WL#1562 (Improving spatial code)

A set of changes improving our RTree indexes and fixed few bugs
found during the tests


myisam/rt_index.c:
  Algorythm for picking the branch to insert was fixed.
  pick_by_perimeter version of the algorythm added (mostly for testing
  purposes)
myisam/rt_index.h:
  minimal size of the page set to 1/3
  It noticeable increases searching performance
myisam/rt_key.c:
  counting of the size of the filled part of the page fixed
  rtree_choose_key moved to rt_index.c
myisam/rt_key.h:
  no need to make rtree_choose_key global
myisam/rt_mbr.c:
  operations for counting the perimeter of MBR added
myisam/rt_mbr.h:
  interface for rtree_perimeter_increase
myisam/rt_split.c:
  my_multi_malloc changed with my_alloca
sql/spatial.cc:
  LINESTRING object can consist of single point

1 files changed, 6 insertions, 1 deletions

diff --git a/sql/spatial.cc b/sql/spatial.cc
index ab415d9af10..f26e7dc3e83 100644
--- a/sql/spatial.cc
+++ b/sql/spatial.cc
@@ -395,7 +395,7 @@ bool Gis_line_string::init_from_wkt(Gis_read_stream *trs, String *wkb)
     if (trs->skip_char(','))			// Didn't find ','
       break;
   }
-  if (n_points < 2)
+  if (n_points < 1)
   {
     trs->set_error_msg("Too few points in LINESTRING");
     return 1;
@@ -484,6 +484,11 @@ int Gis_line_string::is_closed(int *closed) const
   if (no_data(data, 4))
     return 1;
   n_points= uint4korr(data);
+  if (n_points == 1)
+  {
+    *closed=1;
+    return 0;
+  }
   data+= 4;
   if (no_data(data, SIZEOF_STORED_DOUBLE * 2 * n_points))
     return 1;