Limits in IBM Informix
来源于ids_release_note.txt
+----------------------------------+----------------------------------+
| System-Level Parameters | Maximum Capacity per Computer |
| | System |
+----------------------------------+----------------------------------+
| IBM Informix systems per | 255 |
| computer (Dependent on available | |
| system resources) | |
+----------------------------------+----------------------------------+
+----------------------------------+----------------------------------+
| Table-Level Parameters (based on | Maximum Capacity per Table |
| 2K page size) | |
+----------------------------------+----------------------------------+
| Data rows per fragment | 4,277,659,295 |
+----------------------------------+----------------------------------+
| Data pages per fragment | 16,775,134 |
+----------------------------------+----------------------------------+
| Data bytes per fragment | 33,818,671,136 |
| (excludes Smart Large Objects | |
| (BLOB, CLOB) and Simple Large | |
| Objects (BYTE, TEXT) created in | |
| Blobspaces) | |
+----------------------------------+----------------------------------+
| Binary Large Object BLOB/CLOB | 4 TB |
| pages | |
+----------------------------------+----------------------------------+
| Binary Large Objects TEXT/BYTE | 4 TB |
| bytes | |
+----------------------------------+----------------------------------+
| Row length | 32,767 |
+----------------------------------+----------------------------------+
| Number of columns | 32K |
+----------------------------------+----------------------------------+
| Key parts per index | 16 |
+----------------------------------+----------------------------------+
| Columns per functional index | 102 (for C UDRs) 341 (for SPL or |
| | Java UDRs) |
+----------------------------------+----------------------------------+
| Maximum bytes per index key (for | 2K page size = 387 |
| a given page size): | |
| | 4K page size = 796 |
| | |
| | 8K page size = 1615 |
| | |
| | 12K page size = 2435 |
| | |
| | 16K page size = 3254 |
+----------------------------------+----------------------------------+
+----------------------------------------------+----------------------+
| Access Capabilities | Maximum Capacity per |
| | System |
+----------------------------------------------+----------------------+
| Maximum databases per Informix system | 21 million |
+----------------------------------------------+----------------------+
| Maximum tables per Informix system | 477,102,080 |
+----------------------------------------------+----------------------+
| Maximum active users per Informix(minus the | 32K user threads |
| minimum number of system threads) | |
+----------------------------------------------+----------------------+
| Maximum active users per database and table | 32K user threads |
| (also limited by the number of available | |
| locks, a tunable parameter) | |
+----------------------------------------------+----------------------+
| Maximum number of open tables per Informix | Dynamic allocation |
| system | |
+----------------------------------------------+----------------------+
| Maximum number of open tables per user and | Dynamic allocation |
| join | |
+----------------------------------------------+----------------------+
| Maximum locks per Informix system and | Dynamic allocation |
| database | |
+----------------------------------------------+----------------------+
| Maximum number of page cleaners | 128 |
+----------------------------------------------+----------------------+
| Maximum number of recursive synonym mappings | 16 |
+----------------------------------------------+----------------------+
| Maximum number of tables locked with LOCK | 32 |
| TABLE per user | |
+----------------------------------------------+----------------------+
| Maximum number of cursors per user | Machine specific |
+----------------------------------------------+----------------------+
| Maximum Enterprise Replication transaction | 4 TB |
| size | |
+----------------------------------------------+----------------------+
| Maximum chunk size | 4 TB with 2K page |
| | size |
| | 8TB with 4K page |
| | size |
+----------------------------------------------+----------------------+
| Maximum number of chunks | 32,766 |
+----------------------------------------------+----------------------+
| Maximum number of 2K pages per chunk | 2 billion |
+----------------------------------------------+----------------------+
| Maximum number of open Simple Large Objects | 20 |
| (applies only to TEXT and BYTE data types) | |
+----------------------------------------------+----------------------+
| Maximum number of B-tree levels | 20 |
+----------------------------------------------+----------------------+
| Maximum amount of decision support memory | Machine specific |
+----------------------------------------------+----------------------+
| Maximum size of an Informix instance | 8 PB |
+----------------------------------------------+----------------------+
| Maximum size of an SQL statement | 64 K |
+----------------------------------------------+----------------------+
| Utility support for large files | 17 billion GB |
+----------------------------------------------+----------------------+
| Maximum number of storage spaces (dbspaces, | 2047 |
| blobspaces, sbspaces, or extspaces) | |
+----------------------------------------------+----------------------+
| Maximum size of dbspaces and sbspaces | 4 TB with 2K page |
| | size |
| | 8TB with 4K page |
| | size |
+----------------------------------------------+----------------------+
| Maximum number of partitions in a dbspace | 1048431 with 2K page |
| (assuming only 4-bit bitmaps) | size |
| | 1048445 with 4K page |
| | size |
+----------------------------------------------+----------------------+
IBM Informix System Defaults
+----------------------------------+----------------------------------+
| Table lock mode | Page |
+----------------------------------+----------------------------------+
| Initial extent size | 8 pages |
+----------------------------------+----------------------------------+
| Next extent size | 8 pages |
+----------------------------------+----------------------------------+
| Read-only isolation level (with | Committed Read |
| database transactions) | |
+----------------------------------+----------------------------------+
| Read-only isolation level | Repeatable Read |
| (ANSI-compliant database) | |
+----------------------------------+----------------------------------+
| High-availability cluster | Dirty Read |
| secondary server isolation level | |
+----------------------------------+----------------------------------+注：部分限制跟版本相关。
