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ðŸ“„ aligned.h(1.11 KB)
ðŸ“„ aria_backup.h(1.51 KB)
ðŸ“„ assume_aligned.h(2.29 KB)
ðŸ“ atomic
ðŸ“„ authors.h(9.9 KB)
ðŸ“„ backup.h(1.66 KB)
ðŸ“„ bounded_queue.h(5.95 KB)
ðŸ“„ client_settings.h(1.89 KB)
ðŸ“„ compat56.h(2.23 KB)
ðŸ“„ config.h(14.23 KB)
ðŸ“„ contributors.h(4.76 KB)
ðŸ“„ create_options.h(4.42 KB)
ðŸ“„ create_tmp_table.h(2.74 KB)
ðŸ“„ cset_narrowing.h(3.88 KB)
ðŸ“„ custom_conf.h(1.06 KB)
ðŸ“„ datadict.h(1.66 KB)
ðŸ“„ ddl_log.h(12.39 KB)
ðŸ“„ debug.h(1.21 KB)
ðŸ“„ debug_sync.h(2 KB)
ðŸ“„ derived_handler.h(2.32 KB)
ðŸ“„ derror.h(980 B)
ðŸ“„ des_key_file.h(1.21 KB)
ðŸ“„ discover.h(1.53 KB)
ðŸ“„ dur_prop.h(1.06 KB)
ðŸ“„ embedded_priv.h(1.69 KB)
ðŸ“„ event_data_objects.h(4.09 KB)
ðŸ“„ event_db_repository.h(3.56 KB)
ðŸ“„ event_parse_data.h(2.83 KB)
ðŸ“„ event_queue.h(3.36 KB)
ðŸ“„ event_scheduler.h(3.21 KB)
ðŸ“„ events.h(4.59 KB)
ðŸ“„ field.h(215.25 KB)
ðŸ“„ field_comp.h(1.15 KB)
ðŸ“„ filesort.h(7.11 KB)
ðŸ“„ filesort_utils.h(8 KB)
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ðŸ“„ gcalc_tools.h(11.62 KB)
ðŸ“„ grant.h(2.69 KB)
ðŸ“„ group_by_handler.h(3.45 KB)
ðŸ“„ gstream.h(2.38 KB)
ðŸ“„ ha_handler_stats.h(2.28 KB)
ðŸ“„ ha_partition.h(62.9 KB)
ðŸ“„ ha_sequence.h(6.1 KB)
ðŸ“„ handle_connections_win.h(884 B)
ðŸ“„ handler.h(196.46 KB)
ðŸ“„ hash.h(4.34 KB)
ðŸ“„ hash_filo.h(5.55 KB)
ðŸ“„ heap.h(9.26 KB)
ðŸ“„ hostname.h(5.29 KB)
ðŸ“„ ilist.h(6.88 KB)
ðŸ“„ init.h(852 B)
ðŸ“„ innodb_priv.h(1.29 KB)
ðŸ“„ item.h(272.64 KB)
ðŸ“„ item_cmpfunc.h(131.86 KB)
ðŸ“„ item_create.h(11.23 KB)
ðŸ“„ item_func.h(133.45 KB)
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ðŸ“„ item_row.h(5.1 KB)
ðŸ“„ item_strfunc.h(70.55 KB)
ðŸ“„ item_subselect.h(57.77 KB)
ðŸ“„ item_sum.h(70.59 KB)
ðŸ“„ item_timefunc.h(63.1 KB)
ðŸ“„ item_vers.h(4.23 KB)
ðŸ“„ item_windowfunc.h(33.51 KB)
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ðŸ“„ json_table.h(9.28 KB)
ðŸ“„ key.h(2.08 KB)
ðŸ“„ keycaches.h(1.95 KB)
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ðŸ“„ lf.h(6.31 KB)
ðŸ“„ lock.h(2.15 KB)
ðŸ“„ log.h(45 KB)
ðŸ“„ log_event.h(182.04 KB)
ðŸ“„ log_event_data_type.h(1.85 KB)
ðŸ“„ log_event_old.h(19.37 KB)
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ðŸ“„ maria.h(5.73 KB)
ðŸ“„ mariadb.h(1.25 KB)
ðŸ“„ mdl.h(37.57 KB)
