Bug #31158 Spatial, Union, LONGBLOB vs BLOB bug (crops data)

max_length parameter for BLOB-returning functions must be big enough
for any possible content. Otherwise the field created for a table
will be too small.

mysql-test/r/gis.result

@@ -668,7 +668,7 @@ def	test	t1	t1	g	g	255	4294967295	0	Y	144	0	63
 g
 select asbinary(g) from t1;
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
-def					asbinary(g)	252	8192	0	Y	128	0	63
+def					asbinary(g)	252	4294967295	0	Y	128	0	63
 asbinary(g)
 drop table t1;
 create table t1 (a TEXT, b GEOMETRY NOT NULL, SPATIAL KEY(b));
@@ -730,4 +730,28 @@ select geomfromtext(col9,col89) as a from t1;
 a
 NULL
 DROP TABLE t1;
+CREATE TABLE t1 (
+geomdata polygon NOT NULL,
+SPATIAL KEY index_geom (geomdata)
+) ENGINE=MyISAM DEFAULT CHARSET=latin2 DELAY_KEY_WRITE=1 ROW_FORMAT=FIXED;
+CREATE TABLE t2 (
+geomdata polygon NOT NULL,
+SPATIAL KEY index_geom (geomdata)
+) ENGINE=MyISAM DEFAULT CHARSET=latin2 DELAY_KEY_WRITE=1 ROW_FORMAT=FIXED;
+CREATE TABLE t3
+select 
+aswkb(ws.geomdata) AS geomdatawkb 
+from 
+t1 ws
+union 
+select 
+aswkb(ws.geomdata) AS geomdatawkb 
+from 
+t2 ws;
+describe t3;
+Field	Type	Null	Key	Default	Extra
+geomdatawkb	longblob	YES		NULL	
+drop table t1;
+drop table t2;
+drop table t3;
 End of 4.1 tests

mysql-test/t/gis.test

@@ -427,4 +427,35 @@ INSERT INTO `t1` VALUES ('','0000-00-00');
 select geomfromtext(col9,col89) as a from t1;
 DROP TABLE t1;
 
+#
+# Bug #31158 Spatial, Union, LONGBLOB vs BLOB bug (crops data) 
+#
+
+CREATE TABLE t1 (
+  geomdata polygon NOT NULL,
+  SPATIAL KEY index_geom (geomdata)
+) ENGINE=MyISAM DEFAULT CHARSET=latin2 DELAY_KEY_WRITE=1 ROW_FORMAT=FIXED;
+
+CREATE TABLE t2 (
+  geomdata polygon NOT NULL,
+  SPATIAL KEY index_geom (geomdata)
+) ENGINE=MyISAM DEFAULT CHARSET=latin2 DELAY_KEY_WRITE=1 ROW_FORMAT=FIXED;
+
+CREATE TABLE t3
+select 
+    aswkb(ws.geomdata) AS geomdatawkb 
+  from 
+    t1 ws
+union 
+  select 
+    aswkb(ws.geomdata) AS geomdatawkb 
+  from 
+    t2 ws;
+
+describe t3;
+
+drop table t1;
+drop table t2;
+drop table t3;
+
 --echo End of 4.1 tests

sql/field.cc

@@ -6975,7 +6975,7 @@ uint32 Field_blob::max_length()
   case 3:
     return 16777215 * field_charset->mbmaxlen;
   case 4:
-    return (uint32) 4294967295U;
+    return max_field_size;
   default:
     DBUG_ASSERT(0); // we should never go here
     return 0;

sql/field.h

@@ -26,6 +26,7 @@
 
 #define NOT_FIXED_DEC			31
 #define DATETIME_DEC                     6
+const uint32 max_field_size= (uint32) 4294967295U;
 
 class Send_field;
 class Protocol;

sql/item_geofunc.cc

@@ -29,7 +29,7 @@ void Item_geometry_func::fix_length_and_dec()
 {
   collation.set(&my_charset_bin);
   decimals=0;
-  max_length=MAX_BLOB_WIDTH;
+  max_length= max_field_size;
   maybe_null= 1;
 }