diff -Nru clickhouse-18.16.1+ds/debian/changelog clickhouse-18.16.1+ds/debian/changelog
--- clickhouse-18.16.1+ds/debian/changelog	2019-08-20 11:39:54.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/changelog	2019-08-20 22:07:15.000000000 +0000
@@ -1,3 +1,18 @@
+clickhouse (18.16.1+ds-4ubuntu2) eoan; urgency=medium
+
+  * Fixes for MySQL8, GCC9 and build issues (LP: #1840511)
+    dropped:
+      - d/p/mysql.patch
+      - d/rules: gcc-8 and g++-8 being default compiler
+      - d/control: gcc-8 and g++-8 as Build-Depends
+    added:
+      - d/control: Updated Maintainer to Ubuntu Developers
+      - d/rules: Tests 536 534 429 379 and 281 added to skip list.
+      - d/p/0016-MySQL-8-integr-reqs-previous-decl-checks.patch
+      - d/p/0017-gcc9-mitigation-for-conditional-bug.patch
+
+ -- Rafael David Tinoco <rafaeldtinoco@ubuntu.com>  Tue, 20 Aug 2019 22:07:15 +0000
+
 clickhouse (18.16.1+ds-4ubuntu1) eoan; urgency=medium
 
   * Use gcc-8 to build: see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91500
diff -Nru clickhouse-18.16.1+ds/debian/control clickhouse-18.16.1+ds/debian/control
--- clickhouse-18.16.1+ds/debian/control	2019-08-20 11:39:54.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/control	2019-08-20 22:07:15.000000000 +0000
@@ -1,12 +1,13 @@
 Source: clickhouse
 Section: database
 Priority: optional
-Maintainer: Alexander GQ Gerasiov <gq@debian.org>
+Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
+XSBC-Original-Maintainer: Alexander GQ Gerasiov <gq@debian.org>
 Build-Depends: cmake,
                curl <!nocheck>,
                debhelper (>= 10),
                default-libmysqlclient-dev | libmysqlclient-dev,
-               gcc-8, g++-8,
+               gcc, g++,
                gdb <!nocheck>,
                googletest,
                libboost-dev,
diff -Nru clickhouse-18.16.1+ds/debian/patches/0016-MySQL-8-integr-reqs-previous-decl-checks.patch clickhouse-18.16.1+ds/debian/patches/0016-MySQL-8-integr-reqs-previous-decl-checks.patch
--- clickhouse-18.16.1+ds/debian/patches/0016-MySQL-8-integr-reqs-previous-decl-checks.patch	1970-01-01 00:00:00.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/patches/0016-MySQL-8-integr-reqs-previous-decl-checks.patch	2019-08-20 22:07:15.000000000 +0000
@@ -0,0 +1,46 @@
+Description: MySQL 8 integration requires previous declaration checks
+
+C and C++ differ in the form of types being defined. While C++ structs
+are defined also as new types, in C you have to explicitly typedef the
+struct to have a new type.
+
+Fir this case, it was enough to check if MySQL header was already
+defined in order not to re-declare MYSQL, MYSQL_RES, MYSQL_ROW and
+MYSQL_FIELD.
+
+Signed-off-by: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>
+
+Author: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>
+Origin: upstream, https://github.com/yandex/ClickHouse/commit/d119f22e1322
+Bug: https://github.com/yandex/ClickHouse/issues/6552
+Bug-Ubuntu: https://bugs.launchpad.net/bugs/1840511
+Last-Update: 2019-08-20
+---
+ libs/libmysqlxx/include/mysqlxx/Types.h | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/libs/libmysqlxx/include/mysqlxx/Types.h b/libs/libmysqlxx/include/mysqlxx/Types.h
+index 30abdeb..b5ed709 100644
+--- a/libs/libmysqlxx/include/mysqlxx/Types.h
++++ b/libs/libmysqlxx/include/mysqlxx/Types.h
+@@ -3,6 +3,8 @@
+ #include <cstdint>
+ #include <string>
+ 
++#ifndef _mysql_h
++
+ struct st_mysql;
+ using MYSQL = st_mysql;
+ 
+@@ -14,7 +16,7 @@ using MYSQL_ROW = char**;
+ struct st_mysql_field;
+ using MYSQL_FIELD = st_mysql_field;
+ 
+-
++#endif
+ 
+ namespace mysqlxx
+ {
+-- 
+2.20.1
+
diff -Nru clickhouse-18.16.1+ds/debian/patches/0017-gcc9-mitigation-for-conditional-bug.patch clickhouse-18.16.1+ds/debian/patches/0017-gcc9-mitigation-for-conditional-bug.patch
--- clickhouse-18.16.1+ds/debian/patches/0017-gcc9-mitigation-for-conditional-bug.patch	1970-01-01 00:00:00.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/patches/0017-gcc9-mitigation-for-conditional-bug.patch	2019-08-20 22:07:15.000000000 +0000
@@ -0,0 +1,85 @@
+Description: GCC9 mitigation for conditional bug
+
+The following function:
+
+    std::string toString(const ColumnDefaultKind kind)
+    {
+        ...
+        return it != std::end(map) ? it->second : throw Exception{"Invalid
+            ColumnDefaultKind", ErrorCodes::LOGICAL_ERROR};
+    }
+
+causes gcc9 to crash while other similar function (in related syntax):
+