ðŸ“„ mem_root_array.h(6.94 KB)
ðŸ“„ message.h(1.17 KB)
ðŸ“„ multi_range_read.h(22.64 KB)
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ðŸ“„ my_apc.h(4.64 KB)
ðŸ“„ my_atomic.h(7.11 KB)
ðŸ“„ my_atomic_wrapper.h(2.98 KB)
ðŸ“„ my_base.h(26.57 KB)
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ðŸ“„ my_bitmap.h(5.74 KB)
ðŸ“„ my_check_opt.h(2.56 KB)
ðŸ“„ my_compare.h(10.93 KB)
ðŸ“„ my_counter.h(1.68 KB)
ðŸ“„ my_cpu.h(4.74 KB)
ðŸ“„ my_crypt.h(904 B)
ðŸ“„ my_decimal.h(14.15 KB)
ðŸ“„ my_default.h(1.84 KB)
ðŸ“„ my_handler_errors.h(4.77 KB)
ðŸ“„ my_json_writer.h(17.95 KB)
ðŸ“„ my_libwrap.h(1.16 KB)
ðŸ“„ my_md5.h(1.45 KB)
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ðŸ“„ my_service_manager.h(2 KB)
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ðŸ“„ my_time.h(10.22 KB)
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ðŸ“„ my_uctype.h(67.9 KB)
ðŸ“„ my_user.h(1.1 KB)
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ðŸ“„ myisamchk.h(4.61 KB)
ðŸ“„ myisammrg.h(4.78 KB)
ðŸ“„ myisampack.h(14.58 KB)
ðŸ“„ mysqld.h(39.55 KB)
ðŸ“„ mysqld_default_groups.h(204 B)
ðŸ“„ mysqld_suffix.h(1.17 KB)
ðŸ“„ mysys_err.h(2.95 KB)
ðŸ“„ opt_range.h(58.19 KB)
ðŸ“„ opt_subselect.h(14.21 KB)
ðŸ“„ opt_trace.h(8.29 KB)
ðŸ“„ opt_trace_context.h(3.21 KB)
ðŸ“„ parse_file.h(4.28 KB)
ðŸ“„ partition_element.h(5.09 KB)
ðŸ“„ partition_info.h(18.85 KB)
ðŸ“„ password.h(1.14 KB)
ðŸ“„ pfs_file_provider.h(3.08 KB)
ðŸ“„ pfs_idle_provider.h(1.35 KB)
ðŸ“„ pfs_memory_provider.h(1.59 KB)
ðŸ“„ pfs_metadata_provider.h(1.85 KB)
ðŸ“„ pfs_socket_provider.h(2.21 KB)
ðŸ“„ pfs_stage_provider.h(1.52 KB)
ðŸ“„ pfs_statement_provider.h(4.25 KB)
ðŸ“„ pfs_table_provider.h(2.56 KB)
ðŸ“„ pfs_thread_provider.h(5.43 KB)
ðŸ“„ pfs_transaction_provider.h(2.78 KB)
ðŸ“„ privilege.h(27.97 KB)
ðŸ“„ probes_mysql.h(973 B)
ðŸ“„ probes_mysql_dtrace.h(32.23 KB)
ðŸ“„ probes_mysql_nodtrace.h(4.89 KB)
ðŸ“„ procedure.h(6.63 KB)
ðŸ“„ protocol.h(12.2 KB)
ðŸ“„ proxy_protocol.h(548 B)
ðŸ“„ queues.h(3.4 KB)
ðŸ“„ records.h(3.07 KB)
ðŸ“„ repl_failsafe.h(1.55 KB)
ðŸ“„ replication.h(15.73 KB)
ðŸ“„ rijndael.h(1.67 KB)
ðŸ“„ rowid_filter.h(15.11 KB)
ðŸ“„ rpl_constants.h(3.28 KB)
ðŸ“„ rpl_filter.h(4.43 KB)
ðŸ“„ rpl_gtid.h(13.36 KB)
ðŸ“„ rpl_injector.h(9.4 KB)
ðŸ“„ rpl_mi.h(14.64 KB)
ðŸ“„ rpl_parallel.h(17.05 KB)
ðŸ“„ rpl_record.h(1.55 KB)
