Based on Andres review I have implemented the following changes in libpq_compression:

1. Make it possible to specify list of compression algorithms in connection string.
2. Make it possible to specify compression level.
3. Use "_pq_.compression" instead of "compression"  in startup package.
4. Use full names instead of one-character encoding for compression algorithm names.

So now it is possible to open connection in this way:

    psql "dbname=postgres compression=zstd:5,zlib"


New version of the patch is attached.

--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

diff --git a/configure b/configure
index ace4ed5..deba608 100755
--- a/configure
+++ b/configure
@@ -700,6 +700,7 @@ LD
 LDFLAGS_SL
 LDFLAGS_EX
 with_zlib
+with_zstd
 with_system_tzdata
 with_libxslt
 XML2_LIBS
@@ -867,6 +868,7 @@ with_libxml
 with_libxslt
 with_system_tzdata
 with_zlib
+with_zstd
 with_gnu_ld
 enable_largefile
 '
@@ -8571,6 +8573,85 @@ fi
 
 
 
+#
+# ZStd
+#
+
+
+
+# Check whether --with-zstd was given.
+if test "${with_zstd+set}" = set; then :
+  withval=$with_zstd;
+  case $withval in
+    yes)
+      ;;
+    no)
+      :
+      ;;
+    *)
+      as_fn_error $? "no argument expected for --with-zstd option" "$LINENO" 5
+      ;;
+  esac
+
+else
+  with_zstd=no
+
+fi
+
+
+
+
+if test "$with_zstd" = yes ; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ZSTD_compress in -lzstd" >&5
+$as_echo_n "checking for ZSTD_compress in -lzstd... " >&6; }
+if ${ac_cv_lib_zstd_ZSTD_compress+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lzstd  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char ZSTD_compress ();
+int
+main ()
+{
+return ZSTD_compress ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_zstd_ZSTD_compress=yes
+else
+  ac_cv_lib_zstd_ZSTD_compress=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_zstd_ZSTD_compress" >&5
+$as_echo "$ac_cv_lib_zstd_ZSTD_compress" >&6; }
+if test "x$ac_cv_lib_zstd_ZSTD_compress" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBZSTD 1
+_ACEOF
+
+  LIBS="-lzstd $LIBS"
+
+else
+  as_fn_error $? "library 'zstd' is required for ZSTD support" "$LINENO" 5
+fi
+
+fi
+
+
 
 #
 # Zlib
diff --git a/configure.ac b/configure.ac
index 5b91c83..93a5285 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1000,6 +1000,13 @@ PGAC_ARG_BOOL(with, zlib, yes,
 AC_SUBST(with_zlib)
 
 #
+# Zstd
+#
+PGAC_ARG_BOOL(with, zstd, no,
+              [use zstd])
+AC_SUBST(with_zstd)
+
+#
 # Assignments
 #
 
@@ -1186,6 +1193,14 @@ failure.  It is possible the compiler isn't looking in the proper directory.
 Use --without-zlib to disable zlib support.])])
 fi
 
+if test "$with_zstd" = yes; then
+  AC_CHECK_LIB(zstd, ZSTD_decompressStream, [],
+               [AC_MSG_ERROR([zstd library not found
+If you have zstd already installed, see config.log for details on the
+failure.  It is possible the compiler isn't looking in the proper directory.
+Use --without-zstd to disable zstd support.])])
+fi
+
 if test "$enable_spinlocks" = yes; then
   AC_DEFINE(HAVE_SPINLOCKS, 1, [Define to 1 if you have spinlocks.])
 else
@@ -1400,6 +1415,13 @@ failure.  It is possible the compiler isn't looking in the proper directory.
 Use --without-zlib to disable zlib support.])])
 fi
 
+if test "$with_zstd" = yes; then
+  AC_CHECK_HEADER(zstd.h, [], [AC_MSG_ERROR([zstd header not found
+If you have zstd already installed, see config.log for details on the
+failure.  It is possible the compiler isn't looking in the proper directory.
+Use --without-zstd to disable zstd support.])])
+fi
+
 if test "$with_gssapi" = yes ; then
   AC_CHECK_HEADERS(gssapi/gssapi.h, [],
 	[AC_CHECK_HEADERS(gssapi.h, [], [AC_MSG_ERROR([gssapi.h header file is required for GSSAPI])])])
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 9ce32fb..140724d 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -1225,6 +1225,22 @@ postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
       </listitem>
      </varlistentry>
 
+     <varlistentry id="libpq-connect-compression" xreflabel="compression">
+      <term><literal>compression</literal></term>
+      <listitem>
+      <para>
+        Request compression of libpq traffic. Client sends to the server list of compression algorithms, supported by client library.
+        If server supports one of this algorithms, then it acknowledges use of this algorithm and then all libpq messages send both from client to server and
+        visa versa will be compressed. If server is not supporting any of the suggested algorithms, then it replies with 'n' (no compression)
+        message and it is up to the client whether to continue work without compression or report error.
+        Supported compression algorithms are chosen at configure time. Right now two libraries are supported: zlib (default) and zstd (if Postgres was
+        configured with --with-zstd option). In both cases streaming mode is used.
+        By default compression is disabled. Please notice that using compression together with SSL may add extra vulnerabilities:
+        <ulink url="https://en.wikipedia.org/wiki/CRIME";>CRIME</ulink>
+      </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="libpq-connect-client-encoding" xreflabel="client_encoding">
       <term><literal>client_encoding</literal></term>
       <listitem>
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 9a95d7b..4f68b8a 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -92,6 +92,15 @@
    such as <command>COPY</command>.
   </para>
 
+  <para>
+    It is possible to compress protocol data to reduce traffic and speed-up client-server interaction.
+    Compression is especially useful for importing/exporting data to/from database using COPY command
+    and for replication (both physical and logical). Also compression can reduce server response time
+    in case of queries returning large amount of data (for example returning JSON, BLOBs, text,...)
+    Right now two libraries are supported: zlib (default) and zstd (if Postgres was
+    configured with --with-zstd option).
+  </para>
+
  <sect2 id="protocol-message-concepts">
   <title>Messaging Overview</title>
 
@@ -263,6 +272,27 @@
      </varlistentry>
 
      <varlistentry>
+      <term>CompressionAck</term>
+      <listitem>
+       <para>
+         Server acknowledges using compression for client-server communication protocol.
+         Compression can be requested by client by including "compression" option in connection string.
+         It can be just boolean values enabling or disabling compression
+         ("true"/"false", "on"/"off", "yes"/"no", "1"/"0"), "auto" or explicit list of compression algorithms
+         separated by comma with optional specification of compression level: "zlib,zstd:5".
+         If compression algorithm is not explicitly specified the most efficient one supported both by
+         client and server is chosen. Client sends to the server list of compression algorithms,
+         supported by client library.
+         If server supports one of this algorithms, then it acknowledges use of this algorithm and
+         all subsequent libpq messages send both from client to server and
+         visa versa will be compressed. Server selects most efficient algorithm among list specified by client and returns to the client
+         index of chosen algorithm in this list. If server is not supporting any of the suggested algorithms, then it replies with -1
+         and it is up to the client whether to continue work without compression or report error.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term>AuthenticationOk</term>
       <listitem>
        <para>
@@ -3396,6 +3426,57 @@ following:
 </listitem>
 </varlistentry>
 
+<varlistentry>
+<term>
+CompressionAck (B)
+</term>
+<listitem>
+<para>
+
+<variablelist>
+<varlistentry>
+<term>
+        Byte1('z')
+</term>
+<listitem>
+<para>
+  Acknowledge use of compression for protocol data. Client sends to the server list of compression algorithms, supported by client library.
+  If server supports one of this algorithms, then it acknowledges use of this algorithm and all subsequent libpq messages send both from client to server and
+  visa versa will be compressed. Server selects most efficient algorithm among list specified by client and returns to the client
+  index of chosen algorithm in this list. If server is not supporting any of the suggested algorithms, then it replies with -1
+  and it is up to the client whether to continue work without compression or report error.
+  After receiving this message with algorithm index other than -1, both server and client are switched to compression mode
+  and exchange compressed messages.
+</para>
+</listitem>
+</varlistentry>
+<varlistentry>
+<term>
+        Int32
+</term>
+<listitem>
+<para>
+                Length of message contents in bytes, including self.
+</para>
+</listitem>
+</varlistentry>
+<varlistentry>
+<term>
+        Byte1
+</term>
+<listitem>
+<para>
+        Index of algorithm in the list of supported algotihms specified by client or -1 if none of them is supported.
+</para>
+</listitem>
+</varlistentry>
+</variablelist>
+
+</para>
+</listitem>
+</varlistentry>
+
+
 
 <varlistentry>
 <term>
@@ -5962,6 +6043,19 @@ StartupMessage (F)
 </para>
 </listitem>
 </varlistentry>
+<varlistentry>
+<term>
+                <literal>_pq_.compression</literal>
+</term>
+<listitem>
+<para>
+                        Request compression of libpq traffic. Value is list of compression algorithms supported by client:
+                        <literal>'f'</literal> - Facebook zstd, <literal>'z'</literal> - zlib, <literal>'n'</literal> - no compression.
+                        By default compression is disabled. Please notice that using compression together with SSL may add extra vulnerabilities:
+                        <ulink url="https://en.wikipedia.org/wiki/CRIME";>CRIME</ulink>.
+</para>
+</listitem>
+</varlistentry>
 </variablelist>
 
