test that storage URL does not call server on empty data

Author: CheSema

tests/queries/0_stateless/03519_storage_url.reference

@@ -0,0 +1,42 @@
+dst_remote	2	1
+dst_remote	4	1
+dst_remote	100	1
+dst_remote	200	1
+dst_remote	300	1
+dst_remote	400	1
+Row 1:
+──────
+query:           insert into dst_remote format TSV
+
+written_rows:    2
+HTTPRequests:    0
+HTTPConnections: 0
+
+Row 2:
+──────
+query:           insert into dst_remote format TSV
+
+written_rows:    4
+HTTPRequests:    0
+HTTPConnections: 0
+
+Row 3:
+──────
+query:           insert into src values 
+written_rows:    4
+HTTPRequests:    0
+HTTPConnections: 0
+
+Row 4:
+──────
+query:           insert into src values 
+written_rows:    6
+HTTPRequests:    1
+HTTPConnections: 1
+
+Row 5:
+──────
+query:           insert into src values 
+written_rows:    8
+HTTPRequests:    1
+HTTPConnections: 1

tests/queries/0_stateless/03519_storage_url.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+set -eu
+
+$CLICKHOUSE_CLIENT -q "
+drop table if exists src;
+drop table if exists dst_remote;
+drop table if exists dst;
+drop table if exists mv;
+"
+
+$CLICKHOUSE_CLIENT -q "
+create table src (key Int, value Int)
+engine=MergeTree()
+ORDER BY key;
+
+create table dst_remote (key Int, value Int)
+engine=MergeTree()
+ORDER BY key;
+
+create table dst (key Int, value Int)
+engine=URL('${CLICKHOUSE_URL}&query=insert+into+dst_remote+format+TSV', TSV);
+
+create materialized view mv to dst
+as select * from src where value > 0;
+"
+
+$CLICKHOUSE_CLIENT -q "
+insert into src values (1, 0), (2, 1), (3, 0), (4, 1);
+
+insert into src values (10, 0), (20, 0), (30, 0), (40, 0);
+
+insert into src values (100, 1), (200, 1), (300, 1), (400, 1);
+"
+
+$CLICKHOUSE_CLIENT -q "
+select 'dst_remote', * from dst_remote order by ALL;
+"
+
+$CLICKHOUSE_CLIENT -q "
+system flush logs query_log;
+
+select query, written_rows, ProfileEvents['ReadWriteBufferFromHTTPRequestsSent'] + ProfileEvents['WriteBufferFromHTTPRequestsSent'] as HTTPRequests, ProfileEvents['StorageConnectionsCreated'] + ProfileEvents['StorageConnectionsReused'] as HTTPConnections
+from system.query_log
+where
+    current_database = '${CLICKHOUSE_DATABASE}' and
+    type = 'QueryFinish' and
+    query_kind = 'Insert'
+order by ALL
+format Vertical;
+"