In this article, the advancements in Couchbase Server's global secondary indexing, particularly in version 4.5, are discussed, focusing on the distinction between standard and memory-optimized indexes. The introduction of "circular writes," a new write mode for standard global secondary indexes, is highlighted as a significant improvement over the previous append-only mode, reducing the frequency of compactions and thus improving efficiency. Circular writes reuse orphaned space within files, minimizing the need for new writes and significantly decreasing compaction occurrences, which conserves IO resources. The article explains configuration options for write modes and compaction triggers, emphasizing the benefits of circular writes for new clusters while maintaining append-only writes for backward compatibility. The piece underscores the importance of choosing the appropriate index storage option based on the available memory and performance requirements, with memory-optimized indexes offering superior performance but at a higher memory cost, while standard indexes offer flexibility with efficient disk IO when memory is limited.