Add focused Prometheus protocol tests for user-facing native lowering errors: unsupported-but-parseable functions and invalid date-function arity. These are semantic guardrails for clear errors, not broad coverage padding.

Add native PromQL lowering for classic histogram_quantile over _bucket series using the vector-grid query shape. The lowering groups buckets by timestamp and output labels, drops le and __name__, coalesces duplicate bounds, and applies Prometheus bucket quantile edge semantics through a time-series helper.

Add the missing unordered PromQL evaluation helper used by the classic histogram tests and make NaN bucket bounds deterministic before sorting. The NaN case is a semantic guard for parseable NaN le labels, not coverage padding.

Avoid fork-local wording in the PromQL review base. These are ClickHouse PromQL regression cases and evidence requirements, not fork-specific artifacts.

Avoid fork-local wording in the PromQL review base. These are ClickHouse PromQL regression cases and evidence requirements, not fork-specific artifacts.

Remove the standalone native histogram discovery Markdown note from the PromQL split branches.

Remove the standalone native histogram discovery Markdown note from the PromQL split branches.

Remove downstream promshim-specific evidence and non-goal language from the native PromQL lowering README so the note stays focused on ClickHouse review guidance.

Remove downstream promshim-specific evidence and non-goal language from the native PromQL lowering README so the note stays focused on ClickHouse review guidance.

Rewrite the native PromQL lowering notes around external SQL-transpiler measurements. Document measured and mixed SQL patterns with target PromQL shapes, pseudocode, and the ClickHouse-side validation expected for in-tree changes.

Rewrite the native PromQL lowering notes around external SQL-transpiler measurements. Document measured and mixed SQL patterns with target PromQL shapes, pseudocode, and the ClickHouse-side validation expected for in-tree changes.

Replace external corpus row names with concrete PromQL expressions and query-range context in the native PromQL lowering notes.

Replace external corpus row names with concrete PromQL expressions and query-range context in the native PromQL lowering notes.

Deduplicate expanded compliance cases by query text before checking the
`should_fail` expectation. A query listed once as expected success and once as
expected failure is now reported as conflicting metadata instead of slipping
through as two separate cases.

…plit/promql-classic-histograms

The histogram quantile tests intentionally compare unordered vectors, but the
helper still required the two Prometheus fixtures to return series in the same
order before sorting. Sort both Prometheus responses before comparison so the
helper only checks series content.

Mirror the upstream PromQL compliance corpus for label transformation invalid
label-name cases. These cases should remain should-fail entries so ClickHouse
acceptance of invalid destination labels stays visible as a rejection mismatch
rather than being counted as expected coverage.

…tograms

…on-base

…on-base

…tograms

Do not stop selector validation after finding the first matcher that cannot match an empty label value. Later regex matchers still need syntax validation so equivalent selector reorderings cannot change parse validity.

Add parser regressions for invalid regex matchers after an implicit metric-name matcher and after explicit non-empty matchers.

Add parser and HTTP API coverage for Prometheus selector validation rules: negated non-empty matchers, invalid regex validation after non-empty matchers, and duplicate metric-name matchers. Rejecting duplicate outside/in-brace metric names keeps ClickHouse parsing aligned with Prometheus expression parsing.

Keep `__name__` as part of classic histogram identity while grouping
buckets for `histogram_quantile`, then drop it through the normal result
path so duplicate output labelsets are rejected like Prometheus.

Expand focused histogram tests for q edge values, malformed and sparse
buckets, duplicate bounds, monotonicity repair, tiny deltas, transformed
rate inputs, and post-name-drop collisions.

…tograms

Mirror Prometheus BucketQuantile by treating only exactly zero observations as empty and by letting interpolation handle negative bucket counts. Malformed arithmetic over classic buckets can produce negative cumulative counts, and Prometheus still returns the computed quantile.

Use the existing eps parameter when checking live Prometheus HTTP results against expected JSON, and compare ClickHouse HTTP output against the live Prometheus result. This keeps numeric drift bounded to eps while preserving exact shape, label, and timestamp checks.

…on-base

…tograms

Matcher validation intentionally turns malformed label regexes into PromQL parse errors. Construct RE2 with log_errors disabled so rejected selectors do not also emit internal RE2 error log lines on every parse attempt.

…plit/promql-classic-histograms

…-base

…c-histograms

Build (arm_tidy) flagged the vector-grid finalization predicate because one call cloned an AST pointer while another argument moved the same pointer. C++ argument evaluation order can make that a use-after-move.\n\nCreate separate AST nodes for the null and stale-marker checks so the generated predicate stays the same without relying on argument evaluation order.

Parse `@ start()` and `@ end()` as timestamp modifier variants instead of
rewriting the raw query text before parsing. This keeps label values and
regular expressions untouched while resolving symbolic bounds in the query
range planner.

Propagate symbolic `@` modifiers through the PromQL tree and SQL lowering so
instant selectors and range-vector functions bind to the query start or end
consistently with Prometheus.

The selector-matcher validation branch should not also introduce symbolic
`@ start()` and `@ end()` modifier parsing. Remove that parser/evaluation
feature from the base branch so the behavior can be reviewed independently.

Move the symbolic timestamp-modifier compliance cases out with the feature.
Keep the offset-only case here because it exercises existing modifier behavior.

Symbolic `@ start()` and `@ end()` modifiers need parser-level handling so
selectors, string literals, and regular expressions are not rewritten as raw
text. Remove the temporary text-substitution path from the base branch; the
symbolic modifier implementation belongs with the dedicated parser change.

…-base

…-base

…tograms

# Conflicts:
#	src/Storages/TimeSeries/PrometheusQueryToSQL/applyFunction.cpp