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.
- The deleted function modelEvaluate() was superseded by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.
- superseded by catboostEvaluate() which no longer uses the internal
repository for external models
- also removed was statement SYSTEM RELOAD MODELS and the monitoring view
SYSTEM.SYSTEMMODELS
Fixes#39287
ClickHouse uses the same semantics for modulo on floats as Python, i.e.
4.2 % 2.0 = 0.2
and not as previously documented:
4.2 % 2.0 --> (drop decimal places) --> 4 % 2 = 0.
Fixed the documentation.
