Ensure that pg_get_ruledef()'s output matches pg_get_viewdef()'s.

Various cases involving renaming of view columns are handled by having
make_viewdef pass down the view's current relation tupledesc to
get_query_def, which then takes care to use the column names from the
tupledesc for the output column names of the SELECT.  For some reason
though, we'd missed teaching make_ruledef to do similarly when it is
printing an ON SELECT rule, even though this is exactly the same case.
The results from pg_get_ruledef would then be different and arguably wrong.
In particular, this breaks pre-v10 versions of pg_dump, which in some
situations would define views by means of emitting a CREATE RULE ... ON
SELECT command.  Third-party tools might not be happy either.

In passing, clean up some crufty code in make_viewdef; we'd apparently
modernized the equivalent code in make_ruledef somewhere along the way,
and missed this copy.

Per report from Gilles Darold.  Back-patch to all supported versions.

Discussion: https://postgr.es/m/ec05659a-40ff-4510-fc45-ca9d965d0838@dalibo.com

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index a72ccf8a6e0894f1972b470b68fda36d31bdabc1..94aee0b746e35ce8379f2ccb10c7984d2800326c 100644 (file)
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -4033,6 +4033,8 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
    char       *ev_qual;
    char       *ev_action;
    List       *actions = NIL;
+   Relation    ev_relation;
+   TupleDesc   viewResultDesc = NULL;
    int         fno;
    Datum       dat;
    bool        isnull;
@@ -4069,6 +4071,8 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
    if (ev_action != NULL)
        actions = (List *) stringToNode(ev_action);
 
+   ev_relation = heap_open(ev_class, AccessShareLock);
+
    /*
     * Build the rules definition text
     */
@@ -4085,6 +4089,7 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
    {
        case '1':
            appendStringInfoString(buf, "SELECT");
+           viewResultDesc = RelationGetDescr(ev_relation);
            break;
 
        case '2':
@@ -4173,7 +4178,7 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
        foreach(action, actions)
        {
            query = (Query *) lfirst(action);
-           get_query_def(query, buf, NIL, NULL,
+           get_query_def(query, buf, NIL, viewResultDesc,
                          prettyFlags, WRAP_COLUMN_DEFAULT, 0);
            if (prettyFlags)
                appendStringInfoString(buf, ";\n");
@@ -4191,10 +4196,12 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
        Query      *query;
 
        query = (Query *) linitial(actions);
-       get_query_def(query, buf, NIL, NULL,
+       get_query_def(query, buf, NIL, viewResultDesc,
                      prettyFlags, WRAP_COLUMN_DEFAULT, 0);
        appendStringInfoChar(buf, ';');
    }
+
+   heap_close(ev_relation, AccessShareLock);
 }
 
 
@@ -4216,20 +4223,28 @@ make_viewdef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
    List       *actions = NIL;
    Relation    ev_relation;
    int         fno;
+   Datum       dat;
    bool        isnull;
 
    /*
     * Get the attribute values from the rules tuple
     */
    fno = SPI_fnumber(rulettc, "ev_type");
-   ev_type = (char) SPI_getbinval(ruletup, rulettc, fno, &isnull);
+   dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
+   Assert(!isnull);
+   ev_type = DatumGetChar(dat);
 
    fno = SPI_fnumber(rulettc, "ev_class");
-   ev_class = (Oid) SPI_getbinval(ruletup, rulettc, fno, &isnull);
+   dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
+   Assert(!isnull);
+   ev_class = DatumGetObjectId(dat);
 
    fno = SPI_fnumber(rulettc, "is_instead");
-   is_instead = (bool) SPI_getbinval(ruletup, rulettc, fno, &isnull);
+   dat = SPI_getbinval(ruletup, rulettc, fno, &isnull);
+   Assert(!isnull);
+   is_instead = DatumGetBool(dat);
 
+   /* these could be nulls */
    fno = SPI_fnumber(rulettc, "ev_qual");
    ev_qual = SPI_getvalue(ruletup, rulettc, fno);
 

diff --git a/src/test/regress/expected/create_view.out b/src/test/regress/expected/create_view.out
index bec06276509ae2ad8f906a6ed883c94d02861457..e9a017fecb452551d44cfd440abc7bfa85406f04 100644 (file)
--- a/src/test/regress/expected/create_view.out
+++ b/src/test/regress/expected/create_view.out
@@ -1619,6 +1619,35 @@ select pg_get_viewdef('tt22v', true);
       LEFT JOIN tt6 ON TRUE;
 (1 row)
 
+-- check handling of views with immediately-renamed columns
+create view tt23v (col_a, col_b) as
+select q1 as other_name1, q2 as other_name2 from int8_tbl
+union
+select 42, 43;
+select pg_get_viewdef('tt23v', true);
+        pg_get_viewdef         
+-------------------------------
+  SELECT int8_tbl.q1 AS col_a,+
+     int8_tbl.q2 AS col_b     +
+    FROM int8_tbl             +
+ UNION                        +
+  SELECT 42 AS col_a,         +
+     43 AS col_b;
+(1 row)
+
+select pg_get_ruledef(oid, true) from pg_rewrite
+  where ev_class = 'tt23v'::regclass and ev_type = '1';
+                         pg_get_ruledef                          
+-----------------------------------------------------------------
+ CREATE RULE "_RETURN" AS                                       +
+     ON SELECT TO tt23v DO INSTEAD  SELECT int8_tbl.q1 AS col_a,+
+     int8_tbl.q2 AS col_b                                       +
+    FROM int8_tbl                                               +
+ UNION                                                          +
+  SELECT 42 AS col_a,                                           +
+     43 AS col_b;
+(1 row)
+
 -- clean up all the random objects we made above
 set client_min_messages = warning;
 DROP SCHEMA temp_view_test CASCADE;

diff --git a/src/test/regress/sql/create_view.sql b/src/test/regress/sql/create_view.sql
index 2246bade46ca153a71cc590b17f369f08c570b73..8a365749fce1712b6633affbcc8fd2596f3e5a7e 100644 (file)
--- a/src/test/regress/sql/create_view.sql
+++ b/src/test/regress/sql/create_view.sql
@@ -541,6 +541,17 @@ create view tt22v as
 select * from tt5 natural left join tt6;
 select pg_get_viewdef('tt22v', true);
 
+-- check handling of views with immediately-renamed columns
+
+create view tt23v (col_a, col_b) as
+select q1 as other_name1, q2 as other_name2 from int8_tbl
+union
+select 42, 43;
+
+select pg_get_viewdef('tt23v', true);
+select pg_get_ruledef(oid, true) from pg_rewrite
+  where ev_class = 'tt23v'::regclass and ev_type = '1';
+
 -- clean up all the random objects we made above
 set client_min_messages = warning;
 DROP SCHEMA temp_view_test CASCADE;