Re-commit in git:

MDEV-406: ANALYZE $stmt - Ported the old patch to new explain code - New SQL syntax (ANALYZE $stmt) - ANALYZE UPDATE/DELETE is now supported (because EXPLAIN UPDATE/DELETE is supported) - Basic counters are calculated for basic kinds of queries (still need to see what happens with join buffer, ORDER BY...LIMIT queries, etc)

Author: spetrunia

sql/sql_class.cc

@@ -2282,6 +2282,9 @@ int THD::send_explain_fields(select_result *result)
 /*
  Populate the provided field_list with EXPLAIN output columns.
  this->lex->describe has the EXPLAIN flags
+
+ The set/order of columns must be kept in sync with 
+ Explain_query::print_explain and co.
 */
 
 void THD::make_explain_field_list(List<Item> &field_list)
@@ -2317,11 +2320,25 @@ void THD::make_explain_field_list(List<Item> &field_list)
  item->maybe_null=1;
  field_list.push_back(item= new Item_return_int("rows", 10,
  MYSQL_TYPE_LONGLONG));
- if (lex->describe & DESCRIBE_EXTENDED)
+ if (lex->analyze_stmt)
+ {
+ field_list.push_back(item= new Item_return_int("r_rows", 10,
+ MYSQL_TYPE_LONGLONG));
+ item->maybe_null=1;
+ }
+
+ if (lex->analyze_stmt || lex->describe & DESCRIBE_EXTENDED)
  {
  field_list.push_back(item= new Item_float("filtered", 0.1234, 2, 4));
  item->maybe_null=1;
  }
+
+ if (lex->analyze_stmt)
+ {
+ field_list.push_back(item= new Item_float("r_filtered", 0.1234, 2, 4));
+ item->maybe_null=1;
+ }
+
  item->maybe_null= 1;
  field_list.push_back(new Item_empty_string("Extra", 255, cs));
 }

sql/sql_class.h

@@ -3959,6 +3959,18 @@ class select_send :public select_result {
  virtual void cleanup();
 };
 
+class select_send_analyze : public select_send
+{
+bool discard_data;
+ bool send_result_set_metadata(List<Item> &list, uint flags) { return 0; }
+ /* 
+ ANALYZE-todo: we should call val_int() (or val_str() or whatever) to
+ compute the columns. If we don't, it's not full execution.
+ */
+ int send_data(List<Item> &items) { return 0; }
+ bool send_eof() { return 0; }
+ void abort_result_set() {}
+};
 
 class select_to_file :public select_result_interceptor {
 protected:

sql/sql_delete.cc

@@ -223,6 +223,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
  killed_state killed_status= NOT_KILLED;
  THD::enum_binlog_query_type query_type= THD::ROW_QUERY_TYPE;
  bool with_select= !select_lex->item_list.is_empty();
+ Explain_delete *explain;
  Delete_plan query_plan(thd->mem_root);
  query_plan.index= MAX_KEY;
  query_plan.using_filesort= FALSE;
@@ -538,9 +539,11 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
  goto cleanup;
  }
 
+ explain= (Explain_delete*)thd->lex->explain->get_upd_del_plan();
  while (!(error=info.read_record(&info)) && !thd->killed &&
  ! thd->is_error())
  {
+ explain->on_record_read();
  if (table->vfield)
  update_virtual_fields(thd, table,
  table->triggers ? VCOL_UPDATE_ALL :
@@ -549,6 +552,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
  // thd->is_error() is tested to disallow delete row on error
  if (!select || select->skip_record(thd) > 0)
  {
+ explain->on_record_after_where();
  if (table->triggers &&
  table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
  TRG_ACTION_BEFORE, FALSE))
@@ -666,6 +670,11 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
  }
  DBUG_ASSERT(transactional_table || !deleted || thd->transaction.stmt.modified_non_trans_table);
  free_underlaid_joins(thd, select_lex);
+ if (thd->lex->analyze_stmt)
+ {
+ error= thd->lex->explain->send_explain(thd);
+ }
+ else
  if (error < 0 || 
  (thd->lex->ignore && !thd->is_error() && !thd->is_fatal_error))
  {