Describe the Common Performance Issues for User Interfaces and the Techniques to Mitigate Them. PLATFORM-DEVELOPER-II Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   Which client-side practice helps improve UI rendering performance?

   • AUsing inline JavaScript for all logic
   • BMinimizing DOM manipulation
   • CAvoiding caching of static resources
   • DIncreasing the number of DOM elements
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2. 22expert · hard

   A developer is troubleshooting a Lightning component that displays a list of Opportunities. The component uses a SOQL query that filters on a custom field that is not indexed. The query is slow, and the developer wants to improve performance without changing the user interface. Which approach should be taken?

   • AUse a query that orders by the custom field to improve filtering.
   • BUse a query that selects all fields to avoid index lookup.
   • CUse a query that filters on a formula field instead.
   • DAdd a custom index on the custom field used in the WHERE clause.
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4. 23expert · hard

   A developer is working on a Lightning component that displays a list of Contacts. The component uses a SOQL query that filters on a field that is not indexed and also uses a subquery to retrieve related Accounts. The query is slow. Which change would most likely improve the query performance?

   • AAdd an index on the filter field and ensure the query is selective.
   • BUse a query that orders by the filter field to improve performance.
   • CUse a query that retrieves all fields to avoid index lookup.
   • DRemove the subquery and use a separate query for Accounts.
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5. 24foundation · easy

   Which data retrieval strategy helps avoid N+1 queries in Salesforce?

   • AQuerying each related record separately in a loop
   • BUsing multiple SOQL queries without relationship traversal
   • CUsing SOSL for all queries
   • DQuerying related records in a single SOQL query using relationship queries
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6. 25application · medium

   A developer is optimizing a Lightning component that displays a list of Accounts and their Contacts. The component currently queries Accounts and then queries Contacts for each Account in a loop. What is the best way to avoid the N+1 query problem?

   • AUse a query that retrieves all Contacts and then filter in JavaScript.
   • BUse a query that retrieves all Accounts and Contacts separately and then join them in Apex.
   • CUse a single query with a subquery to retrieve Accounts and their Contacts.
   • DUse a query that retrieves all Accounts and then use a separate query for each Account.
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