What is a key disadvantage of using indexes?

Using indexes in a database system like MongoDB can significantly enhance read performance by allowing for quicker data retrieval, but they also bring a notable disadvantage: the write performance cost. Each time a document is added, updated, or deleted, the indexes associated with that document must also be modified to ensure they remain accurate. This additional overhead can slow down the speed at which write operations are performed.

While it might seem beneficial that indexes speed up read operations, the necessity of maintaining those indexes during write operations can lead to increased latency and resource usage when inserting or updating records. Thus, while indexes are powerful tools for enhancing data retrieval efficiency, the trade-off comes in the form of write performance degradation.