Fix pg_dump to not emit invalid SQL for an empty operator class.

tglsfdc · tglsfdc · commit a561254e4c62 · 2017-05-26T12:51:05.000-04:00
If an operator class has no operators or functions, and doesn't need a STORAGE clause, we emitted "CREATE OPERATOR CLASS ... AS ;" which is syntactically invalid. Fix by forcing a STORAGE clause to be emitted anyway in this case. (At some point we might consider changing the grammar to allow CREATE OPERATOR CLASS without an opclass_item_list. But probably we'd want to omit the AS in that case, so that wouldn't fix this pg_dump issue anyway.) It's been like this all along, so back-patch to all supported branches. Daniel Gustafsson, tweaked by me to avoid a dangling-pointer bug Discussion: https://postgr.es/m/D9E5FC64-7A37-4F3D-B946-7E4FB468F88A@yesql.se
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
@@ -10756,7 +10756,8 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 	i_opcfamilynsp = PQfnumber(res, "opcfamilynsp");
 	i_amname = PQfnumber(res, "amname");
 
-	opcintype = PQgetvalue(res, 0, i_opcintype);
+	/* opcintype may still be needed after we PQclear res */
+	opcintype = pg_strdup(PQgetvalue(res, 0, i_opcintype));
 	opckeytype = PQgetvalue(res, 0, i_opckeytype);
 	opcdefault = PQgetvalue(res, 0, i_opcdefault);
 	/* opcfamily will still be needed after we PQclear res */
@@ -10990,6 +10991,15 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 
 	PQclear(res);
 
+	/*
+	 * If needComma is still false it means we haven't added anything after
+	 * the AS keyword.  To avoid printing broken SQL, append a dummy STORAGE
+	 * clause with the same datatype.  This isn't sanctioned by the
+	 * documentation, but actually DefineOpClass will treat it as a no-op.
+	 */
+	if (!needComma)
+		appendPQExpBuffer(q, "STORAGE %s", opcintype);
+
 	appendPQExpBuffer(q, ";\n");
 
 	appendPQExpBuffer(labelq, "OPERATOR CLASS %s",
@@ -11015,6 +11025,8 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 				opcinfo->dobj.namespace->dobj.name, opcinfo->rolname,
 				opcinfo->dobj.catId, 0, opcinfo->dobj.dumpId);
 
+	free(opcintype);
+	free(opcfamily);
 	free(amname);
 	destroyPQExpBuffer(query);
 	destroyPQExpBuffer(q);
