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Annotation of 43BSD/ingres/doc/quel/index.nr, revision 1.1.1.1

1.1       root        1: .th INDEX QUEL 2/21/79
                      2: .sh NAME
                      3: index \- create a secondary index on an existing relation.
                      4: .sh SYNOPSIS
                      5: .bd "index on"
                      6: relname 
                      7: .bd is
                      8: indexname 
                      9: (domain\c
                     10: .it 1 
                     11: { ,domain\c
                     12: .it 2\c
                     13: })
                     14: .sh DESCRIPTION
                     15: .it Index
                     16: is used to create secondary indices on existing relations
                     17: in order to make retrieval and update with secondary keys more
                     18: efficient.
                     19: The secondary key is constructed from relname domains 1, 2,...,6
                     20: in the order given.
                     21: Only the owner of a relation is allowed to
                     22: create secondary indices on that relation.
                     23: .s3
                     24: In order to maintain the integrity of the index, users will NOT
                     25: be allowed to directly update
                     26: secondary indices. 
                     27: However, whenever a primary relation is changed,
                     28: its secondary indices will be automatically updated by the system.
                     29: Secondary indices may be modified to further increase the access
                     30: efficiency of the primary relation.
                     31: When an index is first created, it is automatically
                     32: modified to an isam storage structure
                     33: on all its domains.
                     34: If this structure is undesirable, the user may override
                     35: the default isam structure by using the
                     36: .bd \-n
                     37: switch (see ingres(unix)), or by entering
                     38: a 
                     39: .it modify
                     40: command directly.
                     41: .s3
                     42: If a 
                     43: .it modify 
                     44: or 
                     45: .it destroy 
                     46: command is used on 
                     47: .it relname\c
                     48: , all secondary indices on 
                     49: .it relname 
                     50: are destroyed.
                     51: .s3
                     52: Secondary indices on other indices, or on system
                     53: relations are forbidden.
                     54: .sh EXAMPLE
                     55: .nf
                     56: /\*(** Create a secondary index called ``x'' on relation ``emp'' \*(**/
                     57:    index on emp is x(mgr,sal)
                     58: .fi
                     59: .sh "SEE ALSO"
                     60: copy(quel), destroy(quel), modify(quel)
                     61: .sh BUGS
                     62: At most 6 domains may appear in the key.
                     63: .s3
                     64: The 
                     65: .it copy 
                     66: command cannot be used to copy into
                     67: a relation which has secondary indices.
                     68: .s3
                     69: The default structure isam is a poor choice
                     70: for an index unless the range of retrieval
                     71: is small.

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