diff --git a/include/qsort_arg_mt.h b/include/qsort_arg_mt.h
new file mode 100644
index 0000000000000000000000000000000000000000..a2a5fde8e0b8c1592b01ead8f786a4c2a5a5efec
--- /dev/null
+++ b/include/qsort_arg_mt.h
@@ -0,0 +1,19 @@
+#ifndef QSORT_ARG_H
+#define QSORT_ARG_H
+
+#include <sys/types.h>
+
+#if defined(__cplusplus)
+extern "C" {
+#endif /* defined(__cplusplus) */
+
+/**
+ * Multithread version of qsort_arg
+ */
+void qsort_arg_mt(void *a, size_t n, size_t es, int (*cmp)(const void *a, const void *b, void *arg), void *arg);
+
+#if defined(__cplusplus)
+}
+#endif /* defined(__cplusplus) */
+
+#endif
diff --git a/src/qsort_arg_mt.cc b/src/qsort_arg_mt.cc
new file mode 100644
index 0000000000000000000000000000000000000000..59915e80893107823ebe35bdaeb378352f9d467b
--- /dev/null
+++ b/src/qsort_arg_mt.cc
@@ -0,0 +1,213 @@
+/*
+ * Imported from PostgreSQL sources by Teodor Sigaev <teodor@sigaev.ru>, <sigaev@corp.mail.ru>
+ */
+
+/*
+ * qsort_arg.c: qsort with a passthrough "void *" argument
+ *
+ * Modifications from vanilla NetBSD source:
+ * Add do ... while() macro fix
+ * Remove __inline, _DIAGASSERTs, __P
+ * Remove ill-considered "swap_cnt" switch to insertion sort,
+ * in favor of a simple check for presorted input.
+ *
+ * CAUTION: if you change this file, see also qsort.c
+ *
+ * $PostgreSQL: pgsql/src/port/qsort_arg.c,v 1.4 2007/03/18 05:36:50 neilc Exp $
+ */
+
+/* $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $ */
+
+/*-
+ * Copyright (c) 1992, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <qsort_arg.h>
+#include <stdint.h>
+
+#if defined(__cplusplus)
+extern "C" {
+#endif /* defined(__cplusplus) */
+
+#define min(a, b) (a) < (b) ? a : b
+
+static char *med3(char *a, char *b, char *c,
+ int (*cmp)(const void *a, const void *b, void *arg), void *arg);
+static void swapfunc(char *, char *, size_t, int);
+
+/*
+ * Qsort routine based on J. L. Bentley and M. D. McIlroy,
+ * "Engineering a sort function",
+ * Software--Practice and Experience 23 (1993) 1249-1265.
+ * We have modified their original by adding a check for already-sorted input,
+ * which seems to be a win per discussions on pgsql-hackers around 2006-03-21.
+ */
+#define swapcode(TYPE, parmi, parmj, n) \
+do { \
+ size_t i = (n) / sizeof (TYPE); \
+ TYPE *pi = (TYPE *)(void *)(parmi); \
+ TYPE *pj = (TYPE *)(void *)(parmj); \
+ do { \
+ TYPE t = *pi; \
+ *pi++ = *pj; \
+ *pj++ = t; \
+ } while (--i > 0); \
+} while (0)
+
+#define SWAPINIT(a, es) swaptype = ((char *)(a) - (char *)0) % sizeof(long) || \
+ (es) % sizeof(long) ? 2 : (es) == sizeof(long)? 0 : 1;
+
+static void
+swapfunc(char *a, char *b, size_t n, int swaptype)
+{
+ if (swaptype <= 1)
+ swapcode(long, a, b, n);
+ else
+ swapcode(char, a, b, n);
+}
+
+#define swap(a, b) \
+ if (swaptype == 0) { \
+ long t = *(long *)(void *)(a); \
+ *(long *)(void *)(a) = *(long *)(void *)(b); \
+ *(long *)(void *)(b) = t; \
+ } else \
+ swapfunc(a, b, es, swaptype)
+
+#define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
+
+static char *
+med3(char *a, char *b, char *c, int (*cmp)(const void *a, const void *b, void *arg), void *arg)
+{
+ return cmp(a, b, arg) < 0 ?
+ (cmp(b, c, arg) < 0 ? b : (cmp(a, c, arg) < 0 ? c : a))
+ : (cmp(b, c, arg) > 0 ? b : (cmp(a, c, arg) < 0 ? a : c));
+}
+
+static void
+qsort_arg_mt_internal(void *a, size_t n, size_t es,
+ int (*cmp)(const void *a, const void *b, void *arg), void *arg)
+{
+ char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
+ intptr_t d, r, swaptype, presorted;
+
+ loop:SWAPINIT(a, es);
+ if (n < 7)
+ {
+ for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
+ for (pl = pm; pl > (char *) a && cmp(pl - es, pl, arg) > 0;
+ pl -= es)
+ swap(pl, pl - es);
+ return;
+ }
+ presorted = 1;
+ for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
+ {
+ if (cmp(pm - es, pm, arg) > 0)
+ {
+ presorted = 0;
+ break;
+ }
+ }
+ if (presorted)
+ return;
+ pm = (char *) a + (n / 2) * es;
+ if (n > 7)
+ {
+ pl = (char *) a;
+ pn = (char *) a + (n - 1) * es;
+ if (n > 40)
+ {
+ d = (n / 8) * es;
+ pl = med3(pl, pl + d, pl + 2 * d, cmp, arg);
+ pm = med3(pm - d, pm, pm + d, cmp, arg);
+ pn = med3(pn - 2 * d, pn - d, pn, cmp, arg);
+ }
+ pm = med3(pl, pm, pn, cmp, arg);
+ }
+ swap((char*)a, pm);
+ pa = pb = (char *) a + es;
+ pc = pd = (char *) a + (n - 1) * es;
+ for (;;)
+ {
+ while (pb <= pc && (r = cmp(pb, a, arg)) <= 0)
+ {
+ if (r == 0)
+ {
+ swap(pa, pb);
+ pa += es;
+ }
+ pb += es;
+ }
+ while (pb <= pc && (r = cmp(pc, a, arg)) >= 0)
+ {
+ if (r == 0)
+ {
+ swap(pc, pd);
+ pd -= es;
+ }
+ pc -= es;
+ }
+ if (pb > pc)
+ break;
+ swap(pb, pc);
+ pb += es;
+ pc -= es;
+ }
+ pn = (char *) a + n * es;
+ r = min(pa - (char *) a, pb - pa);
+ vecswap((char*)a, pb - r, r);
+ r = min(pd - pc, pn - pd - es);
+ vecswap(pb, pn - r, r);
+ if ((r = pb - pa) > es) {
+#pragma omp task
+ qsort_arg_mt_internal(a, r / es, es, cmp, arg);
+ }
+ if ((r = pd - pc) > es)
+ {
+ /* Iterate rather than recurse to save stack space */
+ a = pn - r;
+ n = r / es;
+ goto loop;
+ }
+}
+
+void
+qsort_arg_mt(void *a, size_t n, size_t es,
+ int (*cmp)(const void *a, const void *b, void *arg), void *arg)
+{
+#pragma omp parallel
+ {
+#pragma omp single
+ qsort_arg_mt_internal(a, n, es, cmp, arg);
+ }
+}
+
+#if defined(__cplusplus)
+}
+#endif /* defined(__cplusplus) */