If sharing rules are used should a where clause still be applied to a SOQL query?

Question

If a portal user only has permission to access a subset of records, defined via sharing rules, should the SOQL still use a WHERE clause, or should it be left off of the query?

List<MyObject__c> myObjects = [SELECT Id, Name FROM MyObject__c];

vs.

List<MyObect__c> myObjects = [SELECT Id, Name FROM MyObject__c WHERE Parent_Contact__c = :contactId];

Edit:

The bottom line question is: Should the WHERE clause always be added to the query, or would it be considered overkill when sharing is enforced?

Answer 1

While sharing covers most of your access needs as Mohith has mentioned there's another aspect: performance.

If you're planning on dealing with more than a few thousand custom objects in the table then your first query will put signifigantly more stress on salesforce in terms of what sharing calculations to perform, whereas the second will have a much, much smaller result set for salesforce to evaluate sharing against.

Salesforce's sharing model is actually patented, which lets us get a peek under the covers of how it works.

|0046| shows there's a join or join-like operation going on which would need to pull in all share rules and group membership and filter the results from MyObject__c in your first query. If this is in fact the case then the filtering of your table against the sharing table will have more overhead than taking a known shared result set and joining it to the share table.

Answer 2

It will depend whether you have kept your class as "with sharing" and "without Sharing"

When you use with sharing all the sharing rules will apply and query will return result according to the sharing rules set for the logged in user .

http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_classes_keywords_sharing.htm

Following above link will help you .