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charlieviethcharlievieth
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reduce CGO calls when scanning rows
This commit improves the performance of queries by at least 20% by only collecting the information needed to convert sqlite3 values to Go values and by batching CGO calls when scanning rows (the performance improvement scales with the number of columns being scanned). This commit adds a new coltype field to the SQLiteRows struct which stores the declared column type (either data/time or boolean) and the sqlite3 datatype. Previously, this library would fetch the string representation of each column, which is inefficient and rarely needed since the non-standard SQLiteRows.DeclTypes method is rarely called. It also changes the benchmark suite to use an in-memory database since we do not want the file system interfering with benchmark results. goos: darwin goarch: arm64 pkg: github.com/mattn/go-sqlite3 cpu: Apple M1 Max │ base.10.txt │ new.10.txt │ │ sec/op │ sec/op vs base │ CustomFunctions-10 3.318µ ± 2% 3.115µ ± 2% -6.10% (p=0.000 n=10) Suite/BenchmarkExec-10 1.236µ ± 1% 1.240µ ± 2% ~ (p=0.617 n=10) Suite/BenchmarkQuery-10 4.004µ ± 7% 3.363µ ± 2% -16.02% (p=0.000 n=10) Suite/BenchmarkParams-10 4.241µ ± 1% 3.758µ ± 2% -11.40% (p=0.000 n=10) Suite/BenchmarkStmt-10 2.830µ ± 0% 2.378µ ± 2% -15.97% (p=0.000 n=10) Suite/BenchmarkRows-10 126.3µ ± 1% 101.3µ ± 1% -19.79% (p=0.000 n=10) Suite/BenchmarkStmtRows-10 124.9µ ± 1% 100.5µ ± 2% -19.56% (p=0.000 n=10) Suite/BenchmarkStmt10Cols-10 10.130µ ± 0% 7.042µ ± 1% -30.48% (p=0.000 n=10) geomean 8.655µ 7.328µ -15.33% │ base.10.txt │ new.10.txt │ │ B/op │ B/op vs base │ CustomFunctions-10 568.0 ± 0% 576.0 ± 0% +1.41% (p=0.000 n=10) Suite/BenchmarkExec-10 128.0 ± 0% 128.0 ± 0% ~ (p=1.000 n=10) ¹ Suite/BenchmarkQuery-10 688.0 ± 0% 648.0 ± 0% -5.81% (p=0.000 n=10) Suite/BenchmarkParams-10 1.078Ki ± 0% 1.031Ki ± 0% -4.35% (p=0.000 n=10) Suite/BenchmarkStmt-10 920.0 ± 0% 872.0 ± 0% -5.22% (p=0.000 n=10) Suite/BenchmarkRows-10 9.305Ki ± 0% 9.188Ki ± 0% -1.26% (p=0.000 n=10) Suite/BenchmarkStmtRows-10 9.289Ki ± 0% 9.164Ki ± 0% -1.35% (p=0.000 n=10) Suite/BenchmarkStmt10Cols-10 992.0 ± 0% 696.0 ± 0% -29.84% (p=0.000 n=10) geomean 1.181Ki 1.106Ki -6.35% ¹ all samples are equal │ base.10.txt │ new.10.txt │ │ allocs/op │ allocs/op vs base │ CustomFunctions-10 18.00 ± 0% 18.00 ± 0% ~ (p=1.000 n=10) ¹ Suite/BenchmarkExec-10 7.000 ± 0% 7.000 ± 0% ~ (p=1.000 n=10) ¹ Suite/BenchmarkQuery-10 23.00 ± 0% 23.00 ± 0% ~ (p=1.000 n=10) ¹ Suite/BenchmarkParams-10 27.00 ± 0% 27.00 ± 0% ~ (p=1.000 n=10) ¹ Suite/BenchmarkStmt-10 25.00 ± 0% 25.00 ± 0% ~ (p=1.000 n=10) ¹ Suite/BenchmarkRows-10 525.0 ± 0% 519.0 ± 0% -1.14% (p=0.000 n=10) Suite/BenchmarkStmtRows-10 524.0 ± 0% 518.0 ± 0% -1.15% (p=0.000 n=10) Suite/BenchmarkStmt10Cols-10 39.00 ± 0% 19.00 ± 0% -51.28% (p=0.000 n=10) geomean 46.26 42.17 -8.86% ¹ all samples are equal
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2 files changed

