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Amends 0160, decision 2 (the approved extensions). PostGIS joins pgvector, pg_trgm, ltree, citext and pgcrypto. Decision 2 said PostGIS was not approved yet, and this ADR is the future ADR that its Alternatives section asks for.
Lifts the deferral of the geospatial field in 0133, decision 2 and its deferred item, and the v3 Note’s statement that it stays deferred. The field is given as the types GeoPoint, GeoPolygon and GeoLine, set out in decision 2 below.

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Context

Location and tracking data, such as fleet positions, service areas and delivery zones, need geospatial column types and spatial indexes. 0160 approved five Postgres extensions and left PostGIS out until an ADR approved it. The geography work belongs to the geography service, which is a layer 2 platform core service (0201). The owner approved PostGIS on 2026-10-24, with the field types, the macros and the index type below.

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Decision

  1. PostGIS is approved. It joins the approved extensions of 0160, decision 2. It is enabled only by schema.createExtension(name), a step of the migration blueprint of 0159 that emits CREATE EXTENSION IF NOT EXISTS for an approved name and fails for any other, and not by a raw schema.sql file or a raw query.
  2. The geospatial field types, their macros and their index.
    • Geospatial values are field types, not decorators, as the v3 Note of 0133 gives money and JSON. The types are GeoPoint, GeoPolygon and GeoLine.
    • Each type is stored as a PostGIS column with SRID 4326 (WGS 84): GeoPoint is geography(Point, 4326), GeoPolygon is geography(Polygon, 4326) and GeoLine is geography(LineString, 4326).
    • The migration blueprint gains three macros: t.point() for a GeoPoint column, t.polygon() for a GeoPolygon column and t.line() for a GeoLine column.
    • Each geospatial column has a GiST index by default. The index is named with the idx_ prefix of 0231.
    • HasLocation is a trait, named under 0096, that adds location: GeoPoint to a model.
  3. Ownership. The geography service’s package owns the three field types, the macros, the GiST index support and the HasLocation trait. No other package defines its own geospatial field type, macro or location trait.

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Consequences

  • A location feature uses one approved extension, and it does not need a new service.
  • Each environment that runs the geography package needs PostGIS installed in its Postgres, including on-prem and air-gapped deliveries (0179). 0160 already makes every approved extension a dependency of every environment.
  • The deferral of the geospatial field in 0133 is lifted, so no revival trigger is needed.

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Enforcement

planned — gen rejects a schema.createExtension() call that names an extension outside the approved list of 0160, rejects CREATE EXTENSION inside any raw schema.sql step or raw query, and rejects a GeoPoint, GeoPolygon or GeoLine column whose migration drops the default GiST index without another spatial index. Nothing checks these rules yet.

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Supersedes and sources

Supersedes: none. Amends: 0160, decision 2; 0133, decision 2 and the deferred item for the geospatial field. Builds on: 0201 (layer 2), 0096 (trait naming). Sources: owner decision of 2026-10-24 on geospatial and location macros.