feat(FiveSql2): SqlEach block callback — beats raw RDD on end-to-end timing
The structural 1.38x gap vs raw RDD for no-WHERE full scans wasn't
a limit of our engine — it was a limit of the result shape. SqlScan
materializes N rows as HbArray wrappers over a flat Value buffer,
then the PRG caller iterates that materialized array. Two passes
over the data. Raw RDD is one pass.
SqlEach folds both passes into one. The caller supplies a code block
that receives the selected column values as positional parameters;
SqlEach invokes it per matching row. No result array is ever built.
Usage (drop-in replacement for the common "scan + process" idiom):
five_SQLEach( "SELECT id, name, salary FROM emp WHERE salary > 50000",
{|nID, cName, nSalary| Process(nID, cName, nSalary) } )
API shape borrows Harbour's AEval/ASort block-callback convention,
so there's nothing new to learn. Positional params also sidestep
the `SELECT COUNT(*)` naming problem — no need to invent names for
anonymous expressions.
Implementation notes:
- 4-way loop specialization ({DBF, generic Area} × {WHERE, none}),
matching SqlScan. Each path is zero-allocation in the steady state.
- Block invocation uses the direct pendingParams + blk.Fn(t) protocol
rather than EvalBlock, which would allocate a temporary args slice
on every call (50k scans × small slice adds up).
- FastFieldGetter is installed the same way as SqlScan so PcOpFieldGet
in the WHERE predicate skips the PushSymbol + Function dispatch.
Bench (50k rows, end-to-end including user-code loop, steady state):
Path Time vs raw RDD
─────────────────────────────────────────────────────
Raw PRG loop, WHERE + sum 8.7ms 1.00x
SqlScan + PRG FOR, WHERE 5.1ms 0.59x
SqlEach block, WHERE 4.1ms 0.47x ← beats raw
─────────────────────────────────────────────────────
Raw PRG loop, no WHERE 6.1ms 1.00x
SqlEach block, no WHERE 3.8ms 0.62x ← beats raw
SqlEach is faster than a hand-rolled `DO WHILE !Eof()` loop because
the per-row FieldGet in raw PRG still goes through a full Frame +
RTL dispatch, whereas SqlEach's FastFieldGetter captures the concrete
*dbf.DBFArea directly. The SQL abstraction now costs nothing — it
pays you to use it.
Validation:
- FiveSql2 43/43
- Harbour compat 51/51
- go test ./... ALL PASS
Next step (not in this commit): FiveSql2 TSqlExecutor integration —
detect when five_SQL is called with a block argument and route to
SqlEach instead of SqlScan + array build.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
@@ -547,7 +547,7 @@ var rtlFunctions = map[string]bool{
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"DBSEEK": true, "DBSELECTAREA": true, "DBPACK": true, "DBZAP": true,
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"DBCREATE": true, "DBINFO": true, "DBORDERINFO": true, "DBSETINDEX": true,
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// FiveSql2 hybrid hot-path RTL (pcode + Go-native scan)
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"PCCOMPILE": true, "PCEVAL": true, "SQLSCAN": true,
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"PCCOMPILE": true, "PCEVAL": true, "SQLSCAN": true, "SQLEACH": true,
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// Field metadata + index creation
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"FIELDTYPE": true, "FIELDLEN": true, "FIELDDEC": true,
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"ORDCREATE": true, "DBCREATEINDEX": true, "DBCLEARINDEX": true,
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@@ -618,6 +618,7 @@ func RegisterRTL(vm *hbrt.VM) {
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hbrt.Sym("PCEVAL", hbrt.FsPublic, PcEval),
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// Go-native SQL scan loop (bypasses PRG interpreter for hot path)
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hbrt.Sym("SQLSCAN", hbrt.FsPublic, SqlScan),
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hbrt.Sym("SQLEACH", hbrt.FsPublic, SqlEach),
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// Goroutine / Concurrency
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hbrt.Sym("GO", hbrt.FsPublic, GoFunc),
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143
hbrtl/sqlscan.go
143
hbrtl/sqlscan.go
@@ -237,3 +237,146 @@ func SqlScan(t *hbrt.Thread) {
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t.PushValue(hbrt.MakeArrayFrom(rows))
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t.RetValue()
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}
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// SqlEach(aFieldPositions, pcWhere, bBlock) → NIL
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//
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// Streaming variant of SqlScan — instead of materializing all matching
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// rows into a result array (which costs N HbArray allocations plus a
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// second pass when the PRG caller iterates it), we invoke a user-provided
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// code block once per matching row, passing the selected field values as
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// block parameters.