+151
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‎sqlite3.go

Lines changed: 93 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -201,6 +201,53 @@ static int sqlite3_system_errno(sqlite3 *db) {
201201
return 0;
202202
}
203203
#endif
204+
205+
#define GO_SQLITE3_DECL_DATE (1 << 7)
206+
#define GO_SQLITE3_DECL_BOOL (1 << 6)
207+
#define GO_SQLITE3_DECL_MASK (GO_SQLITE3_DECL_DATE | GO_SQLITE3_DECL_BOOL)
208+
#define GO_SQLITE3_TYPE_MASK (GO_SQLITE3_DECL_BOOL - 1)
209+
210+
// _sqlite3_column_decltypes stores the declared column type in the typs array.
211+
// This function must always be called before _sqlite3_column_types since it
212+
// overwrites the datatype.
213+
static void _sqlite3_column_decltypes(sqlite3_stmt* stmt, uint8_t *typs, int ntyps) {
214+
for (int i = 0; i < ntyps; i++) {
215+
const char *typ = sqlite3_column_decltype(stmt, i);
216+
if (typ == NULL) {
217+
typs[i] = 0;
218+
continue;
219+
}
220+
switch (typ[0]) {
221+
case 'b':
222+
case 'B':
223+
if (!sqlite3_stricmp(typ, "boolean")) {
224+
typs[i] = GO_SQLITE3_DECL_BOOL;
225+
}
226+
break;
227+
case 'd':
228+
case 'D':
229+
if (!sqlite3_stricmp(typ, "date") || !sqlite3_stricmp(typ, "datetime")) {
230+
typs[i] = GO_SQLITE3_DECL_DATE;
231+
}
232+
break;
233+
case 't':
234+
case 'T':
235+
if (!sqlite3_stricmp(typ, "timestamp")) {
236+
typs[i] = GO_SQLITE3_DECL_DATE;
237+
}
238+
break;
239+
default:
240+
typs[i] = 0;
241+
}
242+
}
243+
}
244+
245+
static void _sqlite3_column_types(sqlite3_stmt *stmt, uint8_t *typs, int ntyps) {
246+
for (int i = 0; i < ntyps; i++) {
247+
typs[i] &= GO_SQLITE3_DECL_MASK; // clear lower bits
248+
typs[i] |= (uint8_t)sqlite3_column_type(stmt, i);
249+
}
250+
}
204251
*/
205252
import "C"
206253
import (
@@ -239,12 +286,6 @@ var SQLiteTimestampFormats = []string{
239286
"2006-01-02",
240287
}
241288

242-
const (
243-
columnDate string = "date"
244-
columnDatetime string = "datetime"
245-
columnTimestamp string = "timestamp"
246-
)
247-
248289
// This variable can be replaced with -ldflags like below:
249290
// go build -ldflags="-X 'github.com/mattn/go-sqlite3.driverName=my-sqlite3'"
250291
var driverName = "sqlite3"
@@ -390,12 +431,31 @@ type SQLiteResult struct {
390431
changes int64
391432
}
392433

