diff --git b/doc/src/sgml/libpq.sgml a/doc/src/sgml/libpq.sgml
index 7b14366..6b95be8 100644
--- b/doc/src/sgml/libpq.sgml
+++ a/doc/src/sgml/libpq.sgml
@@ -7351,7 +7351,17 @@ typedef struct
        This function must return 1 for success, and 0 for failure.  On
        failure this function should set the error message
        with <function>PGsetRowProcessorErrMsg</function> if the cause
-       is other than out of memory.
+       is other than out of memory.  When non-blocking API is in use,
+       it can also return 2 for early exit
+       from <function>PQisBusy</function> function.  The
+       supplied <parameter>res</parameter>
+       and <parameter>columns</parameter> values will stay valid so
+       row can be processed outside of callback.  Caller is
+       responsible for tracking whether
+       the <parameter>PQisBusy</parameter> returned early from
+       callback or for other reasons.  Usually this should happen via
+       setting cached values to NULL before
+       calling <function>PQisBusy</function>.
      </para>
 
      <para>
diff --git b/src/interfaces/libpq/fe-protocol2.c a/src/interfaces/libpq/fe-protocol2.c
index 7498580..ae4d7b0 100644
--- b/src/interfaces/libpq/fe-protocol2.c
+++ a/src/interfaces/libpq/fe-protocol2.c
@@ -820,6 +820,9 @@ getAnotherTuple(PGconn *conn, bool binary)
 	rp= conn->rowProcessor(result, conn->rowProcessorParam, rowbuf);
 	if (rp == 1)
 		return 0;
+	else if (rp == 2 && pqIsnonblocking(conn))
+		/* processor requested early exit */
+		return EOF;
 	else if (rp != 0)
 		PQsetRowProcessorErrMsg(result, libpq_gettext("invalid return value from row processor\n"));
 
diff --git b/src/interfaces/libpq/fe-protocol3.c a/src/interfaces/libpq/fe-protocol3.c
index a67e3ac..0260ba6 100644
--- b/src/interfaces/libpq/fe-protocol3.c
+++ a/src/interfaces/libpq/fe-protocol3.c
@@ -697,6 +697,11 @@ getAnotherTuple(PGconn *conn, int msgLength)
 		/* everything is good */
 		return 0;
 	}
+	if (rp == 2 && pqIsnonblocking(conn))
+	{
+		/* processor requested early exit */
+		return EOF;
+	}
 
 	/* there was some problem */
 	if (rp == 0)