A new `get_lsn_by_timestamp` command is added to the libpq page service
API.
An extra timestamp field is now stored in an extra field after each
Clog page. It is the timestamp of the latest commit, among all the
transactions on the Clog page. To find the overall latest commit, we
need to scan all Clog pages, but this isn't a very frequent operation
so that's not too bad.
To find the LSN that corresponds to a timestamp, we perform a binary
search. The binary search starts with min = last LSN when GC ran, and
max = latest LSN on the timeline. On each iteration of the search we
check if there are any commits with a higher-than-requested timestamp
at that LSN.
Implements github issue 1361.
* Traverse frozen layer in get_reconstruct_data in reverse order
* Fix comments on frozen layers.
Note explicitly the order that the layers are in the queue.
* Add fail point to reproduce failpoint iteration error
Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
Previously we've used table interface, but there was no easy way to pass
it as an override to pageserver through cli. Use the same strategy as
for remote storage config parsing
Add tenant config API and 'zenith tenant config' CLI command.
Add 'show' query to pageserver protocol for tenantspecific config parameters
Refactoring: move tenant_config code to a separate module.
Save tenant conf file to tenant's directory, when tenant is created to recover it on pageserver restart.
Ignore error during tenant config loading, while it is not supported by console
Define PiTR interval for GC.
refer #1320
This depends on a hacked version of the 'pprof-rs' crate. Because of
that, it's under an optional 'profiling' feature. It is disabled by
default, but enabled for release builds in CircleCI config. It doesn't
currently work on macOS.
The flamegraph is written to 'flamegraph.svg' in the pageserver
workdir when the 'pageserver' process exits.
Add a performance test that runs the perf_pgbench test, with profiling
enabled.
We only checked the cache page version when collecting WAL records in
an in-memory layer, not in a delta layer. Refactor the code so that we
always stop collecting WAL records when we reach a cached materialized
page.
Fix the assertion on the LSN range in
InMemoryLayer::get_value_reconstruct_data. It was supposed to check
that the requested LSN range is within the layer's LSN range, but the
inequality was backwards. That went unnoticed before, because the
caller always passed the layer's start LSN as the requested LSN
range's start LSN, but now we might stop the search earlier, if we have
a cached page version.
Co-authored-by: Konstantin Knizhnik <knizhnik@zenith.tech>
Unlink failure isn't serious on its own, we were about to remove the
file anyway, but it shouldn't happen and could be a symptom of
something more serious.
We just saw "No such file or directory" errors happening from
ephemeral file writeback in staging, and I suspect if we had this
warning in place, we would have seen these warnings too, if the
problem was that the ephemeral file was removed before dropping the
EphemeralFile struct. Next time it happens, we'll have more
information.
It originated from the fact that we were calling to fetch_full_index
without releasing the read guard, and fetch_full_index tries to acquire
read again. For plain mutex it is already a deeadlock, for RW lock
deadlock was achieved by an attempt to acquire write access later in the
code while still having active read guard up in the stack
This is sort of a bandaid because Kirill plans to change this code
during removal of an archiving mechanism
We now use a page cache for those, instead of slurping the whole index into
memory.
Fixes https://github.com/zenithdb/zenith/issues/1356
This is a backwards-incompatible change to the storage format, so
bump STORAGE_FORMAT_VERSION.
This introduces two new abstraction layers for I/O:
- Block I/O, and
- Blob I/O.
The BlockReader trait abstracts a file or something else that can be read
in 8kB pages. It is implemented by EphemeralFiles, and by a new
FileBlockReader struct that allows reading arbitrary VirtualFiles in that
manner, utilizing the page cache.
There is also a new BlockCursor struct that works as a cursor over a
BlockReader. When you create a BlockCursor and read the first page using
it, it keeps the reference to the page. If you access the same page again,
it avoids going to page cache and quickly returns the same page again.
That can save a lot of lookups in the page cache if you perform multiple
reads.
The Blob-oriented API allows reading and writing "blobs" of arbitrary
length. It is a layer on top of the block-oriented API. When you write
a blob with the write_blob() function, it writes a length field
followed by the actual data to the underlying block storage, and
returns the offset where the blob was stored. The blob can be
retrieved later using the offset.
Finally, this replaces the I/O code in image-, delta-, and in-memory
layers to use the new abstractions. These replace the 'bookfile'
crate.
This is a backwards-incompatible change to the storage format.
We have these methods for some time in the API, so mentioning them in the
spec could be useful for console (see zenithdb/console#867), as we generate
pageserver HTTP API golang client there.
It happened in unit tests. If a thread tries to read a buffer while
already holding a lock on one buffer, the code to find a victim buffer
to evict could try to evict the buffer that's already locked. To fix,
skip locked buffers.
