Fix Log family table return wrong rows count after truncate (#50585)

* Fix Log family table return wrong rows count after truncate

* fix test

* update test

* update test

src/Storages/StorageLog.cpp

@@ -775,6 +775,8 @@ void StorageLog::truncate(const ASTPtr &, const StorageMetadataPtr &, ContextPtr
 
     marks_loaded = true;
     num_marks_saved = 0;
+    total_rows = 0;
+    total_bytes = 0;
     getContext()->dropMMappedFileCache();
 }
 

src/Storages/StorageStripeLog.cpp

@@ -424,6 +424,8 @@ void StorageStripeLog::truncate(const ASTPtr &, const StorageMetadataPtr &, Cont
 
     indices_loaded = true;
     num_indices_saved = 0;
+    total_rows = 0;
+    total_bytes = 0;
     getContext()->dropMMappedFileCache();
 }
 

tests/queries/0_stateless/02771_log_faminy_truncate_count.reference

@@ -0,0 +1,2 @@
+0
+0

tests/queries/0_stateless/02771_log_faminy_truncate_count.sql

@@ -0,0 +1,26 @@
+DROP TABLE IF EXISTS test_log;
+CREATE TABLE test_log
+(
+    `crypto_name` String,
+    `trade_date` Date
+)
+ENGINE = Log;
+
+INSERT INTO test_log (crypto_name, trade_date) VALUES ('abc', '2021-01-01'), ('def', '2022-02-02');
+
+TRUNCATE TABLE test_log;
+SELECT count() FROM  test_log;
+
+DROP TABLE IF EXISTS test_log;
+CREATE TABLE test_log
+(
+    `crypto_name` String,
+    `trade_date` Date
+)
+ENGINE = StripeLog;
+
+INSERT INTO test_log (crypto_name, trade_date) VALUES ('abc', '2021-01-01'), ('def', '2022-02-02');
+
+TRUNCATE TABLE test_log;
+SELECT count() FROM  test_log;
+DROP TABLE test_log;