Add a stress test for DROP TABLE

tests/queries/0_stateless/01516_drop_table_stress.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. "$CURDIR"/../shell_config.sh
+
+function drop_database()
+{
+    # redirect stderr since it is racy with DROP TABLE
+    # and tries to remove db_01516.data too.
+    ${CLICKHOUSE_CLIENT} -q "DROP DATABASE IF EXISTS db_01516" 2>/dev/null
+}
+
+function drop_table()
+{
+    ${CLICKHOUSE_CLIENT} -nm <<EOL
+DROP TABLE IF EXISTS db_01516.data3;
+DROP TABLE IF EXISTS db_01516.data1;
+DROP TABLE IF EXISTS db_01516.data2;
+EOL
+}
+
+function create()
+{
+    ${CLICKHOUSE_CLIENT} -nm <<EOL
+CREATE DATABASE IF NOT EXISTS db_01516;
+CREATE TABLE IF NOT EXISTS db_01516.data1 Engine=MergeTree() ORDER BY number AS SELECT * FROM numbers(1);
+CREATE TABLE IF NOT EXISTS db_01516.data2 Engine=MergeTree() ORDER BY number AS SELECT * FROM numbers(1);
+CREATE TABLE IF NOT EXISTS db_01516.data3 Engine=MergeTree() ORDER BY number AS SELECT * FROM numbers(1);
+EOL
+}
+
+for _ in {1..100}; do
+    create
+    drop_table &
+    drop_database &
+    wait
+done