After this, a layer's start bound is always defined to be inclusive, and
end bound exclusive.
For example, if you have a layer in the range 100-200, that layer can be
used for GetPage@LSN requests at LSN 100, 199, or anything in between.
But for LSN 200, you need to look at the next layer (if one exists).
This is one part of a fix for https://github.com/zenithdb/zenith/issues/517.
After this, the page server shouldn't create layers for the same segment
with the same LSN, which avoids the issue. However, the same thing would
still happen, if you managed to create layers with same start LSN again.
That could happen e.g. if you had two page servers running, or in some
weird crash/restart scenario, or due to bugs or features added later. The
next commit makes the layer map more robust, so that it tolerates that
situation without deleting wrong files.
New command has been added to append specially crafted records in safekeeper WAL. This command takes json for append, encodes LogicalMessage based on json fields, and processes new AppendRequest to append and commit WAL in safekeeper.
Python test starts up walkeepers and creates config for walproposer, then appends WAL and checks --sync-safekeepers works without errors. This test is simplest one, more useful test cases (like in #545) for different setups will be added soon.
Postgres commit message:
PQgetCopyData can sometimes indicate that the copy is done if the
backend returns an error response. So while we still expect that the
walkeeper never sends CopyDone, we can't expect it to never produce
errors.
- Turn dropped layers into non-writeable in get_layer_for_write().
- Handle non-writeable dropped layers in checkpointer. They don't need freezing, so just remove them from list of open_segs and write out to disk.
- Remove code that handles dropped layers in freeze() function. It is not used anymore.
Some dropped layers serve as tombstones for earlier layers and thus cannot be garbage collected.
Add new fields to GcResult for layers that are preserved as tombstones
anyhow uses the alternate formatting style ("{:#}") to display all of
the causes of an error instead of the outermost context.
Without this, there's less information available to figure out what's
going on. It's probably too much to display in the compute node logs
though, so it's better to leave that formatting as-is.
In this test safekeepers are restarted one by one, while bank transactions
are executed and validated in the background. Bank transactions consist of
balance transfers and log writes. In the end balance sum should remain the
same and there should be progress from every client, when 2 of 3 safekeeper
nodes are up.
It's not interesting for most tests, and clutters the output. If there
are individual tests where it is worthwhole, let's add pg_controldata calls
to those tests, but I don't think it's needed for now.
If the 'latest' flag in the client request is true, the client wants the
latest page version regardless of the LSN in the request. The LSN is just
a hint in that case, indicating that the page hasn't been modified since
since that LSN. The LSN can be very old, so it's possible that the page
server has already garbage collected away the layer at that LSN. We tried
to fetch the old layer and errored out if that happened. To fix, always
fetch the data as of last-record-LSN, if 'latest' is set in the client
request. We now only use the LSN to wait if the requested LSN hasn't been
received and processed yet.
Fixes https://github.com/zenithdb/zenith/issues/567
- Use different message formats for different kinds of response messages.
- Add an Error message, for passing errors from page server to Postgres.
Previously, we would respond to 'exists' request with 'false', and
to 'nblocks' request with 0, if an error happened. Fix those to return
an error message to the client. GetPage requests had a mechanism to
return an error, but it was just a flag with no error message.
- Add a flag to requests, to indicate that we actually want the latest
page version on the timeline, and the LSN is just a hint that we know
that there haven't been any modifications since that LSN. The flag isn't
used for anything yet, but I'm planning to use it to fix
https://github.com/zenithdb/zenith/issues/567
Most of the previous usages of get_repository_for_tenant were followed
by immediately getting a timeline in that repository, without keeping it
around for longer.
The new `get_timeline_for_tenant` function implements that same
behavior, but in one line.
- Change hardcoded OLDEST_INMEM_DISTANCE value to pageserver config option checkpoint_distance.
- Get rid of 'force' flag in checkpoint_internal(). Use checkpoint_distance=0 instead.
Support is done via pytest-xdist plugin.
To use the feature add -n<concurrency> to pytest invocation
e.g. pytest -n8 to run 8 tests in parallel.
Changes in code are mostly about ports assigning. Previously port for
pageserver was hardcoded without the ability to override through zenith
cli and ports for started compute nodes were calculated twice, in zenith
cli and in test code. Now zenith cli supports port arguments for
pageserver and compute nodes to be passed explicitly.
Tests are modified in such a way that each worker gets a non overlapping
port range which can be configured and now contains 100 ports. These
ports are distributed to test services (pageserver, wal acceptors,
compute nodes) so they can work independently.
