MongoDB Large Table Problems & Solutions

When a single table in MongoDB becomes too large, it can lead to the following issues:

1. Performance decrease: as the amount of data increases, the speed of querying and writing operations on a single table will slow down, as the database needs to scan more data to execute the operations.
2. Memory pressure: Large tables require more memory to store data and indexes. If there is insufficient memory, database performance will be affected.
3. Efficiency of indexing decreases: as the amount of data increases, the efficiency of indexing may decrease, leading to poorer query performance.
4. Maintenance difficulty: Having a large single table will increase the difficulty of database maintenance, including tasks like backup, recovery, and data migration.
5. It is difficult to ensure data consistency: having a single large table can lead to difficulties in maintaining data consistency, due to potential concurrency issues when dealing with large amounts of data and complex queries.

To avoid the above issues, consider optimizing database performance and maintenance by storing data in shards, using appropriate indexes, and regularly cleaning up expired data.