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Doc: clarify that DROP ... CASCADE is recursive.

Browse Source 
Apparently that's not obvious to everybody, so let's belabor the point.

In passing, document that DROP POLICY has CASCADE/RESTRICT options (which
it does, per gram.y) but they do nothing (I assume, anyway).  Also update
some long-obsolete commentary in gram.y.

Discussion: <20160805104837.1412.84915@wrigleys.postgresql.org>
This commit is contained in:
Tom Lane
2016-08-12 18:45:18 -04:00
parent 4b234fd8bf
commit 4997878193
35 changed files with 144 additions and 48 deletions
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23
doc/src/sgml/ddl.sgml
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@ -2611,7 +2611,7 @@ VALUES ('Albany', NULL, NULL, 'NY');
if they are inherited
from any parent tables. If you wish to remove a table and all of its
descendants, one easy way is to drop the parent table with the
<literal>CASCADE</literal> option.
<literal>CASCADE</literal> option (see <xref linkend="ddl-depend">).
</para>
<para>
@ -3586,20 +3586,22 @@ HINT: Use DROP ... CASCADE to drop the dependent objects too.
<screen>
DROP TABLE products CASCADE;
</screen>
and all the dependent objects will be removed. In this case, it
doesn't remove the orders table, it only removes the foreign key
constraint. (If you want to check what <command>DROP ... CASCADE</> will do,
and all the dependent objects will be removed, as will any objects
that depend on them, recursively. In this case, it doesn't remove
the orders table, it only removes the foreign key constraint.
It stops there because nothing depends on the foreign key constraint.
(If you want to check what <command>DROP ... CASCADE</> will do,
run <command>DROP</> without <literal>CASCADE</> and read the
<literal>DETAIL</> output.)
</para>
<para>
All <command>DROP</> commands in <productname>PostgreSQL</> support
Almost all <command>DROP</> commands in <productname>PostgreSQL</> support
specifying <literal>CASCADE</literal>. Of course, the nature of
the possible dependencies varies with the type of the object. You
can also write <literal>RESTRICT</literal> instead of
<literal>CASCADE</literal> to get the default behavior, which is to
prevent the dropping of objects that other objects depend on.
prevent dropping objects that any other objects depend on.
</para>
<note>
@ -3613,6 +3615,15 @@ DROP TABLE products CASCADE;
</para>
</note>
<para>
If a <command>DROP</> command lists multiple
objects, <literal>CASCADE</literal> is only required when there are
dependencies outside the specified group. For example, when saying
<literal>DROP TABLE tab1, tab2</literal> the existence of a foreign
key referencing <literal>tab1</> from <literal>tab2</> would not mean
that <literal>CASCADE</literal> is needed to succeed.
</para>
<para>
For user-defined functions, <productname>PostgreSQL</productname> tracks
dependencies associated with a function's externally-visible properties,

4
doc/src/sgml/ref/alter_domain.sgml
View File

@ -212,7 +212,9 @@ ALTER DOMAIN <replaceable class="PARAMETER">name</replaceable>
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the constraint.
Automatically drop objects that depend on the constraint,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/alter_foreign_table.sgml
View File

@ -431,7 +431,9 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
<listitem>
<para>
Automatically drop objects that depend on the dropped column
or constraint (for example, views referencing the column).
or constraint (for example, views referencing the column),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/alter_table.sgml
View File

@ -823,7 +823,9 @@ ALTER TABLE ALL IN TABLESPACE <replaceable class="PARAMETER">name</replaceable>
<listitem>
<para>
Automatically drop objects that depend on the dropped column
or constraint (for example, views referencing the column).
or constraint (for example, views referencing the column),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_access_method.sgml
View File

@ -62,7 +62,9 @@ DROP ACCESS METHOD [ IF EXISTS ] <replaceable class="parameter">name</replaceabl
<listitem>
<para>
Automatically drop objects that depend on the access method
(such as operator classes, operator families, indexes).
(such as operator classes, operator families, and indexes),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

5
doc/src/sgml/ref/drop_aggregate.sgml
View File

@ -107,7 +107,10 @@ DROP AGGREGATE [ IF EXISTS ] <replaceable>name</replaceable> ( <replaceable>aggr
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the aggregate function.
Automatically drop objects that depend on the aggregate function
(such as views using it),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_collation.sgml
View File

@ -60,7 +60,9 @@ DROP COLLATION [ IF EXISTS ] <replaceable>name</replaceable> [ CASCADE | RESTRIC
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the collation.
Automatically drop objects that depend on the collation,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_domain.sgml
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@ -62,7 +62,9 @@ DROP DOMAIN [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, .
<listitem>
<para>
Automatically drop objects that depend on the domain (such as
table columns).
table columns),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_event_trigger.sgml
View File

