From: Shigeru Hanada <hanada@metrosystems.co.jp>
Date: Tue, 26 Oct 2010 08:16:31 +0000 (+0900)
Subject: Add new per-column generic option "colname" to postgresql_fdw.
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=e08acd7378cf7e03c79bc42a9919394a10bfb35d;p=users%2Fhanada%2Fpostgres.git

Add new per-column generic option "colname" to postgresql_fdw.

The colname option overrides the name of the column in the foreign query.
---

diff --git a/contrib/postgresql_fdw/expected/postgresql_fdw.out b/contrib/postgresql_fdw/expected/postgresql_fdw.out
index 409d465d0a..8012713072 100644
--- a/contrib/postgresql_fdw/expected/postgresql_fdw.out
+++ b/contrib/postgresql_fdw/expected/postgresql_fdw.out
@@ -31,10 +31,12 @@ CREATE TABLE t2(
 );
 COPY t2 FROM stdin;
 CREATE FOREIGN TABLE ft1 (
-	c1 integer,
-	c2 text,
+	c1 integer OPTIONS (colname 'invalid'),
+	c2 text OPTIONS (colname 'C2'),
 	c3 date
 ) SERVER loopback1 OPTIONS (relname 't1');
+ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (SET colname 'C1');
+ALTER FOREIGN TABLE ft1 ALTER COLUMN c2 OPTIONS (DROP colname);
 CREATE FOREIGN TABLE ft2 (
 	c1 integer,
 	c2 text,
@@ -98,7 +100,7 @@ SELECT * FROM ft1 t1 LEFT JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY 1,2,3,4,5,6;
 -- WHERE clause push-down
 set client_min_messages = debug1;
 SELECT * FROM ft1 WHERE c1 = 1 AND c2 = lower('FOO') AND c3 < now();
-DEBUG:  deparsed SQL is "SELECT c1, c2, c3 FROM public.t1 ft1 WHERE ((c1 = 1) AND (c2 = 'foo'::text))"
+DEBUG:  deparsed SQL is "SELECT C1, c2, c3 FROM public.t1 ft1 WHERE ((c1 = 1) AND (c2 = 'foo'::text))"
  c1 | c2  |     c3     
 ----+-----+------------
   1 | foo | 01-01-1970
diff --git a/contrib/postgresql_fdw/postgresql_fdw.c b/contrib/postgresql_fdw/postgresql_fdw.c
index 94a4af173d..63434f9b67 100644
--- a/contrib/postgresql_fdw/postgresql_fdw.c
+++ b/contrib/postgresql_fdw/postgresql_fdw.c
@@ -337,18 +337,36 @@ deparseSql(ForeignScanState *scanstate)
 	first = true;
 	for (i = 0; i < tupdesc->natts; i++)
 	{
+		List	   *options;
+		ListCell   *lc;
+		char	   *colname = NULL;
+
 		/* skip dropped attributes */
 		if (tupdesc->attrs[i]->attisdropped)
 			continue;
 
+		/* Determine column name to be used */
+		options = GetGenericOptionsPerColumn(rte->relid, i + 1);
+		foreach (lc, options)
+		{
+			DefElem	   *def = (DefElem *) lfirst(lc);
+			if (strcmp(def->defname, "colname") == 0)
+			{
+				colname = strVal(def->arg);
+				break;
+			}
+		}
+		if (!colname)
+			colname = tupdesc->attrs[i]->attname.data;
+
 		if (!first)
 			appendStringInfoString(&sql, ", ");
 
 		if (prefix)
-			appendStringInfo(&sql, "%s.%s",
-							aliasname_q, tupdesc->attrs[i]->attname.data);
+			appendStringInfo(&sql, "%s.%s", aliasname_q, colname);
 		else
-			appendStringInfo(&sql, "%s", tupdesc->attrs[i]->attname.data);
+			appendStringInfo(&sql, "%s", colname);
+
 		first = false;
 	}
 
diff --git a/contrib/postgresql_fdw/sql/postgresql_fdw.sql b/contrib/postgresql_fdw/sql/postgresql_fdw.sql
index 8c58311808..0bdcff2700 100644
--- a/contrib/postgresql_fdw/sql/postgresql_fdw.sql
+++ b/contrib/postgresql_fdw/sql/postgresql_fdw.sql
@@ -51,10 +51,12 @@ COPY t2 FROM stdin;
 \.
 
 CREATE FOREIGN TABLE ft1 (
-	c1 integer,
-	c2 text,
+	c1 integer OPTIONS (colname 'invalid'),
+	c2 text OPTIONS (colname 'C2'),
 	c3 date
 ) SERVER loopback1 OPTIONS (relname 't1');
+ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (SET colname 'C1');
+ALTER FOREIGN TABLE ft1 ALTER COLUMN c2 OPTIONS (DROP colname);
 
 CREATE FOREIGN TABLE ft2 (
 	c1 integer,
diff --git a/src/backend/foreign/foreign.c b/src/backend/foreign/foreign.c
index 58f28c26d6..0458a2fc48 100644
--- a/src/backend/foreign/foreign.c
+++ b/src/backend/foreign/foreign.c
@@ -358,6 +358,7 @@ static struct PgFdwOption valid_options[] = {
 	/* Catalog options */
 	{"nspname", ForeignTableRelationId, false},
 	{"relname", ForeignTableRelationId, false},
+	{"colname", AttributeRelationId, false},
 
 	/* Planner cost options */
 	{"connection_cost", ForeignServerRelationId, false},
@@ -602,3 +603,37 @@ flatten_generic_options(List *options, const char **keywords,
 	}
 	return n;
 }
+
+/*
+ * Retrieve per-column generic options in form of DefElem.
+ */
+List *
+GetGenericOptionsPerColumn(Oid relid, int2 attnum)
+{
+	Form_pg_attribute	attform;
+	Datum				datum;
+	HeapTuple			tp;
+	bool				isnull;
+	List			   *options = NIL;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for attribute attnum %u of relation %u", (int) attnum, relid);
+
+	attform = (Form_pg_attribute) GETSTRUCT(tp);
+
+	/* Extract the options */
+	datum = SysCacheGetAttr(ATTNUM,
+							tp,
+							Anum_pg_attribute_attgenoptions,
+							&isnull);
+	if (!isnull)
+		options = untransformRelOptions(datum);
+
+	ReleaseSysCache(tp);
+
+	return options;
+}
diff --git a/src/include/foreign/foreign.h b/src/include/foreign/foreign.h
index 80f277c5de..743a36f2e4 100644
--- a/src/include/foreign/foreign.h
+++ b/src/include/foreign/foreign.h
@@ -86,6 +86,7 @@ extern ForeignTable *GetForeignTable(Oid relid);
 extern FdwRoutine *GetFdwRoutine(Oid fdwhandler);
 extern bool IsForeignTable(Oid relid);
 extern Oid GetFdwValidator(Oid relid);
+extern List *GetGenericOptionsPerColumn(Oid relid, int2 attnum);
 
 extern int flatten_generic_options(List *options,
 						   const char **keywords, const char **values);