optimized SQL generation

src/backend/postgis/__init__.py

@@ -56,7 +56,11 @@ class PostGisBackend:
     self.keep_tiles = 190                # a number of tiles to cache in memory
     self.tile_load_log = []             # used when selecting which tile to unload
     
-  def get_vectors (self, bbox, zoom):
+  def get_vectors (self, bbox, zoom, sql_hint = None):
+    """
+    Fetches vectors for given bbox.
+    sql_hint is a set of (key, sql_for_key)
+    """
     a = psycopg2.connect(self.database)
     b = a.cursor()
     bbox = tuple(projections.from4326(bbox,self.proj))
@@ -64,7 +68,19 @@ class PostGisBackend:
     tables = ("planet_osm_line","planet_osm_polygon")  # FIXME: points
     resp = {}
     for table in tables:
-      b.execute("SELECT * FROM %s WHERE way && SetSRID('BOX3D(%s %s,%s %s)'::box3d,900913);"%(table,bbox[0],bbox[1],bbox[2],bbox[3]))
+      add = ""
+      if sql_hint:
+        add = []
+        b.execute("SELECT * FROM %s LIMIT 1;"%table)
+        names = [q[0] for q in b.description]
+        for t,v in sql_hint:
+          if t in names:
+            add.append(v)
+        add = " OR ".join(add)
+        add = "("+add+") AND"
+      req = "SELECT * FROM %s WHERE %s way && SetSRID('BOX3D(%s %s,%s %s)'::box3d,900913);"%(table,add,bbox[0],bbox[1],bbox[2],bbox[3])
+      print req
+      b.execute(req)
       names = [q[0] for q in b.description]
       for row in b.fetchall():
         

src/kothic.py

@@ -29,7 +29,7 @@ import Queue
 from debug import debug, Timer
 
 from backend.postgis import PostGisBackend as DataBackend
-from backend.vtile import QuadTileBackend as DataBackend
+#from backend.vtile import QuadTileBackend as DataBackend
 #from style import Styling
 from mapcss import MapCSS as Styling
 from render import RasterTile
@@ -80,7 +80,7 @@ class Navigator:
     self.f = True
     undef = None
     self.style = Styling()
-    self.style.parse(open("styles/mapink.mapcss","r").read())
+    self.style.parse(open("styles/openstreetinfo.mapcss","r").read())
     
     da = gtk.DrawingArea()
     da.add_events(gtk.gdk.BUTTON1_MOTION_MASK)

src/mapcss/Condition.py

@@ -72,6 +72,35 @@ class Condition:
       pass
     return False;
 
+  def get_sql(self):
+    params = [re.escape(x) for x in self.params]
+    t = self.type
+    try:
+      if t == 'eq':
+        return params[0], '"%s" = \'%s\''%(params[0], params[1])
+      if t == 'ne':
+        return params[0], 'not("%s" = \'%s\')'%(params[0], params[1])
+      if t == 'regex':
+        return params[0], '"%s" IS NOT NULL'%(params[0])
+      if t == 'true':
+        return params[0], '"%s" IN (\'true\', \'yes\', \'1\')'%(params[0])
+      if t == 'untrue':
+        return params[0], '"%s" NOT IN (\'true\', \'yes\', \'1\')'%(params[0])
+      if t == 'set':
+        return params[0], '"%s" IS NOT NULL'%(params[0])
+      if t == 'unset':
+        return params[0], '"%s" IS NULL'%(params[0])
+        
+      if t == '<':
+        return params[0], '"%s" IS NOT NULL'%(params[0])
+      if t == '<=':
+        return params[0], '"%s" IS NOT NULL'%(params[0])
+      if t == '>':
+        return params[0], '"%s" IS NOT NULL'%(params[0])
+      if t == '>=':
+        return params[0], '"%s" IS NOT NULL'%(params[0])
+    except KeyError:
+      pass
   def __repr__(self):
     return "%s %s "%(self.type, repr(self.params))
 def Number(tt):

src/mapcss/Rule.py

@@ -56,3 +56,14 @@ class Rule():
     for condition in self.conditions:
       a.update(condition.get_interesting_tags())
     return a
+  def get_sql_hints(self, obj, zoom):
+    if obj:
+      if (self.subject!='') & (obj!=self.subject):
+        return set()
+    if zoom:
+      if (zoom < self.minZoom) or (zoom > self.maxZoom):
+        return set()
+    a = set()
+    for condition in self.conditions:
+      a.add(condition.get_sql())
+    return a

src/mapcss/StyleChooser.py

@@ -64,6 +64,17 @@ class StyleChooser:
           if __builtins__["type"](b) == self.eval_type:
             a.update(b.extract_tags())
     return a
+
+  def get_sql_hints(self, type, zoom):
+    """
+    Returns a set of tags that were used in here in form of SQL-hints.
+    """
+    a = set()
+    for c in self.ruleChains:
+      for r in c:
+        a.update(r.get_sql_hints(type, zoom))
+    # no need to check for eval's
+    return a
   # // Update the current StyleList from this StyleChooser
 
   def updateStyles(self,sl,type, tags, zoom, scale, zscale):

src/mapcss/__init__.py

@@ -127,7 +127,14 @@ class MapCSS():
       for chooser in self.choosers:
         tags.update(chooser.get_interesting_tags(type, zoom))
       return tags
-
+    def get_sql_hints(self, type=None, zoom=None):
+      """
+      Get set of interesting tags.
+      """
+      hints = set()
+      for chooser in self.choosers:
+        hints.update(chooser.get_sql_hints(type, zoom))
+      return hints
 
 
     def parse(self, css):

src/render.py

@@ -114,7 +114,11 @@ class RasterTile:
 
     
     datatimer = Timer("Asking backend")
-    vectors = self.data.get_vectors(bbox,self.zoom).values()
+    if "get_sql_hints" in dir(style):
+      hints = style.get_sql_hints('way', self.zoom)
+    else:
+      hints = None
+    vectors = self.data.get_vectors(bbox,self.zoom,sql_hint = hints).values()
     datatimer.stop()
     datatimer = Timer("Applying styles")
     ww = []