There is an error comes when some groups comment on chatter in org and below is the error

Question

System.QueryException: Non-selective query against large object type (more than 200000 rows). Consider an indexed filter or contact salesforce.com about custom indexing.

From documentation:

Even if a field is indexed a filter might still not be selective when:

1. The filter value includes null (for instance binding with a list that contains null)
2. Data skew exists whereby the number of matching rows is very large (for instance, filtering for a particular foreign key value that occurs many times)

Identified the object is having more than 200,000 records and below is the method which is been affected with index field.

jj_sss_Question_And_Answer__c q = [select 
                                             id,
                                             jj_sss_Community__c,
                                             jj_sss_Community__r.jj_sss_Hero1__c,
                                             jj_sss_Community__r.jj_sss_Hero2__c,
                                             jj_sss_Community__r.jj_sss_Hero3__c,
                                             jj_sss_Status__c,
                                             jj_sss_Title__c,
                                             jj_sss_Body__c,
                                             jj_sss_Question_Posted_By__c,
                                             jj_sss_Question_Creation_Date__c,
                                             jj_sss_Feed_Item_Id__c,
                                             jj_sss_First_answer_received_date__c
                                           from jj_sss_Question_And_Answer__c 
                                           where jj_sss_Feed_Item_Id__c = :Comment.FeedItemId and jj_sss_Feed_Comment_Id__c = null];

Can anyone help resolve this issue?

Answer 1

Are jj_sss_Feed_Item_Id__c, jj_sss_Feed_Comment_Id__c indexed fields? You can retest the query by making them external Id which will index them. Also ensure they are not cross object formulas.

Additionally, are you sure your bind variables are assigning a value? If they are passing through null and your table has many rows where those values are null, you will also hit this issue.

If your table size is simply too massive you may need to consider other approaches to be able to query effectively, view the query optimiser cheatsheet.

Edit: As David below mentioned, skinny table will purely provide performance improvements in querying and will not bypass errors due to query being unselective