diff --git a/doc/src/sgml/ref/create_rule.sgml b/doc/src/sgml/ref/create_rule.sgml
index 430026a78636028b445deabf8a72fa28973171ee..a2388b09d1111faf85c7b6c9c78a8318d77e7702 100644
--- a/doc/src/sgml/ref/create_rule.sgml
+++ b/doc/src/sgml/ref/create_rule.sgml
@@ -1,5 +1,5 @@
<!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_rule.sgml,v 1.23 2001/05/27 09:59:27 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_rule.sgml,v 1.24 2001/07/09 23:50:31 tgl Exp $
Postgres documentation
-->
@@ -167,7 +167,8 @@ CREATE
<replaceable class="parameter">action</replaceable> part of the rule is
executed. The <replaceable class="parameter">action</replaceable> is
done instead of the original query if INSTEAD is specified; otherwise
- it is done before the original query is performed.
+ it is done after the original query in the case of ON INSERT, or before
+ the original query in the case of ON UPDATE or ON DELETE.
Within both the <replaceable class="parameter">condition</replaceable>
and <replaceable class="parameter">action</replaceable>, values from
fields in the old instance and/or the new instance are substituted for
diff --git a/doc/src/sgml/rules.sgml b/doc/src/sgml/rules.sgml
index 508345a44200be6b7190522198a44e421d4c33d5..512f5f266bb1e433f88dd41f09ad0d55c71f3598 100644
--- a/doc/src/sgml/rules.sgml
+++ b/doc/src/sgml/rules.sgml
@@ -1,3 +1,5 @@
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/rules.sgml,v 1.14 2001/07/09 23:50:32 tgl Exp $ -->
+
<Chapter Id="rules">
<Title>The <ProductName>Postgres</ProductName> Rule System</Title>
@@ -1014,6 +1016,16 @@
for a rule with one action.
</Para>
+<Para>
+ For ON INSERT rules, the original query (if not suppressed by INSTEAD)
+ is done before any actions added by rules. This allows the actions to
+ see the inserted row(s). But for ON UPDATE and ON
+ DELETE rules, the original query is done after the actions added by rules.
+ This ensures that the actions can see the to-be-updated or to-be-deleted
+ rows; otherwise, the actions might do nothing because they find no rows
+ matching their qualifications.
+</Para>
+
<Para>
The parsetrees generated from rule actions are thrown into the
rewrite system again and maybe more rules get applied resulting
@@ -1022,8 +1034,8 @@
or another resultrelation. Otherwise this recursive process will end up in a loop.
There is a compiled in recursion limit of currently 10 iterations.
If after 10 iterations there are still update rules to apply the
- rule system assumes a loop over multiple rule definitions and aborts the
- transaction.
+ rule system assumes a loop over multiple rule definitions and reports
+ an error.
</Para>
<Para>
@@ -1262,10 +1274,8 @@
</Para>
<Para>
- It is important, that the original parsetree is executed last.
- The <ProductName>Postgres</ProductName> "traffic cop" does
- a command counter increment between the execution of the two
- parsetrees so the second one can see changes made by the first.
+ Here we can see why it is important that the original parsetree is
+ executed last.
If the UPDATE would have been executed first, all the rows
are already set to zero, so the logging INSERT
would not find any row where 0 != shoelace_data.sl_avail.
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 3011e54fd7108e7dc9d8dd291e5fc7a3f7e4cd93..3b3d209d468894f36a26e0c85d3a4adb8cf2ec04 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.96 2001/07/06 13:40:47 wieck Exp $
+ * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.97 2001/07/09 23:50:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -831,7 +831,7 @@ deepRewriteQuery(Query *parsetree)
numQueryRewriteInvoked - 1);
}
- instead = FALSE;
+ instead = false;
result = RewriteQuery(parsetree, &instead, &qual_products);
foreach(n, result)
@@ -845,25 +845,41 @@ deepRewriteQuery(Query *parsetree)
}
/*
- * qual_products are the original query with the negated rule
- * qualification of an instead rule
+ * For INSERTs, the original query is done first; for UPDATE/DELETE, it is
+ * done last. This is needed because update and delete rule actions might
+ * not do anything if they are invoked after the update or delete is
+ * performed. The command counter increment between the query execution
+ * makes the deleted (and maybe the updated) tuples disappear so the scans
+ * for them in the rule actions cannot find them.
*/
- if (qual_products != NIL)
- rewritten = nconc(rewritten, qual_products);
-
- /*
- * The original query is appended last (if no "instead" rule) because
- * update and delete rule actions might not do anything if they are
- * invoked after the update or delete is performed. The command
- * counter increment between the query execution makes the deleted
- * (and maybe the updated) tuples disappear so the scans for them in
- * the rule actions cannot find them.
