This week, we released an update to the MongoDB indexer to replace pending data atomically.

Users indexing large collections (millions of documents or more) were experiencing "flashing" data between pending blocks. This happens because the indexer replaces data derived from pending blocks by first removing data from the previous version of the pending block, and then inserting the new data.

The latest version of the MongoDB indexer ships with the --replace-data-inside-transaction=true flag to wrap the update operation in a transaction, resulting in atomic updates of pending data. Notice that a MongoDB deployment with replication enabled is required for this feature to work. If you are using MongoDB Atlas, it will work out of the box.