Databases Reference
In-Depth Information
In step 13, we investigate the objects of the
SH
schema present in the Buffer Cache, obtaining
the following output:
There's more...
To understand the operations discussed in this recipe, we need to provide more details about
the Buffer Cache operations.
Buffer Cache is used to store the data read from disk onto the database blocks. Due to the
I/O operation, which is slower on-disk than on-memory, it's obviously preferable that the
database makes a few I/O operations on-disk. This result is achievable when most of the
requests are satisfied by the data already in the Buffer Cache.
The Buffer Cache operates using an LRU list in order to keep track of the database blocks
most often used and a dirty list. The dirty list stores the modified blocks that are required to
be written to the disks.
The main use of the LRU list is to add blocks to the LRU end using a full table scan, while the
normal operations add blocks to the MRU end of the list, and hence they are quickly replaced
by the blocks required for subsequent operations.
