Hi, could use some thoughts here.  Trying to get a trigger to populate a lookup field when an account record is created or updated.  I have a custom object, Sales_Grid_Assignment__c, for storing zipcodes and related data.  The intent of the trigger is to match the account's zipcode to a custom object record and populate the lookup field with the custom object record id.   Code works great in Sandbox.  In production, if the account record creation is by lead conversion, I get following error, but only if the user wants to create an opportunity upon conversion as well as a new company record.

Error: System.LimitException: Too many query rows: 50001 (System Code) Class.AssignSalesGrid.getGrid: line 6, column 1 Trigger.PrimaryAccountTrigger: line 4, column 1

I don't have anywhere near 50,000 custom object records, but I tried putting a LIMIT on the query anyway.  No joy.  Anyone see any glaring omissions or mistakes?  Thanks!

Here is the code for Trigger and Class...

TRIGGER:

trigger PrimaryAccountTrigger on Account (before insert, before update) {
    
 LIST<Account> company = Trigger.new;
 AssignSalesGrid.getGrid(company);

}

CLASS:

public class AssignSalesGrid {

    public static void getGrid(LIST<Account> company){
        
        List<Sales_Grid_Assignment__c> salesgrids = new List<Sales_Grid_Assignment__c>();
        salesgrids = [Select Id, Name
                from Sales_Grid_Assignment__c LIMIT 50000];
        
        Map <string,Id> mapGrids = new Map<string,Id>();
            for (Sales_Grid_Assignment__c sg: salesgrids)  {
          
                mapGrids.put(sg.Name,sg.Id);    
            }
    for (Account a :company){
            a.Sales_Grid_Assignment__c = mapGrids.get(a.BillingPostalCode);
        }
        
    }
}