How to handle 800k points as MVT - leaflet

Question

I have a table with about 800k points with information that includes bathimetry stored on PostGIS and served using ST_AsMVTGeom this is connected to a Web App develop using Leaflet but a certain levels (0-5) a single Vector-tile it's contaning all the data which makes the Query very slow (it takes minutes). I wonder if there exists (whitin PostGIS) a way to simplify the rows output depending on zoom level.
I'm using the following Query to create the tiles:
SELECT ST_AsMVT(q.*, 'bathymetry_layer', 4096, 'geom')
FROM (
SELECT
c.gid AS id,
c.x,
c.y,
c.z,
c.name,
c.inst,
ST_AsMVTGeom(
geom,
ST_MakeEnvelope(-86.8798828125, 20.632784250388028, -86.8359375, 20.673905264672843, 4326),
4096,
256,
false
) geom
FROM bathymetry_table WHERE geom && ST_MakeEnvelope(-86.8798828125, 20.632784250388028, -86.8359375, 20.673905264672843, 4326) AND ST_Intersects(geom, ST_MakeEnvelope(-86.8798828125, 20.632784250388028, -86.8359375, 20.673905264672843, 4326))
) q
Result of EXPLAIN ANALYZE:
Index Scan using geodat_batimetria_catoche_xcalak_geom_idx on geodat_batimetria_catoche_xcalak c (cost=0.29..8.56 rows=1 width=101) (actual time=0.117..11539.038 rows=434271 loops=1)
Index Cond: ((geom && '0103000020E610000001000000050000002B8716D9CECB55C0516B9A779CA234402B8716D9CECB55C0D34D621058493540492EFF21FD9E55C0D34D621058493540492EFF21FD9E55C0516B9A779CA234402B8716D9CECB55C0516B9A779CA23440'::geometry) AND (geom && '0103000020E610000001000000050000002B8716D9CECB55C0516B9A779CA234402B8716D9CECB55C0D34D621058493540492EFF21FD9E55C0D34D621058493540492EFF21FD9E55C0516B9A779CA234402B8716D9CECB55C0516B9A779CA23440'::geometry))
Filter: _st_intersects(geom, '0103000020E610000001000000050000002B8716D9CECB55C0516B9A779CA234402B8716D9CECB55C0D34D621058493540492EFF21FD9E55C0D34D621058493540492EFF21FD9E55C0516B9A779CA234402B8716D9CECB55C0516B9A779CA23440'::geometry)
Rows Removed by Filter: 5
Planning time: 7.222 ms
Execution time: 11579.044 ms

Answer 1

This function would generate vector tiles for all zooms, clustering points together for low zooms (0-10), and keeping them as is for zooms 11+.
CREATE OR REPLACE FUNCTION get_tile(z integer, x integer, y integer) RETURNS bytea AS
$$
-- MVTs can be combined by concatenating them together.
SELECT STRING_AGG(mvt, '') AS mvt
FROM (
-- Each `mvt` must be non-NULL, otherwise UNION ALL will skip them all
-- First generate the tile for the zoomed-out layer, clustering points together
SELECT COALESCE(ST_AsMVT(tile, 'bathymetry_layer', 4096, 'geom'), '') AS mvt
FROM (
-- Create a cluster of points for each tile
SELECT ST_AsMVTGeom(ST_Transform(center, 3857),
ST_TileEnvelope(z, x, y),
extent => 4096)
AS geom
-- need to add all the other columns here,
-- but they either have to be aggregated for each cluster,
-- or you need to pick one point to represent the whole cluster
FROM (
-- Cluster points into groups using DBSCAN algorithm
SELECT ST_Centroid(ST_Collect(geom)) AS center
FROM (SELECT *,
ST_ClusterDBSCAN(ST_TRANSFORM(geom, 3857),
-- Decide how many clusters you want per tile.
-- at zoom 0, earth circumference equals 1 tile. At each subsequent zoom level,
-- there are twice as many tiles for the same circumference.
-- Additionally, break each tile into 256 clusters
(40075016.6855785 / (256 * 2 ^ z)),
1) OVER () AS cluster_id
FROM bathymetry_table
-- This assumes your data should be clustered before zoom 11, and shouldn't after.
-- Keep this value in sync with the one below
WHERE z < 11
-- This assumes your data is in 4326. The envelope is always generated in 3857.
AND geom && ST_Transform(ST_TileEnvelope(z, x, y), 4326))
AS cluster
group by cluster_id) AS clusters) as tile
UNION ALL
SELECT COALESCE(ST_AsMVT(tile, 'bathymetry_layer', 4096, 'geom', 'id'), '') AS mvt
FROM (
-- Once zoomed in, there is no longer a need to cluster points
-- Note that the list of columns is different from the one above - you many want to adjust that.
SELECT ST_AsMVTGeom(ST_Transform(coord, 3857),
ST_TileEnvelope(z, x, y),
extent => 4096)
AS geom
, c.gid AS id
, c.x
, c.y
, c.z
, c.name
, c.inst
FROM bathymetry_table c
WHERE z >= 11
AND c.geom && ST_Transform(ST_TileEnvelope(z, x, y), 4326)) as tile) AS mvt
;
$$ LANGUAGE SQL IMMUTABLE
STRICT
PARALLEL SAFE;