Department of second thoughts: make checks for replacing a view slightly
more flexible, and improve the error reporting. Also, add documentation for REPLACE RULE/VIEW.
This commit is contained in:
Tom Lane
parent
b4d24d78a9
commit
8f60f43f2e
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@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_rule.sgml,v 1.36 2002/05/18 15:44:47 petere Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_rule.sgml,v 1.37 2002/09/02 20:04:39 tgl Exp $
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PostgreSQL documentation
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-->
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@ -21,17 +21,15 @@ PostgreSQL documentation
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<date>2001-01-05</date>
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</refsynopsisdivinfo>
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<synopsis>
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CREATE RULE <replaceable class="parameter">name</replaceable> AS ON <replaceable class="parameter">event</replaceable>
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CREATE [ OR REPLACE ] RULE <replaceable class="parameter">name</replaceable> AS ON <replaceable class="parameter">event</replaceable>
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TO <replaceable class="parameter">table</replaceable> [ WHERE <replaceable class="parameter">condition</replaceable> ]
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DO [ INSTEAD ] <replaceable class="parameter">action</replaceable>
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where <replaceable class="PARAMETER">action</replaceable> can be:
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NOTHING
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<replaceable class="parameter">query</replaceable>
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( <replaceable class="parameter">query</replaceable> ; <replaceable class="parameter">query</replaceable> ... )
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| <replaceable class="parameter">query</replaceable>
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| ( <replaceable class="parameter">query</replaceable> ; <replaceable class="parameter">query</replaceable> ... )
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</synopsis>
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<refsect2 id="R2-SQL-CREATERULE-1">
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@ -76,9 +74,10 @@ NOTHING
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<term><replaceable class="parameter">condition</replaceable></term>
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<listitem>
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<para>
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Any SQL conditional expression (returning <type>boolean</type>). The condition expression may not
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Any SQL conditional expression (returning <type>boolean</type>).
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The condition expression may not
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refer to any tables except <literal>new</literal> and
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<literal>old</literal>.
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<literal>old</literal>, and may not contain aggregate functions.
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</para>
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</listitem>
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</varlistentry>
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@ -142,6 +141,14 @@ CREATE RULE
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Description
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</title>
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<para>
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<command>CREATE RULE</command> defines a new rule applying to a specified
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table or view.
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<command>CREATE OR REPLACE RULE</command> will either create a
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new rule, or replace an existing rule of the same name for the same
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table.
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</para>
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<para>
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The <productname>PostgreSQL</productname>
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<firstterm>rule system</firstterm> allows one to define an
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@ -318,7 +325,7 @@ UPDATE mytable SET name = 'foo' WHERE id = 42;
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</title>
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<para>
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<command>CREATE RULE</command> statement is a <productname>PostgreSQL</productname>
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<command>CREATE RULE</command> is a <productname>PostgreSQL</productname>
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language extension.
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There is no <command>CREATE RULE</command> statement in <acronym>SQL92</acronym>.
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</para>
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@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_view.sgml,v 1.18 2002/05/18 15:44:47 petere Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_view.sgml,v 1.19 2002/09/02 20:04:39 tgl Exp $
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PostgreSQL documentation
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-->
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@ -21,7 +21,7 @@ PostgreSQL documentation
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<date>2000-03-25</date>
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</refsynopsisdivinfo>
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<synopsis>
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CREATE VIEW <replaceable class="PARAMETER">view</replaceable> [ ( <replaceable
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CREATE [ OR REPLACE ] VIEW <replaceable class="PARAMETER">view</replaceable> [ ( <replaceable
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class="PARAMETER">column name list</replaceable> ) ] AS SELECT <replaceable class="PARAMETER">query</replaceable>
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</synopsis>
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@ -132,13 +132,21 @@ CREATE VIEW vista AS SELECT text 'Hello World'
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<title>
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Description
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</title>
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<para>
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<command>CREATE VIEW</command> will define a view of a query.
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<command>CREATE VIEW</command> defines a view of a query.
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The view is not physically materialized. Instead, a query
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rewrite rule (an <literal>ON SELECT</> rule) is automatically generated to
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support SELECT operations on views.
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</para>
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<para>
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<command>CREATE OR REPLACE VIEW</command> is similar, but if a view
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of the same name already exists, it is replaced. You can only replace
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a view with a new query that generates the identical set of columns
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(i.e., same column names and data types).
