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.
Support for bigfile tablespaces were introduced in Oracle 10g.
create tablespace x1 datafile '/tmp/x1.dbf' size 1M;
create smallfile tablespace x2 datafile '/tmp/x2.dbf' size 1M;
create bigfile tablespace x3 datafile '/tmp/x3.dbf' size 1M;
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;
- Tablespace - Normal smallfile tablespaces
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