pitrou commented on code in PR #41335:
URL: https://github.com/apache/arrow/pull/41335#discussion_r1599962402
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cpp/src/arrow/acero/hash_join_node_test.cc:
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@@ -3201,5 +3203,55 @@ TEST(HashJoin, ChainedIntegerHashJoins) {
}
}
+// Test that a large number of joins don't overflow the temp vector stack,
like GH-39582
+// and GH-39951.
+TEST(HashJoin, ManyJoins) {
+ // The idea of this case is to create many nested join nodes that may
possibly cause
+ // recursive usage of temp vector stack. To make sure that the recursion
happens:
+ // 1. A left-deep join tree is created so that the left-most (the final
probe side)
+ // table will go through all the hash tables from the right side.
+ // 2. Left-outer join is used so that every join will increase the
cardinality.
+ // 3. The left-most table contains rows of unique integers from 0 to N.
+ // 4. Each right table at level i contains two rows of integer i, so that
the probing of
+ // each level will increase the result by one row.
+ // 5. The left-most table is a single batch of enough rows, so that at each
level, the
+ // probing will accumulate enough result rows to have to output to the
subsequent level
+ // before finishing the current batch (releasing the buffer allocated on the
temp vector
+ // stack), which is essentially the recursive usage of the temp vector stack.
+
+ // A fair number of joins to guarantee temp vector stack overflow before
GH-41335.
+ const int num_joins = 64;
+
+ // `ExecBatchBuilder::num_rows_max()` is the number of rows for swiss join
to accumulate
+ // before outputting.
+ const int num_left_rows = ExecBatchBuilder::num_rows_max();
+ ASSERT_OK_AND_ASSIGN(
+ auto left_batches,
+ MakeIntegerBatches({[](int row_id) -> int64_t { return row_id; }},
+ schema({field("l_key", int8())}),
Review Comment:
Shouldn't this use a wider type in case `num_rows_max` is above 127?
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