Does this answer your question?
If, by "live" you mean a production environment, then you will want to practice first on a production copy (you may use #fullBackup to make a copy of production while it is live without disruption of service). Adding new indexes to a large collection can take some time, of course, and the collection cannot be updated while that takes place, so you may want to build an entirely new MagmaCollection "off to the side" (but still in the same db) so that, once built, you can "switch over" to it in a single commit by simply replacing your pointer to the old with the new.. However, that would require that you keep track of any updates that came in to the collection being replaced *during* the index rebuild...
- Chris
On Wed, Nov 17, 2010 at 12:44 AM, Amir Ansari fractallyte@csi.com wrote:
What is the best practise for updating a 'live' environment?
More specifically: suppose I have a database that is accessed by several instances of an application (say, a load-balanced Seaside app), but need to change the objects comprising the database in any of the following ways:
(1) Add/remove instance variables to/from a class that is persisted in a MagmaCollection; (2) Add/remove indexes to/from a particular MagmaCollection (perhaps after the changes in (1)); (3) Re-factor some of the classes, thus making minor changes to the schema
... how could the database be updated? Is there also some way to update all the existing objects in the database to reflect the new changes?
Amir _______________________________________________ Magma mailing list Magma@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/magma
Thanks, that's exactly what I was looking for! I'm not in that situation, but it's good to know that solutions exist.
Amir
On Wed, 17 Nov 2010 09:48:06 -0600 Chris Muller asqueaker@gmail.com wrote:
Hi Amir, for inst-vars of a class persisted in Magma, it just works like standard Smalltalk, please see:
http://wiki.squeak.org/squeak/5602
Indexes on MagmaCollections may be removed with the #removeIndex message (within a commit, of course).
Does this answer your question?
If, by "live" you mean a production environment, then you will want to practice first on a production copy (you may use #fullBackup to make a copy of production while it is live without disruption of service). Adding new indexes to a large collection can take some time, of course, and the collection cannot be updated while that takes place, so you may want to build an entirely new MagmaCollection "off to the side" (but still in the same db) so that, once built, you can "switch over" to it in a single commit by simply replacing your pointer to the old with the new.. However, that would require that you keep track of any updates that came in to the collection being replaced *during* the index rebuild...
- Chris
magma@lists.squeakfoundation.org
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Amir Ansari -
Chris Muller