The size of the Oracle data block

Standard blocks are used for temporal and system tablespaces, and are also the default values for a tablespace data block. The size of the standard data block is determined by the parameter db_block_size when the database is created. To change this setting, you must rebuild the database.

Db_cache_size sets the size of the database cache. Its minimum size is one granule, and the size of the cached data block must be equal to the size of the standard block, since the standard block is the basic unit and the smallest unit of the database input and output, and the minimum data capacity that the data is loaded into memory by the data file must be a standard chunk.

If you want to use non-standard blocks in your database, you must define the Db_cache_size and Db_nk_cache_size parameters. The Db_nk_cache_size parameter defines the size of the cache data block corresponding to the nonstandard block of data used

The principle of using multiple data block sizes:

1. All partitions of the partition object must be stored in the same block size table space

2. All temporary table spaces, including permanent table spaces used as default temporary tablespace, must use standard blocks of data.

When you create a nonstandard block of data, you can add the BlockSize NK clause after the CREATE statement. You must also define the Db_cache_size and db_nk_cache_size parameters, and N in the blocksize clause must correspond to n in Db_nk_cache_size to create such a tablespace.

Note: If it is not necessary to avoid creating a non-standard chunk size tablespace. Using a non-standard block size tablespace increases the overhead of memory and complicates the management and maintenance of the database.