How do you handle trigger recursion and governor limits?

1 What are triggers?

Triggers are code blocks that execute automatically when certain events occur in the database, such as insert, update, delete, or undelete. You can use triggers to perform custom logic, validations, calculations, integrations, or other actions that are not possible with standard features. Triggers can also invoke other triggers, creating a chain of events that can affect multiple records and objects.

2 What is trigger recursion?

Trigger recursion is when a trigger causes itself or another trigger to fire repeatedly, creating an infinite loop. This can happen when a trigger updates or inserts a record that triggers another trigger, which updates or inserts another record, and so on. Trigger recursion can cause unexpected results, data inconsistencies, and performance issues. To avoid trigger recursion, you need to implement a mechanism that prevents triggers from firing more than once for the same record or event.

3 What are governor limits?

Governor limits are system-defined restrictions that limit the amount of resources and operations that can be used by triggers and other code in a single transaction. These measures are put in place to ensure the database runs efficiently and reliably, and no single process consumes too much resources. Common governor limits include the number of SOQL queries (100), DML statements (150), records processed by DML (10,000), callouts (100), and CPU time (10 seconds). If a trigger exceeds any of these limits, it will cause an exception and roll back the transaction. To prevent hitting governor limits, you need to optimize your trigger code and use bulkified patterns that can handle large sets of records.

4 How to test triggers?

Testing triggers is essential to ensure that they work as expected and do not cause any errors or side effects. You can use Apex test classes and methods to write unit tests that verify the functionality and performance of your triggers. You can also use test data and test scenarios that mimic real-world situations and cover different edge cases. To run your tests, you can use the Developer Console, the Apex Test Execution page, or the Salesforce CLI.

5 How to debug triggers?

Debugging triggers involves finding and fixing errors or bugs in trigger code. To accomplish this, you can use debug logs, checkpoints, and exceptions. Debug logs are records of the events and messages that occur during the execution of your triggers and other code. You can examine these logs through the Developer Console, the Debug Logs page, or the Salesforce CLI. Checkpoints are markers that you can set in your code to pause execution and inspect values of variables, expressions, and heap at that point. The Developer Console or the Apex Replay Debugger can be used to set and view checkpoints. Exceptions are errors that occur when your code violates a rule or a condition, such as a governor limit or a validation rule. You can use try-catch-finally blocks to handle exceptions and display custom error messages or perform recovery actions.

6 Best practices for triggers

Writing effective and efficient triggers requires following certain best practices and guidelines, such as using trigger handlers and helper classes. Trigger handlers are classes that contain the logic for triggers, while helper classes contain reusable methods or functions that perform common tasks or calculations. Additionally, collections and maps are data structures that can store multiple values or records in a single variable, helping reduce the number of SOQL queries and DML statements. Context variables are also useful as they provide information about the trigger events and records, enabling you to condition your logic based on the trigger context and avoid unnecessary operations.