fix: raise default max_replication_slots from 5 to 10 in the postgres AMI - #2387
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max_replication_slots is a single shared pool covering both logical and physical slots (confirmed against PostgreSQL's own docs). At 5, a project running Realtime plus a couple of read replicas plus any customer logical replication is already at or near the ceiling, with only 31 projects fleet-wide currently overriding this key. Matches PostgreSQL's own upstream default (10) and max_wal_senders, already 10 in this same file. Resolves INDATA-1301
The generated README feature bullet and its generator both hardcoded = 5, which the prior commit's default bump missed. Fixing README.md alone would revert on the next update_readme run, so both need the same edit.
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Closing: review surfaced that supabase-admin-api's per-instance-size settings (pico/nano hardcode max_replication_slots=5, micro+ already at 10) override this template's default at boot via generated-optimizations.conf, which is included after this setting and wins under Postgres's last-assignment-wins parsing. This change has no observable effect at any instance size as written, so there's nothing to ship here. |
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August 21, 2026 18:23
PostgreSQL Extension Dependency Analysis: PR #2387
SummaryNo extensions had dependencies with MAJOR version updates. Full Analysis ResultsPostgreSQL 15 Extension DependenciesPostgreSQL 17 Extension DependenciesOrioleDB 17 Extension Dependencies |
PostgreSQL Package Dependency Analysis: PR #2387
SummaryNo packages had MAJOR version updates. Full Analysis ResultsPostgreSQL 15 Dependency ChangesExtracting PostgreSQL 15 dependencies...
Runtime Closure Size
Raw Dependency ClosurePostgreSQL 17 Dependency ChangesExtracting PostgreSQL 17 dependencies...
Runtime Closure Size
Raw Dependency Closure |
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Summary
The AMI's postgresql.conf template caps
max_replication_slotsat 5, overriding PostgreSQL's own upstream default of 10. This is a single shared pool covering both logical and physical replication slots, so Realtime, customer logical replication, and physical read-replica slots all draw from the same ceiling. Raises the default to 10 to match upstream and give more headroom before that ceiling is hit.Details
ansible/files/postgresql_config/postgresql.conf.j2—max_replication_slots5 → 10, matchingmax_wal_senders(already 10 in this same file) and PostgreSQL's own upstream default.Surfaced while reviewing supabase/platform#35057 (physical replication slots for read replicas): every read replica now permanently consumes one of these slots on its primary. Only 31 projects fleet-wide currently override this key, meaning almost every project is capped at the AMI's default — a project running Realtime plus a couple of read replicas plus any customer logical replication is already at or near 5.
Only affects newly-provisioned instances going forward; existing instances keep their current setting until their next config regeneration/restart (
max_replication_slotsispostmaster-context).Testing
grep -rn max_replication_slots)Resolves INDATA-1301