                 In addition to the above, other parameters may be listed.
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index 7ca1e9a..9e11599 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -196,6 +196,7 @@ with_llvm	= @with_llvm@
 with_system_tzdata = @with_system_tzdata@
 with_uuid	= @with_uuid@
 with_zlib	= @with_zlib@
+with_zstd   = @with_zstd@
 enable_rpath	= @enable_rpath@
 enable_nls	= @enable_nls@
 enable_debug	= @enable_debug@
diff --git a/src/backend/Makefile b/src/backend/Makefile
index 9706a95..f32a780 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -54,6 +54,14 @@ ifeq ($(with_systemd),yes)
 LIBS += -lsystemd
 endif
 
+ifeq ($(with_zstd),yes)
+LIBS += -lzstd
+endif
+
+ifeq ($(with_zlib),yes)
+LIBS += -lz
+endif
+
 ##########################################################################
 
 all: submake-libpgport submake-catalog-headers submake-utils-headers postgres $(POSTGRES_IMP)
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c6dd084..6b69d77 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -770,6 +770,15 @@ CREATE VIEW pg_stat_activity AS
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
 
+CREATE VIEW pg_stat_network_traffic AS
+    SELECT
+	    S.pid,
+        S.rx_raw_bytes,
+        S.tx_raw_bytes,
+        S.rx_compressed_bytes,
+        S.tx_compressed_bytes
+    FROM pg_stat_get_activity(NULL) AS S;
+
 CREATE VIEW pg_stat_replication AS
     SELECT
             S.pid,
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index ac986c0..4fb36ce 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -71,6 +71,7 @@
 #include <signal.h>
 #include <fcntl.h>
 #include <grp.h>
+#include <pgstat.h>
 #include <unistd.h>
 #include <sys/file.h>
 #include <sys/socket.h>
@@ -93,6 +94,8 @@
 #include "storage/ipc.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
+#include "utils/builtins.h"
+#include "common/zpq_stream.h"
 
 /*
  * Cope with the various platform-specific ways to spell TCP keepalive socket
@@ -141,6 +144,9 @@ static char PqRecvBuffer[PQ_RECV_BUFFER_SIZE];
 static int	PqRecvPointer;		/* Next index to read a byte from PqRecvBuffer */
 static int	PqRecvLength;		/* End of data available in PqRecvBuffer */
 
+static ZpqStream* PqStream;
+
+
 /*
  * Message status
  */
@@ -183,6 +189,99 @@ const PQcommMethods *PqCommMethods = &PqCommSocketMethods;
 
 WaitEventSet *FeBeWaitSet;
 
+static ssize_t write_compressed(void* arg, void const* data, size_t size)
+{
+	ssize_t rc = secure_write((Port*)arg, (void*)data, size);
+	if (rc > 0)
+		pgstat_report_network_traffic(0, 0, 0, rc);
+	return rc;
+}
+
+static ssize_t read_compressed(void* arg, void* data, size_t size)
+{
+	ssize_t rc = secure_read((Port*)arg, data, size);
+	if (rc > 0)
+		pgstat_report_network_traffic(0, 0, rc, 0);
+	return rc;
+}
+
+
+/* --------------------------------
+ *		pq_configure - configure connection using port settings
+ *
+ * Right now only compression is toggled in the configure.
+ * Function returns 0 in case of success, non-null in case of error
+ * --------------------------------
+ */
+int
+pq_configure(Port* port)
+{
+	char* client_compression_algorithms = port->compression_algorithms;
+
+	/*
+	 * If client request compression, it sends list of supported compression algorithms separated by comma.
+	 */
+	if (client_compression_algorithms)
+	{
+		int compression_level = ZPQ_DEFAULT_COMPRESSION_LEVEL;
+		char compression[6] = {'z',0,0,0,5,0}; /* message length = 5 */
+		int impl = -1;
+		int rc;
+		char** server_compression_algorithms = zpq_get_supported_algorithms();
+		int index = -1;
+
+		for (int i = 0; *client_compression_algorithms; i++)
+		{
+			char* sep = strchr(client_compression_algorithms, ',');
+			char* level;
+			if (sep != NULL)
+				*sep = '\0';
+
+			level = strchr(client_compression_algorithms, ':');
+			if (level != NULL)
+			{
+				*level = '\0'; /* compression level is ignored now */
+				if (sscanf("%d", level+1, &compression_level) != 1)
+					ereport(LOG,
+							(errmsg("Invalid compression level: %s", level+1)));
+			}
+			for (impl = 0; server_compression_algorithms[impl] != NULL; impl++)
+			{
+				if (pg_strcasecmp(client_compression_algorithms, server_compression_algorithms[impl]) == 0)
+				{
+					index = i;
+					goto SendCompressionAck;
+				}
+			}
+
+			if (sep != NULL)
+				client_compression_algorithms = sep+1;
+			else
+				break;
+		}
+	  SendCompressionAck:
+		free(server_compression_algorithms);
+		compression[5] = (char)index;
+		/* Send 'z' message to the client with selected compression algorithm (or -1 if not found) */
+		socket_set_nonblocking(false);
+		while ((rc = secure_write(MyProcPort, compression, sizeof(compression))) < 0
+			   && errno == EINTR);
+		if ((size_t)rc != sizeof(compression))
+			return -1;
+
+		if (index >= 0) /* Use compression */
+		{
+			PqStream = zpq_create(impl, compression_level, write_compressed, read_compressed, MyProcPort, NULL, 0);
+			if (!PqStream)
+			{
+				ereport(LOG,
+						(errmsg("Failed to initialize compressor %s", server_compression_algorithms[impl])));
+				return -1;
+			}
+		}
+	}
+	return 0;
+}
 
 /* --------------------------------
  *		pq_init - initialize libpq at backend startup
@@ -280,6 +379,9 @@ socket_close(int code, Datum arg)
 		free(MyProcPort->gss);
 #endif							/* ENABLE_GSS || ENABLE_SSPI */
 
+		/* Release compression streams */
+		zpq_free(PqStream);
+
 		/*
 		 * Cleanly shut down SSL layer.  Nowhere else does a postmaster child
 		 * call this, so this is safe when interrupting BackendInitialize().
@@ -919,12 +1021,15 @@ socket_set_nonblocking(bool nonblocking)
 /* --------------------------------
  *		pq_recvbuf - load some bytes into the input buffer
  *
- *		returns 0 if OK, EOF if trouble
+ *      nowait parameter toggles non-blocking mode. 
+ *		returns number of read bytes, EOF if trouble
  * --------------------------------
  */
 static int
-pq_recvbuf(void)
+pq_recvbuf(bool nowait)
 {
+	int			   r;
+
 	if (PqRecvPointer > 0)
 	{
 		if (PqRecvLength > PqRecvPointer)
@@ -940,21 +1045,36 @@ pq_recvbuf(void)
 	}
 
 	/* Ensure that we're in blocking mode */
-	socket_set_nonblocking(false);
+	socket_set_nonblocking(nowait);
 
 	/* Can fill buffer from PqRecvLength and upwards */
 	for (;;)
 	{
-		int			r;
-
-		r = secure_read(MyProcPort, PqRecvBuffer + PqRecvLength,
-						PQ_RECV_BUFFER_SIZE - PqRecvLength);
+		/* If streaming compression is enabled then use correspondent compression read function. */
+		r = PqStream
+			? zpq_read(PqStream, PqRecvBuffer + PqRecvLength,
+					   PQ_RECV_BUFFER_SIZE - PqRecvLength)
+			: secure_read(MyProcPort, PqRecvBuffer + PqRecvLength,
+						  PQ_RECV_BUFFER_SIZE - PqRecvLength);
 
 		if (r < 0)
 		{
+			if (r == ZPQ_DECOMPRESS_ERROR)
+			{
+				char const* msg = zpq_error(PqStream);
+				if (msg == NULL)
+					msg = "end of stream";
+				ereport(COMMERROR,
+						(errcode_for_socket_access(),
+						 errmsg("failed to decompress data: %s", msg)));
+				return EOF;
+			}
 			if (errno == EINTR)
 				continue;		/* Ok if interrupted */
 
+			if (nowait && (errno == EAGAIN || errno == EWOULDBLOCK))
+				return 0;
+
 			/*
 			 * Careful: an ereport() that tries to write to the client would
 			 * cause recursion to here, leading to stack overflow and core
@@ -975,7 +1095,8 @@ pq_recvbuf(void)
 		}
 		/* r contains number of bytes read, so just incr length */
 		PqRecvLength += r;
-		return 0;
+		pgstat_report_network_traffic(r, 0, 0, 0);
+		return r;
 	}
 }
 
@@ -990,7 +1111,7 @@ pq_getbyte(void)
 
 	while (PqRecvPointer >= PqRecvLength)
 	{
-		if (pq_recvbuf())		/* If nothing in buffer, then recv some */
+		if (pq_recvbuf(false) == EOF)		/* If nothing in buffer, then recv some */
 			return EOF;			/* Failed to recv data */
 	}
 	return (unsigned char) PqRecvBuffer[PqRecvPointer++];
@@ -1009,7 +1130,7 @@ pq_peekbyte(void)
 
 	while (PqRecvPointer >= PqRecvLength)
 	{
-		if (pq_recvbuf())		/* If nothing in buffer, then recv some */
+		if (pq_recvbuf(false) == EOF)		/* If nothing in buffer, then recv some */
 			return EOF;			/* Failed to recv data */
 	}
 	return (unsigned char) PqRecvBuffer[PqRecvPointer];
@@ -1026,48 +1147,15 @@ pq_peekbyte(void)
 int
 pq_getbyte_if_available(unsigned char *c)
 {
-	int			r;
+	int			r = 0;
 
