github-actions[bot] commented on code in PR #67922:
URL: https://github.com/apache/doris/pull/67922#discussion_r4004207754
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be/src/format_v2/parquet/reader/native_column_reader.cpp:
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@@ -347,7 +348,10 @@ Status NativeColumnReader::init(
const size_t max_group_buffer = config::parquet_rowgroup_max_buffer_mb <<
20;
const size_t max_column_buffer = config::parquet_column_max_buffer_mb <<
20;
- const size_t max_buffer_size = std::min(max_group_buffer,
max_column_buffer);
+ // Sparse exact-row fetches need demand pages, not one read-ahead buffer
per physical leaf.
+ // Passing zero through the native tree also prevents wide nested
projections multiplying it.
+ const size_t max_buffer_size =
Review Comment:
[P2] Retain indexed navigation when disabling read-ahead
Zero configured read-ahead is appropriate for exact-row payloads, but
predicate-free row-ID requests never populate `row_group_plan.offset_indexes`:
the only current path is `load_native_page_indexes()`, gated on a zonemap
predicate, while the validated standalone `load_native_offset_indexes()` has no
caller. For a late ID, flat Page V1/V2 and all-V2 nested readers therefore
parse every preceding page header to discover row bounds. Each page incurs a
PageCache lookup and, on an ordinary cold miss, a demand FileReader operation
per projected leaf (lower file-cache layers may still coalesce network
traffic). This is distinct from the existing nested-Page-V1 thread: these modes
already support indexed navigation, so loading their validated OffsetIndexes is
sufficient. Please load them for row-ID projections with the existing
malformed/absent-index fallback, and test a late row with a header/read-call
bound.
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