ðŸ“„ rpl_record_old.h(1.37 KB)
ðŸ“„ rpl_reporting.h(3.63 KB)
ðŸ“„ rpl_rli.h(31.98 KB)
ðŸ“„ rpl_tblmap.h(3.1 KB)
ðŸ“„ rpl_utility.h(9.4 KB)
ðŸ“„ scheduler.h(3.12 KB)
ðŸ“„ scope.h(4.29 KB)
ðŸ“„ select_handler.h(2.18 KB)
ðŸ“„ semisync.h(2.23 KB)
ðŸ“„ semisync_master.h(24.96 KB)
ðŸ“„ semisync_master_ack_receiver.h(8.5 KB)
ðŸ“„ semisync_slave.h(3.65 KB)
ðŸ“„ service_versions.h(2 KB)
ðŸ“„ session_tracker.h(13.94 KB)
ðŸ“„ set_var.h(16.16 KB)
ðŸ“„ slave.h(11.99 KB)
ðŸ“„ socketpair.h(842 B)
ðŸ“„ source_revision.h(67 B)
ðŸ“„ sp.h(22.06 KB)
ðŸ“„ sp_cache.h(2 KB)
ðŸ“„ sp_head.h(63 KB)
ðŸ“„ sp_pcontext.h(24.31 KB)
ðŸ“„ sp_rcontext.h(14 KB)
ðŸ“„ span.h(3.84 KB)
ðŸ“„ spatial.h(21.78 KB)
ðŸ“„ sql_acl.h(13.8 KB)
ðŸ“„ sql_admin.h(2.85 KB)
ðŸ“„ sql_alloc.h(1.69 KB)
ðŸ“„ sql_alter.h(14.92 KB)
ðŸ“„ sql_analyse.h(10.86 KB)
ðŸ“„ sql_analyze_stmt.h(12.38 KB)
ðŸ“„ sql_array.h(6.71 KB)
ðŸ“„ sql_audit.h(13.62 KB)
ðŸ“„ sql_base.h(25.27 KB)
ðŸ“„ sql_basic_types.h(9.3 KB)
ðŸ“„ sql_binlog.h(895 B)
ðŸ“„ sql_bitmap.h(7.66 KB)
ðŸ“„ sql_bootstrap.h(1.77 KB)
ðŸ“„ sql_cache.h(21.17 KB)
ðŸ“„ sql_callback.h(1.51 KB)
ðŸ“„ sql_class.h(261.11 KB)
ðŸ“„ sql_cmd.h(9.2 KB)
ðŸ“„ sql_connect.h(3.99 KB)
ðŸ“„ sql_const.h(10.96 KB)
ðŸ“„ sql_crypt.h(1.4 KB)
ðŸ“„ sql_cte.h(16.15 KB)
ðŸ“„ sql_cursor.h(2.26 KB)
ðŸ“„ sql_db.h(2.38 KB)
ðŸ“„ sql_debug.h(5.51 KB)
ðŸ“„ sql_delete.h(1.31 KB)
ðŸ“„ sql_derived.h(1.26 KB)
ðŸ“„ sql_digest.h(3.73 KB)
ðŸ“„ sql_digest_stream.h(1.53 KB)
ðŸ“„ sql_do.h(954 B)
ðŸ“„ sql_error.h(38.66 KB)
ðŸ“„ sql_explain.h(28.34 KB)
ðŸ“„ sql_expression_cache.h(4.26 KB)
ðŸ“„ sql_get_diagnostics.h(7.68 KB)
ðŸ“„ sql_handler.h(2.84 KB)
ðŸ“„ sql_help.h(995 B)
ðŸ“„ sql_hset.h(3.32 KB)
ðŸ“„ sql_i_s.h(8.04 KB)
ðŸ“„ sql_insert.h(2.59 KB)
ðŸ“„ sql_join_cache.h(47.53 KB)
ðŸ“„ sql_lex.h(168.5 KB)
ðŸ“„ sql_lifo_buffer.h(9.45 KB)
ðŸ“„ sql_limit.h(3.11 KB)
ðŸ“„ sql_list.h(21.93 KB)
ðŸ“„ sql_load.h(1.25 KB)
ðŸ“„ sql_locale.h(2.64 KB)
ðŸ“„ sql_manager.h(960 B)
ðŸ“„ sql_mode.h(6.58 KB)
ðŸ“„ sql_parse.h(8.43 KB)
ðŸ“„ sql_partition.h(11.79 KB)
ðŸ“„ sql_partition_admin.h(5.8 KB)
ðŸ“„ sql_plist.h(7.55 KB)
ðŸ“„ sql_plugin.h(7.37 KB)
ðŸ“„ sql_plugin_compat.h(2.18 KB)
ðŸ“„ sql_prepare.h(11.14 KB)
ðŸ“„ sql_priv.h(18.16 KB)
ðŸ“„ sql_profile.h(7.63 KB)
ðŸ“„ sql_reload.h(1.01 KB)
ðŸ“„ sql_rename.h(982 B)
ðŸ“„ sql_repl.h(2.97 KB)
