Adding upstream version 1:10.11.6.upstream/1%10.11.6upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 173 insertions, 0 deletions

diff --git a/sql/select_handler.cc b/sql/select_handler.cc
new file mode 100644
index 00000000..b0b8e586
--- /dev/null
+++ b/sql/select_handler.cc
@@ -0,0 +1,173 @@
+/*
+   Copyright (c) 2018, 2020, MariaDB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1301 USA */
+
+#include "mariadb.h"
+#include "sql_priv.h"
+#include "sql_select.h"
+#include "select_handler.h"
+
+
+/**
+  The methods of the select_handler class.
+
+  The objects of this class are used for pushdown of the select queries
+  into engines. The main  method of the class is select_handler::execute()
+  that initiates execution of a select query by a foreign engine, receives the
+  rows of the result set, put it in a buffer of a temporary table and send
+  them from the buffer directly into output.
+
+  The method uses the functions of the select_handle interface to do this.
+  It also employes plus some helper functions to create the needed temporary
+  table and to send rows from the temporary table into output.
+  The constructor of the class gets the select_handler interface as a parameter.
+*/
+
+
+select_handler::select_handler(THD *thd_arg, handlerton *ht_arg)
+ : thd(thd_arg), ht(ht_arg), table(NULL),
+   is_analyze(thd_arg->lex->analyze_stmt)
+{}
+
+
+select_handler::~select_handler()
+{
+  if (table)
+    free_tmp_table(thd, table);
+}
+
+
+TABLE *select_handler::create_tmp_table(THD *thd, SELECT_LEX *select)
+{
+  List<Item> types;
+  TMP_TABLE_PARAM tmp_table_param;
+  TABLE *table;
+  DBUG_ENTER("select_handler::create_tmp_table");
+
+  if (select->master_unit()->join_union_item_types(thd, types, 1))
+    DBUG_RETURN(NULL);
+  tmp_table_param.init();
+  tmp_table_param.field_count= tmp_table_param.func_count= types.elements;
+  table= ::create_tmp_table(thd, &tmp_table_param, types,
+                            (ORDER *) 0, false, 0,
+                            TMP_TABLE_ALL_COLUMNS, 1,
+                            &empty_clex_str, true, false);
+  DBUG_RETURN(table);
+}
+
+
+bool select_handler::prepare()
+{
+  DBUG_ENTER("select_handler::prepare");
+  /*
+    Some engines (e.g. XPand) initialize "table" on their own.
+    So we need to create a temporary table only if "table" is NULL.
+  */
+  if (!table && !(table= create_tmp_table(thd, select)))
+    DBUG_RETURN(true);
+  DBUG_RETURN(table->fill_item_list(&result_columns));
+}
+
+
+bool select_handler::send_result_set_metadata()
+{
+  DBUG_ENTER("select_handler::send_result_set_metadata");
+
+#ifdef WITH_WSREP
+  if (WSREP(thd) && thd->wsrep_retry_query)
+  {
+    WSREP_DEBUG("skipping select metadata");
+    DBUG_RETURN(false);
+  }
+  #endif /* WITH_WSREP */
+  if (select->join->result->send_result_set_metadata(result_columns,
+                                         Protocol::SEND_NUM_ROWS |
+                                         Protocol::SEND_EOF))
+    DBUG_RETURN(true);
+
+  DBUG_RETURN(false);
+}
+
+
+bool select_handler::send_data()
+{
+  DBUG_ENTER("Pushdown_select::send_data");
+
+  if (select->join->result->send_data(result_columns))
+    DBUG_RETURN(true);
+
+  DBUG_RETURN(false);
+}
+
+
+bool select_handler::send_eof()
+{
+  DBUG_ENTER("select_handler::send_eof");
+
+  if (select->join->result->send_eof())
+    DBUG_RETURN(true);
+  DBUG_RETURN(false);
+}
+
+
+int select_handler::execute()
+{
+  int err;
+
+  DBUG_ENTER("select_handler::execute");
+
+  if ((err= init_scan()))
+    goto error;
+
+  if (is_analyze)
+  {
+    end_scan();
+    DBUG_RETURN(0);
+  }
+
+  if (send_result_set_metadata())
+    DBUG_RETURN(-1);
+
+  while (!(err= next_row()))
+  {
+    if (thd->check_killed() || send_data())
+    {
+      end_scan();
+      DBUG_RETURN(-1);
+    }
+  }
+
+  if (err != 0 && err != HA_ERR_END_OF_FILE)
+    goto error;
+
+  if ((err= end_scan()))
+   goto error_2;
+
+  if (send_eof())
+    DBUG_RETURN(-1);
+
+  DBUG_RETURN(0);
+
+error:
+  end_scan();
+error_2:
+  print_error(err, MYF(0));
+  DBUG_RETURN(-1);                              // Error not sent to client
+}
+
+void select_handler::print_error(int error, myf errflag)
+{
+  my_error(ER_GET_ERRNO, MYF(0), error, hton_name(ht)->str);
+}