+    ColumnDefaultKind columnDefaultKindFromString(const std::string & str)
+    {
+        ...
+        return it != std::end(map) ? it->second : throw Exception{"Unknown
+            column default specifier: " + str, ErrorCodes::LOGICAL_ERROR};
+    }
+
+does not. Changing the syntax to:
+
+    std::string toString(const ColumnDefaultKind kind)
+    {
+        ...
+
+        const auto it = map.find(kind);
+
+        if (it == std::end(map))
+            throw Exception{"Invalid ColumnDefaultKind",
+                ErrorCodes::LOGICAL_ERROR};
+
+        return it->second;
+    }
+
+fixes the issue.
+
+Upstream bug: https://github.com/yandex/ClickHouse/issues/6560
+Upstream bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91493
+Upstream bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91500
+
+Signed-off-by: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>
+
+Author: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>
+Bug: https://github.com/yandex/ClickHouse/issues/6560
+Bug-Ubuntu: https://bugs.launchpad.net/bugs/1840511
+Last-Update: 2019-08-20
+
+---
+ dbms/src/Storages/ColumnDefault.cpp | 12 ++++++++++--
+ 1 file changed, 10 insertions(+), 2 deletions(-)
+
+diff --git a/dbms/src/Storages/ColumnDefault.cpp b/dbms/src/Storages/ColumnDefault.cpp
+index 19ba69c..27b8eb0 100644
+--- a/dbms/src/Storages/ColumnDefault.cpp
++++ b/dbms/src/Storages/ColumnDefault.cpp
+@@ -31,7 +31,11 @@ ColumnDefaultKind columnDefaultKindFromString(const std::string & str)
+     };
+ 
+     const auto it = map.find(str);
+-    return it != std::end(map) ? it->second : throw Exception{"Unknown column default specifier: " + str, ErrorCodes::LOGICAL_ERROR};
++
++    if (it == std::end(map))
++        throw Exception{"Unknown column default specifier: " + str, ErrorCodes::LOGICAL_ERROR};
++
++    return it->second;
+ }
+ 
+ 
+@@ -44,7 +48,11 @@ std::string toString(const ColumnDefaultKind kind)
+     };
+ 
+     const auto it = map.find(kind);
+-    return it != std::end(map) ? it->second : throw Exception{"Invalid ColumnDefaultKind", ErrorCodes::LOGICAL_ERROR};
++
++    if (it == std::end(map))
++        throw Exception{"Invalid ColumnDefaultKind", ErrorCodes::LOGICAL_ERROR};
++
++   return it->second;
+ }
+ 
+ 
+-- 
+2.20.1
+
diff -Nru clickhouse-18.16.1+ds/debian/patches/mysql.patch clickhouse-18.16.1+ds/debian/patches/mysql.patch
--- clickhouse-18.16.1+ds/debian/patches/mysql.patch	2019-08-20 11:39:54.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/patches/mysql.patch	1970-01-01 00:00:00.000000000 +0000
@@ -1,25 +0,0 @@
-Description: Use mysql.h constants
-Author: Gianfranco Costamagna <locutusofborg@debian.org>
-Last-Update: 2019-08-20
-
---- clickhouse-18.16.1+ds.orig/libs/libmysqlxx/include/mysqlxx/Types.h
-+++ clickhouse-18.16.1+ds/libs/libmysqlxx/include/mysqlxx/Types.h
-@@ -3,17 +3,7 @@
- #include <cstdint>
- #include <string>
- 
--struct st_mysql;
--using MYSQL = st_mysql;
--
--struct st_mysql_res;
--using MYSQL_RES = st_mysql_res;
--
--using MYSQL_ROW = char**;
--
--struct st_mysql_field;
--using MYSQL_FIELD = st_mysql_field;
--
-+#include <mysql/mysql.h>
- 
- 
- namespace mysqlxx
diff -Nru clickhouse-18.16.1+ds/debian/patches/series clickhouse-18.16.1+ds/debian/patches/series
--- clickhouse-18.16.1+ds/debian/patches/series	2019-08-20 11:39:54.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/patches/series	2019-08-20 22:07:15.000000000 +0000
@@ -13,4 +13,5 @@
 0013-server-config.xml-Set-log-level-to-warning.patch
 0014-Set-default-umask-to-027.patch
 0015-Fix-fallback-lz4-decomression.patch
-mysql.patch
+0016-MySQL-8-integr-reqs-previous-decl-checks.patch
+0017-gcc9-mitigation-for-conditional-bug.patch
diff -Nru clickhouse-18.16.1+ds/debian/rules clickhouse-18.16.1+ds/debian/rules
--- clickhouse-18.16.1+ds/debian/rules	2019-08-20 10:24:06.000000000 +0000
+++ clickhouse-18.16.1+ds/debian/rules	2019-08-20 22:07:15.000000000 +0000
@@ -5,9 +5,6 @@
 export DH_VERBOSE=1
 #export DEB_BUILD_OPTIONS+=nocheck
 
-export CC=gcc-8
-export CXX=g++-8
-
 DEB_HOST_ARCH := $(shell dpkg-architecture -qDEB_HOST_ARCH)
 
 SKIP_TESTS=long
@@ -30,6 +27,24 @@
 	SKIP_TESTS+=00047
 endif
 
+#
+# LP: #1840511 cleanup
+#
+
+# libm precision on exp() related functions
+SKIP_TESTS+=00536 00534
+
+# long_http_bufferization ?
+SKIP_TESTS+=00429
+
+# system processes port ? (bind: error already in use)
+SKIP_TESTS+=00379
+
+# clickhouse-clang not found
+SKIP_TESTS+=00281
+
+# end of LP: #1840511 cleanup
+
 export TEST_OPT=--skip ${SKIP_TESTS}
 
 ifdef DH_VERBOSE