Hybrid layout design for HashJoin/Sort

[ruochenj123]

What problem does this PR solve?

Issue Number: #11

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 🚀 Performance improvement (optimization)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)
• 🔨 Refactoring (no logic changes)
• 🔧 Build/CI or Infrastructure changes
• 📝 Documentation only

Description

Currently HashJoin and Sort operations store data in row-based RowContainer, which incurs non-trivial layout conversion overhead. This PR introduces a hybrid storage design that keeps payload columns in their original columnar format while only storing keys in RowContainer, reducing this layout conversion overhead.

Main Changes

1. HybridContainer

   • Separates key storage (in RowContainer) from payload storage (kept as RowVectorPtr).
   • Introduces encoded HybridRowId to reference payload rows.
   • HybridRowId encodes {containerId, rowId} to support multi-driver parallel execution in HashJoin.

2. Multi-driver support in HashJoin

   • Each driver builds its own HybridContainer.
   • After table merge, the allContainers_ map enables cross-container payload extraction during the probe phase.

3. Extraction optimizations

   • coalesceBatches() flattens multiple payload batches into a single contiguous batch to reduce TLB misses during extraction.
   • sortByContainerId() reorders rows by containerId before extraction to improve cache locality in multi-container scenarios.
   • Prefetching during extraction to hide memory latency and reduce data loading time.
   • isSingleContainer() provides a fast path that skips sorting overhead in the single-driver scenario.

4. Configuration options

   • hybrid_join_enabled / hybrid_sort_enabled to opt in to hybrid execution.
   • hybrid_join_reorder_enabled to control row reordering (disabled in tests to preserve deterministic output).

Performance Impact

• No Impact: This change does not affect the critical path (e.g., build system, doc, error handling).

• Positive Impact: I have run benchmarks.

  Click to view Benchmark Results

  Paste your google-benchmark or TPC-H results here.
  Before: 10.5s
  After:   8.2s  (+20%)
  

• Negative Impact: Explained below (e.g., trade-off for correctness).

Tested on bolt_tpch_benchmark with sf=10 iteration=5. The performances are almost the same.

+----------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
| Type     | q1   | q2   | q3   | q4   | q5   | q6   | q7   | q8   | q9   | q10  | q11  | q12  | q13  | q14  | q15  | q16  | q17  | q18  | q19  | q20  | q21  | q22  |
+----------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
| baseline | 856  | 287.4| 1096 | 2492 | 1374 | 453.6| 1090 | 1420 | 1990 | 1662 | 151  | 558.8| 1544 | 874  | 717.4| 353.6| 3816 | 2250 | 952  | 639.2| 2234 | 583.2|
| hybrid   | 882.8| 315  | 1100 | 2390 | 1370 | 450.4| 1078 | 1266 | 2072 | 1738 | 149.2| 631  | 1532 | 852.6| 698.6| 343.4| 4052 | 2062 | 918.4| 664.4| 2248 | 545.4|
+----------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+

Release Note

Please describe the changes in this PR

Release Note:

Release Note:
- Fixed a crash in `substr` when input is null.
- optimized `group by` performance by 20%.

Checklist (For Author)

• I have added/updated unit tests (ctest).
• I have verified the code with local build (Release/Debug).
• I have run clang-format / linters.
• (Optional) I have run Sanitizers (ASAN/TSAN) locally for complex C++ changes.
• No need to test or manual test.

Breaking Changes

• No

• Yes (Description: ...)

  Click to view Breaking Changes

  Breaking Changes:
  - Description of the breaking change.
  - Possible solutions or workarounds.
  - Any other relevant information.
  

[CLAassistant]

All committers have signed the CLA.

[yangzhg]

typo disabled

[yangzhg]

why hardcode limit to 255?

[ruochenj123]

Currently we store a BIGINT (64 bits) of rowId where the top 8 bits represents the driverId and the remaining 56 bits represents the rowId for each driver. So the max # of driver it supports is 255. Maybe we can make it as a config.

[yangzhg]

Does the magic number 16 fit for all the arch? e.g. x86 arm?

[ruochenj123]

I'm not sure. I tuned it on a x86_64 machine, k = 8-32 perform similarly.