MDEV-17124: mariadb 10.1.34, views and prepared statements: ERROR 1615 (HY000): Prepared statement needs to be re-prepared

The problem is that if table definition cache (TDC) is full of real tables
which are in tables cache, view definition can not stay there so will be
removed by its own underlying tables.
In situation above old mechanism of detection matching definition in PS
and current version always require reprepare and so prevent executing
the PS.

One work around is to increase TDC, other - improve version check for
views/triggers (which is done here). Now in suspicious cases we check:
 - timestamp (microseconds) of the view to be sure that version really
   have changed;
 - time (microseconds) of creation of a trigger related to time
   (microseconds) of statement preparation.

1 files changed, 59 insertions, 8 deletions

diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index b0b4b075046..68a8410f559 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -786,7 +786,7 @@ static File_option view_parameters[]=
   my_offsetof(TABLE_LIST, with_check),
   FILE_OPTIONS_ULONGLONG},
  {{ STRING_WITH_LEN("timestamp")},
-  my_offsetof(TABLE_LIST, timestamp),
+  my_offsetof(TABLE_LIST, hr_timestamp),
   FILE_OPTIONS_TIMESTAMP},
  {{ STRING_WITH_LEN("create-version")},
   my_offsetof(TABLE_LIST, file_version),
@@ -810,6 +810,15 @@ static File_option view_parameters[]=
   FILE_OPTIONS_STRING}
 };
 
+
+static File_option view_timestamp_parameters[]=
+{
+
+ {{ C_STRING_WITH_LEN("timestamp")}, 0, FILE_OPTIONS_TIMESTAMP},
+ {{NullS, 0}, 0, FILE_OPTIONS_STRING}
+};
+
+
 static LEX_CSTRING view_file_type[]= {{STRING_WITH_LEN("VIEW") }};
 
 
@@ -827,8 +836,8 @@ int mariadb_fix_view(THD *thd, TABLE_LIST *view, bool wrong_checksum,
                      &path, path_buff, sizeof(path_buff),
                      &file, view);
   /* init timestamp */
-  if (!view->timestamp.str)
-    view->timestamp.str= view->timestamp_buffer;
+  if (!view->hr_timestamp.str)
+    view->hr_timestamp.str= view->timestamp_buffer;
 
   if (swap_alg && view->algorithm != VIEW_ALGORITHM_UNDEFINED)
   {
@@ -1029,8 +1038,8 @@ loop_out:
                      &path, path_buff, sizeof(path_buff),
                      &file, view);
   /* init timestamp */
-  if (!view->timestamp.str)
-    view->timestamp.str= view->timestamp_buffer;
+  if (!view->hr_timestamp.str)
+    view->hr_timestamp.str= view->timestamp_buffer;
 
   /* check old .frm */
   {
@@ -1155,7 +1164,32 @@ err:
   DBUG_RETURN(error);
 }
 
+/**
+  Reads view definition "version"
 
+  @param[in]  share               Share object of view
+
+  @return true on error, otherwise false
+*/
+
+bool mariadb_view_version_get(TABLE_SHARE *share)
+{
+  DBUG_ASSERT(share->is_view);
+
+  if (!(share->tabledef_version.str=
+        (uchar*) alloc_root(&share->mem_root,
+                            MICROSECOND_TIMESTAMP_BUFFER_SIZE)))
+    return TRUE;
+  share->tabledef_version.length= 0; // safety if the drfinition file is brocken
+
+  DBUG_ASSERT(share->view_def != NULL);
+  if (share->view_def->parse((uchar *) &share->tabledef_version, NULL,
+                             view_timestamp_parameters, 1,
+                             &file_parser_dummy_hook))
+    return TRUE;
+  DBUG_ASSERT(share->tabledef_version.length == MICROSECOND_TIMESTAMP_BUFFER_SIZE-1);
+  return FALSE;
+}
 
 /**
   read VIEW .frm and create structures
@@ -1217,6 +1251,10 @@ bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table,
     mysql_derived_reinit(thd, NULL, table);
 
     DEBUG_SYNC(thd, "after_cached_view_opened");
+    if (!share->tabledef_version.length)
+    {
+      mariadb_view_version_get(share);
+    }
     DBUG_RETURN(0);
   }
 
@@ -1253,8 +1291,8 @@ bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table,
   arena= thd->activate_stmt_arena_if_needed(&backup);
 
   /* init timestamp */
-  if (!table->timestamp.str)
-    table->timestamp.str= table->timestamp_buffer;
+  if (!table->hr_timestamp.str)
+    table->hr_timestamp.str= table->timestamp_buffer;
   /* prepare default values for old format */
   table->view_suid= TRUE;
   table->definer.user.str= table->definer.host.str= 0;
@@ -1270,6 +1308,19 @@ bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table,
                                       required_view_parameters,
                                       &file_parser_dummy_hook)))
     goto end;
+  if (!share->tabledef_version.length)
+  {
+    share->tabledef_version.str= (const uchar *)
+                                 memdup_root(&share->mem_root,
+                                             (const void *)
+                                             table->hr_timestamp.str,
+                                             (share->tabledef_version.length=
+                                              table->hr_timestamp.length));
+  }
+  if (!table->tabledef_version.length)
+  {
+    table->set_view_def_version(&table->hr_timestamp);
+  }
 
   /*
     check old format view .frm
@@ -2200,7 +2251,7 @@ mysql_rename_view(THD *thd,
       object for it.
     */
     view_def.reset();
-    view_def.timestamp.str= view_def.timestamp_buffer;
+    view_def.hr_timestamp.str= view_def.timestamp_buffer;
     view_def.view_suid= TRUE;
 
     /* get view definition and source */