Physical Database Limits
| Item | Type of Limit | Limit Value | 
|---|---|---|
| Database Block Size | Minimum | 2048bytes; must be a multiple of operating system physical block size | 
| Database Block Size | Maximum | Operating system dependent; never more than 32KB | 
| Database Blocks | Minimum in initial extent of a segment | 2 blocks | 
| Database Blocks | Maximum per datafile | Platform dependent; typically 222 - 1 blocks | 
| Controlfiles | Number of control files | 1minimum;2or more (on separate devices) strongly recommended | 
| Controlfiles | Size of a control file | Dependent on operating system and database creation options; maximum of 20,000x (database block size) | 
| Database files | Maximum per tablespace | Operating system dependent; usually 1022 | 
| Database files | Maximum per database | 65533 
May be less on some operating systems 
Limited also by size of database blocks and by the  DB_FILESinitialization parameter for a particular instance | 
| Database extents | Maximum per dictionary managed tablespace | 4GB * physical block size (with K/M modifier);4GB (without K/M modifier) | 
| Database extents | Maximum per locally managed (uniform) tablespace | 2GB * physical block size (with K/M modifier);2GB (without K/M modifier) | 
| Database file size | Maximum | Operating system dependent. Limited by maximum operating system file size; typically 222 or 4MB blocks | 
| MAXEXTENTS | Default value | Derived from tablespace default storage or DB_BLOCK_SIZEinitialization parameter | 
| MAXEXTENTS | Maximum | Unlimited | 
| Redo Log Files | Maximum number of logfiles | Limited by value of MAXLOGFILESparameter in theCREATE DATABASEstatement
Control file can be resized to allow more entries; ultimately an operating system limit | 
| Redo Log Files | Maximum number of logfiles per group | Unlimited | 
| Redo Log File Size | Minimum size | 4 MB | 
| Redo Log File Size | Maximum Size | Operating system limit; typically 2GB | 
| Tablespaces | Maximum number per database | 64 K
Number of tablespaces cannot exceed the number of database files because each tablespace must include at least one file | 
| Bigfile Tablespaces | Number of blocks | A bigfile tablespace contains only one datafile or tempfile, which can contain up to approximately 4 billion ( 232 ) blocks. The maximum size of the single datafile or tempfile is 128 terabytes (TB) for a tablespace with 32 K blocks and 32 TB for a tablespace with 8 K blocks. | 
| Smallfile (traditional) Tablespaces | Number of blocks | A smallfile tablespace is a traditional Oracle tablespace, which can contain 1022 datafiles or tempfiles, each of which can contain up to approximately 4 million (222) blocks. | 
| External Tables file | Maximum size | Dependent on the operating system. 
An external table can be composed of multiple files. | 
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