 	Assert(PqCommReadingMsg);
 
-	if (PqRecvPointer < PqRecvLength)
+	if (PqRecvPointer < PqRecvLength || (r = pq_recvbuf(true)) > 0)
 	{
 		*c = PqRecvBuffer[PqRecvPointer++];
 		return 1;
 	}
-
-	/* Put the socket into non-blocking mode */
-	socket_set_nonblocking(true);
-
-	r = secure_read(MyProcPort, c, 1);
-	if (r < 0)
-	{
-		/*
-		 * Ok if no data available without blocking or interrupted (though
-		 * EINTR really shouldn't happen with a non-blocking socket). Report
-		 * other errors.
-		 */
-		if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
-			r = 0;
-		else
-		{
-			/*
-			 * Careful: an ereport() that tries to write to the client would
-			 * cause recursion to here, leading to stack overflow and core
-			 * dump!  This message must go *only* to the postmaster log.
-			 */
-			ereport(COMMERROR,
-					(errcode_for_socket_access(),
-					 errmsg("could not receive data from client: %m")));
-			r = EOF;
-		}
-	}
-	else if (r == 0)
-	{
-		/* EOF detected */
-		r = EOF;
-	}
-
 	return r;
 }
 
@@ -1088,7 +1176,7 @@ pq_getbytes(char *s, size_t len)
 	{
 		while (PqRecvPointer >= PqRecvLength)
 		{
-			if (pq_recvbuf())	/* If nothing in buffer, then recv some */
+			if (pq_recvbuf(false) == EOF)	/* If nothing in buffer, then recv some */
 				return EOF;		/* Failed to recv data */
 		}
 		amount = PqRecvLength - PqRecvPointer;
@@ -1122,7 +1210,7 @@ pq_discardbytes(size_t len)
 	{
 		while (PqRecvPointer >= PqRecvLength)
 		{
-			if (pq_recvbuf())	/* If nothing in buffer, then recv some */
+			if (pq_recvbuf(false) == EOF)	/* If nothing in buffer, then recv some */
 				return EOF;		/* Failed to recv data */
 		}
 		amount = PqRecvLength - PqRecvPointer;
@@ -1163,7 +1251,7 @@ pq_getstring(StringInfo s)
 	{
 		while (PqRecvPointer >= PqRecvLength)
 		{
-			if (pq_recvbuf())	/* If nothing in buffer, then recv some */
+			if (pq_recvbuf(false) == EOF)	/* If nothing in buffer, then recv some */
 				return EOF;		/* Failed to recv data */
 		}
 
@@ -1413,13 +1501,19 @@ internal_flush(void)
 	char	   *bufptr = PqSendBuffer + PqSendStart;
 	char	   *bufend = PqSendBuffer + PqSendPointer;
 
-	while (bufptr < bufend)
+	while (bufptr < bufend || zpq_buffered_tx(PqStream) != 0)
+    /* has more data to flush or unsent data in internal compression buffer */
 	{
-		int			r;
-
-		r = secure_write(MyProcPort, bufptr, bufend - bufptr);
-
-		if (r <= 0)
+		int		r;
+		size_t  processed = 0;
+		size_t  available = bufend - bufptr;
+		r = PqStream
+			? zpq_write(PqStream, bufptr, available, &processed)
+			: secure_write(MyProcPort, bufptr, available);
+		bufptr += processed;
+		PqSendStart += processed;
+
+		if (r < 0 || (r == 0 && available))
 		{
 			if (errno == EINTR)
 				continue;		/* Ok if we were interrupted */
@@ -1462,12 +1556,12 @@ internal_flush(void)
 			InterruptPending = 1;
 			return EOF;
 		}
+		pgstat_report_network_traffic(0, r, 0, 0);
 
 		last_reported_send_errno = 0;	/* reset after any successful send */
 		bufptr += r;
 		PqSendStart += r;
 	}
-
 	PqSendStart = PqSendPointer = 0;
 	return 0;
 }
@@ -1484,7 +1578,7 @@ socket_flush_if_writable(void)
 	int			res;
 
 	/* Quick exit if nothing to do */
-	if (PqSendPointer == PqSendStart)
+	if ((PqSendPointer == PqSendStart) && (zpq_buffered_tx(PqStream) == 0))
 		return 0;
 
 	/* No-op if reentrant call */
@@ -1507,7 +1601,7 @@ socket_flush_if_writable(void)
 static bool
 socket_is_send_pending(void)
 {
-	return (PqSendStart < PqSendPointer);
+	return (PqSendStart < PqSendPointer || (zpq_buffered_tx(PqStream) != 0));
 }
 
 /* --------------------------------
@@ -1985,3 +2079,15 @@ pq_settcpusertimeout(int timeout, Port *port)
 
 	return STATUS_OK;
 }
+
+PG_FUNCTION_INFO_V1(pg_compression_algorithm);
+
+Datum
+pg_compression_algorithm(PG_FUNCTION_ARGS)
+{
+	char const* algorithm_name = PqStream ? zpq_algorithm_name(PqStream) : NULL;
+	if (algorithm_name)
+		PG_RETURN_TEXT_P(cstring_to_text(algorithm_name));
+	else
+		PG_RETURN_NULL();
+}
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 822f0eb..33aee92 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3112,6 +3112,9 @@ pgstat_bestart(void)
 	lbeentry.st_xact_start_timestamp = 0;
 	lbeentry.st_databaseid = MyDatabaseId;
 
+	lbeentry.st_tx_raw_bytes = lbeentry.st_rx_raw_bytes =
+		lbeentry.st_tx_compressed_bytes = lbeentry.st_rx_compressed_bytes = 0;
+
 	/* We have userid for client-backends, wal-sender and bgworker processes */
 	if (lbeentry.st_backendType == B_BACKEND
 		|| lbeentry.st_backendType == B_WAL_SENDER
@@ -3493,6 +3496,33 @@ pgstat_report_xact_timestamp(TimestampTz tstamp)
 	PGSTAT_END_WRITE_ACTIVITY(beentry);
 }
 
+/*
+ * Report current transaction start timestamp as the specified value.
+ * Zero means there is no active transaction.
+ */
+void
+pgstat_report_network_traffic(uint64 rx_raw_bytes, uint64 tx_raw_bytes, uint64 rx_compressed_bytes, uint64 tx_compressed_bytes)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	if (!pgstat_track_activities || !beentry)
+		return;
+
+	/*
+	 * Update my status entry, following the protocol of bumping
+	 * st_changecount before and after.  We use a volatile pointer here to
+	 * ensure the compiler doesn't try to get cute.
+	 */
+	PGSTAT_BEGIN_WRITE_ACTIVITY(beentry);
+
+	beentry->st_rx_raw_bytes += rx_raw_bytes;
+	beentry->st_tx_raw_bytes += tx_raw_bytes;
+	beentry->st_rx_compressed_bytes += rx_compressed_bytes;
+	beentry->st_tx_compressed_bytes += tx_compressed_bytes;
+
+	PGSTAT_END_WRITE_ACTIVITY(beentry);
+}
+
 /* ----------
  * pgstat_read_current_status() -
  *
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 959e3b8..95a0456 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -2151,6 +2151,8 @@ retry1:
 				port->database_name = pstrdup(valptr);
 			else if (strcmp(nameptr, "user") == 0)
 				port->user_name = pstrdup(valptr);
+			else if (strcmp(nameptr, "_pq_.compression") == 0)
+				port->compression_algorithms = pstrdup(valptr);
 			else if (strcmp(nameptr, "options") == 0)
 				port->cmdline_options = pstrdup(valptr);
 			else if (strcmp(nameptr, "replication") == 0)
@@ -4458,6 +4460,14 @@ BackendInitialize(Port *port)
 	if (status != STATUS_OK)
 		proc_exit(0);
 
+	if (pq_configure(port))
+	{
+		ereport(COMMERROR,
+				(errcode_for_socket_access(),
+				 errmsg("failed to send compression message: %m")));
+		proc_exit(0);
+	}
+
 	/*
 	 * Now that we have the user and database name, we can set the process
 	 * title for ps.  It's good to do this as early as possible in startup.
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 472fa59..eef4ead 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -567,7 +567,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	30
+#define PG_STAT_GET_ACTIVITY_COLS	34
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -913,6 +913,10 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				values[28] = BoolGetDatum(false);	/* GSS Encryption not in
 													 * use */
 			}
+			values[30] = beentry->st_rx_raw_bytes;
+			values[31] = beentry->st_tx_raw_bytes;
+			values[32] = beentry->st_rx_compressed_bytes;
+			values[33] = beentry->st_tx_compressed_bytes;
 		}
 		else
 		{
@@ -941,6 +945,10 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[27] = true;
 			nulls[28] = true;
 			nulls[29] = true;
+			nulls[30] = true;
+			nulls[31] = true;
+			nulls[32] = true;
+			nulls[33] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
@@ -1140,6 +1148,46 @@ pg_stat_get_backend_start(PG_FUNCTION_ARGS)
 	PG_RETURN_TIMESTAMPTZ(result);
 }
 
