Major changes and new concepts:
Simplify Repository to a value-store
------------------------------------
Move the responsibility of tracking relation metadata, like which relations
exist and what are their sizes, from Repository to a new module,
pgdatadir_mapping.rs. The interface to Repository is now a simple key-value
PUT/GET operations.
It's still not any old key-value store though. A Repository is still
responsible from handling branching, and every GET operation comes with
an LSN.
Key
---
The key to the Repository key-value store is a Key struct, which consists
of a few integer fields. It's wide enough to store a full RelFileNode,
fork and block number, and to distinguish those from metadata keys.
See pgdatadir_mapping.rs for how relation blocks and metadata keys are
mapped to the Key struct.
Store arbitrary key-ranges in the layer files
---------------------------------------------
The concept of a "segment" is gone. Each layer file can store an arbitrary
range of Keys.
TODO:
- Deleting keys, to reclaim space. This isn't visible to Postgres, dropping
or truncating a relation works as you would expect if you look at it from
the compute node. If you drop a relation, for example, the relation is
removed from the metadata entry, so that it appears to be gone. However,
the layered repository implementation never reclaims the storage.
- Tracking "logical database size", for disk space quotas. That ought to
be reimplemented now in pgdatadir_mapping.rs, or perhaps in walingest.rs.
- LSM compaction. The logic for checkpointing and creating image layers is
very dumb. AFAIK the *read* code could deal with a full-fledged LSM tree
now consisting of the delta and image layers. But there's no code to
take a bunch of delta layers and compact them, and the heuristics for
when to create image layers is pretty dumb.
- The code to track the layers is inefficient. All layers are just stored in
a vector, and whenever we need to find a layer, we do a linear search in
it.
* Add --id argument to safekeeper setting its unique u64 id.
In preparation for storage node messaging. IDs are supposed to be monotonically
assigned by the console. In tests it is issued by ZenithEnv; at the zenith cli
level and fixtures, string name is completely replaced by integer id. Example
TOML configs are adjusted accordingly.
Sequential ids are chosen over Zid mainly because they are compact and easy to
type/remember.
* add node id to pageserver
This adds node id parameter to pageserver configuration. Also I use a
simple builder to construct pageserver config struct to avoid setting
node id to some temporary invalid value. Some of the changes in test
fixtures are needed to split init and start operations for envrionment.
Co-authored-by: Arseny Sher <sher-ars@yandex.ru>
Since commit fdd987c3ad, it was only used in InMemoryLayers. Let's
just "inline" the code into InMemoryLayer itself.
I originally did this as part of a bigger PR (#1267). With that PR,
one in-memory layer, and one ephemeral file, would hold page versions
belonging to multiple segments. Currently, PageVersions can only hold
versions for a single segment, so that would need to be changed.
Rather than modify PageVersions to support that, just remove it
altogether.
These tests have intimate knowledge of the directory layeout and layer
file names used by the LayeredRepository implementation of the
Repository trait. Move them, so that all the tests that remain in
repository.rs are expected to work without changes with any
implementation of Repository. Not that we have any plans to create
another Repository implementaiton any time soon, but as long as we
have the Repository interface, let's try to maintain that abstraction
in the tests too.
The test creates a page version with a string like "foo 123 at 0/10"
as the content. But the LSN stored in that string was wrong: the page
version stored at LSN 0/20 would say "foo <blk> at 0/10".
Previous version of spec caused parsing errors in generated clients
as return type is object not array, also one field was missing. In
a passing set `format: hex` on ancestor_id too as value conforms to
that format.
If a heap UPDATE record modified two pages, and both pages needed to have
their VM bits cleared, and the VM bits were located on the same VM page,
we would emit two ZenithWalRecord::ClearVisibilityMapFlags records for
the same VM page. That produced warnings like this in the pageserver log:
Page version Wal(ClearVisibilityMapFlags { heap_blkno: 18, flags: 3 }) of rel 1663/13949/2619_vm blk 0 at 2A/346046A0 already exists
To fix, change ClearVisibilityMapFlags so that it can update the bits
for both pages as one operation.
This was already covered by several python tests, so no need to add a
new one. Fixes#1125.
Co-authored-by: Konstantin Knizhnik <knizhnik@zenith.tech>
Use log::error!() instead. I spotted a few of these "connection error"
lines in the logs, without timestamps and the other stuff we print for
all other log messages.
* Freeze vectors at the same end LSN
* Fix calculation of last LSN for inmem layer
* Do not advance disk_consistent_lsn is no open layer was evicted
* Fix calculation of freeze_end_lsn
* Let start_lsn be larger than oldest_pending_lsn
* Rename 'oldest_pending_lsn' and 'last_lsn', add comments.
* Fix future_layerfiles test
* Update comments conserning olest_lsn
* Update comments conserning olest_lsn
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
* Reproduce github issue #1047.
* Use RwLock to protect gc_cuttof_lsn
* Eeduce number of updates in test_gc_aggressive
* Change test_prohibit_get_page_at_lsn_for_garbage_collected_pages test
* Change test_prohibit_get_page_at_lsn_for_garbage_collected_pages
* Lock latest_gc_cutoff_lsn in all operations accessing storage to prevent race conditions with GC
* Remove random sleep between wait_for_lsn and get_page_at_lsn
* Initialize latest_gc_cutoff with initdb_lsn and remove separate check that lsn >= initdb_lsn
* Update test_prohibit_branch_creation_on_pre_initdb_lsn test
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
to pass current_timeline_size to compute node
Put standby_status_update fields into ZenithFeedback and send them as one message.
Pass values sizes together with keys in ZenithFeedback message.
This patch includes attach/detach http endpoints in pageservers. Some
changes in callmemaybe handling inside safekeeper and an integrational
test to check migration with and without load. There are still some
rough edges that will be addressed in follow up patches
* Do not delete layers beyand cutoff LSN
* Update pageserver/src/layered_repository/layer_map.rs
Co-authored-by: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Co-authored-by: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Heikki Linnakangas
Kirill Bulatov
Dmitry RodionovandArseny Sher
anastasia
Stas Kelvich
Konstantin KnizhnikandHeikki Linnakangas
