From 66e0f1a529239252c4f0f43d9086895013a18c53 Mon Sep 17 00:00:00 2001
From: Reynold PJ <reynold@abacus.ai>
Date: Fri, 15 May 2026 15:07:48 +0000
Subject: [PATCH] add generic _pragma URI parameter support

Implements the _pragma DSN parameter (repeatable, executed in declaration
order on every connection) to fix connection-pool PRAGMA persistence.
Matches the interface already supported by modernc and ncruces drivers.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 sqlite3.go      | 12 ++++++++
 sqlite3_test.go | 81 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+)

diff --git a/sqlite3.go b/sqlite3.go
index b9deb72a..5c990e42 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -1206,6 +1206,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	writableSchema := -1
 	vfsName := ""
 	var cacheSize *int64
+	var pragmas []string
 	stmtCacheSize := 0
 
 	pos := strings.IndexRune(dsn, '?')
@@ -1295,6 +1296,9 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 			}
 		}
 
+		// _pragma (generic, repeatable — executed in order on every connection)
+		pragmas = params["_pragma"]
+
 		// Busy Timeout (_busy_timeout)
 		//
 		// https://www.sqlite.org/pragma.html#pragma_busy_timeout
@@ -1880,6 +1884,14 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 		}
 	}
 
+	// Generic _pragma parameters — run last so they override specific defaults
+	for _, p := range pragmas {
+		if err := exec(fmt.Sprintf("PRAGMA %s;", p)); err != nil {
+			C.sqlite3_close_v2(db)
+			return nil, err
+		}
+	}
+
 	if len(d.Extensions) > 0 {
 		if err := conn.loadExtensions(d.Extensions); err != nil {
 			conn.Close()
diff --git a/sqlite3_test.go b/sqlite3_test.go
index ac81458c..0ace51d5 100644
--- a/sqlite3_test.go
+++ b/sqlite3_test.go
@@ -2131,6 +2131,87 @@ func BenchmarkCustomFunctions(b *testing.B) {
 	}
 }
 
+func TestGenericPragma(t *testing.T) {
+	// Single _pragma applied correctly
+	t.Run("single", func(t *testing.T) {
+		tempFilename := TempFilename(t)
+		defer os.Remove(tempFilename)
+		db, err := sql.Open("sqlite3", tempFilename+"?_pragma=synchronous(NORMAL)")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer db.Close()
+
+		var mode int
+		if err := db.QueryRow("PRAGMA synchronous").Scan(&mode); err != nil {
+			t.Fatal(err)
+		}
+		if mode != 1 { // 1 = NORMAL
+			t.Errorf("expected synchronous=1 (NORMAL), got %d", mode)
+		}
+	})
+
+	// Multiple _pragma values applied in order
+	t.Run("multiple", func(t *testing.T) {
+		tempFilename := TempFilename(t)
+		defer os.Remove(tempFilename)
+		db, err := sql.Open("sqlite3", tempFilename+"?_pragma=synchronous(NORMAL)&_pragma=busy_timeout(1234)")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer db.Close()
+
+		var sync, timeout int
+		if err := db.QueryRow("PRAGMA synchronous").Scan(&sync); err != nil {
+			t.Fatal(err)
+		}
+		if err := db.QueryRow("PRAGMA busy_timeout").Scan(&timeout); err != nil {
+			t.Fatal(err)
+		}
+		if sync != 1 {
+			t.Errorf("expected synchronous=1 (NORMAL), got %d", sync)
+		}
+		if timeout != 1234 {
+			t.Errorf("expected busy_timeout=1234, got %d", timeout)
+		}
+	})
+
+	// PRAGMAs are re-applied on every connection the pool opens
+	t.Run("pool_reapply", func(t *testing.T) {
+		tempFilename := TempFilename(t)
+		defer os.Remove(tempFilename)
+		db, err := sql.Open("sqlite3", tempFilename+"?_pragma=synchronous(NORMAL)")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer db.Close()
+		// Force the pool to open multiple distinct connections
+		db.SetMaxOpenConns(4)
+
+		const workers = 4
+		errc := make(chan error, workers)
+		for i := 0; i < workers; i++ {
+			go func() {
+				var mode int
+				if err := db.QueryRow("PRAGMA synchronous").Scan(&mode); err != nil {
+					errc <- err
+					return
+				}
+				if mode != 1 {
+					errc <- fmt.Errorf("connection got synchronous=%d, want 1 (NORMAL)", mode)
+					return
+				}
+				errc <- nil
+			}()
+		}
+		for i := 0; i < workers; i++ {
+			if err := <-errc; err != nil {
+				t.Error(err)
+			}
+		}
+	})
+}
+
 func TestSuite(t *testing.T) {
 	initializeTestDB(t)
 	defer freeTestDB()