|author||Boris Kolpackov <email@example.com>||2015-02-04 17:23:54 +0200|
|committer||Boris Kolpackov <firstname.lastname@example.org>||2015-02-04 17:23:54 +0200|
Implement object loading views
See section 10.2 in the manual for details.
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++ Object loading views
+- The joined object can be joined just to be used in the query condition or
+ to load the data. How to distinguish the two cases and what should be the
+- All the non-lazy object pointers, containers, and sections should probably
+ be loaded one way or another (if the user wants an "incomplete" load, then
+ he should use the normal view and specify the data members). This can all
+ be controlled via lazy pointers/sections on the user side.
+ So the behavior seems to be load all the non-lazy pointed-to object
+ either with a single SELECT, if it were joined by the view, or by
+ issuing a separate SELECT otherwise.
+ The only uncertain case is a JOIN'ed lazy pointed-to object. Here
+ the user will have to specify whether to load the object (within
+ a single SELECT) or it was JOIN'ed only for the query condition.
+ Since this is a performance feature, the defaul should probably
+ not to load. The mechanism used to specify this should probably
+ also be used to specify whether to SELECT FOR UPDATE joined objects.
+- Support both object pointer and direct member as an object (similar
+ to the load() signature). Might have to rely on delay loading. E.g.,
+ first load all the JOIN'ed objects (and enter them in object cache).
+ At the same time prevent nested object load by locking the statements.
+ Then load all the delayed objects which will be resolved via the cache.
+ That's probably the only way to support a pointer to the same object
+ in both another object and the view itself.
+- Can ask the user to use a session to help resolve the object pointers,
+ if, for example, the same object is used to initialize another object
+ member and a view member.
+- Can/should this be used to implement SELECT FOR UPDATE? What about JOIN'ed
+- Need to think also how this is related to containers. E.g., container
+ loading queries?
+- Implementation-wise, we probably want to create a combined image out
+ of inidividual object images and to delegate to the object code as
+ soon as possible.
+- Interraction with other features:
+ - Polymorphism will be tricky. Probably ok not to support this initially
+ since often there will be a followup SELECT to load the dynamic part
+ of the object.
+- See also:
+ See email from <email@example.com>/30-Oct-2014.