## Problem
We saw a scale test failure when one shard went
secondary->attached->secondary in a short period of time -- the metrics
for the shard failed a validation assertion that is meant to ensure the
size metric matches the sum of layer sizes in the SecondaryDetail
struct.
This appears to be due to two SecondaryTenants being alive at the same
time -- the first one was shut down but still had its contributions to
the metrics.
Closes: https://github.com/neondatabase/neon/issues/9628
## Summary of changes
- Refactor code for validating metrics and call it in shutdown as well
as during downloads
- Move code for dropping per-tenant secondary metrics from drop() into
shutdown(), so that once shutdown() completes it is definitely safe to
instantiate another SecondaryTenant for the same tenant.
Before, `OpenTelemetry` errors were printed to stdout/stderr directly,
causing one of the few log lines without a timestamp, like:
```
OpenTelemetry trace error occurred. error sending request for url (http://localhost:4318/v1/traces)
```
Now, we print:
```
2024-11-21T02:24:20.511160Z INFO OpenTelemetry error: error sending request for url (http://localhost:4318/v1/traces)
```
I found this while investigating #9731.
## Problem
```
curl -H "Neon-Connection-String: postgresql://neondb_owner:PASSWORD@ep-autumn-rain-a58lubg0.us-east-2.aws.neon.tech/neondb?sslmode=require" https://ep-autumn-rain-a58lubg0.us-east-2.aws.neon.tech/sql -d '{"query":"SELECT 1","params":[]}'
```
For such a query, I also need to send `params`. Do I really need it?
## Summary of changes
I've marked `params` as optional
Adds support to the `find_garbage` command to restrict itself to a
partial tenant ID prefix, say `a`, and then it only traverses tenants
with IDs starting with `a`. One can now pass the `--tenant-id-prefix`
parameter.
That way, one can shard the `find_garbage` command and make it run in
parallel.
The PR also does a change of how `remote_storage` first removes trailing
`/`s, only to then add them in the listing function. It turns out that
this isn't neccessary and it prevents the prefix functionality from
working. S3 doesn't do this either.
## Problem
We were hitting this assertion in debug mode tests sometimes.
This case was being hit when the parent shard has no resident layers.
For instance, this is the case on split retry where the previous attempt
shut-down the parent and deleted local state for it. If the logical size
calculation does not download some layers before we get to the
hardlinking, then the assertion is hit.
## Summary of Changes
Remove the assertion. It's fine for the ancestor to not have any
resident layers at the time of the split.
Closes https://github.com/neondatabase/neon/issues/9412
Follow up to #9803
See https://github.com/neondatabase/cloud/issues/14378
In collaboration with @cloneable and @awarus, we sifted through logs and
simply demoted some logs to debug. This is not at all finished and there
are more logs to review, but we ran out of time in the session we
organised. In any slightly more nuanced cases, we didn't touch the log,
instead leaving a TODO comment.
I've also slightly refactored the sql-over-http body read/length reject
code. I can split that into a separate PR. It just felt natural after I
switched to `read_body_with_limit` as we discussed during the meet.
## Problem
Long ago, in #5299 the tenant states for migration are added, but
respected only in a coarse-grained way: when hinted not to do deletions,
tenants will just avoid doing all GC or compaction.
Skipping compaction is not necessary for AttachedMulti, as we will soon
become the primary attached location, and it is not a waste of resources
to proceed with compaction. Instead, per the RFC
https://github.com/neondatabase/neon/pull/5029/files), deletions should
be queued up in this state, and executed later when we switch to
AttachedSingle.
Avoiding compaction in AttachedMulti can have an operational impact if a
tenant is under significant write load, as a long-running migration can
result in a large accumulation of delta layers with commensurate impact
on read latency.
Closes: https://github.com/neondatabase/neon/issues/5396
## Summary of changes
- Add a 'config' part to RemoteTimelineClient so that it can be aware of
the mode of the tenant it belongs to, and wire this through for
construction + updates
- Add a special buffer for delayed deletions, and when in AttachedMulti
route deletions here instead of into the main remote client queue. This
is drained when transitioning to AttachedSingle. If the tenant is
detached or our process dies before then, then these objects are leaked.
- As a quality of life improvement, also use the remote timeline
client's knowledge of the tenant state to avoid submitting remote
consistent LSN updates for validation when in AttachedStale (as we know
these will fail)
## 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
## Problem
SLRU blocks, which can add up to several gigabytes, are currently
ingested by all shards, multiplying their capacity cost by the shard
count and slowing down ingest. We do this because all shards need the
SLRU pages to do timestamp->LSN lookup for GC.
Related: https://github.com/neondatabase/neon/issues/7512
## Summary of changes
- On non-zero shards, learn the GC offset from shard 0's index instead
of calculating it.
- Add a test `test_sharding_gc` that exercises this
- Do GC in test_pg_regress as a general smoke test that GC functions run
(e.g. this would fail if we were using SLRUs we didn't have)
In this PR we are still ingesting SLRUs everywhere, but not using them
any more. Part 2 PR (https://github.com/neondatabase/neon/pull/9786)
makes the change to not store them at all.
## 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
## Problem
This test uses a gratuitous number of pageservers (16). This works fine
when there are plenty of system resources, but causes issues on test
runners that have limited resources and run many tests concurrently.
Related: https://github.com/neondatabase/neon/issues/9802
## Summary of changes
- Split from 2 shards to 4, instead of 4 to 8
- Don't give every shard a separate pageserver, let two locations share
each pageserver.
Net result is 4 pageservers instead of 16