+Datum
+pg_stat_get_network_traffic(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_NETWORK_TRAFFIC_COLS	4
+	TupleDesc	tupdesc;
+	Datum		values[PG_STAT_NETWORK_TRAFFIC_COLS];
+	bool		nulls[PG_STAT_NETWORK_TRAFFIC_COLS];
+	int32		beid = PG_GETARG_INT32(0);
+	PgBackendStatus *beentry;
+
+	if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
+		PG_RETURN_NULL();
+	else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
+		PG_RETURN_NULL();
+
+	/* Initialise values and NULL flags arrays */
+	MemSet(values, 0, sizeof(values));
+	MemSet(nulls, 0, sizeof(nulls));
+
+	/* Initialise attributes information in the tuple descriptor */
+	tupdesc = CreateTemplateTupleDesc(PG_STAT_NETWORK_TRAFFIC_COLS);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "rx_raw_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "tx_raw_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "rx_compressed_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "tx_compressed_bytes",
+					   INT8OID, -1, 0);
+	BlessTupleDesc(tupdesc);
+
+	/* Fill values and NULLs */
+	values[0] = beentry->st_rx_raw_bytes;
+	values[1] = beentry->st_tx_raw_bytes;
+	values[2] = beentry->st_rx_compressed_bytes;
+	values[3] = beentry->st_tx_compressed_bytes;
+
+	/* Returns the record as Datum */
+	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
+}
 
 Datum
 pg_stat_get_backend_client_addr(PG_FUNCTION_ARGS)
diff --git a/src/common/Makefile b/src/common/Makefile
index 25c55bd..bc6cba8 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -77,7 +77,8 @@ OBJS_COMMON = \
 	unicode_norm.o \
 	username.o \
 	wait_error.o \
-	wchar.o
+	wchar.o \
+	zpq_stream.o
 
