CharlesKWON
64b7cf6676
FiveSql2's HashJoin only recognized bare equi-terms (xOnCond[1]=ND_BIN,
xOnCond[2]="="), so a compound ON predicate like
ON e.dept_id = t.dept_id AND e.salary = t.max_sal
fell through to the nested-loop ELSE branch:
dbSelectArea(nInnerWA)
dbGoTop()
WHILE !Eof()
IF SqlIsTrue(EvalExpr(xOnCond))
JoinRecurse(...)
ENDIF
dbSkip()
ENDDO
That's O(outer × inner) per outer row, re-evaluating the full AND tree
every probe. Query Q7 in the complex benchmark (CTE top_emp joined back
to emp on compound key) ran at 4.6 seconds for 100 inner × 10k outer.
Fix has two pieces:
1. **Probe-term extraction in JoinRecurse**: when xOnCond is an AND,
walk the left-associative chain looking for the first equi-term
(`a.x = b.x`). Use that as the hash-probe key, drive the normal
hash-join code path through it.
2. **Post-filter in HashJoin**: after a hash match, if the *original*
xOnCond was compound, re-evaluate the full predicate with
EvalExpr to drop matches that satisfied the hash key but not the
rest of the AND (e.g. same dept but different salary). Bare equi-
joins still skip the re-eval — the hash match is conclusive.
Bench (10k × 100 × compound ON predicate):
Query Before After Speedup
─────────────────────────────────────────────────────────
Q7 CTE + JOIN compound ON 4573ms 209ms 21.9x
Still works for the existing bare equi case (43-test unchanged) and
the 3-way JOIN case (no regression). Falls back to the generic nested
loop only when no probe-term can be extracted at all.
Validation:
- FiveSql2 43/43
- Harbour compat 51/51
- go test ./... ALL PASS
- Q7 result: 100 rows (correct)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
FiveSql2 — SQL Engine for Harbour DBF/NTX/CDX
Pratt parser + SQL:1992-2023 full standard support Supports both NTX (Clipper) and CDX (FoxPro/ADS) indexes
Architecture
five_SQL("SELECT ...")
│
├── TSqlLexer Tokenizer
├── TSqlParser2 Pratt parser (data-driven operators)
├── TSqlExecutor Query executor (Volcano model)
│ ├── TSqlAlias Central alias manager (no collisions)
│ ├── TSqlIndex NTX/CDX index optimization (auto-detect)
│ ├── TSqlAgg GROUP BY / aggregation
│ ├── TSqlSort ORDER BY / DISTINCT
│ ├── TSqlDDL CREATE/DROP/ALTER TABLE/INDEX
│ └── TSqlTxn BEGIN/COMMIT/ROLLBACK
├── TSqlExpr AST nodes + expression evaluation
└── TSqlFunc 60+ scalar functions
Build & Test
export PATH="/path/to/harbour-core/bin/linux/gcc:$PATH"
export HB_INSTALL_PREFIX="/path/to/harbour-core"
make # Build all tests
make test # Run all 157 tests
make bench # Parser benchmark
make clean # Clean
SQL Standard Coverage
| Standard | Features | Tests |
|---|---|---|
| SQL:1992 | SELECT, JOIN, GROUP BY, HAVING, Subquery, CASE, CAST | 43 |
| SQL:1999 | CTE, Recursive CTE, Window Functions, MERGE | 10 |
| SQL:2003 | SIMILAR TO, GROUPING SETS, LATERAL, Window frames | 64 |
| SQL:2008 | FETCH/OFFSET, FOR UPDATE, Extended MERGE | (incl.) |
| SQL:2016 | JSON functions, LISTAGG | (incl.) |
| SQL:2023 | ANY_VALUE, GREATEST/LEAST, BOOL_AND/OR | (incl.) |
| Challenge | LeetCode-level complex queries | 15 |
| Extreme | Production analytics stress tests | 15 |
Adding New Operators
Edit TSqlParser2.prg, method InitInfixTables():
::hInfixTT[ TK_MYOP ] := { "<=>", 40, 41, ND_BIN }
One line. No structural changes needed.
Copyright
Copyright (c) 2025-2026 Charles KWON (Charles KWON OhJun) Email: charleskwonohjun@gmail.com All rights reserved.