When is it advisable to rebuild a large site's search index?

• A. During peak hours
• B. Overnight or downtime
• C. On Mondays only
• D. Never, it's automatic

Answer: (B)

Rebuilding a large search index is a heavy maintenance task that consumes a lot of server resources—CPU, memory, and disk I/O. To keep the site responsive for users, you want to run this kind of operation during off-peak times when traffic is low. Scheduling it overnight or during planned downtime minimizes the risk of slow searches or outages for everyone. Doing it during peak hours would slow down queries for many users and degrade the experience. The idea of restricting it to a particular weekday isn’t practical for real maintenance windows, and the notion that you never need a rebuild because indexing is automatic misses the reality that, on a large site, a controlled, timed rebuild often delivers the best balance between data freshness and performance.