canton v3.6.3

Release of Canton 3.6.3

Canton 3.6.3 has been released on October 20, 2026.

Summary

This patch release fixes slow topology store lookups on Postgres that could cause high participant database load
and make the ACS commitment processor fall behind on large topology states.

What’s New

Faster topology store lookups on Postgres

Background

Some topology store queries filter topology transactions by a list of parties (UIDs) or namespaces. On Postgres,
once that list had more than a handful of entries, the query planner switched from index lookups to a hash join
over all topology transactions of the requested types. On large topology states this was orders of magnitude slower.
It caused high participant database load and made the ACS commitment process fall behind.

Specific Changes

• On Postgres, topology store queries that filter by parties or namespaces now do one index lookup per filter entry,
  so their cost depends on the number of filter entries rather than on the size of the topology state.
• H2 behavior is unchanged.

Impact and Migration

Participants with large topology states see lower database load, and the ACS commitment processor no longer falls
behind because of these queries. Query results are unchanged.

Compatibility

The following Canton protocol versions are supported:

Dependency	Version
Canton protocol versions	34, 35, 36

Canton has been tested against the following versions of its dependencies:

Dependency	Version
Java Runtime	OpenJDK 64-Bit Server VM (build 21.0.12+2-nixos, mixed mode, sharing)
Postgres	Recommended: PostgreSQL 17.11 (Debian 17.11-1.pgdg13+2) – Also tested: PostgreSQL 14.24 (Debian 14.24-1.pgdg13+2), PostgreSQL 15.19 (Debian 15.19-1.pgdg13+2), PostgreSQL 16.15 (Debian 16.15-1.pgdg13+2), PostgreSQL 18.6 (Debian 18.6-1.pgdg13+2)