Non-Selective Query Against Large Object Type

What does this error mean?

Salesforce requires queries against large objects (200,000+ records) to be selective — meaning the WHERE clause must filter on an indexed field that narrows results below a system-defined threshold. The threshold is 10% of the first million records, or 5% for records beyond a million, with an absolute ceiling of 333,333 records.

Without a selective filter, Salesforce would perform a full table scan on every query — unacceptable in a multi-tenant environment where one org's inefficient query could impact others. This error is thrown proactively to protect platform performance.

Common Causes

1. Filtering on non-indexed custom fields

Custom fields are not indexed by default. A WHERE Custom_Status__c = 'Active' on a large object forces a full table scan.

2. Using != NULL on any field

Negative filters like WHERE Field__c != null or WHERE Field__c != 'value' are inherently non-selective because they potentially match most records in the table.

3. Trigger queries without ID-based filters

Trigger queries that join to large objects by non-indexed relationship fields rather than primary key IDs.

How to Fix It

Solution 1: Filter on standard indexed fields

Salesforce automatically indexes: Id, Name, OwnerId, CreatedDate, LastModifiedDate, RecordTypeId, and all lookup/master-detail fields. Use these in your WHERE clause.

-- ❌ NON-SELECTIVE — custom field, no index
SELECT Id FROM Case WHERE Custom_Status__c = 'Open'

-- ✅ SELECTIVE — indexed standard field
SELECT Id FROM Case
WHERE CreatedDate = LAST_N_DAYS:30
  AND OwnerId = :currentUserId

-- ✅ SELECTIVE — primary key in trigger context
SELECT Id, Status FROM Case
WHERE Id IN :Trigger.newMap.keySet()

Solution 2: Request a custom index from Salesforce

If your business logic requires filtering on a specific custom field, raise a Salesforce Support case requesting a custom index on that field. Custom indexes are free and Salesforce reviews them against selectivity criteria.

Solution 3: Add a skinny table for reporting queries

For complex reporting queries that can't be made selective, ask Salesforce Support about a skinny table — a denormalized read-only copy of frequently queried fields that can speed up otherwise non-selective queries.