From a8f98c068e82e9487d3e884aa35f8f5dc6a8d85c Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 28 May 2008 00:45:40 +0000
Subject: [PATCH] Improve GRANT documentation to point out that UPDATE and
 DELETE typically require SELECT privilege as well, since you normally need to
 read existing column values within such commands.  This behavior is according
 to spec, but we'd never documented it before.  Per gripe from Volkan Yazici.

---
 doc/src/sgml/ref/grant.sgml | 40 +++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/doc/src/sgml/ref/grant.sgml b/doc/src/sgml/ref/grant.sgml
index 7b1295f9eb6..14013c50ad2 100644
--- a/doc/src/sgml/ref/grant.sgml
+++ b/doc/src/sgml/ref/grant.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/grant.sgml,v 1.68 2008/05/05 01:21:03 adunstan Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/grant.sgml,v 1.69 2008/05/28 00:45:40 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -135,10 +135,15 @@ GRANT <replaceable class="PARAMETER">role</replaceable> [, ...] TO <replaceable
      <term>SELECT</term>
      <listitem>
       <para>
-       Allows <xref linkend="sql-select" endterm="sql-select-title"> from any column of the
-       specified table, view, or sequence.  Also allows the use of
-       <xref linkend="sql-copy" endterm="sql-copy-title"> TO.  For sequences, this
-       privilege also allows the use of the <function>currval</function> function.
+       Allows <xref linkend="sql-select" endterm="sql-select-title"> from
+       any column of the specified table, view, or sequence.
+       Also allows the use of
+       <xref linkend="sql-copy" endterm="sql-copy-title"> TO.
+       This privilege is also needed to reference existing column values in
+       <xref linkend="sql-update" endterm="sql-update-title"> or
+       <xref linkend="sql-delete" endterm="sql-delete-title">.
+       For sequences, this privilege also allows the use of the
+       <function>currval</function> function.
       </para>
      </listitem>
     </varlistentry>
@@ -147,8 +152,9 @@ GRANT <replaceable class="PARAMETER">role</replaceable> [, ...] TO <replaceable
      <term>INSERT</term>
      <listitem>
       <para>
-       Allows <xref linkend="sql-insert" endterm="sql-insert-title"> of a new row into the
-       specified table.  Also allows <xref linkend="sql-copy" endterm="sql-copy-title"> FROM.
+       Allows <xref linkend="sql-insert" endterm="sql-insert-title"> of a new
+       row into the specified table.
+       Also allows <xref linkend="sql-copy" endterm="sql-copy-title"> FROM.
       </para>
      </listitem>
     </varlistentry>
@@ -158,10 +164,15 @@ GRANT <replaceable class="PARAMETER">role</replaceable> [, ...] TO <replaceable
      <listitem>
       <para>
        Allows <xref linkend="sql-update" endterm="sql-update-title"> of any
-       column of the specified table.  <literal>SELECT ... FOR UPDATE</literal>
+       column of the specified table.
+       (In practice, any nontrivial <command>UPDATE</> command will require
+       <literal>SELECT</> privilege as well, since it must reference table
+       columns to determine which rows to update, and/or to compute new
+       values for columns.)
+       <literal>SELECT ... FOR UPDATE</literal>
        and <literal>SELECT ... FOR SHARE</literal>
-       also require this privilege (besides the
-       <literal>SELECT</literal> privilege).  For sequences, this
+       also require this privilege, in addition to the
+       <literal>SELECT</literal> privilege.  For sequences, this
        privilege allows the use of the <function>nextval</function> and
        <function>setval</function> functions.
       </para>
@@ -172,8 +183,11 @@ GRANT <replaceable class="PARAMETER">role</replaceable> [, ...] TO <replaceable
      <term>DELETE</term>
      <listitem>
       <para>
-       Allows <xref linkend="sql-delete" endterm="sql-delete-title"> of a row from the
-       specified table.
+       Allows <xref linkend="sql-delete" endterm="sql-delete-title"> of a row
+       from the specified table.
+       (In practice, any nontrivial <command>DELETE</> command will require
+       <literal>SELECT</> privilege as well, since it must reference table
+       columns to determine which rows to delete.)
       </para>
      </listitem>
     </varlistentry>
@@ -235,7 +249,7 @@ GRANT <replaceable class="PARAMETER">role</replaceable> [, ...] TO <replaceable
      <term>TEMP</term>
      <listitem>
       <para>
-       Allows temporary tables to be created while using the database.
+       Allows temporary tables to be created while using the specified database.
       </para>
      </listitem>
     </varlistentry>