Re: [myexperiment-hackers] Problem with /home caching

[Jiten Bhagat]

Danius Michaelides wrote:
> [snip]
> > > I guess some of this will change with Sergey's news code. 
> >
> > Sergey's news code just affects the "my news" box on the home page 
> > (and other user and group show pages) and will be the mechanism for 
> > subscriptions that require events spanning *different* models. It 
> > won't be used for the other boxes on the home page, as those are 
> > events pivoted on one model and using the ActivityLog stuff would 
> > mean having to at least one extra query, with extra logic, and also 
> > require it's own caching.
>
> Hang on, ignoring caching for the minute, are you saying that Sergey's
> ActvityLog stuff wont be driving updated items? If so, I dont understand
> your explaination, can you or Sergey go into more detail?

Sure.... the ActivityLog stuff stores events in the following general 
pattern - <culprit> did <action> <ActivityLoggable> affecting 
<referenced>. E.g: (User 201) did (add) (PackContributableEntry 500) 
affecting (Pack 20). Note: this is NOT the wording in the news feed, 
just the pattern of how events are stored in the model/db. For some 
events, the <referenced> is not needed.

When it comes to news generation (for disparate events), you start by 
querying the ActivityLog table (Sergey: please can you briefly elaborate 
on the different types of root queries needed on ActivityLog, for the 
different types of news feeds) and then other tables need to be queried 
to get back the relevant items (and to see if they exist), and then 
authorisation needs to take place.

So, going back to the "Updated Items" box... this is pivoted on one 
model - Contribution. So it gets the last 15 contributions added to the 
contributions table and then builds the view by getting the 
contributable. Policy and Permissions are eager loaded with the 
Contributions so authorisation can take place without going back to the 
db. Using ActivityLog for this won't help as You would first need to get 
the events from the ActivityLog and then get the contributable items and 
authorisation stuff anyways.

We could have stored a bit of text like: "John added the Blast Workflow 
to the TestWorkflows pack" but this suffers from two issues:
1) it's not easily queryable so it's hard to reuse the activity log for 
different kinds of news feeds and also for different kinds of subscriptions.
2) authorisation information needs to be retrieved from somewhere.

Does this help?

Jits



> Danius
>
>
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