[SalesForce] How many times trigger will be invoked if I want to process 30K records

As per trailhead module :

trigger SoqlTriggerBulk on Account(after update) {  
    // Perform SOQL query once.    
    // Get the related opportunities for the accounts in this trigger,
    // and iterate over those records.
    for(Opportunity opp : [SELECT Id,Name,CloseDate FROM Opportunity
        WHERE AccountId IN :Trigger.New]) {

        // Do some other processing
    }
}

Triggers execute on batches of 200 records at a time. So if 400
records cause a trigger to fire, the trigger fires twice, once for
each 200 records. For this reason, you don’t get the benefit of SOQL
for loop record batching in triggers, because triggers batch up
records as well. The SOQL for loop is called twice in this example,
but a standalone SOQL query would also be called twice. However, the
SOQL for loop still looks more elegant than iterating over a
collection variable!

I am processing 30K records and my trigger will be invoked 150 times.

Will I get SOQL 101 queries error if my trigger is invoked 1000 times?

Best Answer

Yes, you will get the 101 query exception¹.

The reason is that all of the trigger "chunks" (I prefer using "chunk" over "batch", because "batch" in Salesforce is a separate thing) are part of the same transaction, and governor limits are enforced per-transaction.

If you use one query in your trigger, then your trigger can handle (at most) 20,000 records.

The number of records that you can handle decreases as your trigger becomes more complex (more queries and interactions with other triggers, workflow rules, or process builder).

+edit:
Of course, the other limit that you need to worry about is the DML rows limit, which is a hard cap of 10,000 records per transaction.

^{1: Well, you would if Salesforce didn't restrict the number of DML rows. If you try to dml 30K records, I'd expect you to receive a DmlException for the number of DML rows before you'd get a QueryExceptionfor the number of queries}

Related Solutions

[SalesForce] SOQL query 101 error when calling trigger. Want to fix using Batch Apex. Is it feasible

Based on the comments, it looks like there isn't anything wrong with the trigger posted. There appears to be another trigger also firing that is causing the issue.

[SalesForce] How to access trigger.oldmap outside the for loop

To access a Map (as in oldMap), you will need to access by Id. If it is just the old Opportunity Owner ID you are after, you can simply access it as - no need to perform the query:

trigger TestTrigger on Opportunity (before update) {
    for(Opportunity opp : Trigger.new){
       Opportunity oldOpportunity = Trigger.oldMap.get(opp.ID);
       oppOwnerId = oldOpportunity.OwnerId;
       ...
    }
}

However, i suspect you are not and that you do need to perform the query to retrieve some other information, in which case you are thinking about this the wrong way. You need to 'bulkify' your Trigger.

What you will have to do instead of what you are suggesting is refactor your trigger a little. You should first collect a set of OwnerIds from the 'old' collection, for example:

Set<Id> ownerIds = new Set<Id>();
for( Opportunity opp : Trigger.old ) {
    ownerIds.add( opp.OwnerId );
}

Then, using that set, you should query all of the Users outside of the loop (i.e. once for all the OwnerIds) and create a Map for easy access, for example:

Map<Id,User>  userMap = new Map<Id,User> ( [ Select Id From user Where Id IN ownerIds ] );

Then, from within the Loop, you can access the User as you wish using the map:

for( Opportunity opp : Trigger.new ) {
    User oppOwnerId = userMap.get( Trigger.oldMap.get( opp.Id ).OwnerId );
}

This is a rather futile example because the code is only returning the User Id which you essentially have already anyway (in the oldMap).

Best Answer

Related Solutions

[SalesForce] SOQL query 101 error when calling trigger. Want to fix using Batch Apex. Is it feasible

[SalesForce] How to access trigger.oldmap outside the for loop

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