 ifeq ($(with_openssl),yes)
 OBJS_COMMON += \
diff --git a/src/common/zpq_stream.c b/src/common/zpq_stream.c
new file mode 100644
index 0000000..4595662
--- /dev/null
+++ b/src/common/zpq_stream.c
@@ -0,0 +1,543 @@
+#include "postgres_fe.h"
+#include "common/zpq_stream.h"
+#include "c.h"
+#include "pg_config.h"
+
+/*
+ * Functions implementing streaming compression algorithm
+ */
+typedef struct
+{
+	/*
+	 * Returns name of compression algorithm.
+	 */
+	char const* (*name)(void);
+
+	/*
+	 * Create compression stream with using rx/tx function for fetching/sending compressed data.
+	 * level: compression level
+	 * tx_func: function for writing compressed data in underlying stream
+	 * rx_func: function for receiving compressed data from underlying stream
+	 * arg: context passed to the function
+     * rx_data: received data (compressed data already fetched from input stream)
+	 * rx_data_size: size of data fetched from input stream
+	 */
+	ZpqStream* (*create)(int level, zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg, char* rx_data, size_t rx_data_size);
+
+	/*
+	 * Read up to "size" raw (decompressed) bytes.
+	 * Returns number of decompressed bytes or error code.
+	 * Error code is either ZPQ_DECOMPRESS_ERROR either error code returned by the rx function.
+	 */
+	ssize_t (*read)(ZpqStream *zs, void *buf, size_t size);
+
+	/*
+	 * Write up to "size" raw (decompressed) bytes.
+	 * Returns number of written raw bytes or error code returned by tx function.
+	 * In the last case amount of written raw bytes is stored in *processed.
+	 */
+	ssize_t (*write)(ZpqStream *zs, void const *buf, size_t size, size_t *processed);
+
+	/*
+	 * Free stream created by create function.
+	 */
+	void    (*free)(ZpqStream *zs);
+
+	/*
+	 * Get error message.
+	 */
+	char const* (*error)(ZpqStream *zs);
+
+	/*
+	 * Returns amount of data in internal tx decompression buffer.
+	 */
+	size_t  (*buffered_tx)(ZpqStream *zs);
+
+	/*
+	 * Returns amount of data in internal rx compression buffer.
+	 */
+	size_t  (*buffered_rx)(ZpqStream *zs);
+} ZpqAlgorithm;
+
+struct ZpqStream
+{
+	ZpqAlgorithm const* algorithm;
+};
+
+#if HAVE_LIBZSTD
+
+#include <stdlib.h>
+#include <zstd.h>
+
+#define ZSTD_BUFFER_SIZE (8*1024)
+
+typedef struct ZstdStream
+{
+	ZpqStream      common;
+	ZSTD_CStream*  tx_stream;
+	ZSTD_DStream*  rx_stream;
+	ZSTD_outBuffer tx;
+	ZSTD_inBuffer  rx;
+	size_t         tx_not_flushed; /* Amount of data in internal zstd buffer */
+	size_t         tx_buffered;    /* Data which is consumed by ztd_write but not yet sent */
+	size_t         rx_buffered;    /* Data which is needed for ztd_read */
+	zpq_tx_func    tx_func;
+	zpq_rx_func    rx_func;
+	void*          arg;
+	char const*    rx_error;    /* Decompress error message */
+	size_t         tx_total;
+	size_t         tx_total_raw;
+	size_t         rx_total;
+	size_t         rx_total_raw;
+	char           tx_buf[ZSTD_BUFFER_SIZE];
+	char           rx_buf[ZSTD_BUFFER_SIZE];
+} ZstdStream;
+
+static ZpqStream*
+zstd_create(int level, zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg, char* rx_data, size_t rx_data_size)
+{
+	ZstdStream* zs = (ZstdStream*)malloc(sizeof(ZstdStream));
+
+	zs->tx_stream = ZSTD_createCStream();
+	ZSTD_initCStream(zs->tx_stream, level);
+	zs->rx_stream = ZSTD_createDStream();
+	ZSTD_initDStream(zs->rx_stream);
+	zs->tx.dst = zs->tx_buf;
+	zs->tx.pos = 0;
+	zs->tx.size = ZSTD_BUFFER_SIZE;
+	zs->rx.src = zs->rx_buf;
+	zs->rx.pos = 0;
+	zs->rx.size = 0;
+	zs->rx_func = rx_func;
+	zs->tx_func = tx_func;
+	zs->tx_buffered = 0;
+	zs->rx_buffered = 0;
+	zs->tx_not_flushed = 0;
+	zs->rx_error = NULL;
+	zs->arg = arg;
+	zs->tx_total = zs->tx_total_raw = 0;
+	zs->rx_total = zs->rx_total_raw = 0;
+	zs->rx.size = rx_data_size;
+	Assert(rx_data_size < ZSTD_BUFFER_SIZE);
+	memcpy(zs->rx_buf, rx_data, rx_data_size);
+
+	return (ZpqStream*)zs;
+}
+
+static ssize_t
+zstd_read(ZpqStream *zstream, void *buf, size_t size)
+{
+	ZstdStream* zs = (ZstdStream*)zstream;
+	ssize_t rc;
+	ZSTD_outBuffer out;
+	out.dst = buf;
+	out.pos = 0;
+	out.size = size;
+
+	while (1)
+	{
+		if (zs->rx.pos != zs->rx.size || zs->rx_buffered == 0)
+		{
+			rc = ZSTD_decompressStream(zs->rx_stream, &out, &zs->rx);
+			if (ZSTD_isError(rc))
+			{
+				zs->rx_error = ZSTD_getErrorName(rc);
+				return ZPQ_DECOMPRESS_ERROR;
+			}
+			/* Return result if we fill requested amount of bytes or read operation was performed */
+			if (out.pos != 0)
+			{
+				zs->rx_total_raw += out.pos;
+				zs->rx_buffered = 0;
+				return out.pos;
+			}
+			zs->rx_buffered = rc;
+			if (zs->rx.pos == zs->rx.size)
+			{
+				zs->rx.pos = zs->rx.size = 0; /* Reset rx buffer */
+			}
+		}
+		rc = zs->rx_func(zs->arg, (char*)zs->rx.src + zs->rx.size, ZSTD_BUFFER_SIZE - zs->rx.size);
+		if (rc > 0) /* read fetches some data */
+		{
+			zs->rx.size += rc;
+			zs->rx_total += rc;
+		}
+		else /* read failed */
+		{
+			zs->rx_total_raw += out.pos;
+			return rc;
+		}
+	}
+}
+
+static ssize_t
+zstd_write(ZpqStream *zstream, void const *buf, size_t size, size_t *processed)
+{
+	ZstdStream* zs = (ZstdStream*)zstream;
+	ssize_t rc;
+	ZSTD_inBuffer in_buf;
+	in_buf.src = buf;
+	in_buf.pos = 0;
+	in_buf.size = size;
+
+	do
+	{
+		if (zs->tx.pos == 0) /* Compress buffer is empty */
+		{
+			zs->tx.dst = zs->tx_buf; /* Reset pointer to the beginning of buffer */
+
+			if (in_buf.pos < size) /* Has something to compress in input buffer */
+				ZSTD_compressStream(zs->tx_stream, &zs->tx, &in_buf);
+
+			if (in_buf.pos == size) /* All data is compressed: flushed internal zstd buffer */
+			{
+				zs->tx_not_flushed = ZSTD_flushStream(zs->tx_stream, &zs->tx);
+			}
+		}
+		rc = zs->tx_func(zs->arg, zs->tx.dst, zs->tx.pos);
+		if (rc > 0)
+		{
+			zs->tx.pos -= rc;
+			zs->tx.dst = (char*)zs->tx.dst + rc;
+			zs->tx_total += rc;
+		}
+		else
+		{
+			*processed = in_buf.pos;
+			zs->tx_buffered = zs->tx.pos;
+			zs->tx_total_raw += in_buf.pos;
+			return rc;
+		}
+    /* repeat sending while there is some data in input or internal zstd buffer */
+    } while (in_buf.pos < size || zs->tx_not_flushed);
+
+	zs->tx_total_raw += in_buf.pos;
+	zs->tx_buffered = zs->tx.pos;
+	return in_buf.pos;
+}
+
+static void
+zstd_free(ZpqStream *zstream)
+{
+	ZstdStream* zs = (ZstdStream*)zstream;
+	if (zs != NULL)
+	{
+		ZSTD_freeCStream(zs->tx_stream);
+		ZSTD_freeDStream(zs->rx_stream);
+		free(zs);
+	}
+}
+
+static char const*
+zstd_error(ZpqStream *zstream)
+{
+	ZstdStream* zs = (ZstdStream*)zstream;
+	return zs->rx_error;
+}
+
+static size_t
+zstd_buffered_tx(ZpqStream *zstream)
+{
+	ZstdStream* zs = (ZstdStream*)zstream;
+	return zs != NULL ? zs->tx_buffered + zs->tx_not_flushed : 0;
+}
+
+static size_t
+zstd_buffered_rx(ZpqStream *zstream)
+{
+	ZstdStream* zs = (ZstdStream*)zstream;
+	return zs != NULL ? zs->rx.size - zs->rx.pos : 0;
+}
+
+static char const*
+zstd_name(void)
+{
+	return "zstd";
+}
+
+#endif
+
+#if HAVE_LIBZ
+
+#include <stdlib.h>
+#include <zlib.h>
+
+#define ZLIB_BUFFER_SIZE       8192 /* We have to flush stream after each protocol command
+									 * and command is mostly limited by record length,
+									 * which in turn usually less than page size (except TOAST)
+									 */
+
+typedef struct ZlibStream
+{
+	ZpqStream      common;
+
+	z_stream tx;
+	z_stream rx;
+
+	zpq_tx_func    tx_func;
+	zpq_rx_func    rx_func;
+	void*          arg;
+    unsigned       tx_deflate_pending;
+	size_t         tx_buffered;
+
+	Bytef          tx_buf[ZLIB_BUFFER_SIZE];
+	Bytef          rx_buf[ZLIB_BUFFER_SIZE];
+} ZlibStream;
+
+static ZpqStream*
+zlib_create(int level, zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg, char* rx_data, size_t rx_data_size)
+{
+	int rc;
+	ZlibStream* zs = (ZlibStream*)malloc(sizeof(ZlibStream));
+	memset(&zs->tx, 0, sizeof(zs->tx));
+	zs->tx.next_out = zs->tx_buf;
+	zs->tx.avail_out = ZLIB_BUFFER_SIZE;
+	zs->tx_buffered = 0;
+	rc = deflateInit(&zs->tx, level);
+	if (rc != Z_OK)
+	{
+		free(zs);
+		return NULL;
+	}
+	Assert(zs->tx.next_out == zs->tx_buf && zs->tx.avail_out == ZLIB_BUFFER_SIZE);
+
+	memset(&zs->rx, 0, sizeof(zs->tx));
+	zs->rx.next_in = zs->rx_buf;
+	zs->rx.avail_in = ZLIB_BUFFER_SIZE;
+	zs->tx_deflate_pending = 0;
+	rc = inflateInit(&zs->rx);
+	if (rc != Z_OK)
+	{
+		free(zs);
+		return NULL;
+	}
+	Assert(zs->rx.next_in == zs->rx_buf && zs->rx.avail_in == ZLIB_BUFFER_SIZE);
+
+	zs->rx.avail_in = rx_data_size;
+	Assert(rx_data_size < ZLIB_BUFFER_SIZE);
+	memcpy(zs->rx_buf, rx_data, rx_data_size);
+
+	zs->rx_func = rx_func;
+	zs->tx_func = tx_func;
+	zs->arg = arg;
+
+	return (ZpqStream*)zs;
+}
+
+static ssize_t
+zlib_read(ZpqStream *zstream, void *buf, size_t size)
+{
+	ZlibStream* zs = (ZlibStream*)zstream;
+	int rc;
+	zs->rx.next_out = (Bytef *)buf;
+	zs->rx.avail_out = size;
+
+	while (1)
+	{
+		if (zs->rx.avail_in != 0) /* If there is some data in receiver buffer, then decompress it */
+		{
+			rc = inflate(&zs->rx, Z_SYNC_FLUSH);
+			if (rc != Z_OK && rc != Z_BUF_ERROR)
+			{
+				return ZPQ_DECOMPRESS_ERROR;
+			}
+			if (zs->rx.avail_out != size)
+			{
+				return size - zs->rx.avail_out;
+			}
+			if (zs->rx.avail_in == 0)
+			{
+				zs->rx.next_in = zs->rx_buf;
+			}
+		}
+		else
+		{
+			zs->rx.next_in = zs->rx_buf;
+		}
+		rc = zs->rx_func(zs->arg, zs->rx.next_in + zs->rx.avail_in, zs->rx_buf + ZLIB_BUFFER_SIZE - zs->rx.next_in - zs->rx.avail_in);
+		if (rc > 0)
+		{
+			zs->rx.avail_in += rc;
+		}
+		else
+		{
+			return rc;
+		}
+	}
+}
+
+static ssize_t
+zlib_write(ZpqStream *zstream, void const *buf, size_t size, size_t *processed)
+{
+	ZlibStream* zs = (ZlibStream*)zstream;
+    int rc;
+	zs->tx.next_in = (Bytef *)buf;
+	zs->tx.avail_in = size;
+	do
+	{
+		if (zs->tx.avail_out == ZLIB_BUFFER_SIZE) /* Compress buffer is empty */
+		{
+			zs->tx.next_out = zs->tx_buf; /* Reset pointer to the  beginning of buffer */
+
+			if (zs->tx.avail_in != 0 || (zs->tx_deflate_pending > 0)) /* Has something in input or deflate buffer */
+			{
+				rc = deflate(&zs->tx, Z_SYNC_FLUSH);
+				Assert(rc == Z_OK);
+                deflatePending(&zs->tx, &zs->tx_deflate_pending, Z_NULL); /* check if any data left in deflate buffer */
+				zs->tx.next_out = zs->tx_buf; /* Reset pointer to the  beginning of buffer */
+			}
+		}
+		rc = zs->tx_func(zs->arg, zs->tx.next_out, ZLIB_BUFFER_SIZE - zs->tx.avail_out);
+		if (rc > 0)
+		{
+			zs->tx.next_out += rc;
+			zs->tx.avail_out += rc;
+		}
+		else
+		{
+			*processed = size - zs->tx.avail_in;
+			zs->tx_buffered = ZLIB_BUFFER_SIZE - zs->tx.avail_out;
+			return rc;
+		}
+    /* repeat sending while there is some data in input or deflate buffer */
+	} while (zs->tx.avail_in != 0 || zs->tx_deflate_pending > 0);
+
+	zs->tx_buffered = ZLIB_BUFFER_SIZE - zs->tx.avail_out;
+
+	return size - zs->tx.avail_in;
+}
+
+static void
+zlib_free(ZpqStream *zstream)
+{
+	ZlibStream* zs = (ZlibStream*)zstream;
+	if (zs != NULL)
+	{
+		inflateEnd(&zs->rx);
+		deflateEnd(&zs->tx);
+		free(zs);
+	}
+}
+
+static char const*
+zlib_error(ZpqStream *zstream)
+{
+	ZlibStream* zs = (ZlibStream*)zstream;
+	return zs->rx.msg;
+}
+
+static size_t
+zlib_buffered_tx(ZpqStream *zstream)
+{
+	ZlibStream* zs = (ZlibStream*)zstream;
+	return zs != NULL ? zs->tx_buffered + zs->tx_deflate_pending : 0;
+}
+
+static size_t
+zlib_buffered_rx(ZpqStream *zstream)
+{
+	ZlibStream* zs = (ZlibStream*)zstream;
+	return zs != NULL ? zs->rx.avail_in : 0;
+}
+
+static char const*
+zlib_name(void)
+{
+	return "zlib";
+}
+
+#endif
+
+static char const*
+no_compression_name(void)
+{
+	return NULL;
+}
+
+/*
+ * Array with all supported compression algorithms.
+ */
+static ZpqAlgorithm const zpq_algorithms[] =
+{
+#if HAVE_LIBZSTD
+	{zstd_name, zstd_create, zstd_read, zstd_write, zstd_free, zstd_error, zstd_buffered_tx, zstd_buffered_rx},
+#endif
+#if HAVE_LIBZ
+	{zlib_name, zlib_create, zlib_read, zlib_write, zlib_free, zlib_error, zlib_buffered_tx, zlib_buffered_rx},
+#endif
+	{no_compression_name}
+};
+
+/*
+ * Index of used compression algorithm in zpq_algorithms array.
+ */
+ZpqStream*
+zpq_create(int algorithm_impl, int level, zpq_tx_func tx_func, zpq_rx_func rx_func, void *arg, char* rx_data, size_t rx_data_size)
+{
+	ZpqStream* stream = zpq_algorithms[algorithm_impl].create(level, tx_func, rx_func, arg, rx_data, rx_data_size);
+	if (stream)
+		stream->algorithm = &zpq_algorithms[algorithm_impl];
+	return stream;
+}
+
+ssize_t
+zpq_read(ZpqStream *zs, void *buf, size_t size)
+{
+	return zs->algorithm->read(zs, buf, size);
+}
+
+ssize_t
+zpq_write(ZpqStream *zs, void const *buf, size_t size, size_t* processed)
+{
+	return zs->algorithm->write(zs, buf, size, processed);
+}
+
+void
+zpq_free(ZpqStream *zs)
+{
+	if (zs)
+		zs->algorithm->free(zs);
+}
+
+char const*
+zpq_error(ZpqStream *zs)
+{
+	return zs->algorithm->error(zs);
+}
+
+
+size_t
+zpq_buffered_rx(ZpqStream *zs)
+{
+	return zs ? zs->algorithm->buffered_rx(zs) : 0;
+}
+
+size_t
+zpq_buffered_tx(ZpqStream *zs)
+{
+	return zs ? zs->algorithm->buffered_tx(zs) : 0;
+}
+
+/*
+ * Get list of the supported algorithms.
+ */
+char**
+zpq_get_supported_algorithms(void)
+{
+	size_t n_algorithms = sizeof(zpq_algorithms)/sizeof(*zpq_algorithms);
+	char** algorithm_names = malloc(n_algorithms*sizeof(char*));
+
+	for (size_t i = 0; i < n_algorithms; i++)
+	{
+		algorithm_names[i] = (char*)zpq_algorithms[i].name();
+	}
+
+	return algorithm_names;
+}
+
+char const*
+zpq_algorithm_name(ZpqStream *zs)
+{
+	return zs ? zs->algorithm->name() : NULL;
+}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index a66870b..cf599fd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5228,9 +5228,9 @@
   proname => 'pg_stat_get_activity', prorows => '100', proisstrict => 'f',
   proretset => 't', provolatile => 's', proparallel => 'r',
   prorettype => 'record', proargtypes => 'int4',
-  proallargtypes => '{int4,oid,int4,oid,text,text,text,text,text,timestamptz,timestamptz,timestamptz,timestamptz,inet,text,int4,xid,xid,text,bool,text,text,int4,bool,text,numeric,text,bool,text,bool,int4}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,sslcompression,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,leader_pid}',
+  proallargtypes => '{int4,oid,int4,oid,text,text,text,text,text,timestamptz,timestamptz,timestamptz,timestamptz,inet,text,int4,xid,xid,text,bool,text,text,int4,bool,text,numeric,text,bool,text,bool,int4,int8,int8,int8,int8}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,sslcompression,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,leader_pid,rx_raw_bytes,tx_raw_bytes,rx_compressed_bytes,tx_compressed_bytes}',
   prosrc => 'pg_stat_get_activity' },
 { oid => '3318',
   descr => 'statistics: information about progress of backends running maintenance command',
@@ -5497,6 +5497,14 @@
   proargnames => '{wal_buffers_full,stats_reset}',
   prosrc => 'pg_stat_get_wal' },
 
