add system sync file cache

src/Access/Common/AccessType.h

@@ -171,6 +171,7 @@ enum class AccessType
     M(SYSTEM_WAIT_LOADING_PARTS, "WAIT LOADING PARTS", TABLE, SYSTEM) \
     M(SYSTEM_SYNC_DATABASE_REPLICA, "SYNC DATABASE REPLICA", DATABASE, SYSTEM) \
     M(SYSTEM_SYNC_TRANSACTION_LOG, "SYNC TRANSACTION LOG", GLOBAL, SYSTEM) \
+    M(SYSTEM_SYNC_FILE_CACHE, "SYNC SYSCALL", GLOBAL, SYSTEM) \
     M(SYSTEM_FLUSH_DISTRIBUTED, "FLUSH DISTRIBUTED", TABLE, SYSTEM_FLUSH) \
     M(SYSTEM_FLUSH_LOGS, "FLUSH LOGS", GLOBAL, SYSTEM_FLUSH) \
     M(SYSTEM_FLUSH, "", GROUP, SYSTEM) \

src/Interpreters/InterpreterSystemQuery.cpp

@@ -56,6 +56,7 @@
 #include <Common/ThreadFuzzer.h>
 #include <csignal>
 #include <algorithm>
+#include <unistd.h>
 
 #include "config.h"
 
@@ -292,6 +293,13 @@ BlockIO InterpreterSystemQuery::execute()
             res->wait();
             break;
         }
+        case Type::SYNC_FILE_CACHE:
+        {
+            // It's too heavy.
+            LOG_DEBUG(log, "will call syscall sync() function, It's too heavy.");
+            sync();
+            break;
+        }
         case Type::DROP_DNS_CACHE:
         {
             getContext()->checkAccess(AccessType::SYSTEM_DROP_DNS_CACHE);
@@ -1133,6 +1141,11 @@ AccessRightsElements InterpreterSystemQuery::getRequiredAccessForDDLOnCluster()
             required_access.emplace_back(AccessType::SYSTEM_UNFREEZE);
             break;
         }
+        case Type::SYNC_FILE_CACHE:
+        {
+            required_access.emplace_back(AccessType::SYSTEM_SYNC_FILE_CACHE);
+            break;
+        }
         case Type::STOP_LISTEN_QUERIES:
         case Type::START_LISTEN_QUERIES:
         case Type::STOP_THREAD_FUZZER:

src/Parsers/ASTSystemQuery.cpp

@@ -206,6 +206,10 @@ void ASTSystemQuery::formatImpl(const FormatSettings & settings, FormatState &,
     {
         settings.ostr << (settings.hilite ? hilite_identifier : "") << backQuoteIfNeed(backup_name);
     }
+    else if (type == Type::SYNC_FILE_CACHE)
+    {
+        settings.ostr << (settings.hilite ? hilite_none : "");
+    }
 }
 
 

src/Parsers/ASTSystemQuery.h

@@ -42,6 +42,7 @@ public:
         SYNC_REPLICA,
         SYNC_DATABASE_REPLICA,
         SYNC_TRANSACTION_LOG,
+        SYNC_FILE_CACHE,
         RELOAD_DICTIONARY,
         RELOAD_DICTIONARIES,
         RELOAD_MODEL,