Bigfile tablespace

A Bigfile Tablespace (BFT) is a special kind of tablespace than can only have a single (normally very large) datafile. Normal/traditional tablespaces are referred to as smallfile tablespaces.

• A BFT can only have one file, whereas a traditional tablespace (smallfile type) can contain up to 1,022 files.
• BFT's simplify management. It reduces the number of databfiles to manage and storage properties can be specified on tablespace rather than datafile level.
• Bigfile tablespaces should only be used with ASM or with other logical volume managers that support dynamically extensible logical volumes, striping and RAID.
• A BFT can be up to 128 TB in size (with a 32k block size), while smallfile tablespaces can have a maximum size of 128 GB.

History

Support for bigfile tablespaces were introduced in Oracle 10g.

Examples

Smallfile tablespaces:

create           tablespace x1 datafile '/tmp/x1.dbf' size 1M;

create smallfile tablespace x2 datafile '/tmp/x2.dbf' size 1M;

Bigfile tablespaces:

create bigfile   tablespace x3 datafile '/tmp/x3.dbf' size 1M;

Monitor

To check if a given tablespace is a bigfile tablespace:

SELECT tablespace_name, bigfile FROM dba_tablespaces;

Backup and restore

With such large files, bigfile tablespaces can take considerably longer to backup or restore. To backup and restore them in parallel, specify a "SECTION SIZE" (chunk size to be handled by a single backup piece). This feature was introduced in Oracle 11g. Example:

RMAN> CONFIGURE DEVICE TYPE DISK PARALLELISM 4;
RMAN> BACKUP TABLESPACE bigts SECTION SIZE 100m;

Also see

• Tablespace - Normal smallfile tablespaces

Glossary of Terms
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