Added a test for RENAME / Merge table race condition

dbms/tests/queries/0_stateless/01001_rename_merge_race_condition.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+set -e
+
+$CLICKHOUSE_CLIENT --query "DROP TABLE IF EXISTS test1";
+$CLICKHOUSE_CLIENT --query "DROP TABLE IF EXISTS test2";
+$CLICKHOUSE_CLIENT --query "CREATE TABLE test1 (x UInt64) ENGINE = Memory";
+
+
+function thread1()
+{
+    while true; do 
+        seq 1 1000 | sed -r -e 's/.+/RENAME TABLE test1 TO test2; RENAME TABLE test2 TO test1;/' | $CLICKHOUSE_CLIENT -n
+    done
+}
+
+function thread2()
+{
+    while true; do
+        $CLICKHOUSE_CLIENT --query "SELECT * FROM merge(currentDatabase(), '^test[12]$')"
+    done
+}
+
+# https://stackoverflow.com/questions/9954794/execute-a-shell-function-with-timeout
+export -f thread1;
+export -f thread2;
+
+TIMEOUT=10
+
+timeout $TIMEOUT bash -c thread1 2> /dev/null &
+timeout $TIMEOUT bash -c thread2 2> /dev/null &
+
+wait
+
+$CLICKHOUSE_CLIENT --query "DROP TABLE IF EXISTS test1";
+$CLICKHOUSE_CLIENT --query "DROP TABLE IF EXISTS test2";