- */
- if (!instead)
- if (parsetree->commandType == CMD_INSERT)
+ if (parsetree->commandType == CMD_INSERT)
+ {
+ /*
+ * qual_products are the original query with the negated rule
+ * qualification of an INSTEAD rule
+ */
+ if (qual_products != NIL)
+ rewritten = nconc(qual_products, rewritten);
+ /*
+ * Add the unmodified original query, if no INSTEAD rule was seen.
+ */
+ if (!instead)
rewritten = lcons(parsetree, rewritten);
- else
+ }
+ else
+ {
+ /*
+ * qual_products are the original query with the negated rule
+ * qualification of an INSTEAD rule
+ */
+ if (qual_products != NIL)
+ rewritten = nconc(rewritten, qual_products);
+ /*
+ * Add the unmodified original query, if no INSTEAD rule was seen.
+ */
+ if (!instead)
rewritten = lappend(rewritten, parsetree);
+ }
return rewritten;
}
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 1c4fabd28bd7bd2d83fd7665dffbdec2ed83937f..acf6aa47f06d3615dbab85ee8581b47cfd31a1f0 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -107,7 +107,7 @@ create table rtest_nothn2 (a int4, b text);
create table rtest_nothn3 (a int4, b text);
create table rtest_nothn4 (a int4, b text);
create rule rtest_nothn_r1 as on insert to rtest_nothn1
- where new.a >= 10 and new.a < 20 do instead (select 1);
+ where new.a >= 10 and new.a < 20 do instead nothing;
create rule rtest_nothn_r2 as on insert to rtest_nothn1
where new.a >= 30 and new.a < 40 do instead nothing;
create rule rtest_nothn_r3 as on insert to rtest_nothn2
@@ -1313,7 +1313,7 @@ SELECT tablename, rulename, definition FROM pg_rules
rtest_emp | rtest_emp_del | CREATE RULE rtest_emp_del AS ON DELETE TO rtest_emp DO INSERT INTO rtest_emplog (ename, who, "action", newsal, oldsal) VALUES (old.ename, "current_user"(), 'fired '::bpchar, '$0.00'::money, old.salary);
rtest_emp | rtest_emp_ins | CREATE RULE rtest_emp_ins AS ON INSERT TO rtest_emp DO INSERT INTO rtest_emplog (ename, who, "action", newsal, oldsal) VALUES (new.ename, "current_user"(), 'hired '::bpchar, new.salary, '$0.00'::money);
rtest_emp | rtest_emp_upd | CREATE RULE rtest_emp_upd AS ON UPDATE TO rtest_emp WHERE (new.salary <> old.salary) DO INSERT INTO rtest_emplog (ename, who, "action", newsal, oldsal) VALUES (new.ename, "current_user"(), 'honored '::bpchar, new.salary, old.salary);
- rtest_nothn1 | rtest_nothn_r1 | CREATE RULE rtest_nothn_r1 AS ON INSERT TO rtest_nothn1 WHERE ((new.a >= 10) AND (new.a < 20)) DO INSTEAD SELECT 1;
+ rtest_nothn1 | rtest_nothn_r1 | CREATE RULE rtest_nothn_r1 AS ON INSERT TO rtest_nothn1 WHERE ((new.a >= 10) AND (new.a < 20)) DO INSTEAD NOTHING;
rtest_nothn1 | rtest_nothn_r2 | CREATE RULE rtest_nothn_r2 AS ON INSERT TO rtest_nothn1 WHERE ((new.a >= 30) AND (new.a < 40)) DO INSTEAD NOTHING;
rtest_nothn2 | rtest_nothn_r3 | CREATE RULE rtest_nothn_r3 AS ON INSERT TO rtest_nothn2 WHERE (new.a >= 100) DO INSTEAD INSERT INTO rtest_nothn3 (a, b) VALUES (new.a, new.b);
rtest_nothn2 | rtest_nothn_r4 | CREATE RULE rtest_nothn_r4 AS ON INSERT TO rtest_nothn2 DO INSTEAD NOTHING;
diff --git a/src/test/regress/sql/rules.sql b/src/test/regress/sql/rules.sql
index 9a04ed3a3dc3e2d44f3d625382da7b0af51b500b..5068face885978a7a26a19f58edda51c564ca996 100644
--- a/src/test/regress/sql/rules.sql
+++ b/src/test/regress/sql/rules.sql
@@ -131,7 +131,7 @@ create table rtest_nothn3 (a int4, b text);
create table rtest_nothn4 (a int4, b text);
create rule rtest_nothn_r1 as on insert to rtest_nothn1
- where new.a >= 10 and new.a < 20 do instead (select 1);
+ where new.a >= 10 and new.a < 20 do instead nothing;
create rule rtest_nothn_r2 as on insert to rtest_nothn1
where new.a >= 30 and new.a < 40 do instead nothing;