Fixed the content of the error message (#133)

Fixed the content of the error message

If the "rum" index is created without the "WITH" operator,
two columns must be specified for "ORDER BY" to work.
But now error message in this case looks like:

  "ERROR: cannot order without attribute ... in WHERE clause"

Fixed the content of error message: "WHERE" replaced by "ORDER BY".

Added a test that checks the case when only one column is
specified in the "ORDER BY" and error message for this.

Tags: rum.

Author: arseny114

expected/orderby.out

@@ -460,6 +460,11 @@ SELECT id, d FROM tsts WHERE  t @@ 'wr&qh' AND d >= '2016-05-16 14:21:25' ORDER
  458 | Fri May 20 21:21:22.326724 2016
 (3 rows)
 
+-- Test "ORDER BY" error message
+DROP INDEX tsts_idx;
+CREATE INDEX tsts_idx ON tsts USING rum (t rum_tsvector_addon_ops, d);
+SELECT id, d, d <=> '2016-05-16 14:21:25' FROM tsts WHERE t @@ 'wr&qh' ORDER BY d <=> '2016-05-16 14:21:25' LIMIT 5;
+ERROR:  cannot order without attribute 2 in ORDER BY clause
 -- Test multicolumn index
 RESET enable_indexscan;
 RESET enable_indexonlyscan;

sql/orderby.sql

@@ -95,6 +95,13 @@ SELECT id, d FROM tsts WHERE  t @@ 'wr&qh' AND d <= '2016-05-16 14:21:25' ORDER
 SELECT id, d FROM tsts WHERE  t @@ 'wr&qh' AND d >= '2016-05-16 14:21:25' ORDER BY d ASC LIMIT 3;
 SELECT id, d FROM tsts WHERE  t @@ 'wr&qh' AND d >= '2016-05-16 14:21:25' ORDER BY d DESC LIMIT 3;
 
+-- Test "ORDER BY" error message
+DROP INDEX tsts_idx;
+
+CREATE INDEX tsts_idx ON tsts USING rum (t rum_tsvector_addon_ops, d);
+
+SELECT id, d, d <=> '2016-05-16 14:21:25' FROM tsts WHERE t @@ 'wr&qh' ORDER BY d <=> '2016-05-16 14:21:25' LIMIT 5;
+
 -- Test multicolumn index
 
 RESET enable_indexscan;

src/rumscan.c

@@ -214,7 +214,7 @@ rumFillScanKey(RumScanOpaque so, OffsetNumber attnum,
 				}
 
 				if (scanKey == NULL)
-					elog(ERROR, "cannot order without attribute %d in WHERE clause",
+					elog(ERROR, "cannot order without attribute %d in ORDER BY clause",
 						 key->attnum);
 				else if (scanKey->nentries > 1)
 					elog(ERROR, "scan key should contain only one value");