- Add UInt32 metric_locality_id on inner DATA MergeTree before id; ORDER BY
  (metric_locality_id, id, timestamp). Shared locality helper and
  timeSeriesMetricLocalityId via built-in SQL UDF (registered after persisted
  UDFs in Server and LocalServer); remove native function from stress list.
- Prometheus remote write fills locality when the physical DATA table has the
  column; omit it when an external DATA table has only id/timestamp/value.
- StorageTimeSeriesSelector: tuple IN vs id IN + synthetic locality from
  literal __name__ when the data target has no metric_locality_id column;
  optional locality validation for external DATA targets.
- Integration: test_timeseries_metric_locality, prometheus external tables,
  remote_write_label_demographics (PRW v1 label ordering).

Made-with: Cursor

…ocality-id

Made-with: Cursor

…t DATA locality

- Register timeSeriesMetricLocalityId as a built-in function (same semantics as
  sipHash64→UInt32) so CREATE FUNCTION cannot override it (addresses review).
- Remove SQL UDF registration stub from registerBuiltinSQLUserDefinedFunctions.
- Add allow_time_series_selector_regex_without_metric_locality_id (default true):
  when DATA has no metric_locality_id, allow regex __name__ matchers and emit
  zero metric_locality_id; set false to require literal __name__ (addresses review).
- Extend gtest_functions_stress with the new function name.

Made-with: Cursor

…est doc

- Declare metric_locality_id using config.metric_locality_id_data_type (matches readImpl casts).
- Reword integration test module doc for legacy DATA without physical locality column.

Made-with: Cursor

… write

validateColumnForMetricLocalityId allows Nullable(UInt32); createColumn returns ColumnNullable. Store IColumn* and insert via ColumnUInt32 or ColumnNullable instead of typeid_cast to ColumnUInt32 only.

Made-with: Cursor

- Remove duplicate Parsers/ASTLiteral.h include (readability-duplicate-include / arm_tidy).
- Replace EXPLAIN-based PK assertion with system.tables.sorting_key: planner may use timestamp prefix for range scans while ORDER BY remains (metric_locality_id, id, timestamp).

Made-with: Cursor

…unction

- Clarify integration tests need a branch-built binary (metric_locality_id on DATA).
- Replace (metric_locality_id, id) IN subquery: analyzer cannot resolve metric_locality_id inside tuple over timeSeriesData(); use id IN (...) AND d.metric_locality_id = sipHash literal for single-metric equivalence.
- Assert stored locality vs sipHash via join without requiring SQL UDF registration in the server.

Made-with: Cursor

PR feedback (AI review): unconditional startup validation of timeSeriesMetricLocalityId can break upgrades when a persisted UDF of the same name exists for non-TimeSeries use.

- registerBuiltinSQLUserDefinedFunctions: only register canonical UDF if absent (same as before strict startup check).
- ensureTimeSeriesMetricLocalityIdUserDefinedFunction: keep full validate-or-register for TimeSeries paths (timeSeriesSelector).

Integration test_timeseries_metric_locality requires a branch-built clickhouse binary (metric_locality_id on DATA).

Made-with: Cursor

…t startup

Startup registration now skips if a WebAssembly or executable UDF already owns
the name, uses replace_if_exists=false, and TimeSeries paths throw BAD_ARGUMENTS
when the SQL UDF is missing but a non-SQL UDF blocks registration.

Adds an integration test that reloads the server with a same-name WASM function
and asserts it is not replaced by the builtin SQL UDF (WasmEdge engine in config
to match typical builds).

Made-with: Cursor