434+
// A columnType is a compact representation of sqlite3 columns datatype and
435+
// declared type. The first two bits store the declared type and the remaining
436+
// six bits store the sqlite3 datatype.
437+
type columnType uint8
438+
439+
// DeclType returns the declared type, which is currently GO_SQLITE3_DECL_DATE
440+
// or GO_SQLITE3_DECL_BOOL, since those are the only two types that we need for
441+
// converting values.
442+
func (c columnType) DeclType() int {
443+
return int(c) & C.GO_SQLITE3_DECL_MASK
444+
}
445+
446+
// DataType returns the sqlite3 datatype code of the column, which is the
447+
// result of sqlite3_column_type.
448+
func (c columnType) DataType() int {
449+
return int(c) & C.GO_SQLITE3_TYPE_MASK
450+
}
451+
393452
// SQLiteRows implements driver.Rows.
394453
type SQLiteRows struct {
395454
s *SQLiteStmt
396455
nc int
397456
cols []string
398457
decltype []string
458+
coltype []columnType
399459
cls bool
400460
closed bool
401461
ctx context.Context // no better alternative to pass context into Next() method
@@ -2149,7 +2209,10 @@ func (rc *SQLiteRows) Columns() []string {
21492209
return rc.cols
21502210
}
21512211

2152-
func (rc *SQLiteRows) declTypes() []string {
2212+
// DeclTypes return column types.
2213+
func (rc *SQLiteRows) DeclTypes() []string {
2214+
rc.s.mu.Lock()
2215+
defer rc.s.mu.Unlock()
21532216
if rc.s.s != nil && rc.decltype == nil {
21542217
rc.decltype = make([]string, rc.nc)
21552218
for i := 0; i < rc.nc; i++ {
@@ -2159,13 +2222,6 @@ func (rc *SQLiteRows) declTypes() []string {
21592222
return rc.decltype
21602223
}
21612224

2162-
// DeclTypes return column types.
2163-
func (rc *SQLiteRows) DeclTypes() []string {
2164-
rc.s.mu.Lock()
2165-
defer rc.s.mu.Unlock()
2166-
return rc.declTypes()
2167-
}
2168-
21692225
// Next move cursor to next. Attempts to honor context timeout from QueryContext call.
21702226
func (rc *SQLiteRows) Next(dest []driver.Value) error {
21712227
rc.s.mu.Lock()
@@ -2211,6 +2267,13 @@ func (rc *SQLiteRows) Next(dest []driver.Value) error {
22112267
return err
22122268
}
22132269

2270+
func (rc *SQLiteRows) colTypePtr() *C.uint8_t {
2271+
if len(rc.coltype) == 0 {
2272+
return nil
2273+
}
2274+
return (*C.uint8_t)(unsafe.Pointer(&rc.coltype[0]))
2275+
}
2276+
22142277
// nextSyncLocked moves cursor to next; must be called with locked mutex.
22152278
func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
22162279
rv := C._sqlite3_step_internal(rc.s.s)
@@ -2224,15 +2287,24 @@ func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
22242287
}
22252288
return nil
22262289
}
2290+
if len(dest) == 0 {
2291+
return nil
2292+
}
22272293

2228-
rc.declTypes()
2294+
if rc.coltype == nil {
2295+
rc.coltype = make([]columnType, rc.nc)
2296+
C._sqlite3_column_decltypes(rc.s.s, rc.colTypePtr(), C.int(rc.nc))
2297+
}
2298+
// Must call this each time since sqlite3 is loosely
2299+
// typed and the column types can vary between rows.
2300+
C._sqlite3_column_types(rc.s.s, rc.colTypePtr(), C.int(rc.nc))
22292301

22302302
for i := range dest {
2231-
switch C.sqlite3_column_type(rc.s.s, C.int(i)) {
2303+
switch rc.coltype[i].DataType() {
22322304
case C.SQLITE_INTEGER:
22332305
val := int64(C.sqlite3_column_int64(rc.s.s, C.int(i)))
2234-
switch rc.decltype[i] {
2235-
case columnTimestamp, columnDatetime, columnDate:
2306+
switch rc.coltype[i].DeclType() {
2307+
case C.GO_SQLITE3_DECL_DATE:
22362308
var t time.Time
22372309
// Assume a millisecond unix timestamp if it's 13 digits -- too
22382310
// large to be a reasonable timestamp in seconds.
@@ -2247,7 +2319,7 @@ func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
22472319
t = t.In(rc.s.c.loc)
22482320
}
22492321
dest[i] = t
2250-
case "boolean":
2322+
case C.GO_SQLITE3_DECL_BOOL:
22512323
dest[i] = val > 0
22522324
default:
22532325
dest[i] = val
@@ -2271,8 +2343,7 @@ func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
22712343
n := int(C.sqlite3_column_bytes(rc.s.s, C.int(i)))
22722344
s := C.GoStringN((*C.char)(unsafe.Pointer(C.sqlite3_column_text(rc.s.s, C.int(i)))), C.int(n))
22732345

