Executing SOQL queries inside loops is a critical performance anti-pattern in Apex development that can quickly exhaust Salesforce’s governor
limits.
Salesforce enforces strict limits on the number of SOQL queries that can be executed in a single transaction: 100 queries in synchronous contexts
and 200 in asynchronous contexts. When you place a SOQL query inside a loop, each iteration executes a separate query against the database.
For example, if you have a loop that processes 50 records and each iteration executes one SOQL query, you’ll consume 50 of your 100 available
queries in a single operation. This approach doesn’t scale - processing 150 records would exceed the governor limit and cause a runtime exception.
Beyond governor limits, this pattern creates significant performance issues. Each SOQL query requires a round trip to the database, and multiple
individual queries are much slower than a single bulk query that retrieves all needed data at once.
The solution is to use bulk processing patterns: collect all the criteria (like IDs) before the loop, execute a single SOQL query with an
IN clause or similar bulk operator, and then process the retrieved records. This approach scales efficiently regardless of data volume
and respects Salesforce’s platform constraints.
What is the potential impact?
This issue can cause runtime exceptions when governor limits are exceeded, leading to transaction failures and poor user experience. It also
creates significant performance degradation, especially as data volume increases, making applications slow and unresponsive.