+{ oid => '1137', descr => 'statistics: information about network traffic',
+  proname => 'pg_stat_get_network_traffic', proisstrict => 'f', provolatile => 's',
+  proparallel => 'r', prorettype => 'record', proargtypes => 'int4',
+  proallargtypes => '{int4,int8,int8,int8,int8}',
+  proargmodes => '{i,o,o,o,o}',
+  proargnames => '{_beid,rx_raw_bytes,tx_raw_bytes,rx_compressed_bytes,tx_compressed_bytes}',
+  prosrc => 'pg_stat_get_network_traffic' },
+
 { oid => '2306', descr => 'statistics: information about SLRU caches',
   proname => 'pg_stat_get_slru', prorows => '100', proisstrict => 'f',
   proretset => 't', provolatile => 's', proparallel => 'r',
@@ -5627,6 +5635,10 @@
   proname => 'pg_tablespace_location', provolatile => 's', prorettype => 'text',
   proargtypes => 'oid', prosrc => 'pg_tablespace_location' },
 
+{ oid => '4142', descr => 'connection compression algorithm',
+  proname => 'pg_compression_algorithm', provolatile => 's', prorettype => 'text',
+  proargtypes => '', prosrc => 'pg_compression_algorithm' },
+
 { oid => '1946',
   descr => 'convert bytea value into some ascii-only text string',
   proname => 'encode', prorettype => 'text', proargtypes => 'bytea text',
diff --git a/src/include/common/zpq_stream.h b/src/include/common/zpq_stream.h
new file mode 100644
index 0000000..27aef0a
--- /dev/null
+++ b/src/include/common/zpq_stream.h
@@ -0,0 +1,36 @@
+/*
+ * zpq_stream.h
+ *     Streaiming compression for libpq
+ */
+
+#ifndef ZPQ_STREAM_H
+#define ZPQ_STREAM_H
+
+#include <stdlib.h>
+
+#define ZPQ_IO_ERROR (-1)
+#define ZPQ_DECOMPRESS_ERROR (-2)
+
+#define ZPQ_DEFAULT_COMPRESSION_LEVEL (1)
+
+struct ZpqStream;
+typedef struct ZpqStream ZpqStream;
+
+typedef ssize_t(*zpq_tx_func)(void* arg, void const* data, size_t size);
+typedef ssize_t(*zpq_rx_func)(void* arg, void* data, size_t size);
+
+ZpqStream* zpq_create(int impl, int level, zpq_tx_func tx_func, zpq_rx_func rx_func, void* arg, char* rx_data, size_t rx_data_size);
+ssize_t zpq_read(ZpqStream* zs, void* buf, size_t size);
+ssize_t zpq_write(ZpqStream* zs, void const* buf, size_t size, size_t* processed);
+char const* zpq_error(ZpqStream* zs);
+size_t zpq_buffered_rx(ZpqStream* zs);
+size_t zpq_buffered_tx(ZpqStream* zs);
+void zpq_free(ZpqStream* zs);
+char const* zpq_algorithm_name(ZpqStream* zs);
+
+/*
+  Returns zero terminated array with compression algorithms names
+*/
+char** zpq_get_supported_algorithms(void);
+
+#endif
diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h
index 0a23281..5289f9f 100644
--- a/src/include/libpq/libpq-be.h
+++ b/src/include/libpq/libpq-be.h
@@ -170,6 +170,8 @@ typedef struct Port
 	int			keepalives_count;
 	int			tcp_user_timeout;
 
+	char*       compression_algorithms; /* Compression algorithms supported by client */
+
 	/*
 	 * GSSAPI structures.
 	 */
diff --git a/src/include/libpq/libpq.h b/src/include/libpq/libpq.h
index b115247..224ff3d 100644
--- a/src/include/libpq/libpq.h
+++ b/src/include/libpq/libpq.h
@@ -63,6 +63,7 @@ extern void StreamClose(pgsocket sock);
 extern void TouchSocketFiles(void);
 extern void RemoveSocketFiles(void);
 extern void pq_init(void);
+extern int  pq_configure(Port* port);
 extern int	pq_getbytes(char *s, size_t len);
 extern int	pq_getstring(StringInfo s);
 extern void pq_startmsgread(void);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index fb270df..b829fed 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -349,6 +349,9 @@
 /* Define to 1 if you have the `link' function. */
 #undef HAVE_LINK
 
+/* Define to 1 if you have the `zstd' library (-lzstd). */
+#undef HAVE_LIBZSTD
+
 /* Define to 1 if the system has the type `locale_t'. */
 #undef HAVE_LOCALE_T
 
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index a821ff4..5732796 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -1184,6 +1184,12 @@ typedef struct PgBackendStatus
 	/* application name; MUST be null-terminated */
 	char	   *st_appname;
 
+	/* client-server traffic information */
+	uint64      st_rx_raw_bytes;
+	uint64      st_tx_raw_bytes;
+	uint64      st_rx_compressed_bytes;
+	uint64      st_tx_compressed_bytes;
+
 	/*
 	 * Current command string; MUST be null-terminated. Note that this string
 	 * possibly is truncated in the middle of a multi-byte character. As
@@ -1397,6 +1403,7 @@ extern void pgstat_report_activity(BackendState state, const char *cmd_str);
 extern void pgstat_report_tempfile(size_t filesize);
 extern void pgstat_report_appname(const char *appname);
 extern void pgstat_report_xact_timestamp(TimestampTz tstamp);
+extern void pgstat_report_network_traffic(uint64 rx_raw_bytes, uint64 tx_raw_bytes, uint64 rx_compressed_bytes, uint64 tx_compressed_bytes);
 extern const char *pgstat_get_wait_event(uint32 wait_event_info);
 extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile
index 4ac5f4b..be8cb34 100644
--- a/src/interfaces/libpq/Makefile
+++ b/src/interfaces/libpq/Makefile
@@ -29,6 +29,20 @@ endif
 # The MSVC build system scrapes OBJS from this file.  If you change any of
 # the conditional additions of files to OBJS, update Mkvcbuild.pm to match.
 
