What information does the CLI command # diagnose sql show hcache-size provide?

The command # diagnose sql show hcache-size is specifically designed to display the size of the Hcache (History Cache) on the file system of FortiAnalyzer. Hcache is utilized for improving the performance of SQL queries by caching frequently accessed data, thus reducing the time it takes for these queries to complete. By knowing the Hcache size, administrators can understand how much data can be temporarily stored in memory, which can directly impact the efficiency of log querying and processing.

Understanding this command's output is crucial for managing performance effectively, as too small an Hcache may lead to slower report generation and query processing times, while a larger Hcache could help in optimizing those processes. In contrast, the other options do not accurately reflect the function of this specific command. Log retention period refers to how long logs are stored; data storage capacity pertains to the total storage available on the device; and report generation speed would be influenced by multiple factors, not just the Hcache size alone.