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146 lines
4.2 KiB
Plaintext
146 lines
4.2 KiB
Plaintext
.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/doc/man/Attic/create_table.l,v 1.1.1.1 1996/08/18 22:14:22 scrappy Exp $
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.TH "CREATE TABLE" SQL 11/05/95 Postgres95 Postgres95
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.SH NAME
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create table \(em create a new class
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.SH SYNOPSIS
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.nf
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\fBcreate table \fR classname \fB(\fPattname-1 type-1 {\fB,\fP attname-i type-i}\fB)\fP
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[\fBinherits\fR \fB(\fR classname-1 {\fB,\fR classname-i} \fB)\fR]
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[\fBarchive\fR \fB=\fR archive_mode]
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[\fBstore\fR \fB=\fR \*(lqsmgr_name\*(rq]
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[\fBarch_store\fR \fB=\fR \*(lqsmgr_name\*(rq]
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.fi
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.SH DESCRIPTION
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.BR "Create table"
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will enter a new class into the current data base. The class will be
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\*(lqowned\*(rq by the user issuing the command. The name of the
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class is
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.IR classname
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and the attributes are as specified in the list of
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.IR attname s.
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The
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.IR i th
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attribute is created with the type specified by
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.IR type "-i."
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Each type may be a simple type, a complex type (set) or an array type.
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.PP
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Each array attribute stores arrays that must have the same number of
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dimensions but may have different sizes and array index bounds. An
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array of dimension
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.IR n
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is specified by appending
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.IR n
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pairs of square brackets:
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.nf
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att_name = type[][]..[]
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.fi
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.PP
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The optional
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.BR inherits
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clause specifies a collection of class names from which this class
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automatically inherits all fields. If any inherited field name
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appears more than once, Postgres reports an error. Postgres automatically
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allows the created class to inherit functions on classes above it in
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the inheritance hierarchy. Inheritance of functions is done according
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to the conventions of the Common Lisp Object System (CLOS).
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.PP
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Each new class
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.IR classname
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is automatically created as a type. Therefore, one or more instances
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from the class are automatically a type and can be used in
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.IR alter table(l)
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or other
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.BR "create table"
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statements. See
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.IR introduction (l)
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for a further discussion of this point.
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.PP
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The optional
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.BR store
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and
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.BR arch_store
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keywords may be used to specify a storage manager to use for the new
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class. The released version of Postgres supports only \*(lqmagnetic
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disk\*(rq as a storage manager name; the research system at UC Berkeley
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provides additional storage managers.
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.BR Store
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controls the location of current data,
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and
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.BR arch_store
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controls the location of historical data.
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.BR Arch_store
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may only be specified if
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.BR archive
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is also specified. If either
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.BR store
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or
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.BR arch_store
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is not declared, it defaults to \*(lqmagnetic disk\*(rq.
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.PP
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The new class is created as a heap with no initial data. A class can
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have no more than 1600 attributes (realistically, this is limited by the
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fact that tuple sizes must be less than 8192 bytes), but this limit
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may be configured lower at some sites. A class cannot have the same
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name as a system catalog class.
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.PP
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The
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.BR archive
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keyword specifies whether historical data is to be saved or discarded.
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.IR Arch_mode
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may be one of:
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.TP 10n
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.IR none
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No historical access is supported.
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.TP 10n
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.IR light
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Historical access is allowed and optimized for light update activity.
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.TP 10n
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.IR heavy
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Historical access is allowed and optimized for heavy update activity.
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.PP
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.IR Arch_mode
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defaults to \*(lqnone\*(rq. Once the archive status is set, there is
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no way to change it. For details of the optimization, see [STON87].
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.SH EXAMPLES
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.nf
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--
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-- Create class emp with attributes name, sal and bdate
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--
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create table emp (name char16, salary float4, bdate abstime)
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.fi
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.nf
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--
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--Create class permemp with pension information that
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--inherits all fields of emp
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--
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create table permemp (plan char16) inherits (emp)
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.fi
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.nf
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--
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--Create class foo on magnetic disk and archive historical data
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--
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create table foo (bar int4) archive = heavy
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store = "magnetic disk"
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.fi
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.nf
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--
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--Create class tictactoe to store noughts-and-crosses
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--boards as a 2-dimensional array
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--
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create table tictactoe (game int4, board = char[][])
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.fi
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.nf
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--
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--Create a class newemp with a set attribute "manager". A
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--set (complex) attribute may be of the same type as the
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--relation being defined (as here) or of a different complex
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--type. The type must exist in the "pg_type" catalog or be
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--the one currently being defined.
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--
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create table newemp (name text, manager = newemp)
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.fi
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.SH "SEE ALSO"
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drop table(l).
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