What is System.LimitException: Too many query rows: 50001 in Apex and Triggers?

Hi,

Because Apex runs in a multitenant environment, the Apex runtime engine strictly enforces limits to ensure that runaway Apex code or processes don’t monopolize shared resources. If some Apex code exceeds a limit, the associated governor issues a runtime exception that cannot be handled. These limits count for each Apex transaction. For Batch Apex, these limits are reset for each execution of a batch of records in the execute method.

In a SOQL query with parent-child relationship subqueries, each parent-child relationship counts as an extra query. These types of queries have a limit of three times the number for top-level queries. The limit for subqueries corresponds to the value that Limits.getLimitAggregateQueries() returns.The row counts from these relationship queries contribute to the row counts of the overall code execution. This limit doesn’t apply to custom metadata types. In a single Apex transaction, custom metadata records can have unlimited SOQL queries. In addition to static SOQL statements, calls to the following methods count against the number of SOQL statements issued in a request.Database.countQuery
Database.getQueryLocator
Database.query

Hope this helps!