Fix Execute SQL larger than sharedBufferSize

connection.go

@@ -76,7 +76,7 @@ func Connect(parameters ConnectionParameters) (c *Connection, err error) {
 		}
 	}
 
-	c.buf = bytes.NewBuffer(make([]byte, sharedBufferSize))
+	c.buf = bytes.NewBuffer(make([]byte, 0, sharedBufferSize))
 	c.runtimeParams = make(map[string]string)
 	c.preparedStatements = make(map[string]*PreparedStatement)
 
@@ -402,7 +402,6 @@ func (c *Connection) Execute(sql string, arguments ...interface{}) (commandTag s
 		var t byte
 		var r *MessageReader
 		if t, r, err = c.rxMsg(); err == nil {
-			// fmt.Printf("Execute received: %c\n", t)
 			switch t {
 			case readyForQuery:
 				return
@@ -611,7 +610,7 @@ func (c *Connection) txPasswordMessage(password string) (err error) {
 func (c *Connection) getBuf() *bytes.Buffer {
 	c.buf.Reset()
 	if cap(c.buf.Bytes()) > sharedBufferSize {
-		c.buf = bytes.NewBuffer(make([]byte, sharedBufferSize))
+		c.buf = bytes.NewBuffer(make([]byte, 0, sharedBufferSize))
 	}
 	return c.buf
 }

connection_test.go

@@ -2,6 +2,7 @@ package pgx
 
 import (
 	"bytes"
+	"strings"
 	"testing"
 )
 
@@ -170,6 +171,15 @@ func TestExecute(t *testing.T) {
 		t.Error("Unexpected results from Execute")
 	}
 
+	// Can execute longer SQL strings than sharedBufferSize
+	results, err = conn.Execute(strings.Repeat("select 42; ", 1000))
+	if err != nil {
+		t.Fatal("Execute failed: " + err.Error())
+	}
+	if results != "SELECT 1" {
+		t.Errorf("Unexpected results from Execute: %v", results)
+	}
+
 }
 
 func TestSelectFunc(t *testing.T) {