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1 | 1 | .\" This is -*-nroff-*- |
2 | 2 | .\" XXX standard disclaimer belongs here.... |
3 | | -.\" $Header: /cvsroot/pgsql/src/man/Attic/create_index.l,v 1.3 1996/12/11 00:27:14 momjian Exp $ |
| 3 | +.\" $Header: /cvsroot/pgsql/src/man/Attic/create_index.l,v 1.4 1997/01/13 17:22:25 momjian Exp $ |
4 | 4 | .TH "CREATE INDEX" SQL 11/05/95 PostgreSQL PostgreSQL |
5 | 5 | .SH NAME |
6 | 6 | create index\(em construct a secondary index |
@@ -62,6 +62,11 @@ and then comparing it to the value on the other side of the operator. |
62 | 62 | Obviously, the decision to build a functional index represents a |
63 | 63 | tradeoff between space (for the index) and execution time. |
64 | 64 | .PP |
| 65 | +The\fBunique\fR keyword causes the system to check for duplicate |
| 66 | +values when the index is created (if data already exist) and each |
| 67 | +time data is added. |
| 68 | +Attempts to insert or update non-duplicate data will generate an error. |
| 69 | +.PP |
65 | 70 | Postgres provides btree, rtree and hash access methods for |
66 | 71 | secondary indices. The btree access method is an implementation of |
67 | 72 | the Lehman-Yao high-concurrency btrees. The rtree access method |
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