New White Paper and Compression impact on Memory
Sanjay Mishra just published the following White Paper, ” Data Compression: Strategy, Capacity Planning and Best Practices “, highly recommended and much anticipated. On this same topic, I received a question from a colleague the other day, asking what the impact of data compression on memory was. The assumptions I had were as follows: Page or Row compression allows for more data to fit in memory (compressed page on disk matches compressed page in the buffer cache) When the data is read from memory for use in a query – it is uncompressed during that time A little unsure of the specifics, I still wanted confirmation on these assumptions, so thank you to Sunil Agarwal for confirming that this was correct. Compressed data does reside in the buffer pool in a compressed form (which you can test in a before/after data compression using sys.dm_os_buffer_descriptors), but when compressed data is referenced, it is uncompressed as needed. Sanjay’s paper also discusses this topic in more detail in the “Application Workload” section.
