CharlesKWON
93cf5c8bfa
Foundation for the upcoming PostgreSQL-wire server. The SQL engine
previously held transaction state and the plan cache in module-level
STATICs:
TSqlTxn.prg:16-18
STATIC s_aTxnLog := {}
STATIC s_lInTxn := .F.
STATIC s_hSavepoints := NIL
TFiveSQL.prg:37
STATIC s_hPlanCache := { => }
gengo emits PRG STATIC as Go *package* variables, so two clients
sharing one process serialised through a single transaction log:
client A's `BEGIN; INSERT;` followed by client B's `ROLLBACK`
would silently undo A's insert. Acceptable for embedded single-
caller use; show-stopper for a multi-connection daemon.
Moved each of those into instance fields on a new TSqlSession class.
Every executor instance now carries an oSession pointer that's
inherited by nested subquery executors. A process-default session
is lazy-initialised by SqlDefaultSession() so embedded
`five_SQL(cSQL)` callers (today's only consumer) keep working
unchanged.
Changes
-------
* `_FiveSql2/src/TSqlSession.prg` (new) — class holding the four
ex-STATICs plus seats for auth/ACL state and a list of workareas
the session opened (used later for disconnect cleanup). Module-
level `SqlDefaultSession()` lazily creates one process-wide
default for embedded callers.
* `_FiveSql2/src/TSqlTxn.prg` — added `oSession` DATA; New() takes
an optional oSession and falls back to the default. All STATIC
reads/writes rewritten as `::oSession:aTxnLog`,
`::oSession:lInTxn`, etc.
* `_FiveSql2/src/TFiveSQL.prg` — added `oSession` DATA; New() takes
an optional second arg. Plan-cache reads/writes route through
`::oSession:hPlanCache`. SQL_PLAN_CACHE_MAX now caps each session
independently (a chatty client only flushes its own cache, not
the shared one).
* `_FiveSql2/src/TSqlExecutor.prg` — added `oSession` DATA; New()
takes an optional third arg; `::oTxn := TSqlTxn():New(::oSession)`
propagates the binding. Every in-class `TSqlExecutor():New(...)`
call site for subqueries / UNION / IN-list materialisation /
EXISTS / lifted subqueries now passes `::oSession` through, so a
child executor inherits the parent's session. Standalone helper
functions (SqlEvalExprNode / SqlFetchRowArr / SqlJoinRecurse /
SqlMaterializeSubquery) intentionally fall back to the default
session — they don't BEGIN/COMMIT and the plan cache is keyed by
schema-version anyway.
* `_FiveSql2/src/FiveSqlCls.prg` — `five_SQL()` gains an optional
fourth arg `oSession`. Existing 1-/2-/3-arg callers keep working;
pgserver will create one TSqlSession per connection and pass it.
Verification
------------
Per-session isolation pinned by a fresh PRG-level regression
(reproducer not committed yet — will land with pgserver test
suite). The scenario:
oSessA := TSqlSession():New()
oSessB := TSqlSession():New()
oSqlA := TFiveSQL():New(NIL, oSessA)
oSqlB := TFiveSQL():New(NIL, oSessB)
oSqlA:Execute("BEGIN") -- A in txn
oSqlB:Execute("BEGIN") -- B in txn, A unaffected
oSqlB:Execute("INSERT ... VALUES(2,'b-row')")
oSqlB:Execute("COMMIT") -- B committed, A still in txn
oSqlA:Execute("ROLLBACK") -- A's empty rollback, B's row survives
All four assertions pass post-refactor, would fail pre-refactor
because both sessions wrote the same `s_aTxnLog`.
All six release gates green:
go test ./... ✓
FiveSql2 SQL:1999 43/43 ✓
Harbour compat 56/56 ✓
std.ch 17/17 ✓
FRB 7/7 ✓
examples 65/71 ✓ (unchanged baseline)
Co-Authored-By: Claude Opus 4.7 (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.