This adds a new log line that shows each schema cache query time individually, only on
`log-level=debug`. Like so:
```
$ PGRST_LOG_LEVEL=debug postgrest-with-pg-17 -f test/spec/fixtures/load.sql postgrest-run
....
10/Apr/2026:21:48:45 -0500: Schema cache queried in 192.2 milliseconds
10/Apr/2026:21:48:45 -0500: tables: 72.027 ms, keydeps: 20.118 ms, rels: 6.189 ms, funcs: 35.010 ms, comprels: 4.319 ms, dreps: 1.614 ms, mhandlers: 7.419 ms, tzones: 43.025 ms
```
This helps debug specific schema cache queries being slow like on
https://github.com/PostgREST/postgrest/issues/4613#issuecomment-4210191065 and
https://github.com/PostgREST/postgrest/issues/3046#issuecomment-3469059948.
It also closes https://github.com/PostgREST/postgrest/issues/3215,
which main motivation was to find out which query is slow.
Implementation details
---------------------
To time each query inside a transaction in pure SQL, we do:
```sql
-- start timer
select set_config('pgrst.tmp_x', clock_timestamp()::text, false);
-- run the query
select <query>
-- end timer
select set_config('pgrst.tmp_x', (clock_timestamp() - current_setting('pgrst.tmp_x', false)::timestamptz)::text, false);
-- .... repeated for every query
-- at the end we capture all the timings with
select extract('milliseconds' from current_setting('pgrst.tmp_x', false)::interval), extract(..;
```
Considerations
--------------
Only added this on `log-level=debug` because while the queries are fast
and the data is valuable, it triples the amount of queries we run during schema cache refresh,
which could be troublesome on slow networks. It's possible to reduce the
amount of queries by starting and stopping timers in one statement, but
this would still double the amount of queries and makes the code messy,
doesn't seem worth it.
Also it would pollute pg_stat_statements, it's only required to debug certain
extreme cases anyway.
Some helpers are provided for introspecting metrics already (used in JWT cache tests). This change provides facilities to additionally validate emited Observation events.
A new Spec module is also implemented, adding basic tests of schema cache reloading - their main goal is to excercise the new infrastructure.
There is unnecessary coupling between observation messages and emited log entries. This causes schema loading logic to emit redundant events: SchemaCacheSummaryObs and SchemaCacheLoadedObs.
Logically - we want to emit a single event containing both summary and timing information. How it is logged is a different matter and should be decoupled.
This commit
* changes observationMessage function returning Text to observationMessages returning [Text] so that it is possible to return multiple (or zero) messages to log based on an observation event
* Removes SchemaCacheSummaryObs constructor from Observation type and adds summary text to SchemaCacheLoadedObs
Observation module exports observationMessage and isDbListenerBug functions. The first one is used only in Logger module and the second one - only in Listener.
This change moves observationMessage function to Logger module and isDbListenerBug function to Listener module, making all three modules more cohesive and lessening dependencies.
It also gives the compiler more opportunities for intra-module inlining and optimization.
Set error verbosity using this config. The verbosity can
be set to `verbose` or `minimal` for client error responses.
This only affects client side HTTP responses, server side logs
are not affected by this config.
Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>
PoolAcqTimeoutObs is always created with SQL.AcquisitionTimeoutUsageError so the parameter does not provide any useful information.
On the other hand, it complicates debouncing logic in Logger as logWithDebounce has to lazily create the debouncer (which is error prone and hence the logic has a race condition).
This change removes the parameter from PoolAcqTimeoutObs. It is a prerequisite to simplifying logWithDebounce.
Fixes#4646. Using the repro on #4646, this now produces the log:
```
11/Feb/2026:09:40:08 -0500: Warp server error: stack overflow
```
When:
```
$ curl localhost:3000/
curl: (52) Empty reply from server
```
Diagnosing problems with listener channel notifications not being handled properly by PostgREST connected to read replicas is difficult. Issues might be related to lost connections and listener not being connected to the right host after failover or database server restarts.
This patch adds logging of actual host:port used by libpq connection opened by the listener. It should make it easier to find out if PostgREST is connected to the right host.
Closes https://github.com/PostgREST/postgrest/issues/4226.
This requires moving query generation to the top App.hs module.
At this point is also simple to log the transaction variables + the
pre-request function call but this is not done here to reduce scope.
Replaces the "API server listening on unix socket" with simpler
"API server listening on " observation. This allows refactoring
redundant code.
Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>
Changes:
1. Refactoring and some cleanup of JWT handling code:
* Instead of caching AuthResult cache decoded claims (which signature was verified). Validating claims and determining role is done after cache lookup
* Cleaned up API so that usage of it is simplified: lookupJwtCache cache key >>= parseClaims configJwtAud time
* Handling of JwtCacheState initialization and updates of configuration is encapsulated in Auth.JwtCache module
2. Generic high performance (hopefully) scalable, dynamically resizeable cache implementation based on stm, stm-hamt and sieve algorithm. It also integrates with PostgREST measurements infrastructure providing usage stats (ie. hit ratio, evictions count)
It's important for observability to have an historic trace of the pool
size. Currently we expose it on the metrics endpoint, but not all
deployments use it.
This logs the pool size after the successful connection log to make it
more visible:
<timestamp>: Connection Pool initialized with a maximum size of 4 connections
It's not immediately clear on which port the API server is listening.
Also it's not clear that the "pgrst" channel is for database
notifications.
Goes from:
<timestamp>: Admin server listening on 0.0.0.0:3001
<timestamp>: Listening on 0.0.0.0:3000
<timestamp>: Listening for notifications on the "pgrst" channel
To:
<timestamp>: Admin server listening on 0.0.0.0:3001
<timestamp>: API server listening on 0.0.0.0:3000
<timestamp>: Listening for database notifications on the "pgrst" channel
Fixes https://github.com/PostgREST/postgrest/issues/3523.
Now if there's a failure when obtaining the pg version OR schema cache,
we do the same retrying process. This way we don't add two retries.
Refactors and renames the "connectionWorker" to "schemaCacheLoader".
This makes more sense since what we really want is the schema cache,
the version is the pre-requisite for ensuring our
schema cache queries work.
Additionally, we no longer log ` Attempting to connect to the database...`
at startup unnecessarily. This is only logged whenever there's a retry attempt.
Update hasql-notifications to include the fix on
https://github.com/diogob/hasql-notifications/issues/24.
Which now reveals the following error:
```
$ postgrest-with-postgresql-16 --replica -f test/spec/fixtures/load.sql postgrest-run
17/May/2024:18:35:38 -0500: Successfully connected to PostgreSQL 16.2 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 13.2.0, 64-bit
17/May/2024:18:35:38 -0500: Could not listen for notifications on the "pgrst" channel. ERROR: cannot execute LISTEN during recovery
17/May/2024:18:35:38 -0500: Retrying listening for notifications...
```
This is still not good because the LISTEN channel will be retried
forever without a backoff.
The fatal logic is now inside `usePool`. It centralizes the
logic which is better for Locality of Behavior.
Removes:
- The need to do checkIsFatal on other parts of the code
- SCFatalFail/ConnFatalFail states which are no longer needed.
With this:
- Is no longer necessary to pass observer as an argument
to every function that needs observations.
- We can invoke the observer on every function that uses AppConfig.
However it'd be better to just call the observer in the upper modules
(like on App.hs).
steve-chavez