ðŸ“„ sql_schema.h(3.23 KB)
ðŸ“„ sql_select.h(86.81 KB)
ðŸ“„ sql_sequence.h(5.06 KB)
ðŸ“„ sql_servers.h(1.74 KB)
ðŸ“„ sql_show.h(9.39 KB)
ðŸ“„ sql_signal.h(3.28 KB)
ðŸ“„ sql_sort.h(21.45 KB)
ðŸ“„ sql_statistics.h(12.16 KB)
ðŸ“„ sql_string.h(38.84 KB)
ðŸ“„ sql_table.h(9.39 KB)
ðŸ“„ sql_tablespace.h(956 B)
ðŸ“„ sql_test.h(1.55 KB)
ðŸ“„ sql_time.h(8.18 KB)
ðŸ“„ sql_trigger.h(12.04 KB)
ðŸ“„ sql_truncate.h(2.03 KB)
ðŸ“„ sql_tvc.h(2.36 KB)
ðŸ“„ sql_type.h(288.51 KB)
ðŸ“„ sql_type_fixedbin.h(62.81 KB)
ðŸ“„ sql_type_fixedbin_storage.h(5.34 KB)
ðŸ“„ sql_type_geom.h(18.64 KB)
ðŸ“„ sql_type_int.h(9.77 KB)
ðŸ“„ sql_type_json.h(6.01 KB)
ðŸ“„ sql_type_real.h(1.23 KB)
ðŸ“„ sql_type_string.h(1.59 KB)
ðŸ“„ sql_udf.h(4.74 KB)
ðŸ“„ sql_union.h(1.04 KB)
ðŸ“„ sql_update.h(1.88 KB)
ðŸ“„ sql_view.h(2.41 KB)
ðŸ“„ sql_window.h(6.65 KB)
ðŸ“„ ssl_compat.h(3.07 KB)
ðŸ“„ strfunc.h(2.22 KB)
ðŸ“„ structs.h(25.76 KB)
ðŸ“„ sys_vars_shared.h(2.67 KB)
ðŸ“„ t_ctype.h(5.51 KB)
ðŸ“„ table.h(113.03 KB)
ðŸ“„ table_cache.h(4.13 KB)
ðŸ“„ thr_alarm.h(2.86 KB)
ðŸ“„ thr_lock.h(7.18 KB)
ðŸ“„ thr_malloc.h(1.17 KB)
ðŸ“„ thr_timer.h(1.53 KB)
ðŸ“„ thread_cache.h(5.77 KB)
ðŸ“„ threadpool.h(4.7 KB)
ðŸ“„ threadpool_generic.h(3.88 KB)
ðŸ“„ threadpool_winsockets.h(2.24 KB)
ðŸ“„ transaction.h(1.43 KB)
ðŸ“„ tzfile.h(4.9 KB)
ðŸ“„ tztime.h(3.32 KB)
ðŸ“„ uniques.h(4.12 KB)
ðŸ“„ unireg.h(7.54 KB)
ðŸ“„ vers_string.h(2.47 KB)
ðŸ“„ violite.h(9.85 KB)
ðŸ“„ waiting_threads.h(4.43 KB)
ðŸ“„ welcome_copyright_notice.h(1.19 KB)
ðŸ“„ win_tzname_data.h(6.35 KB)
ðŸ“„ winservice.h(1.17 KB)
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ðŸ“„ wsrep_applier.h(2.64 KB)
ðŸ“„ wsrep_binlog.h(3.36 KB)
ðŸ“„ wsrep_client_service.h(2.5 KB)
ðŸ“„ wsrep_client_state.h(1.53 KB)
ðŸ“„ wsrep_condition_variable.h(1.45 KB)
ðŸ“„ wsrep_high_priority_service.h(4.8 KB)
ðŸ“„ wsrep_mutex.h(1.19 KB)
ðŸ“„ wsrep_mysqld.h(20.64 KB)
ðŸ“„ wsrep_mysqld_c.h(1.2 KB)
ðŸ“„ wsrep_on.h(1.68 KB)
ðŸ“„ wsrep_priv.h(1.6 KB)
ðŸ“„ wsrep_schema.h(4.83 KB)
ðŸ“„ wsrep_server_service.h(3.55 KB)
ðŸ“„ wsrep_server_state.h(2.23 KB)
ðŸ“„ wsrep_sst.h(3.86 KB)
ðŸ“„ wsrep_storage_service.h(1.77 KB)
ðŸ“„ wsrep_thd.h(10.9 KB)
ðŸ“„ wsrep_trans_observer.h(17.69 KB)
ðŸ“„ wsrep_types.h(997 B)
ðŸ“„ wsrep_utils.h(9.07 KB)
ðŸ“„ wsrep_var.h(4.5 KB)
ðŸ“„ wsrep_xid.h(1.51 KB)
ðŸ“„ xa.h(1.8 KB)