+ifeq ($(with_zstd),yes)
+LIBS += -lzstd
+SHLIB_LINK += -lzstd
+endif
+
+ifeq ($(with_zlib),yes)
+LIBS += -lz
+SHLIB_LINK += -lz
+endif
+
+# We can't use Makefile variables here because the MSVC build system scrapes
+# OBJS from this file.
+
+
 OBJS = \
 	$(WIN32RES) \
 	fe-auth-scram.o \
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index b0ca37c..78b466a 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -24,6 +24,7 @@
 #include "common/ip.h"
 #include "common/link-canary.h"
 #include "common/scram-common.h"
+#include "common/zpq_stream.h"
 #include "common/string.h"
 #include "fe-auth.h"
 #include "libpq-fe.h"
@@ -350,6 +351,10 @@ static const internalPQconninfoOption PQconninfoOptions[] = {
 		"Replication", "D", 5,
 	offsetof(struct pg_conn, replication)},
 
+	{"compression", "COMPRESSION", NULL, NULL,
+		"Libpq-compression", "", 16,
+	offsetof(struct pg_conn, compression)},
+
 	{"target_session_attrs", "PGTARGETSESSIONATTRS",
 		DefaultTargetSessionAttrs, NULL,
 		"Target-Session-Attrs", "", 11, /* sizeof("read-write") = 11 */
@@ -458,6 +463,10 @@ pgthreadlock_t pg_g_threadlock = default_threadlock;
 void
 pqDropConnection(PGconn *conn, bool flushInput)
 {
+	/* Release compression streams */
+	zpq_free(conn->zstream);
+	conn->zstream = NULL;
+
 	/* Drop any SSL state */
 	pqsecure_close(conn);
 
@@ -2148,6 +2157,12 @@ connectDBComplete(PGconn *conn)
 				return 1;		/* success! */
 
 			case PGRES_POLLING_READING:
+			    /* if there is some buffered RX data in ZpqStream
+			     * then don't proceed to pqWaitTimed */
+			    if (zpq_buffered_rx(conn->zstream)) {
+			        break;
+			    }
+
 				ret = pqWaitTimed(1, 0, conn, finish_time);
 				if (ret == -1)
 				{
@@ -3216,11 +3231,62 @@ keep_going:						/* We will come back to here until there is
 				 */
 				conn->inCursor = conn->inStart;
 
-				/* Read type byte */
-				if (pqGetc(&beresp, conn))
+				while (1)
 				{
-					/* We'll come back when there is more data */
-					return PGRES_POLLING_READING;
+					/* Read type byte */
+					if (pqGetc(&beresp, conn))
+					{
+						/* We'll come back when there is more data */
+						return PGRES_POLLING_READING;
+					}
+
+					if (beresp == 'z') /* Switch on compression */
+					{
+						int index;
+						char resp;
+						/* Read message length word */
+						if (pqGetInt(&msgLength, 4, conn))
+						{
+							/* We'll come back when there is more data */
+							return PGRES_POLLING_READING;
+						}
+						if (msgLength != 5)
+						{
+							appendPQExpBuffer(&conn->errorMessage,
+											  libpq_gettext(
+												  "expected compression algorithm specification message length is 5 bytes, but %d is received\n"),
+											  msgLength);
+							goto error_return;
+						}
+						pqGetc(&resp, conn);
+						index = resp;
+						if (index == (char)-1)
+						{
+							appendPQExpBuffer(&conn->errorMessage,
+											  libpq_gettext(
+												  "server is not supported requested compression algorithms %s\n"),
+											  conn->compression);
+							goto error_return;
+						}
+						Assert(!conn->zstream);
+						conn->zstream = zpq_create(conn->compressors[index].impl,
+												   conn->compressors[index].level,
+												   (zpq_tx_func)pqsecure_write, (zpq_rx_func)pqsecure_read, conn,
+												   &conn->inBuffer[conn->inCursor], conn->inEnd-conn->inCursor);
+						if (!conn->zstream)
+						{
+							char** supported_algorithms = zpq_get_supported_algorithms();
+							appendPQExpBuffer(&conn->errorMessage,
+											  libpq_gettext(
+												  "failed to initialize compressor %s\n"),
+											  supported_algorithms[conn->compressors[index].impl]);
+							free(supported_algorithms);
+							goto error_return;
+						}
+						/* reset buffer */
+						conn->inStart = conn->inCursor = conn->inEnd = 0;
+					} else
+						break;
 				}
 
 				/*
@@ -4020,6 +4086,8 @@ freePGconn(PGconn *conn)
 		free(conn->dbName);
 	if (conn->replication)
 		free(conn->replication);
+	if (conn->compression)
+		free(conn->compression);
 	if (conn->pguser)
 		free(conn->pguser);
 	if (conn->pgpass)
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index eea0237..00ccefb 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -1810,8 +1810,8 @@ PQgetResult(PGconn *conn)
 		 * EOF indication.  We expect therefore that this won't result in any
 		 * undue delay in reporting a previous write failure.)
 		 */
-		if (flushResult ||
-			pqWait(true, false, conn) ||
+		if (flushResult || (zpq_buffered_rx(conn->zstream) == 0 &&
+			pqWait(true, false, conn)) ||
 			pqReadData(conn) < 0)
 		{
 			/*
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 4ffc7f3..4f39f66 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -53,12 +53,21 @@
 #include "pg_config_paths.h"
 #include "port/pg_bswap.h"
 
+#include  <common/zpq_stream.h>
+
 static int	pqPutMsgBytes(const void *buf, size_t len, PGconn *conn);
 static int	pqSendSome(PGconn *conn, int len);
 static int	pqSocketCheck(PGconn *conn, int forRead, int forWrite,
 						  time_t end_time);
 static int	pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time);
 
+#define pq_read_conn(conn)												\
+	(conn->zstream														\
+	 ? zpq_read(conn->zstream, conn->inBuffer + conn->inEnd,			\
+				conn->inBufSize - conn->inEnd)							\
+	 : pqsecure_read(conn, conn->inBuffer + conn->inEnd,				\
+					 conn->inBufSize - conn->inEnd))
+
 /*
  * PQlibVersion: return the libpq version number
  */
@@ -664,10 +673,17 @@ pqReadData(PGconn *conn)
 
 	/* OK, try to read some data */
 retry3:
-	nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
-						  conn->inBufSize - conn->inEnd);
+	nread = pq_read_conn(conn);
 	if (nread < 0)
 	{
+		if (nread == ZPQ_DECOMPRESS_ERROR)
+		{
+			printfPQExpBuffer(&conn->errorMessage,
+							  libpq_gettext("decompress error: %s\n"),
+							  zpq_error(conn->zstream));
+			return -1;
+		}
+
 		switch (SOCK_ERRNO)
 		{
 			case EINTR:
@@ -759,10 +775,18 @@ retry3:
 	 * arrived.
 	 */
 retry4:
-	nread = pqsecure_read(conn, conn->inBuffer + conn->inEnd,
-						  conn->inBufSize - conn->inEnd);
+	nread = pq_read_conn(conn);
+
 	if (nread < 0)
 	{
+		if (nread == ZPQ_DECOMPRESS_ERROR)
+		{
+			printfPQExpBuffer(&conn->errorMessage,
+							  libpq_gettext("decompress error: %s\n"),
+							  zpq_error(conn->zstream));
+			return -1;
+		}
+
 		switch (SOCK_ERRNO)
 		{
 			case EINTR:
@@ -875,12 +899,14 @@ pqSendSome(PGconn *conn, int len)
 	}
 
 	/* while there's still data to send */
-	while (len > 0)
+	while (len > 0 || zpq_buffered_tx(conn->zstream))
 	{
 		int			sent;
-
+		size_t      processed = 0;
+		sent = conn->zstream
+			? zpq_write(conn->zstream, ptr, len, &processed)
 #ifndef WIN32
-		sent = pqsecure_write(conn, ptr, len);
+			: pqsecure_write(conn, ptr, len);
 #else
 
 		/*
@@ -888,8 +914,11 @@ pqSendSome(PGconn *conn, int len)
 		 * failure-point appears to be different in different versions of
 		 * Windows, but 64k should always be safe.
 		 */
-		sent = pqsecure_write(conn, ptr, Min(len, 65536));
+			: pqsecure_write(conn, ptr, Min(len, 65536));
 #endif
+		ptr += processed;
+		len -= processed;
+		remaining -= processed;
 
 		if (sent < 0)
 		{
@@ -943,7 +972,7 @@ pqSendSome(PGconn *conn, int len)
 			remaining -= sent;
 		}
 
-		if (len > 0)
+		if (len > 0 || sent < 0 || zpq_buffered_tx(conn->zstream))
 		{
 			/*
 			 * We didn't send it all, wait till we can send more.
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 1696525..b83dc06 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -1679,7 +1679,7 @@ pqGetCopyData3(PGconn *conn, char **buffer, int async)
 			if (async)
 				return 0;
 			/* Need to load more data */
-			if (pqWait(true, false, conn) ||
+			if ((zpq_buffered_rx(conn->zstream) == 0 && pqWait(true, false, conn)) ||
 				pqReadData(conn) < 0)
 				return -2;
 			continue;
@@ -1737,7 +1737,7 @@ pqGetline3(PGconn *conn, char *s, int maxlen)
 	while ((status = PQgetlineAsync(conn, s, maxlen - 1)) == 0)
 	{
 		/* need to load more data */
-		if (pqWait(true, false, conn) ||
+		if ((zpq_buffered_rx(conn->zstream) == 0 && pqWait(true, false, conn)) ||
 			pqReadData(conn) < 0)
 		{
 			*s = '\0';
@@ -1975,7 +1975,7 @@ pqFunctionCall3(PGconn *conn, Oid fnid,
 		if (needInput)
 		{
 			/* Wait for some data to arrive (or for the channel to close) */
-			if (pqWait(true, false, conn) ||
+			if ((zpq_buffered_rx(conn->zstream) == 0 && pqWait(true, false, conn)) ||
 				pqReadData(conn) < 0)
 				break;
 		}
@@ -2135,6 +2135,148 @@ pqBuildStartupPacket3(PGconn *conn, int *packetlen,
 }
 
