The links at the very beginning of
https://clickhouse.com/docs/en/sql-reference/statements/system
don't work. They are reference other sections of the same document. This
is weird because there is a small index already on the right side. I
searched our documentation and this seems to be the only pages which do
so. Therefore removing the links altogether instead of fixing them.
- This commit restores statements "SYSTEM RELOAD MODEL(S)" which provide
a mechanism to update a model explicitly. It also saves potentially
unnecessary reloads of a model from disk after it's initial load.
To keep the complexity low, the semantics of "SYSTEM RELOAD MODEL(S)
was changed from eager to lazy. This means that both statements
previously immedately reloaded the specified/all models, whereas now
the statements only trigger an unload and the first call to
catboostEvaluate() does the actual load.
- Monitoring view SYSTEM.MODELS is also restored but with some obsolete
fields removed. The view was not documented in the past and for now it
remains undocumented. The commit is thus not considered a breach of
ClickHouse's public interface.
- The deleted function modelEvaluate() was superseded by
catboostEvaluate().
- Also delete the external model repository, as modelEvaluate() was it's
last user. Additionally remove the system view SYSTEM.MODELS for
inspecting the repository.
- SYSTEM RELOAD MODELS is also obsolete. HOWEVER, it was retained and
made a no-op instead of deleted.
Why?
The reason is that RBAC in distributed setups works by storing
privileges (granted and revoked) as plain SQL statements in Keeper.
Nodes read these statements at startup and parse them. If a privilege
for SYSTEM RELOAD MODELS exists but parser doesn't recognize it
nodes would fail to come up.
Considered but rejected alternatives:
- Ignore SYSTEM RELOAD MODELS during parsing RBAC privileges and
return an error for regular SYSTEM RELOAD MODELS SQL. Special-case
of no-op behavior, too brittle.
- Remove SYSTEM RELOAD MODELS manually from Keeper via command-line
manipulation of Keeper nodes or via SQL by dropping the privileges.
Needs user intervention during upgrade.
* initial commit: add setting and stub
* typo
* added test stub
* fix
* wip merging new integration test and code proto
* adding steps interpreters
* adding firstly proposed solution (moving parts etc)
* added checking zookeeper path existence
* fixing the include
* fixing and sorting includes
* fixing outdated struct
* fix the name
* added ast ptr as level of indirection
* fix ref
* updating the changes
* working on test stub
* fix iterator -> reference
* revert rocksdb submodule update
* fixed show privileges test
* updated the test stub
* replaced rand() with thread_local_rng(), updated the tests
updated the test
fixed test config path
test fix
removed error messages
fixed the test
updated the test
fixed string literal
fixed literal
typo: =
* fixed the empty replica error message
* updated the test and the code with logs
* updated the possible test cases, updated
* added the code/test milestone comments
* updated the test (added more testcases)
* replaced native assert with CH one
* individual replicas recursive delete fix
* updated the AS db.name AST
* two small logging fixes
* manually generated AST fixes
* Updated the test, added the possible algo change
* Some thoughts about optimizing the solution:
ALTER MOVE PARTITION .. TO TABLE -> move to detached/ + ALTER ... ATTACH
* fix
* Removed the replica sync in test as it's invalid
* Some test tweaks
* tmp
* Rewrote the algo by using the executeQuery instead of
hand-crafting the ASTPtr.
Two questions still active.
* tr: logging active parts
* Extracted the parts moving algo into a separate helper function
* Fixed the test data and the queries slightly
* Replaced query to system.parts to direct invocation,
started building the test that breaks on various parts.
* Added the case for tables when at least one replica is alive
* Updated the test to test replicas restoration by detaching/attaching
* Altered the test to check restoration without replica restart
* Added the tables swap in the start if the server failed last time
* Hotfix when only /replicas/replica... path was deleted
* Restore ZK paths while creating a replicated MergeTree table
* Updated the docs, fixed the algo for individual replicas restoration case
* Initial parts table storage fix, tests sync fix
* Reverted individual replica restoration to general algo
* Slightly optimised getDataParts
* Trying another solution with parts detaching
* Rewrote algo without any steps, added ON CLUSTER support
* Attaching parts from other replica on restoration
* Getting part checksums from ZK
* Removed ON CLUSTER, finished working solution
* Multiple small changes after review
* Fixing parallel test
* Supporting rewritten form on cluster
* Test fix
* Moar logging
* Using source replica as checksum provider
* improve test, remove some code from parser
* Trying solution with move to detached + forget
* Moving all parts (not only Committed) to detached
* Edited docs for RESTORE REPLICA
* Re-merging
* minor fixes
Co-authored-by: Alexander Tokmakov <avtokmakov@yandex-team.ru>
