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Diffstat (limited to 'doc/man/create_version.l')
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diff --git a/doc/man/create_version.l b/doc/man/create_version.l new file mode 100644 index 00000000000..ca8bd4fac25 --- /dev/null +++ b/doc/man/create_version.l @@ -0,0 +1,69 @@ +.\" This is -*-nroff-*- +.\" XXX standard disclaimer belongs here.... +.\" $Header: /cvsroot/pgsql/doc/man/Attic/create_version.l,v 1.1.1.1 1996/08/18 22:14:22 scrappy Exp $ +.TH "CREATE VERSION" SQL 01/23/93 Postgres95 Postgres95 +.SH NAME +create version \(em construct a version class +.SH SYNOPSIS +.nf +\fBcreate version\fP classname1 \fBfrom\fP classname2 [\fB[\fPabstime\fB]\fP] +.fi +.SH DESCRIPTION +.IR "Currently, the versioning facility is not working." +.PP +This command creates a version class +.IR classname1 +which is related +to its parent class, +.IR classname2 . +Initially, +.IR classname1 +has the same contents as +.IR classname2. +As updates to +.IR classname1 +occur, however, +the content of +.IR classname1 +diverges from +.IR classname2. +On the other hand, any updates to +.IR classname2 +show transparently through to +.IR classname1 , +unless the instance in question has already been updated in +.IR classname1 . +.PP +If the optional +.IR abstime +clause is specified, then the version is constructed relative to a +.BR snapshot +of +.IR classname2 +as of the time specified. +.PP +Postgres uses the query rewrite rule system to ensure that +.IR classname1 +is differentially encoded relative to +.IR classname2. +Moreover, +.IR classname1 +is automatically constructed to have the same indexes as +.IR classname2 . +It is legal to cascade versions arbitrarily, so a tree of versions can +ultimately result. The algorithms that control versions are explained +in [ONG90]. +.SH EXAMPLE +.nf +-- +--create a version foobar from a snapshot of +--barfoo as of January 17, 1990 +-- +create version foobar from barfoo [ "Jan 17 1990" ] +.fi +.SH "SEE ALSO" +create view(l), merge(l). +.SH "BUGS" +Snapshots (i.e., the optional +.IR abstime +clause) are not implemented in Postgres. |