@ -63,7 +63,9 @@ DROP EVENT TRIGGER [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceabl
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the trigger.
Automatically drop objects that depend on the trigger,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_extension.sgml
View File

@ -66,7 +66,9 @@ DROP EXTENSION [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the extension.
Automatically drop objects that depend on the extension,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

6
doc/src/sgml/ref/drop_foreign_data_wrapper.sgml
View File

@ -63,7 +63,9 @@ DROP FOREIGN DATA WRAPPER [ IF EXISTS ] <replaceable class="parameter">name</rep
<listitem>
<para>
Automatically drop objects that depend on the foreign-data
wrapper (such as servers).
wrapper (such as foreign tables and servers),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>
@ -72,7 +74,7 @@ DROP FOREIGN DATA WRAPPER [ IF EXISTS ] <replaceable class="parameter">name</rep
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Refuse to drop the foreign-data wrappers if any objects depend
Refuse to drop the foreign-data wrapper if any objects depend
on it. This is the default.
</para>
</listitem>

3
doc/src/sgml/ref/drop_foreign_table.sgml
View File

@ -59,7 +59,8 @@ DROP FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceabl
<listitem>
<para>
Automatically drop objects that depend on the foreign table (such as
views).
views), and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_function.sgml
View File

@ -107,7 +107,9 @@ DROP FUNCTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> (
<listitem>
<para>
Automatically drop objects that depend on the function (such as
operators or triggers).
operators or triggers),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_index.sgml
View File

@ -84,7 +84,9 @@ DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] <replaceable class="PARAMETER">name</r
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the index.
Automatically drop objects that depend on the index,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_language.sgml
View File

@ -74,7 +74,9 @@ DROP [ PROCEDURAL ] LANGUAGE [ IF EXISTS ] <replaceable class="PARAMETER">name</
<listitem>
<para>
Automatically drop objects that depend on the language (such as
functions in the language).
functions in the language),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_materialized_view.sgml
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@ -64,7 +64,9 @@ DROP MATERIALIZED VIEW [ IF EXISTS ] <replaceable class="PARAMETER">name</replac
<listitem>
<para>
Automatically drop objects that depend on the materialized view (such as
other materialized views, or regular views).
other materialized views, or regular views),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_opclass.sgml
View File

@ -78,7 +78,9 @@ DROP OPERATOR CLASS [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the operator class.
Automatically drop objects that depend on the operator class (such as
indexes), and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_operator.sgml
View File

@ -83,7 +83,9 @@ DROP OPERATOR [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> (
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the operator.
Automatically drop objects that depend on the operator (such as views
using it), and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_opfamily.sgml
View File

@ -79,7 +79,9 @@ DROP OPERATOR FAMILY [ IF EXISTS ] <replaceable class="PARAMETER">name</replacea
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the operator family.
Automatically drop objects that depend on the operator family,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_owned.sgml
View File

@ -55,7 +55,9 @@ DROP OWNED BY { <replaceable class="PARAMETER">name</replaceable> | CURRENT_USER
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the affected objects.
Automatically drop objects that depend on the affected objects,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

14
doc/src/sgml/ref/drop_policy.sgml
View File

@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
DROP POLICY [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ON <replaceable class="parameter">table_name</replaceable>
DROP POLICY [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ON <replaceable class="parameter">table_name</replaceable> [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
@ -72,6 +72,18 @@ DROP POLICY [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ON <
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
These key words do not have any effect, since there are no
dependencies on policies.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>

4
doc/src/sgml/ref/drop_rule.sgml
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@ -71,7 +71,9 @@ DROP RULE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> ON <re
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the rule.
Automatically drop objects that depend on the rule,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

13
doc/src/sgml/ref/drop_schema.sgml
View File

@ -67,7 +67,9 @@ DROP SCHEMA [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, .
<listitem>
<para>
Automatically drop objects (tables, functions, etc.) that are
contained in the schema.
contained in the schema,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>
@ -84,6 +86,15 @@ DROP SCHEMA [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, .
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Using the <literal>CASCADE</literal> option might make the command
remove objects in other schemas besides the one(s) named.
</para>
</refsect1>
<refsect1>
<title>Examples</title>

4
doc/src/sgml/ref/drop_sequence.sgml
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@ -61,7 +61,9 @@ DROP SEQUENCE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [,
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the sequence.
Automatically drop objects that depend on the sequence,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_server.sgml
View File

