Merge pull request #10359 from ClickHouse/system-tables-lazy-load

System tables eager creation, continuation

src/Interpreters/SystemLog.cpp

@@ -96,6 +96,14 @@ SystemLogs::SystemLogs(Context & global_context, const Poco::Util::AbstractConfi
         logs.emplace_back(text_log.get());
     if (metric_log)
         logs.emplace_back(metric_log.get());
+
+    bool lazy_load = config.getBool("system_tables_lazy_load", true);
+    for (auto & log : logs)
+    {
+        if (!lazy_load)
+            log->prepareTable();
+        log->startup();
+    }
 }
 
 

src/Interpreters/SystemLog.h

@@ -73,6 +73,8 @@ public:
     virtual String getName() = 0;
     virtual ASTPtr getCreateTableQuery() = 0;
     virtual void flush() = 0;
+    virtual void prepareTable() = 0;
+    virtual void startup() = 0;
     virtual void shutdown() = 0;
     virtual ~ISystemLog() = default;
 };
@@ -129,6 +131,9 @@ public:
     /// Flush data in the buffer to disk
     void flush() override;
 
+    /// Start the background thread.
+    void startup() override;
+
     /// Stop the background flush thread before destructor. No more data will be written.
     void shutdown() override
     {
@@ -177,7 +182,7 @@ private:
       * Renames old table if its structure is not suitable.
       * This cannot be done in constructor to avoid deadlock while renaming a table under locked Context when SystemLog object is created.
       */
-    void prepareTable();
+    void prepareTable() override;
 
     /// flushImpl can be executed only in saving_thread.
     void flushImpl(const std::vector<LogElement> & to_flush, uint64_t to_flush_end);
@@ -197,7 +202,12 @@ SystemLog<LogElement>::SystemLog(Context & context_,
 {
     assert(database_name_ == DatabaseCatalog::SYSTEM_DATABASE);
     log = &Logger::get("SystemLog (" + database_name_ + "." + table_name_ + ")");
+}
+
 
+template <typename LogElement>
+void SystemLog<LogElement>::startup()
+{
     saving_thread = ThreadFromGlobalPool([this] { savingThreadFunction(); });
 }
 

tests/integration/test_system_tables_non_lazy_load/configs/config_non_lazy.xml

+<?xml version="1.0"?>
+<yandex>
+    <system_tables_lazy_load>false</system_tables_lazy_load>
+</yandex>

tests/integration/test_system_tables_non_lazy_load/test_system_tables_non_lazy_load.py

+import time
+import pytest
+import os
+
+from helpers.cluster import ClickHouseCluster
+
+cluster = ClickHouseCluster(__file__)
+node1 = cluster.add_instance('node1', config_dir="configs")
+
+@pytest.fixture(scope="module")
+def start_cluster():
+    try:
+        cluster.start()
+        yield cluster
+    finally:
+        cluster.shutdown()
+
+def test_system_tables_non_lazy_load(start_cluster):
+    assert node1.query_and_get_error("SELECT * FROM system.part_log") == ""
+    assert node1.query_and_get_error("SELECT * FROM system.query_log") == ""
+    assert node1.query_and_get_error("SELECT * FROM system.query_thread_log") == ""
+    assert node1.query_and_get_error("SELECT * FROM system.text_log") == ""
+    assert node1.query_and_get_error("SELECT * FROM system.trace_log") == ""
+    assert node1.query_and_get_error("SELECT * FROM system.metric_log") == ""