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Fix max overviews level usage

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Note that _CDB_Feature_Density_Ref_Z_Strategy returns the first
level for which overviews should not be used, and that in some
cases _CDB_Feature_Density should look beyond the max level to
compute a feature density estimate.
This commit is contained in:
Javier Goizueta 2016-05-25 14:00:55 +02:00
parent 803b3671d0
commit 3399f2b9a5
1 changed files with 17 additions and 4 deletions
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21
scripts-available/CDB_Overviews.sql
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@ -15,6 +15,15 @@ AS $$
END; END;
$$ LANGUAGE PLPGSQL IMMUTABLE; $$ LANGUAGE PLPGSQL IMMUTABLE;
-- Maximum zoom level usable with integer coordinates
CREATE OR REPLACE FUNCTION _CDB_MaxZoomLevel()
RETURNS INTEGER
AS $$
BEGIN
RETURN 31;
END;
$$ LANGUAGE PLPGSQL IMMUTABLE;
-- Information about tables in a schema. -- Information about tables in a schema.
-- If the schema name parameter is NULL, then tables from all schemas -- If the schema name parameter is NULL, then tables from all schemas
-- that may contain user tables are returned. -- that may contain user tables are returned.
@ -314,7 +323,11 @@ AS $$
WITH RECURSIVE t(x, y, z, e) AS ( WITH RECURSIVE t(x, y, z, e) AS (
WITH ext AS (SELECT _cdb_estimated_extent(%6$s) as g), WITH ext AS (SELECT _cdb_estimated_extent(%6$s) as g),
base AS ( base AS (
SELECT (-floor(log(2, (greatest(ST_XMax(ext.g)-ST_XMin(ext.g), ST_YMax(ext.g)-ST_YMin(ext.g))/(%4$s*%5$s))::numeric)))::integer z SELECT
least(
-floor(log(2, (greatest(ST_XMax(ext.g)-ST_XMin(ext.g), ST_YMax(ext.g)-ST_YMin(ext.g))/(%4$s*%5$s))::numeric)),
_CDB_MaxOverviewLevel()+1
)::integer z
FROM ext FROM ext
), ),
lim AS ( lim AS (
@ -326,7 +339,7 @@ AS $$
FROM ext, base FROM ext, base
), ),
seed AS ( seed AS (
SELECT xt, yt, least(base.z, _CDB_MaxOverviewLevel()), ( SELECT xt, yt, base.z, (
SELECT count(*) FROM %1$s SELECT count(*) FROM %1$s
WHERE the_geom_webmercator && CDB_XYZ_Extent(xt, yt, base.z) WHERE the_geom_webmercator && CDB_XYZ_Extent(xt, yt, base.z)
) e ) e
@ -339,7 +352,7 @@ AS $$
WHERE the_geom_webmercator && CDB_XYZ_Extent(x*2 + xx, y*2 + yy, t.z+1) WHERE the_geom_webmercator && CDB_XYZ_Extent(x*2 + xx, y*2 + yy, t.z+1)
) )
FROM t, base, (VALUES (0, 0), (0, 1), (1, 1), (1, 0)) AS c(xx, yy) FROM t, base, (VALUES (0, 0), (0, 1), (1, 1), (1, 0)) AS c(xx, yy)
WHERE t.e > %2$s AND t.z < (base.z + %3$s) AND t.z < _CDB_MaxOverviewLevel() WHERE t.e > %2$s AND t.z < least(base.z + %3$s, _CDB_MaxZoomLevel())
) )
SELECT MAX(e/ST_Area(CDB_XYZ_Extent(x,y,z))) FROM t where e > 0; SELECT MAX(e/ST_Area(CDB_XYZ_Extent(x,y,z))) FROM t where e > 0;
', reloid::text, min_features, nz, n, c, reloid::oid) ', reloid::text, min_features, nz, n, c, reloid::oid)
@ -380,7 +393,7 @@ AS $$
-- find minimum z so that fd*ta(z) <= lim -- find minimum z so that fd*ta(z) <= lim
-- compute a rough 'feature density' value -- compute a rough 'feature density' value
SELECT CDB_XYZ_Resolution(-8) INTO c; SELECT CDB_XYZ_Resolution(-8) INTO c;
RETURN least(_CDB_MaxOverviewLevel(), ceil(log(2.0, (c*c*fd/lim)::numeric)/2)); RETURN least(_CDB_MaxOverviewLevel()+1, ceil(log(2.0, (c*c*fd/lim)::numeric)/2));
END; END;
$$ LANGUAGE PLPGSQL STABLE; $$ LANGUAGE PLPGSQL STABLE;