Currently, the exporter exposes the same LFC metrics that are exposed by
the "autoscaling" sql_exporter in the docker image. With this, we can
remove the dedicated sql_exporter instance. (Actually doing the removal
is left as a TODO until this is rolled out to production and we have
changed autoscaling-agent to fetch the metrics from this new endpoint.)
The exporter runs as a Postgres background worker process. This is
extracted from the Rust communicator rewrite project, which will use the
same worker process for much more, to handle the communications with the
pageservers. For now, though, it merely handles the metrics requests.
In the future, we will add more metrics, and perhaps even APIs to
control the running Postgres instance.
The exporter listens on a Unix Domain socket within the Postgres data
directory. A Unix Domain socket is a bit unconventional, but it has some
advantages:
- Permissions are taken care of. Only processes that can access the data
directory, and therefore already have full access to the running
Postgres instance, can connect to it.
- No need to allocate and manage a new port number for the listener
It has some downsides too: it's not immediately accessible from the
outside world, and the functions to work with Unix Domain sockets are
more low-level than TCP sockets (see the symlink hack in
`postgres_metrics_client.rs`, for example).
To expose the metrics from the local Unix Domain Socket to the
autoscaling agent, introduce a new '/autoscaling_metrics' endpoint in
the compute_ctl's HTTP server. Currently it merely forwards the request
to the Postgres instance, but we could add rate limiting and access
control there in the future.
---------
Co-authored-by: Conrad Ludgate <conrad@neon.tech>
## Problem
Test lfc working set approximation becomes flaky after recent changes in
prefetch.
May be it is caused by updating HLL in `lfc_write`, may be by some other
reasons.
## Summary of changes
1. Disable autovacuum in this test (as possible source of extra page
accesses).
2. Increase upper boundary for WS approximation from 12 to 20.
---------
Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
## Problem
`TYPE_CHECKING` is used inconsistently across Python tests.
## Summary of changes
- Update `ruff`: 0.7.0 -> 0.11.2
- Enable TC (flake8-type-checking):
https://docs.astral.sh/ruff/rules/#flake8-type-checking-tc
- (auto)fix all new issues
## Problem
See https://neondb.slack.com/archives/C04DGM6SMTM/p1741176713523469
The problem is that this function is using `PQgetCopyData(shard->conn,
&resp_buff.data, 1 /* async = true */)`
to try to fetch next message. But this function returns 0 if the whole
message is not present in the buffer.
And input buffer may contain only part of message so result is not
fetched.
## Summary of changes
Use `PQisBusy` + `WaitEventSetWait` to check if data is available and
`PQgetCopyData(shard->conn, &resp_buff.data, 0)` to read whole message
in this case.
---------
Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
## Problem
LFC is not enabled by default in tests, but it is enabled in production.
This increases the risk of errors in the production environment, which
were not found during the routine workflow.
However, enabling LFC for all the tests may overload the disk on our
servers and increase the number of failures.
So, we try enabling LFC in one case to evaluate the possible risk.
## Summary of changes
A new environment variable, USE_LFC is introduced. If it is set to true,
LFC is enabled by default in all the tests.
In our workflow, we enable LFC for PG17, release, x86-64, and disabled
for all other combinations.
---------
Co-authored-by: Alexey Masterov <alexeymasterov@neon.tech>
Co-authored-by: a-masterov <72613290+a-masterov@users.noreply.github.com>
## Problem
See #7466
## Summary of changes
Implement algorithm descried in
https://hal.science/hal-00465313/document
Now new GUC is added:
`neon.wss_max_duration` which specifies size of sliding window (in
seconds). Default value is 1 hour.
It is possible to request estimation of working set sizes (within this
window using new function
`approximate_working_set_size_seconds`. Old function
`approximate_working_set_size` is preserved for backward compatibility.
But its scope is also limited by `neon.wss_max_duration`.
Version of Neon extension is changed to 1.4
## Checklist before requesting a review
- [ ] I have performed a self-review of my code.
- [ ] If it is a core feature, I have added thorough tests.
- [ ] Do we need to implement analytics? if so did you add the relevant
metrics to the dashboard?
- [ ] If this PR requires public announcement, mark it with
/release-notes label and add several sentences in this section.
## Checklist before merging
- [ ] Do not forget to reformat commit message to not include the above
checklist
---------
Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
Co-authored-by: Matthias van de Meent <matthias@neon.tech>
