Support EXECUTE IMMEDIATE

Use EXECUTE IMMEDIATE sent in the HTTP request body, instead of putting
the query text in HTTP headers. This should allow sending large query
text. It can be enabled by setting the `explicitPrepare` option to
true in the connection string.

trino/etc/config.properties

@@ -12,3 +12,5 @@ http-server.https.port=8443
 http-server.authentication.allow-insecure-over-http=true
 http-server.https.keystore.path=/etc/trino/secrets/certificate_with_key.pem
 internal-communication.shared-secret=gotrino
+
+query.max-length=2000000

trino/etc/jvm.config

@@ -1,4 +1,4 @@
--Xmx1G
+-Xmx4G
 -XX:+UseG1GC
 -XX:G1HeapRegionSize=32M
 -XX:+UseGCOverheadLimit

trino/integration_test.go

@@ -1112,3 +1112,25 @@ func TestIntegrationDayToHourIntervalMilliPrecision(t *testing.T) {
 		})
 	}
 }
+
+func TestIntegrationLargeQuery(t *testing.T) {
+	dsn := *integrationServerFlag
+	dsn += "?explicitPrepare=false"
+	db := integrationOpen(t, dsn)
+	defer db.Close()
+	rows, err := db.Query("SELECT ?"+strings.Repeat(", 'b', 'c', 'd', 'e', 'f'", 40000), 42)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer rows.Close()
+	count := 0
+	for rows.Next() {
+		count++
+	}
+	if rows.Err() != nil {
+		t.Fatal(err)
+	}
+	if count != 1 {
+		t.Fatal("not enough rows returned:", count)
+	}
+}

trino/trino.go

@@ -141,6 +141,7 @@ const (
 	sslCertPathConfig               = "SSLCertPath"
 	sslCertConfig                   = "SSLCert"
 	accessTokenConfig               = "accessToken"
+	explicitPrepareConfig           = "explicitPrepare"
 )
 
 var (
@@ -282,6 +283,7 @@ type Conn struct {
 	kerberosRemoteServiceName string
 	progressUpdater           ProgressUpdater
 	progressUpdaterPeriod     queryProgressCallbackPeriod
+	useExplicitPrepare        bool
 }
 
 var (
@@ -298,6 +300,10 @@ func newConn(dsn string) (*Conn, error) {
 	query := serverURL.Query()
 
 	kerberosEnabled, _ := strconv.ParseBool(query.Get(kerberosEnabledConfig))
+	useExplicitPrepare := true
+	if query.Get(explicitPrepareConfig) != "" {
+		useExplicitPrepare, _ = strconv.ParseBool(query.Get(explicitPrepareConfig))
+	}
 
 	var kerberosClient *client.Client
 
@@ -356,6 +362,7 @@ func newConn(dsn string) (*Conn, error) {
 		kerberosClient:            kerberosClient,
 		kerberosEnabled:           kerberosEnabled,
 		kerberosRemoteServiceName: query.Get(kerberosRemoteServiceNameConfig),
+		useExplicitPrepare:        useExplicitPrepare,
 	}
 
 	var user string
@@ -867,7 +874,7 @@ func (st *driverStmt) exec(ctx context.Context, args []driver.NamedValue) (*stmt
 
 				hs.Add(arg.Name, headerValue)
 			} else {
-				if hs.Get(preparedStatementHeader) == "" {
+				if st.conn.useExplicitPrepare && hs.Get(preparedStatementHeader) == "" {
 					for _, v := range st.conn.httpHeaders.Values(preparedStatementHeader) {
 						hs.Add(preparedStatementHeader, v)
 					}
@@ -880,7 +887,11 @@ func (st *driverStmt) exec(ctx context.Context, args []driver.NamedValue) (*stmt
 			return nil, ErrInvalidProgressCallbackHeader
 		}
 		if len(ss) > 0 {
-			query = "EXECUTE " + preparedStatementName + " USING " + strings.Join(ss, ", ")
+			if st.conn.useExplicitPrepare {
+				query = "EXECUTE " + preparedStatementName + " USING " + strings.Join(ss, ", ")
+			} else {
+				query = "EXECUTE IMMEDIATE " + formatStringLiteral(st.query) + " USING " + strings.Join(ss, ", ")
+			}
 		}
 	}
 
@@ -1028,6 +1039,10 @@ func (st *driverStmt) exec(ctx context.Context, args []driver.NamedValue) (*stmt
 	return &sr, handleResponseError(resp.StatusCode, sr.Error)
 }
 
+func formatStringLiteral(query string) string {
+	return "'" + strings.ReplaceAll(query, "'", "''") + "'"
+}
+
 type driverRows struct {
 	ctx     context.Context
 	stmt    *driverStmt