diff --git a/client.go b/client.go
index 535dbb48..050b4d34 100644
--- a/client.go
+++ b/client.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"crypto/tls"
 	"fmt"
-	"io"
 	"net"
 	"strconv"
 	"strings"
@@ -94,6 +93,7 @@ func (c *Client) Close() error {
 		return errors.Wrap(err, "conn")
 	}
 
+	c.buf.Reset() // avoid memory leak.
 	return nil
 }
 
@@ -269,15 +269,13 @@ func (c *Client) flushBuf(ctx context.Context, b *proto.Buffer) error {
 		// Reset deadline.
 		defer func() { _ = c.conn.SetWriteDeadline(time.Time{}) }()
 	}
-	n, err := c.conn.Write(b.Buf)
+	b.Buffers = append(b.Buffers, b.Buf)
+	n, err := b.Buffers.WriteTo(c.conn)
 	if err != nil {
 		return errors.Wrap(err, "write")
 	}
-	if n != len(b.Buf) {
-		return errors.Wrap(io.ErrShortWrite, "wrote less than expected")
-	}
 	if ce := c.lg.Check(zap.DebugLevel, "Flush"); ce != nil {
-		ce.Write(zap.Int("bytes", n))
+		ce.Write(zap.Int("bytes", int(n)))
 	}
 	b.Reset()
 	return nil
diff --git a/proto/block.go b/proto/block.go
index 34548067..b0acfab9 100644
--- a/proto/block.go
+++ b/proto/block.go
@@ -178,7 +178,14 @@ func (b Block) EncodeRawBlock(buf *Buffer, version int, input []InputColumn) err
 		if v, ok := col.Data.(StateEncoder); ok {
 			v.EncodeState(buf)
 		}
-		col.Data.EncodeColumn(buf)
+		if v, ok := col.Data.(*ColStr); ok {
+			// TODO SUPPORT OTHER COLUMN.
+			buf.Buffers = append(buf.Buffers, buf.Buf)
+			buf.Buf = nil
+			buf.Buffers = append(buf.Buffers, v.Buf)
+		} else {
+			col.Data.EncodeColumn(buf)
+		}
 	}
 	return nil
 }
diff --git a/proto/buffer.go b/proto/buffer.go
index e2b1e8f1..370f4f96 100644
--- a/proto/buffer.go
+++ b/proto/buffer.go
@@ -5,11 +5,13 @@ import (
 	"encoding/binary"
 	"io"
 	"math"
+	"net"
 )
 
 // Buffer implements ClickHouse binary protocol encoding.
 type Buffer struct {
 	Buf []byte
+	net.Buffers
 }
 
 // Reader returns new *Reader from *Buffer.
@@ -45,6 +47,7 @@ func (b *Buffer) Encode(e Encoder) {
 // Reset buffer to zero length.
 func (b *Buffer) Reset() {
 	b.Buf = b.Buf[:0]
+	b.Buffers = nil
 }
 
 // Read implements io.Reader.
diff --git a/proto/col_str.go b/proto/col_str.go
index 8f48ad7f..574cb047 100644
--- a/proto/col_str.go
+++ b/proto/col_str.go
@@ -21,6 +21,7 @@ type ColStr struct {
 
 // Append string to column.
 func (c *ColStr) Append(v string) {
+	c.Buf = binary.AppendUvarint(c.Buf, uint64(len(v)))
 	start := len(c.Buf)
 	c.Buf = append(c.Buf, v...)
 	end := len(c.Buf)
@@ -29,6 +30,7 @@ func (c *ColStr) Append(v string) {
 
 // AppendBytes append byte slice as string to column.
 func (c *ColStr) AppendBytes(v []byte) {
+	c.Buf = binary.AppendUvarint(c.Buf, uint64(len(v)))
 	start := len(c.Buf)
 	c.Buf = append(c.Buf, v...)
 	end := len(c.Buf)
diff --git a/query.go b/query.go
index a3dcd17b..762b2c98 100644
--- a/query.go
+++ b/query.go
@@ -301,6 +301,7 @@ func (c *Client) encodeBlock(ctx context.Context, tableName string, input []prot
 	// Note: only blocks are compressed.
 	// See "Compressible" method of server or client code for reference.
 	if c.compression == proto.CompressionEnabled {
+		// TODO SUPPORT COMPRESS
 		data := c.buf.Buf[start:]
 		if err := c.compressor.Compress(c.compressionMethod, data); err != nil {
 			return errors.Wrap(err, "compress")