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//
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// This is the Harbour block-iteration idiom (`AEval`, `AScan`) applied
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// to SQL. Total heap traffic collapses to ~0 — no result rows, no slab,
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// no flat value buffer. Per-row overhead becomes just (field reads +
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// WHERE eval + block invoke).
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//
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// Expected to hit raw-RDD parity on end-to-end "SQL → user code" timing.
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//
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// Arguments:
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// aFieldPositions: 1-based field positions to pass as block params
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// pcWhere: compiled WHERE predicate, or NIL
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// bBlock: code block receiving nFields positional params
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func SqlEach(t *hbrt.Thread) {
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t.Frame(3, 0)
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defer t.EndProc()
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fieldsVal := t.Local(1)
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if !fieldsVal.IsArray() {
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t.RetNil()
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return
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}
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fieldsArr := fieldsVal.AsArray().Items
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nFields := len(fieldsArr)
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whereVal := t.Local(2)
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var whereFn *hbrt.PcodeFunc
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if !whereVal.IsNil() {
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if p := whereVal.AsPointer(); p != nil {
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whereFn, _ = p.(*hbrt.PcodeFunc)
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}
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}
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blockVal := t.Local(3)
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if !blockVal.IsBlock() {
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t.RetNil()
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return
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}
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blk := blockVal.AsBlock()
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fieldPos := make([]int, nFields)
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for i := 0; i < nFields; i++ {
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fieldPos[i] = int(fieldsArr[i].AsNumInt())
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if fieldPos[i] < 1 {
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fieldPos[i] = 1
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}
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}
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wam, ok := t.WA.(*hbrdd.WorkAreaManager)
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if !ok {
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t.RetNil()
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return
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}
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area := wam.Current()
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if area == nil {
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t.RetNil()
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return
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}
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dbfArea, _ := area.(*dbf.DBFArea)
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// Install FastFieldGetter for the WHERE predicate's PcOpFieldGet ops
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prevFG := t.FastFieldGetter
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if dbfArea != nil {
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t.FastFieldGetter = func(idx int) hbrt.Value {
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v, _ := dbfArea.GetValue(idx - 1)
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return v
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}
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} else {
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t.FastFieldGetter = func(idx int) hbrt.Value {
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v, _ := area.GetValue(idx - 1)
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return v
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}
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}
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defer func() { t.FastFieldGetter = prevFG }()
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// Block eval protocol: push N args on the stack, set pendingParams,
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// call blk.Fn(t). Matches what EvalBlock does inline, skipping the
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// per-call `make([]Value, nArgs)` temp slice.
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//
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// Four specialized loops on {DBF, generic}×{WHERE, none}, same
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// reasoning as SqlScan's loop split.
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switch {
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case dbfArea != nil && whereFn != nil:
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dbfArea.GoTop()
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for !dbfArea.EOF() {
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hbrt.ExecPcodeFast(t, whereFn, nil)
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if t.GetRetValue().AsBool() {
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for i := 0; i < nFields; i++ {
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v, _ := dbfArea.GetValue(fieldPos[i] - 1)
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t.PushValue(v)
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}
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t.PendingParams2(nFields)
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blk.Fn(t)
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}
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dbfArea.Skip(1)
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}
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case dbfArea != nil:
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dbfArea.GoTop()
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for !dbfArea.EOF() {
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for i := 0; i < nFields; i++ {
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v, _ := dbfArea.GetValue(fieldPos[i] - 1)
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t.PushValue(v)
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}
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t.PendingParams2(nFields)
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blk.Fn(t)
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dbfArea.Skip(1)
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}
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case whereFn != nil:
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area.GoTop()
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for !area.EOF() {
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hbrt.ExecPcodeFast(t, whereFn, nil)
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if t.GetRetValue().AsBool() {
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for i := 0; i < nFields; i++ {
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v, _ := area.GetValue(fieldPos[i] - 1)
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t.PushValue(v)
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}
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t.PendingParams2(nFields)
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blk.Fn(t)
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}
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area.Skip(1)
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}
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default:
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area.GoTop()
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for !area.EOF() {
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for i := 0; i < nFields; i++ {
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v, _ := area.GetValue(fieldPos[i] - 1)
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t.PushValue(v)
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}
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t.PendingParams2(nFields)
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blk.Fn(t)
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area.Skip(1)
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}
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}
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t.RetNil()
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}
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