2274-
switch rc.decltype[i] {
2275-
case columnTimestamp, columnDatetime, columnDate:
2346+
if rc.coltype[i].DeclType() == C.GO_SQLITE3_DECL_DATE {
22762347
var t time.Time
22772348
s = strings.TrimSuffix(s, "Z")
22782349
for _, format := range SQLiteTimestampFormats {
@@ -2289,7 +2360,7 @@ func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
22892360
t = t.In(rc.s.c.loc)
22902361
}
22912362
dest[i] = t
2292-
default:
2363+
} else {
22932364
dest[i] = s
22942365
}
22952366
}

‎sqlite3_test.go

Lines changed: 58 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2120,6 +2120,7 @@ var benchmarks = []testing.InternalBenchmark{
21202120
{Name: "BenchmarkStmt", F: benchmarkStmt},
21212121
{Name: "BenchmarkRows", F: benchmarkRows},
21222122
{Name: "BenchmarkStmtRows", F: benchmarkStmtRows},
2123+
{Name: "BenchmarkStmt10Cols", F: benchmarkStmt10Cols},
21232124
}
21242125

21252126
func (db *TestDB) mustExec(sql string, args ...any) sql.Result {
@@ -2636,3 +2637,60 @@ func benchmarkStmtRows(b *testing.B) {
26362637
}
26372638
}
26382639
}
2640+
2641+
func benchmarkStmt10Cols(b *testing.B) {
2642+
db.once.Do(makeBench)
2643+
2644+
const createTableStmt = `
2645+
DROP TABLE IF EXISTS bench_cols;
2646+
VACUUM;
2647+
CREATE TABLE bench_cols (
2648+
r0 INTEGER NOT NULL,
2649+
r1 INTEGER NOT NULL,
2650+
r2 INTEGER NOT NULL,
2651+
r3 INTEGER NOT NULL,
2652+
r4 INTEGER NOT NULL,
2653+
r5 INTEGER NOT NULL,
2654+
r6 INTEGER NOT NULL,
2655+
r7 INTEGER NOT NULL,
2656+
r8 INTEGER NOT NULL,
2657+
r9 INTEGER NOT NULL
2658+
);`
2659+
if _, err := db.Exec(createTableStmt); err != nil {
2660+
b.Fatal(err)
2661+
}
2662+
for i := int64(0); i < 4; i++ {
2663+
_, err := db.Exec("INSERT INTO bench_cols VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?);",
2664+
i, i, i, i, i, i, i, i, i, i)
2665+
if err != nil {
2666+
b.Fatal(err)
2667+
}
2668+
}
2669+
2670+
stmt, err := db.Prepare("SELECT * FROM bench_cols;")
2671+
if err != nil {
2672+
b.Fatal(err)
2673+
}
2674+
defer stmt.Close()
2675+
2676+
b.ResetTimer()
2677+
var (
2678+
v0, v1, v2, v3, v4 int64
2679+
v5, v6, v7, v8, v9 int64
2680+
)
2681+
for i := 0; i < b.N; i++ {
2682+
rows, err := stmt.Query()
2683+
if err != nil {
2684+
b.Fatal(err)
2685+
}
2686+
for rows.Next() {
2687+
err := rows.Scan(&v0, &v1, &v2, &v3, &v4, &v5, &v6, &v7, &v8, &v9)
2688+
if err != nil {
2689+
b.Fatal(err)
2690+
}
2691+
}
2692+
if err := rows.Err(); err != nil {
2693+
b.Fatal(err)
2694+
}
2695+
}
2696+
}

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