What is the minimum Oracle block size?
Oracle recommends smaller Oracle Database block sizes (2 KB or 4 KB) for online transaction processing (OLTP) or mixed workload environments and larger block sizes (8 KB, 16 KB, or 32 KB) for decision support system (DSS) workload environments.
What is default size of Oracle data block?
For uniform extents, you can specify an extent size or use the default size, which is 1 MB. Ensure that each extent contains at least five database blocks, given the database block size. Temporary tablespaces that manage their extents locally can only use this type of allocation.
How do I change the block size in Oracle?
You cannot modify the data block size after a database is created. You can only create a new database with the correct block size, export the old database and do a full import into the new database.
What is DB block size in Oracle?
DB_BLOCK_SIZE specifies (in bytes) the size of Oracle database blocks. Typical values are 4096 and 8192 . The value of this parameter must be a multiple of the physical block size at the device level. The value for DB_BLOCK_SIZE in effect at the time you create the database determines the size of the blocks.
Can we change db block size?
The DB block size is one of the Oracle system parameters. The default DB block size cannot be changed once the database is created, but multiple DB block sizes can be set up to meet the requirement.
What is block size in tablespace?
The DB_BLOCK_SIZE is the size of the default data block size when the database is created. Since Oracle 10g Release 2, each tablespace can have a different block size, thus making block size selection a less critical selection before the database is created.
Can we create tablespace with different block size?
You can create tablespaces with block sizes different from the standard database block size, which is specified by the DB_BLOCK_SIZE initialization parameter. Use the BLOCKSIZE clause of the CREATE TABLESPACE statement to create a tablespace with a block size different from the database standard block size.
What should the DB block size be in Oracle?
DB_BLOCK_SIZE specifies (in bytes) the size of Oracle database blocks. Typical values are 4096 and 8192. The value of this parameter must be a multiple of the physical block size at the device level. The value for DB_BLOCK_SIZE in effect at the time you create the database determines the size of the blocks.
Why does Oracle use one database block per freelist?
For Real Application Clusters, this parameter affects the maximum value of the FREELISTS storage parameter for tables and indexes. Oracle uses one database block for each freelist group. Decision support system (DSS) and data warehouse database environments tend to benefit from larger block size values.
Where can I find the block size of a table?
You can query the user_tablespaces or dba_tablespaces (if you have access) and see the block size for each tablespace; these views usually run instantly.
Which is the correct query for my block size?
Since the block size is different for each tablespace you better use the following query : Yes, then you have a major problem. Querying user_segments can be really slow, especially when running SAP or Infor BAAN that create ten thousands of segments and tend to fragment the data dictionary.