@ -63,7 +63,9 @@ DROP SERVER [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ CA
<listitem>
<para>
Automatically drop objects that depend on the server (such as
user mappings).
user mappings),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_table.sgml
View File

@ -75,7 +75,9 @@ DROP TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, ..
<listitem>
<para>
Automatically drop objects that depend on the table (such as
views).
views),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

6
doc/src/sgml/ref/drop_transform.sgml
View File

@ -18,7 +18,7 @@
<refsynopsisdiv>
<synopsis>
DROP TRANSFORM [ IF EXISTS ] FOR <replaceable>type_name</replaceable> LANGUAGE <replaceable>lang_name</replaceable>
DROP TRANSFORM [ IF EXISTS ] FOR <replaceable>type_name</replaceable> LANGUAGE <replaceable>lang_name</replaceable> [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
@ -74,7 +74,9 @@ DROP TRANSFORM [ IF EXISTS ] FOR <replaceable>type_name</replaceable> LANGUAGE <
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the transform.
Automatically drop objects that depend on the transform,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_trigger.sgml
View File

@ -73,7 +73,9 @@ DROP TRIGGER [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> ON
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the trigger.
Automatically drop objects that depend on the trigger,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_tsconfig.sgml
View File

@ -64,7 +64,9 @@ DROP TEXT SEARCH CONFIGURATION [ IF EXISTS ] <replaceable class="PARAMETER">name
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the text search configuration.
Automatically drop objects that depend on the text search configuration,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_tsdictionary.sgml
View File

@ -64,7 +64,9 @@ DROP TEXT SEARCH DICTIONARY [ IF EXISTS ] <replaceable class="PARAMETER">name</r
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the text search dictionary.
Automatically drop objects that depend on the text search dictionary,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_tsparser.sgml
View File

@ -62,7 +62,9 @@ DROP TEXT SEARCH PARSER [ IF EXISTS ] <replaceable class="PARAMETER">name</repla
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the text search parser.
Automatically drop objects that depend on the text search parser,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_tstemplate.sgml
View File

@ -63,7 +63,9 @@ DROP TEXT SEARCH TEMPLATE [ IF EXISTS ] <replaceable class="PARAMETER">name</rep
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the text search template.
Automatically drop objects that depend on the text search template,
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_type.sgml
View File

@ -62,7 +62,9 @@ DROP TYPE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, ...
<listitem>
<para>
Automatically drop objects that depend on the type (such as
table columns, functions, operators).
table columns, functions, and operators),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/drop_view.sgml
View File

@ -62,7 +62,9 @@ DROP VIEW [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, ...
<listitem>
<para>
Automatically drop objects that depend on the view (such as
other views).
other views),
and in turn all objects that depend on those objects
(see <xref linkend="ddl-depend">).
</para>
</listitem>
</varlistentry>

14
src/backend/parser/gram.y
View File

@ -1126,9 +1126,9 @@ AlterUserSetStmt:
*
* Drop a postgresql DBMS role
*
* XXX Ideally this would have CASCADE/RESTRICT options, but since a role
* might own objects in multiple databases, there is presently no way to
* implement either cascading or restricting. Caveat DBA.
* XXX Ideally this would have CASCADE/RESTRICT options, but a role
* might own objects in multiple databases, and there is presently no way to
* implement cascading to other databases. So we always behave as RESTRICT.
*****************************************************************************/
DropRoleStmt:
@ -1152,9 +1152,7 @@ DropRoleStmt:
*
* Drop a postgresql DBMS user
*
* XXX Ideally this would have CASCADE/RESTRICT options, but since a user
* might own objects in multiple databases, there is presently no way to
* implement either cascading or restricting. Caveat DBA.
* XXX As with DROP ROLE, no CASCADE/RESTRICT here.
*****************************************************************************/
DropUserStmt:
@ -1220,7 +1218,7 @@ add_drop: ADD_P { $$ = +1; }
*
* Drop a postgresql group
*
* XXX see above notes about cascading DROP USER; groups have same problem.
* XXX As with DROP ROLE, no CASCADE/RESTRICT here.
*****************************************************************************/
DropGroupStmt:
@ -4574,6 +4572,8 @@ auth_ident: RoleSpec { $$ = $1; }
* QUERY :
* DROP USER MAPPING FOR auth_ident SERVER name
*
* XXX you'd think this should have a CASCADE/RESTRICT option, even if it's
* only pro forma; but the SQL standard doesn't show one.
****************************************************************************/
DropUserMappingStmt: DROP USER MAPPING FOR auth_ident SERVER name