Allow to disable replicated max parallel fetches/sends [#CLICKHOUSE-2960].

dbms/src/Storages/MergeTree/DataPartsExchange.cpp

@@ -55,8 +55,8 @@ void Service::processQuery(const Poco::Net::HTMLForm & params, ReadBuffer & body
 
     static std::atomic_uint total_sends {0};
 
-    if (total_sends >= data.settings.replicated_max_parallel_sends
-        || data.current_table_sends >= data.settings.replicated_max_parallel_sends_for_table)
+    if ((data.settings.replicated_max_parallel_sends && total_sends >= data.settings.replicated_max_parallel_sends)
+        || (data.settings.replicated_max_parallel_sends_for_table && data.current_table_sends >= data.settings.replicated_max_parallel_sends_for_table))
     {
         response.setStatus(std::to_string(HTTP_TOO_MANY_REQUESTS));
         response.setReason("Too many concurrent fetches, try again later");

dbms/src/Storages/MergeTree/MergeTreeSettings.h

 #pragma once
 
 #include <Poco/Util/AbstractConfiguration.h>
+#include <Core/Defines.h>
 #include <Core/Types.h>
 
 

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -1255,7 +1255,7 @@ bool StorageReplicatedMergeTree::executeLogEntry(const LogEntry & entry)
         String replica = findReplicaHavingCoveringPart(entry.new_part_name, true, covering_part);
 
         static std::atomic_uint total_fetches {0};
-        if (total_fetches >= data.settings.replicated_max_parallel_fetches)
+        if (data.settings.replicated_max_parallel_fetches && total_fetches >= data.settings.replicated_max_parallel_fetches)
         {
             throw Exception("Too much total fetches from replicas, maximum: " + toString(data.settings.replicated_max_parallel_fetches),
                 ErrorCodes::TOO_MUCH_FETCHES);
@@ -1264,7 +1264,7 @@ bool StorageReplicatedMergeTree::executeLogEntry(const LogEntry & entry)
         ++total_fetches;
         SCOPE_EXIT({--total_fetches;});
 
-        if (current_table_fetches >= data.settings.replicated_max_parallel_fetches_for_table)
+        if (data.settings.replicated_max_parallel_fetches_for_table && current_table_fetches >= data.settings.replicated_max_parallel_fetches_for_table)
         {
             throw Exception("Too much fetches from replicas for table, maximum: " + toString(data.settings.replicated_max_parallel_fetches_for_table),
                 ErrorCodes::TOO_MUCH_FETCHES);