What can be done to combine smaller files into larger files to improve query performance?

The OPTIMIZE command is specifically designed to enhance query performance by merging smaller files into larger ones. When dealing with datasets, particularly in storage systems like data lakes or cloud storage, having many small files can lead to inefficiencies during query execution. This is primarily due to the overhead associated with opening and reading multiple small files instead of fewer larger ones, which can cause increased I/O operations and longer query execution times.

By running the OPTIMIZE command, the system reorganizes the stored data, combining smaller files and often rewriting data in a way that improves access efficiency. This reduces file fragmentation and can improve the overall performance of data queries since the query engine can read from fewer files, leveraging more efficient block reads.

Other options, while potentially helpful in different contexts, do not directly address the primary issue of file size optimization for query performance in the same direct way as the OPTIMIZE command. For instance, deleting unnecessary files, though it can help with available storage and reduce clutter, does not combine files. Adjusting partition size might help optimize access to data in some architectures, but it does not inherently reduce the number of files being accessed. Changing the data format can enhance compatibility or compression but does not affect file count directly.