Bug #54768 linestring function produces null if arguments have asbinary applied

• Submitted: 24 Jun 2010 10:36
• Modified: 26 Jul 2012 6:28
• Reporter: Clive Cox
• Status: Not a Bug
• Category: MySQL Server: GIS
• Severity: S3 (Non-critical)
• Version: 5.0.82, 5.5.5-m3
• OS: Any
• CPU Architecture: Any
• Tags: GIS linestring asbinary

[24 Jun 2010 10:36] Clive Cox

Description:
From mysql 5.0.82

select linestring(asbinary(GeomFromText("point(52.1 0.1)")),asbinary(GeomFromText("point(52.1 0.1)")));

produces NULL

but

select astext(linestring(GeomFromText("point(52.1 0.1)"),GeomFromText("point(52.1 0.1)")));

works 

How to repeat:
as described in description above.

[24 Jun 2010 10:59] Valeriy Kravchuk

Verified just as described. Also with current mysql-trunk from bzr:

mysql> select version();
+----------------+
| version()      |
+----------------+
| 5.5.5-m3-debug |
+----------------+
1 row in set (0.00 sec)

mysql> select linestring(asbinary(GeomFromText("point(52.1
0.1)")),asbinary(GeomFromText("point(52.1 0.1)"))) as a;
+------+
| a    |
+------+
| NULL |
+------+
1 row in set (0.01 sec)

mysql> select astext(linestring(GeomFromText("point(52.1 0.1)"),GeomFromText("point(52.1
0.1)"))) as a;
+-------------------------------+
| a                             |
+-------------------------------+
| LINESTRING(52.1 0.1,52.1 0.1) |
+-------------------------------+
1 row in set (0.00 sec)

[6 Feb 2012 19:27] Rob Porter

Still present in 5.0.92

[26 Jul 2012 6:28] Alexander Barkov

This is not a bug.

The function LineString() expects arguments of data type Geometry,
and specifically, Point.

Point (like any other Geometry types) consists of two pieces of information:
- SRID
- WKB

The result of the function AsBinary() is not a valid Geometry value.
It's a binary array VARBINARY(N), representing the WKB part of the
original Geometry value, without SRID.

The function LineString correctly returns NULL,
because of the wrong arguments' data type: VARBINARY(N) vs GEOMETRY.