 /*
+ * Build comma-separated list of compression algorithms suggested by client to the server.
+ * It can be either explicitly specified by user in connection string, either
+ * include all algorithms supported by clit library.
+ * This functions returns true if compression string is successfully parsed and
+ * stores comma-separated list of algorithms in *client_compressors.
+ * If compression is disabled, then NULL is assigned to  *client_compressors.
+ * Also it creates array of compressor descriptors, each element of which corresponds
+ * the correspondent algorithm name in *client_compressors list. This array is stored in PGconn
+ * and is used during handshake when compassion acknowledgment response is received from the server.
+ */
+static bool
+build_compressors_list(PGconn *conn, char** client_compressors, bool build_descriptors)
+{
+	char** supported_algorithms = zpq_get_supported_algorithms();
+	char* value = conn->compression;
+	int n_supported_algorithms;
+	int total_len = 0;
+	int i;
+
+	for (n_supported_algorithms = 0; supported_algorithms[n_supported_algorithms] != NULL; n_supported_algorithms++)
+	{
+		total_len += strlen(supported_algorithms[n_supported_algorithms])+1;
+	}
+
+	if (pg_strcasecmp(value, "true") == 0 ||
+		pg_strcasecmp(value, "yes") == 0 ||
+		pg_strcasecmp(value, "on") == 0 ||
+		pg_strcasecmp(value, "any") == 0 ||
+		pg_strcasecmp(value, "1") == 0)
+	{
+		/* Compression is enabled: choose algorithm automatically */
+		char* p;
+
+		if (n_supported_algorithms == 0)
+		{
+			*client_compressors = NULL; /* no compressors are avaialable */
+			conn->compressors = NULL;
+			return true;
+		}
+		*client_compressors = p = malloc(total_len);
+		if (build_descriptors)
+			conn->compressors = malloc(n_supported_algorithms*sizeof(pg_conn_compressor));
+		for (i = 0; i < n_supported_algorithms; i++)
+		{
+			strcpy(p, supported_algorithms[i]);
+			p += strlen(p);
+			*p++ = ',';
+			if (build_descriptors)
+			{
+				conn->compressors[i].impl = i;
+				conn->compressors[i].level = ZPQ_DEFAULT_COMPRESSION_LEVEL;
+			}
+		}
+		p[-1] = '\0';
+		return true;
+	}
+	else if (*value == 0 ||
+			 pg_strcasecmp(value, "false") == 0 ||
+			 pg_strcasecmp(value, "no") == 0 ||
+			 pg_strcasecmp(value, "off") == 0 ||
+			 pg_strcasecmp(value, "0") == 0)
+	{
+		/* Compression is disabled */
+		*client_compressors = NULL;
+		conn->compressors = NULL;
+		return true;
+	}
+	else
+	{
+		/* List of compresison algorithms separated by commas */
+		char *src, *dst;
+		int n_suggested_algorithms = 0;
+
+		*client_compressors = src = dst = strdup(value);
+
+		if (build_descriptors)
+			conn->compressors = malloc(n_supported_algorithms*sizeof(pg_conn_compressor));
+
+		while (*src != '\0')
+		{
+			char* sep = strchr(src, ',');
+			char* col;
+			int compression_level = ZPQ_DEFAULT_COMPRESSION_LEVEL;
+
+			if (sep != NULL)
+				*sep = '\0';
+
+			strcpy(dst, src);
+
+			col = strchr(src, ':');
+			if (col != NULL)
+			{
+				*col = '\0';
+				if (sscanf(col+1, "%d", &compression_level) != 1 && !build_descriptors)
+				{
+					fprintf(stderr,
+							libpq_gettext("WARNING: invlaid compression level %s in compression option '%s'\n"),
+							col+1, value);
+					return false;
+				}
+			}
+			for (i = 0; supported_algorithms[i] != NULL; i++)
+			{
+				if (pg_strcasecmp(src, supported_algorithms[i]) == 0)
+				{
+					if (build_descriptors)
+					{
+						conn->compressors[n_suggested_algorithms].impl = i;
+						conn->compressors[n_suggested_algorithms].level = compression_level;
+					}
+					n_suggested_algorithms += 1;
+					dst += strlen(dst);
+					*dst++ = ',';
+					break;
+				}
+			}
+			if (sep)
+				src = sep+1;
+			else
+				break;
+		}
+		if (n_suggested_algorithms == 0)
+		{
+			if (!build_descriptors)
+				fprintf(stderr,
+						libpq_gettext("WARNING: none of specified algirthms %s is supported by client\n"),
+						value);
+			else
+			{
+				free(conn->compressors);
+				conn->compressors = NULL;
+			}
+			free(*client_compressors);
+			*client_compressors = NULL;
+			return false;
+		}
+		dst[-1] = '\0';
+		return true;
+	}
+}
+
+/*
  * Build a startup packet given a filled-in PGconn structure.
  *
  * We need to figure out how much space is needed, then fill it in.
@@ -2180,6 +2322,17 @@ build_startup_packet(const PGconn *conn, char *packet,
 		ADD_STARTUP_OPTION("replication", conn->replication);
 	if (conn->pgoptions && conn->pgoptions[0])
 		ADD_STARTUP_OPTION("options", conn->pgoptions);
+	if (conn->compression && conn->compression[0])
+	{
+		char* client_compression_algorithms;
+		if (build_compressors_list((PGconn*)conn, &client_compression_algorithms, packet == NULL))
+		{
+			if (client_compression_algorithms)
+			{
+				ADD_STARTUP_OPTION("_pq_.compression", client_compression_algorithms);
+			}
+		}
+	}
 	if (conn->send_appname)
 	{
 		/* Use appname if present, otherwise use fallback */
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 1de91ae..47716c7 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -40,6 +40,7 @@
 /* include stuff common to fe and be */
 #include "getaddrinfo.h"
 #include "libpq/pqcomm.h"
+#include "common/zpq_stream.h"
 /* include stuff found in fe only */
 #include "pqexpbuffer.h"
 
@@ -317,6 +318,16 @@ typedef struct pg_conn_host
 								 * found in password file. */
 } pg_conn_host;
 
+
+/*
+ * Descriptos of compression algorithms chosen by client
+ */
+typedef struct pg_conn_compressor
+{
+	int        impl;            /* compression implementation index */
+	int        level;           /* compression level */
+} pg_conn_compressor;
+
 /*
  * PGconn stores all the state data associated with a single connection
  * to a backend.
@@ -370,6 +381,9 @@ struct pg_conn
 	char	   *ssl_min_protocol_version;	/* minimum TLS protocol version */
 	char	   *ssl_max_protocol_version;	/* maximum TLS protocol version */
 
+	char	   *compression;    /* stream compression (boolean value, "any" or list of compression algorithms separated by comma) */
+	pg_conn_compressor* compressors; /* descriptors of compression algorithms chosen by client */
+
 	/* Type of connection to make.  Possible values: any, read-write. */
 	char	   *target_session_attrs;
 
@@ -527,6 +541,9 @@ struct pg_conn
 
 	/* Buffer for receiving various parts of messages */
 	PQExpBufferData workBuffer; /* expansible string */
+
+	/* Compression stream */
+	ZpqStream* zstream;
 };
 
 /* PGcancel stores all data necessary to cancel a connection. A copy of this
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 492cdcf..043267f 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1762,7 +1762,7 @@ pg_stat_activity| SELECT s.datid,
     s.backend_xmin,
     s.query,
     s.backend_type
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid, rx_raw_bytes, tx_raw_bytes, rx_compressed_bytes, tx_compressed_bytes)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1867,8 +1867,14 @@ pg_stat_gssapi| SELECT s.pid,
     s.gss_auth AS gss_authenticated,
     s.gss_princ AS principal,
     s.gss_enc AS encrypted
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid)
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid, rx_raw_bytes, tx_raw_bytes, rx_compressed_bytes, tx_compressed_bytes)
   WHERE (s.client_port IS NOT NULL);
+pg_stat_network_traffic| SELECT s.pid,
+    s.rx_raw_bytes,
+    s.tx_raw_bytes,
+    s.rx_compressed_bytes,
+    s.tx_compressed_bytes
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid, rx_raw_bytes, tx_raw_bytes, rx_compressed_bytes, tx_compressed_bytes);
 pg_stat_progress_analyze| SELECT s.pid,
     s.datid,
     d.datname,
@@ -2015,7 +2021,7 @@ pg_stat_replication| SELECT s.pid,
     w.sync_priority,
     w.sync_state,
     w.reply_time
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid, rx_raw_bytes, tx_raw_bytes, rx_compressed_bytes, tx_compressed_bytes)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
@@ -2043,7 +2049,7 @@ pg_stat_ssl| SELECT s.pid,
     s.ssl_client_dn AS client_dn,
     s.ssl_client_serial AS client_serial,
     s.ssl_issuer_dn AS issuer_dn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid)
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid, rx_raw_bytes, tx_raw_bytes, rx_compressed_bytes, tx_compressed_bytes)
   WHERE (s.client_port IS NOT NULL);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 90594bd..daac58c 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -123,7 +123,7 @@ sub mkvcbuild
 	  config_info.c controldata_utils.c d2s.c encnames.c exec.c
 	  f2s.c file_perm.c file_utils.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
-	  pg_get_line.c pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
+	  pg_get_line.c zpq_stream.c pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
 	  wait_error.c wchar.c);
 

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