|
|
@ -1,6 +1,6 @@ |
|
|
|
.\" This is -*-nroff-*- |
|
|
|
.\" This is -*-nroff-*- |
|
|
|
.\" XXX standard disclaimer belongs here.... |
|
|
|
.\" XXX standard disclaimer belongs here.... |
|
|
|
.\" $Header: /cvsroot/pgsql/src/man/Attic/create_index.l,v 1.6 1997/05/14 01:38:34 vadim Exp $ |
|
|
|
.\" $Header: /cvsroot/pgsql/src/man/Attic/create_index.l,v 1.7 1997/10/30 18:41:03 momjian Exp $ |
|
|
|
.TH "CREATE INDEX" SQL 11/05/95 PostgreSQL PostgreSQL |
|
|
|
.TH "CREATE INDEX" SQL 11/05/95 PostgreSQL PostgreSQL |
|
|
|
.SH NAME |
|
|
|
.SH NAME |
|
|
|
create index \(em construct a secondary index |
|
|
|
create index \(em construct a secondary index |
|
|
@ -44,14 +44,7 @@ result of a user-defined function |
|
|
|
.IR funcname |
|
|
|
.IR funcname |
|
|
|
applied to one or more attributes of a single class. These |
|
|
|
applied to one or more attributes of a single class. These |
|
|
|
.IR "functional indices" |
|
|
|
.IR "functional indices" |
|
|
|
are primarily useful in two situations. First, functional indices can |
|
|
|
can be used to obtain fast access to data based on |
|
|
|
be used to simulate multi-key indices. That is, the user can define a |
|
|
|
|
|
|
|
new base type (a simple combination of, say, \*(lqoid\*(rq and |
|
|
|
|
|
|
|
\*(lqint2\*(rq) and the associated functions and operators on this new |
|
|
|
|
|
|
|
type such that the access method can use it. Once this has been done, |
|
|
|
|
|
|
|
the standard techniques for interfacing new types to access methods |
|
|
|
|
|
|
|
(described in the Postgres user manual) can be applied. Second, |
|
|
|
|
|
|
|
functional indices can be used to obtain fast access to data based on |
|
|
|
|
|
|
|
operators that would normally require some transformation to be |
|
|
|
operators that would normally require some transformation to be |
|
|
|
applied to the base data. For example, say you have an attribute in |
|
|
|
applied to the base data. For example, say you have an attribute in |
|
|
|
class \*(lqmyclass\*(rq called \*(lqpt\*(rq that consists of a 2D |
|
|
|
class \*(lqmyclass\*(rq called \*(lqpt\*(rq that consists of a 2D |
|
|
|