What are physical and logical reads?
The main work of database is to store and retrieve data. In other words lot of reads and writes to the disk. Read and writes consume lot of resources and take long time for completion. SQL server allocates virtual memory for cache to speed up I/O operations. Every instance of SQL server has its own cache. When data is read it is stored in the SQL cache until it’s not referenced or the cache is needed for some purpose. So rather than reading from physical disk its read from SQL cache. In the same way for writing, data is written back to disk only if it’s modified. So when data is fetched from SQL cache its terms as logical read and when its read from physical database its termed as physical read.
