Remove tile_for_point SQL functions

[rails.git] / db / functions / functions.sql

diff --git a/db/functions/functions.sql b/db/functions/functions.sql
deleted file mode 100644 (file)
index 4f1f7c7..0000000
--- a/db/functions/functions.sql
+++ /dev/null
@@ -1,100 +0,0 @@
---------------------------------------------------------------------------------
--- SQL versions of the C database functions.
---
--- Pure pl/pgsql versions are *slower* than the C versions, and not recommended
--- for production use. However, they are significantly easier to install, and
--- require fewer dependencies.
---------------------------------------------------------------------------------
-
--- tile_for_point function returns a Morton-encoded integer representing a z16
--- tile which contains the given (scaled_lon, scaled_lat) coordinate. Note that
--- these are passed into the function as (lat, lon) and should be scaled by
--- 10^7.
---
--- The Morton encoding packs two dimensions down to one with fairly good
--- spatial locality, and can be used to index points without the need for a
--- proper 2D index.
-CREATE OR REPLACE FUNCTION tile_for_point(scaled_lat int4, scaled_lon int4)
-  RETURNS int8
-  AS $$
-DECLARE
-  x int8; -- quantized x from lon,
-  y int8; -- quantized y from lat,
-BEGIN
-  x := round(((scaled_lon / 10000000.0) + 180.0) * 65535.0 / 360.0);
-  y := round(((scaled_lat / 10000000.0) +  90.0) * 65535.0 / 180.0);
-
-  -- these bit-masks are special numbers used in the bit interleaving algorithm.
-  -- see https://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN
-  -- for the original algorithm and more details.
-  x := (x | (x << 8)) &   16711935; -- 0x00FF00FF
-  x := (x | (x << 4)) &  252645135; -- 0x0F0F0F0F
-  x := (x | (x << 2)) &  858993459; -- 0x33333333
-  x := (x | (x << 1)) & 1431655765; -- 0x55555555
-
-  y := (y | (y << 8)) &   16711935; -- 0x00FF00FF
-  y := (y | (y << 4)) &  252645135; -- 0x0F0F0F0F
-  y := (y | (y << 2)) &  858993459; -- 0x33333333
-  y := (y | (y << 1)) & 1431655765; -- 0x55555555
-
-  RETURN (x << 1) | y;
-END;
-$$ LANGUAGE plpgsql IMMUTABLE;
-
-
--- maptile_for_point returns an integer representing the tile at the given zoom
--- which contains the point (scaled_lon, scaled_lat). Note that the arguments
--- are in the order (lat, lon), and should be scaled by 10^7.
---
--- The maptile_for_point function is used only for grouping the results of the
--- (deprecated?) /changes API call. Please don't use it for anything else, as
--- it might go away in the future.
-CREATE OR REPLACE FUNCTION maptile_for_point(scaled_lat int8, scaled_lon int8, zoom int4)
-  RETURNS int4
-  AS $$
-DECLARE
-  lat CONSTANT DOUBLE PRECISION := scaled_lat / 10000000.0;
-  lon CONSTANT DOUBLE PRECISION := scaled_lon / 10000000.0;
-  zscale CONSTANT DOUBLE PRECISION := 2.0 ^ zoom;
-  pi CONSTANT DOUBLE PRECISION := 3.141592653589793;
-  r_per_d CONSTANT DOUBLE PRECISION := pi / 180.0;
-  x int4;
-  y int4;
-BEGIN
-  -- straight port of the C code. see db/functions/maptile.c
-  x := floor((lon + 180.0) * zscale / 360.0);
-  y := floor((1.0 - ln(tan(lat * r_per_d) + 1.0 / cos(lat * r_per_d)) / pi) * zscale / 2.0);
-
-  RETURN (x << zoom) | y;
-END;
-$$ LANGUAGE plpgsql IMMUTABLE;
-
--- xid_to_int4 converts a PostgreSQL transaction ID (xid) to a 32-bit integer
--- which can then be used to efficiently find rows which have changed between
--- two given transactions. This is currently used by Osmosis to extract a
--- stream of edits for "diff replication" **HOWEVER** this is a pain point, as
--- (ab)using the xid in this way is _not_ supported or recommended by Postgres
--- devs. It is preventing us upgrading to PostgreSQL version 10+, and will
--- hopefully be replaced Real Soon Now.
---
--- From the Osmosis distribution by Brett Henderson:
--- https://github.com/openstreetmap/osmosis/blob/master/package/script/contrib/apidb_0.6_osmosis_xid_indexing.sql
-CREATE OR REPLACE FUNCTION xid_to_int4(t xid)
-  RETURNS integer
-  AS
-$$
-DECLARE
-  tl bigint;
-  ti int;
-BEGIN
-  tl := t;
-
-  IF tl >= 2147483648 THEN
-    tl := tl - 4294967296;
-  END IF;
-
-  ti := tl;
-
-  RETURN ti;
-END;
-$$ LANGUAGE 'plpgsql' IMMUTABLE STRICT;