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Remove useless WHERE clauses from the transportation layer (#1168)

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This PR removes several redundant/unnecessary WHERE clauses from the transportation layer.  Specifically:

The table `osm_transportation_merge_linestring` is a view of `osm_highway_linestring` which exposes only motorway/trunk/primary roads:
9e4be3e3b0/layers/transportation/update_transportation_merge.sql (L122-L123)

However, the create statement for the table `osm_transportation_merge_linestring_gen_z8`, which is a view of `osm_transportation_merge_linestring`, also contains  a `WHERE` clause which selects down to motorway/trunk/primary roads.  This `WHERE` is unnecessary:
9e4be3e3b0/layers/transportation/update_transportation_merge.sql (L144-L145)

This unneeded `WHERE` clause is similarly present in the create statement for `osm_transportation_merge_linestring_gen_z7`, which is a view of `osm_transportation_merge_linestring_gen_z8`:
9e4be3e3b0/layers/transportation/update_transportation_merge.sql (L163-L164)

Likewise, there is a similar redundant `WHERE` clause in the `osm_transportation_merge_linestring_gen_z5` and `osm_transportation_merge_linestring_gen_z6` tables, both of which select down to `motorway` and `trunk`.  This `WHERE` clause is only needed on the z6 table, and is redundant on the z5 table.

I am not sure what the performance penalty is for these redundant `WHERE` clauses, but there does not appear to be any reason to keep them, and they may incur a performance cost.
This commit is contained in:
Brian Sperlongano 2021-08-10 11:55:16 -04:00 committed by GitHub
parent 893d1df4c5
commit 09078f6d7d
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1 changed files with 5 additions and 7 deletions
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12
layers/transportation/update_transportation_merge.sql
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@ -148,8 +148,7 @@ SELECT ST_Simplify(geometry, ZRes(10)) AS geometry,
is_ford,
z_order
FROM osm_transportation_merge_linestring
WHERE highway IN ('motorway', 'trunk', 'primary')
OR highway = 'construction' AND construction IN ('motorway', 'trunk', 'primary')
-- Current view: motorway/trunk/primary
) /* DELAY_MATERIALIZED_VIEW_CREATION */;
CREATE INDEX IF NOT EXISTS osm_transportation_merge_linestring_gen_z8_geometry_idx
ON osm_transportation_merge_linestring_gen_z8 USING gist (geometry);
@ -168,9 +167,8 @@ SELECT ST_Simplify(geometry, ZRes(9)) AS geometry,
is_ford,
z_order
FROM osm_transportation_merge_linestring_gen_z8
WHERE (highway IN ('motorway', 'trunk', 'primary') OR
highway = 'construction' AND construction IN ('motorway', 'trunk', 'primary'))
AND ST_Length(geometry) > 50
-- Current view: motorway/trunk/primary
WHERE ST_Length(geometry) > 50
) /* DELAY_MATERIALIZED_VIEW_CREATION */;
CREATE INDEX IF NOT EXISTS osm_transportation_merge_linestring_gen_z7_geometry_idx
ON osm_transportation_merge_linestring_gen_z7 USING gist (geometry);
@ -209,8 +207,8 @@ SELECT ST_Simplify(geometry, ZRes(7)) AS geometry,
is_ford,
z_order
FROM osm_transportation_merge_linestring_gen_z6
WHERE (highway IN ('motorway', 'trunk') OR highway = 'construction' AND construction IN ('motorway', 'trunk'))
AND ST_Length(geometry) > 500
WHERE ST_Length(geometry) > 500
-- Current view: motorway/trunk
) /* DELAY_MATERIALIZED_VIEW_CREATION */;
CREATE INDEX IF NOT EXISTS osm_transportation_merge_linestring_gen_z5_geometry_idx
ON osm_transportation_merge_linestring_gen_z5 USING gist (geometry);