Faced such a problem (or maybe it's a bug). I get different results when using the ST_Simplify function in PostGIS 3.0.0 and PostGIS 2.5.3.

There are source data that are simplified by using a query:

SELECT ST_Simplify(geometry, 20) FROM source_table 

For verification, I created two databases on different OS. PostgreSQL11-PostGIS-3 and PostgreSQL11-PostgiGIS-2.5 with the same data mapping and SRID.

Result:

Postgis 2.5.3

Postgis 3.0.0

PostGIS 3 lost a lot of small hole geometries, although the source data and the request are the same. Why is this happening and how to fix it in PostGIS-3?

Faced such a problem (or maybe it's a bug). I get different results when using the ST_Simplify function in PostGIS 3.0.0 and PostGIS 2.5.3.

There are source data that are simplified by using a query:

SELECT ST_Simplify(geometry, 20) FROM source_table 

For verification, I created two databases on different OS. PostgreSQL11-PostGIS-3 and PostgreSQL11-PostgiGIS-2.5 with the same data mapping and SRID.

Result:

Postgis 2.5.3

Postgis 3.0.0

PostGIS 3 lost a lot of small hole geometries, although the source data and the request are the same. Why is this happening and how to fix it in PostGIS-3?

Update

Yes, SRID 3857 in both cases.

I try ST_Simplify(geometry, 20, false) and ST_Simplify(geometry, 20, true) in Postgis 3 it did not help.

Postgis_full_version(); POSTGIS="3.0.0 r17983" [EXTENSION] PGSQL="110" GEOS="3.7.2-CAPI-1.11.2 b55d2125" PROJ="Rel. 5.2.0, September 15th, 2018" LIBXML="2.9.4" LIBJSON="0.13.1" LIBPROTOBUF="1.3.1" WAGYU="0.4.3 (Internal)"

Faced such a problem (or maybe it's a bug). I get different results when using the ST_Simplify function in Postgis 3.0.0 and Postgis 2.5.3.

There are source data that are simplified by using a query:

SELECT ST_Simplify(geometry, 20) FROM source_table 

For verification, I created two databases on different OS. Postgres11-Postgis-3 and Postgres11-Postgis-2.5 with the same data mapping and SRID.

Result:

Postgis 2.5.3

Postgis 3.0.0

Postgis 3 lost a lot of small hole geometries, although the source data and the request are the same. Why is this happening and how to fix it in Postgis-3?

Faced such a problem (or maybe it's a bug). I get different results when using the ST_Simplify function in PostGIS 3.0.0 and PostGIS 2.5.3.

There are source data that are simplified by using a query:

SELECT ST_Simplify(geometry, 20) FROM source_table 

For verification, I created two databases on different OS. PostgreSQL11-PostGIS-3 and PostgreSQL11-PostgiGIS-2.5 with the same data mapping and SRID.

Result:

Postgis 2.5.3

Postgis 3.0.0

PostGIS 3 lost a lot of small hole geometries, although the source data and the request are the same. Why is this happening and how to fix it in PostGIS-3?