github-actions[bot] commented on code in PR #65548:
URL: https://github.com/apache/doris/pull/65548#discussion_r3587923134
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be/src/format_v2/table_reader.h:
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@@ -449,6 +453,16 @@ class TableReader {
VLOG_DEBUG << "TableReader debug: " << debug_string();
}
RETURN_IF_ERROR(_open_mapping_exprs());
+ // COUNT(*) has no semantic column argument, but Nereids retains one
minimum-width scan
+ // slot so the scan node still has an output tuple. For example, in a
Parquet file whose
+ // first and only column is unsupported TIME_MILLIS, validating that
arbitrary placeholder
+ // would fail before the empty aggregate request can count rows from
footer metadata. Mark
+ // placeholders only after the same safety gate used by aggregate
materialization succeeds;
+ // COUNT(col), filters, deletes and pending runtime filters keep
normal column validation.
+ file_request->non_predicate_columns_are_count_star_placeholders =
Review Comment:
This still leaves a COUNT(*) fallback path observing the arbitrary
placeholder column. The marker is set only when
`_supports_aggregate_pushdown(COUNT)` is true, but that returns false as soon
as position deletes, deletion vectors, or Iceberg equality deletes are present.
When table-level row count is not assigned, `get_block()` then falls through to
the normal file-reader path; Parquet validates and later reads every
non-predicate column because the marker is false, while delete filtering only
needs the virtual row-position predicate column. So an Iceberg split whose
retained COUNT(*) placeholder is an unsupported `TIME_MILLIS` leaf can reject
`COUNT(*)` even though the value is never part of the aggregate. Please carry
the explicit COUNT(*) placeholder state into the delete-filter fallback path
and use a row-position/default-row carrier, or otherwise avoid
validating/reading the placeholder while still validating real predicate/delete
columns.
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