15.10 - DATABLOCKSIZE - Teradata Database

Teradata Database SQL Data Definition Language Syntax and Examples

prodname
Teradata Database
vrm_release
15.10
created_date
December 2015
category
Programming Reference
featnum
B035-1144-151K

Maximum data block size for blocks that contain multiple rows as the value data_block_size. The calculation is the same as for the CREATE TABLE statement. For additional information, see the CREATE TABLE (Table Options Clause) topic “DATABLOCKSIZE” in SQL Data Definition Language - Detailed Topics, B035-1184. For detailed information about setting system-wide default data block sizes using DBS Control settings, see Utilities, B035-1102. For information about setting database-wide or user-wide default data block sizes, see CREATE DATABASE or CREATE USER.

data_block_size
Decimal number or integer using exponential notation. For example, you can write one thousand as either 1000 or 1E3.
BYTES
KBYTES
KILOBYTES
BYTES can be abbreviated as BYTE. The default is BYTES. 

KILOBYTES can be abbreviated as KBYTE or KBYTES. For the rounding rules, see CREATE TABLE.
IMMEDIATE
Repackage data blocks into the newly specified size immediately instead of waiting until an affected block is modified or allocated. The new data_block_size value determines the maximum size of multiple-row data blocks subsequently modified or allocated.
  • If you specify IMMEDIATE, the attribute value is changed and the rows in all existing data blocks are repacked into data blocks of the specified size.
  • If you do not specify IMMEDIATE, the existing data blocks are not modified.
You cannot specify IMMEDIATE if you specify the BLOCKCOMPRESSION option.
MINIMUM
The smallest data block size for this table.
MINIMUM DATABLOCKSIZE sets the maximum data block size for blocks that contain multiple rows to the minimum value of 21,504 bytes (42 sectors) for systems with large cylinders or 9,216 bytes (18 sectors) for systems without large cylinders.
You can abbreviate MINIMUM as MIN.
For details about minimum data block sizes, see “DATABLOCKSIZE” in the “CREATE TABLE” section of SQL Data Definition Language - Detailed Topics, B035-1184.
MAXIMUM
The largest data block size for this table.
Systems that do not support block sizes 128KB and larger use a value of 127.5KB.
Systems that allow blocks larger than 127.5KB use a maximum of 1,048,064 bytes (2047 sectors) for large cylinders or 262,144 bytes (512 sectors) for small cylinders.
The value can be expressed either as a decimal number or integer number or using exponential notation. For example, you can write one thousand as either 1000 or 1E3.
You can abbreviate MAXIMUM as MAX.
DEFAULT
The default data block size for this table. See Utilities, B035-1102.

Example: Changing DATABLOCKSIZE

The following ALTER TABLE request changes the maximum data block size to 1,048,064 bytes (2047 sectors) on a system with large cylinders and repacks existing data into blocks of that size:
     ALTER TABLE employee, MAXIMUM DATABLOCKSIZE IMMEDIATE;