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ORACLE数据库最多可以拥有多少个表空间（Tablespace）？数据库 最多拥有多少个数据文件（Database files）、数据库的数据文件最大可以多大？遇到这些问题只能查询官方文档，人的记忆能力是有限的。正所谓好记性不如烂笔头。下面是ORACLE 10g数据库的一些限制，以供参考。
Physical Database Limits
| Item | Type of Limit | Limit Value |
| Database Block Size | Minimum | 2048 bytes; must be a multiple of operating system physical block size |
| Maximum | Operating system dependent; never more than 32 KB | |
| Database Blocks | Minimum in initial extent of a segment. | 2 blocks |
| Maximum per datafile | Platform dependent; typically 222 - 1 blocks | |
| Controlfiles | Number of control files | 1 minimum; 2 or more (on separate devices) strongly recommended |
| Size of a control file | Dependent on operating system and database creation options; maximum of 20,000 x (database block size) | |
| Database files | Maximum per tablespace | Operating system dependent; usually 1022 |
| Maximum per database | 65533 May be less on some operating systems Limited also by size of database blocks and by the DB_FILES initialization parameter for a particular instance | |
| Database extents | Maximum per dictionary managed tablespace | 4 GB * physical block size (with K/M modifier); 4 GB (without K/M modifier) |
| Maximum per locally managed (uniform) tablespace | 2 GB * physical block size (with K/M modifier); 2 GB (without K/M modifier) | |
| Database file size | Maximum | Operating system dependent. Limited by maximum operating system file size; typically 222 or 4 MB blocks |
| MAXEXTENTS | Default value | Derived from tablespace default storage or DB_BLOCK_SIZE initialization parameter |
| Maximum | Unlimited | |
| Redo Log Files | Maximum number of logfiles | Limited by value of MAXLOGFILES parameter in the CREATE DATABASE statement Control file can be resized to allow more entries; ultimately an operating system limit |
| Maximum number of logfiles per group | Unlimited | |
| Redo Log File Size | Minimum size | 50 KB |
| Maximum size | Operating system limit; typically 2 GB | |
| 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 32K blocks and 32TB for a tablespace with 8K 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. |
Logical Database Limits
| Item | Type | Limit |
| CREATE MATERIALIZED VIEWdefinition | Maximum size | 64K Bytes |
| GROUP BY clause | Maximum length | The GROUP BY expression and all of the nondistinct aggregate functions (for example,SUM, AVG) must fit within a single database block. |
| Indexes | Maximum per table | Unlimited |
| total size of indexed column | 75% of the database block size minus some overhead | |
| Columns | Per table | 1000 columns maximum |
| Per index (or clustered index) | 32 columns maximum | |
| Per bitmapped index | 30 columns maximum | |
| Constraints | Maximum per column | Unlimited |
| Subqueries | Maximum levels of subqueries in a SQL statement | Unlimited in the FROM clause of the top-level query 255 subqueries in the WHERE clause |
| Partitions | Maximum length of linear partitioning key | 4 KB - overhead |
| Maximum number of columns in partition key | 16 columns | |
| Maximum number of partitions allowed per table or index | 1024K - 1 | |
| Rows | Maximum number per table | Unlimited |
| Stored Packages | Maximum size | PL/SQL and Developer/2000 may have limits on the size of stored procedures they can call. The limits typically range from 2000 to 3000 lines of code. See Also: Your PL/SQL or Developer/2000 documentation for details |
| Trigger Cascade Limit | Maximum value | Operating system-dependent, typically 32 |
| Users and Roles | Maximum | 2,147,483,638 |
| Tables | Maximum per clustered table | 32 tables |
| Maximum per database | Unlimited |
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