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</para>
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<para>
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If a schema name is given (for example, <literal>CREATE VIEW
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myschema.myview ...</>) then the view is created in the
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@ -206,6 +214,7 @@ SELECT * FROM kinds;
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<title>
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SQL92
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</title>
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<para>
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SQL92 specifies some additional capabilities for the
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<command>CREATE VIEW</command> statement:
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@ -253,6 +262,12 @@ CREATE VIEW <replaceable class="parameter">view</replaceable> [ <replaceable cla
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</varlistentry>
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</variablelist>
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</para>
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<para>
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<command>CREATE OR REPLACE VIEW</command> is a
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<productname>PostgreSQL</productname> language extension.
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</para>
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</refsect2>
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</refsect1>
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</refentry>
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@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.156 2002/08/30 22:18:05 tgl Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.157 2002/09/02 20:04:39 tgl Exp $
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-->
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<appendix id="release">
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@ -24,6 +24,7 @@ CDATA means the content is "SGML-free", so you can write without
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worries about funny characters.
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-->
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<literallayout><![CDATA[
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CREATE OR REPLACE VIEW, CREATE OR REPLACE RULE are available
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No-autocommit mode is available (set autocommit to off)
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Substantial improvements in functionality for functions returning sets
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Client libraries older than 6.3 no longer supported (version 0 protocol removed)
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/view.c,v 1.69 2002/09/02 02:13:01 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/view.c,v 1.70 2002/09/02 20:04:40 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -29,6 +29,9 @@
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#include "utils/lsyscache.h"
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static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
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/*---------------------------------------------------------------------
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* DefineVirtualRelation
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*
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@ -111,15 +114,9 @@ DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace)
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/*
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* Create a tuple descriptor to compare against the existing view,
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* and verify it matches.
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*
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* XXX the error message is a bit cheesy here: would be useful to
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* give a more specific complaint about the difference in the
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* descriptors. No time for it at the moment though.
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*/
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descriptor = BuildDescForRelation(attrList);
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if (!equalTupleDescs(descriptor, rel->rd_att))
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elog(ERROR, "Cannot change column set of existing view %s",
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RelationGetRelationName(rel));
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checkViewTupleDesc(descriptor, rel->rd_att);
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/*
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* Seems okay, so return the OID of the pre-existing view.
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@ -149,6 +146,46 @@ DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace)
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}
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}
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/*
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* Verify that tupledesc associated with proposed new view definition
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* matches tupledesc of old view. This is basically a cut-down version
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* of equalTupleDescs(), with code added to generate specific complaints.
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*/
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static void
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checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)
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{
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int i;
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if (newdesc->natts != olddesc->natts)
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elog(ERROR, "Cannot change number of columns in view");
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/* we can ignore tdhasoid */
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for (i = 0; i < newdesc->natts; i++)
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{
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Form_pg_attribute newattr = newdesc->attrs[i];
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Form_pg_attribute oldattr = olddesc->attrs[i];
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/* XXX not right, but we don't support DROP COL on view anyway */
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if (newattr->attisdropped != oldattr->attisdropped)
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elog(ERROR, "Cannot change number of columns in view");
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if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
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elog(ERROR, "Cannot change name of view column \"%s\"",
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NameStr(oldattr->attname));
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/* XXX would it be safe to allow atttypmod to change? Not sure */
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if (newattr->atttypid != oldattr->atttypid ||
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newattr->atttypmod != oldattr->atttypmod)
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elog(ERROR, "Cannot change datatype of view column \"%s\"",
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NameStr(oldattr->attname));
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/* We can ignore the remaining attributes of an attribute... */
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}
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/*
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* We ignore the constraint fields. The new view desc can't have any
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* constraints, and the only ones that could be on the old view are
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* defaults, which we are happy to leave in place.
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*/
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}
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static RuleStmt *
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FormViewRetrieveRule(const RangeVar *view, Query *viewParse, bool replace)
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{
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@ -44,14 +44,14 @@ SELECT * FROM viewtest;
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-- should fail
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CREATE OR REPLACE VIEW viewtest AS
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SELECT a FROM viewtest_tbl WHERE a <> 20;
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ERROR: Cannot change column set of existing view viewtest
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ERROR: Cannot change number of columns in view
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-- should fail
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CREATE OR REPLACE VIEW viewtest AS
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SELECT 1, * FROM viewtest_tbl;
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ERROR: Cannot change column set of existing view viewtest
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ERROR: Cannot change number of columns in view
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-- should fail
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CREATE OR REPLACE VIEW viewtest AS
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SELECT a, b::numeric FROM viewtest_tbl;
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ERROR: Cannot change column set of existing view viewtest
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ERROR: Cannot change datatype of view column "b"
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DROP VIEW viewtest;
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DROP TABLE viewtest_tbl;
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