[security-dev] Picketlink 3 IDM - Counting of query results

[Shane Bryzak]

On 12/06/2012 08:09 AM, Marek Posolda wrote:
> Hi all,
>
> I have possible request for API change and hope it's not too late for
> first IDM iteration.
>
> My suggestion is to have method on class IdentityStore with signature like:
>
> int countQueryResults(Map<QueryParameter,Object> parameters);
>
> in addition to current:
>
> List<IdentityType> fetchQueryResults(Map<QueryParameter,Object> parameters);
>
>
> Example use-case could be: give me count of all users with first name "John"
>
> My motivation is, that for proper pagination support (searching
> use-cases), you usually need to know total number of pages (records) and
> then show searching results only from first page. Then user can browse
> between pages (if more than one page is available). Something like
> www.google.com is doing :-) Also we need to support this in GateIn portal.
>
> Note that having this method is redundant at first look, as you can
> always obtain same results with: fetchQueryResults(queryParams).size()
> But then we are obviously losing performance. For example in JPA (DB)
> it's way more performant to call DB query like: select count(id) from
> users;
> instead of: select * from users;
>
> Also to properly support this, we may also need additional method on
> IdentityQuery with signature like:
>
> int getResultCount();

I have no problem adding this.

>
>
>
> Also with respect to IdentityQuery, I am not sure how are information
> about offset and limit propagated to IdentityStore? For example I have:
> IdentityQuery query = IdentityManager().<User> createQuery(User.class);
> query.setParameter(User.FIRST_NAME, "John");
> query.setOffset(0);
> query.setLimit(10);
> query.getResultList();
>
> Calling of "getResultList" on last line will invoke
> "fetchQueryResults(queryParams)" of configured IdentityStore. But how is
> ensured that result from IdentityStore will return only first 10 records
> as requested? So I think we can either:
>
> a) Change signature of method on IdentityStore to be:
>
> List<IdentityType> fetchQueryResults(Map<QueryParameter,Object>
> parameters, int offset, int limit);

We should probably just support this:

List<IdentityType> fetchQueryResults(IdentityQuery query);



>
>
> b) Add QueryParameters for pagination support, which will be sent to
> IdentityStore. Maybe we can have something like this on IdentityQuery
> class:
>
> QueryParameter OFFSET = new QueryParameter() {};
>
> QueryParameter LIMIT = new QueryParameter() {};
>
> And something like this on DefaultIdentityQuery class:
>
>       @Override
>       public IdentityQuery<T> setOffset(int offset) {
>           parameters.put(IdentityQuery.OFFSET, offset);
>           return this;
>       }
>
>       @Override
>       public IdentityQuery<T> setLimit(int limit) {
>           parameters.put(IdentityQuery.LIMIT, limit);
>           return this;
>       }
>
> Currently I am not seeing any query parameters for pagination in codebase.
>
> WDYT?
> Marek
>
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