I will have to change these as I change remote_timeline_client api in
#4938. So a bit of cleanup, handle my comments which were just resolved
during initial review.
Cleanup:
- use unwrap in tests instead of mixed `?` and `unwrap`
- use `Handle` instead of `&'static Reactor` to make the
RemoteTimelineClient more natural
- use arrays in tests
- use plain `#[tokio::test]`
## Problem
A customer is having trouble connecting to neon from their production
environment. The logs show a mix of "Internal error" and "authentication
protocol violation" but not the full error
## Summary of changes
Make sure we don't miss any logs during SASL/SCRAM
Rather temporary solution before proper:
https://github.com/neondatabase/neon/issues/5006
It requires more plumbing so lets not attach deleted tenants first and
then implement resume.
Additionally fix `assert_prefix_empty`. It had a buggy prefix calculation,
and since we always asserted for absence of stuff it worked. Here I
started to assert for presence of stuff too and it failed. Added more
"presence" asserts to other places to be confident that it works.
Resolves [#5016](https://github.com/neondatabase/neon/issues/5016)
## Problem
The previous version of neon (that we use in the forward compatibility test)
has installed `amcheck` extension now. We can run `pg_amcheck`
unconditionally.
## Summary of changes
- Run `pg_amcheck` in compatibility tests unconditionally
Before this patch, we had the `off` and `blknum` as function-wide
mutable state. Now it's contained in the `Writer` struct.
The use of `push_bytes` instead of index-based filling of the buffer
also makes it easier to reason about what's going on.
This is prep for https://github.com/neondatabase/neon/pull/4994
Don't download ext_index.json from s3, but instead receive it as a part of spec from control plane.
This eliminates s3 access for most compute starts,
and also allows us to update extensions spec on the fly
Restores #4937 work relating to the ability to use `ResidentDeltaLayer`
(which is an Arc wrapper) in #4938 for the ValueRef's by removing the
borrow from `ValueRef` and providing it from an upper layer.
This should not have any functional changes, most importantly, the
`main` will continue to use the borrowed `DeltaLayerInner`. It might be
that I can change #4938 to be like this. If that is so, I'll gladly rip
out the `Ref` and move the borrow back. But I'll first want to look at
the current test failures.
This makes it more explicit that these are different u64-sized
namespaces.
Re-using one in place of the other would be catastrophic.
Prep for https://github.com/neondatabase/neon/pull/4994
which will eliminate the ephemeral_file::FileId and move the
blob_io::FileId into page_cache.
It makes sense to have this preliminary commit though,
to minimize amount of new concept in #4994 and other
preliminaries that depend on that work.
## Problem
As documented, the global connection pool will be high contention.
## Summary of changes
Use DashMap rather than Mutex<HashMap>.
Of note, DashMap currently uses a RwLock internally, but it's partially
sharded to reduce contention by a factor of N. We could potentially use
flurry which is a port of Java's concurrent hashmap, but I have no good
understanding of it's performance characteristics. Dashmap is at least
equivalent to hashmap but less contention.
See the read heavy benchmark to analyse our expected performance
<https://github.com/xacrimon/conc-map-bench#ready-heavy>
I also spoke with the developer of dashmap recently, and they are
working on porting the implementation to use concurrent HAMT FWIW
## Problem
PR #4839 has already reduced the number of b-tree traversals and vec
creations from 3 to 2, but as pointed out in
https://github.com/neondatabase/neon/pull/4839#discussion_r1279167815 ,
we would ideally just traverse the b-tree once during compaction.
Afer #4836, the two vecs created are one for the list of keys, lsns and
sizes, and one for the list of `(key, lsn, value reference)`. However,
they are not equal, as pointed out in
https://github.com/neondatabase/neon/pull/4839#issuecomment-1660418012
and the following comment: the key vec creation combines multiple
entries for which the lsn is changing but the key stays the same into
one, with the size being the sum of the sub-sizes. In SQL, this would
correspond to something like `SELECT key, lsn, SUM(size) FROM b_tree
GROUP BY key;` and `SELECT key, lsn, val_ref FROM b_tree;`. Therefore,
the join operation is non-trivial.
## Summary of changes
This PR merges the two lists of keys and value references into one. It's
not a trivial change and affects the size pattern of the resulting
files, which is why this is in a separate PR from #4839 .
The key vec is used in compaction for determining when to start a new
layer file. The loop uses various thresholds to come to this conclusion,
but the grouping via the key has led to the behaviour that regardless of
the threshold, it only starts a new file when either a new key is
encountered, or a new delta file.
The new code now does the combination after the merging and sorting of
the various keys from the delta files. This *mostly* does the same as
the old code, except for a detail: with the grouping done on a
per-delta-layer basis, the sorted and merged vec would still have
multiple entries for multiple delta files, but now, we don't have an
easy way to tell when a new input delta layer file is encountered, so we
cannot create multiple entries on that basis easily.
To prevent possibly infinite growth, our new grouping code compares the
combined size with the threshold, and if it is exceeded, it cuts a new
entry so that the downstream code can cut a new output file. Here, we
perform a tradeoff however, as if the threshold is too small, we risk
putting entries for the same key into multiple layer files, but if the
threshold is too big, we can in some instances exceed the target size.
Currently, we set the threshold to the target size, so in theory we
would stay below or roughly at double the `target_file_size`.
We also fix the way the size was calculated for the last key. The calculation
was wrong and accounted for the old layer's btree, even though we
already account for the overhead of the in-construction btree.
Builds on top of #4839 .
Previously list_prefixes was incorrectly used for that purpose. Change
to use list_files. Add a test.
Some drive by refactorings on python side to move helpers out of
specific test file to be widely accessible
resolves https://github.com/neondatabase/neon/issues/4499
