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The following commit(s) were added to refs/heads/master by this push:
new fa4407c Fix bug for cumulative compaction on singleton rowset with
multiple segments (#2719)
fa4407c is described below
commit fa4407cf4f06d5dbad8b6be6ede91118d703bb61
Author: lichaoyong <[email protected]>
AuthorDate: Thu Jan 9 21:08:21 2020 +0800
Fix bug for cumulative compaction on singleton rowset with multiple
segments (#2719)
Row will be scanned mistakenly after cumulative compaction on singleton
rowset.
If I have (1, 1), (2, 2), (3, 3) three records.
Now I have read (1, 1), this bug will make return row is (2, 2)
instead of (1, 1).
---
be/src/olap/rowset/alpha_rowset_reader.cpp | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/be/src/olap/rowset/alpha_rowset_reader.cpp
b/be/src/olap/rowset/alpha_rowset_reader.cpp
index 18aec29..9460601 100644
--- a/be/src/olap/rowset/alpha_rowset_reader.cpp
+++ b/be/src/olap/rowset/alpha_rowset_reader.cpp
@@ -156,6 +156,18 @@ OLAPStatus AlphaRowsetReader::_merge_block(RowBlock**
block) {
copy_row(_dst_cursor, *row_cursor, _read_block->mem_pool());
_read_block->pos_inc();
num_rows_in_block++;
+
+ // MergeHeap should advance one step after row been read.
+ // This function must be called after copy_row
+ // Otherwise, the row has read will be modified instantly before
handled.
+ // For example:
+ // If I have (1, 1), (2, 2), (3, 3) three records.
+ // Now I have read (1, 1).
+ // Before copy_row, I rebuild the heap
+ // The returned row will be (2, 2) instead of (1, 1)
+ AlphaMergeContext* merge_ctx = _merge_heap.top();
+ _merge_heap.pop();
+ RETURN_NOT_OK(_update_merge_ctx_and_build_merge_heap(merge_ctx));
}
_read_block->set_pos(0);
_read_block->set_limit(num_rows_in_block);
@@ -205,9 +217,9 @@ OLAPStatus
AlphaRowsetReader::_pull_next_row_for_merge_rowset_v2(RowCursor** row
if (!_merge_heap.empty()) {
AlphaMergeContext* merge_ctx = _merge_heap.top();
*row = merge_ctx->row_cursor.get();
- _merge_heap.pop();
-
- RETURN_NOT_OK(_update_merge_ctx_and_build_merge_heap(merge_ctx));
+ // Must not rebuild merge_heap in this place.
+ // Because row have not been copied and is a pointer.
+ // If rebuild merge_heap, content in row will be modified.
return OLAP_SUCCESS;
} else {
// all rows are read
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