Editing: opt_subselect.h

/*
   Copyright (c) 2010, 2019, 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 02110-1335 USA */

/*
  Semi-join subquery optimization code definitions
*/

#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

int check_and_do_in_subquery_rewrites(JOIN *join);
bool convert_join_subqueries_to_semijoins(JOIN *join);
int pull_out_semijoin_tables(JOIN *join);
bool optimize_semijoin_nests(JOIN *join, table_map all_table_map);
bool setup_degenerate_jtbm_semi_joins(JOIN *join,
                                      List<TABLE_LIST> *join_list,
                                      List<Item> &eq_list);
bool setup_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list,
                           List<Item> &eq_list);
void cleanup_empty_jtbm_semi_joins(JOIN *join, List<TABLE_LIST> *join_list);

// used by Loose_scan_opt
ulonglong get_bound_sj_equalities(TABLE_LIST *sj_nest, 
                                  table_map remaining_tables);

/*
  This is a class for considering possible loose index scan optimizations.
  It's usage pattern is as follows:
    best_access_path()
    {
       Loose_scan_opt opt;

opt.init()
       for each index we can do ref access with
       {
         opt.next_ref_key();
         for each keyuse 
           opt.add_keyuse();
         opt.check_ref_access();
       }

if (some criteria for range scans)
         opt.check_range_access();
       
       opt.get_best_option();
    }
*/

class Loose_scan_opt
{
  /* All methods must check this before doing anything else */
  bool try_loosescan;

/*
    If we consider (oe1, .. oeN) IN (SELECT ie1, .. ieN) then ieK=oeK is
    called sj-equality. If oeK depends only on preceding tables then such
    equality is called 'bound'.
  */
  ulonglong bound_sj_equalities;
 
  /* Accumulated properties of ref access we're now considering: */
  ulonglong handled_sj_equalities;
  key_part_map loose_scan_keyparts;
  uint max_loose_keypart;
  bool part1_conds_met;

/*
    Use of quick select is a special case. Some of its properties:
  */
  uint quick_uses_applicable_index;
  uint quick_max_loose_keypart;
  
  /* Best loose scan method so far */
  uint   best_loose_scan_key;
  double best_loose_scan_cost;
  double best_loose_scan_records;
  KEYUSE *best_loose_scan_start_key;

uint best_max_loose_keypart;
  table_map best_ref_depend_map;

public:
  Loose_scan_opt():
    try_loosescan(false),
    bound_sj_equalities(0),
    quick_uses_applicable_index(0),
    quick_max_loose_keypart(0),
    best_loose_scan_key(0),
    best_loose_scan_cost(0),
    best_loose_scan_records(0),
    best_loose_scan_start_key(NULL),
    best_max_loose_keypart(0),
    best_ref_depend_map(0)
  {
  }

void init(JOIN *join, JOIN_TAB *s, table_map remaining_tables)
  {
    /*
      Discover the bound equalities. We need to do this if
        1. The next table is an SJ-inner table, and
        2. It is the first table from that semijoin, and
        3. We're not within a semi-join range (i.e. all semi-joins either have
           all or none of their tables in join_table_map), except
           s->emb_sj_nest (which we've just entered, see #2).
        4. All non-IN-equality correlation references from this sj-nest are 
           bound
        5. But some of the IN-equalities aren't (so this can't be handled by 
           FirstMatch strategy)
    */
    best_loose_scan_cost= DBL_MAX;
    if (!join->emb_sjm_nest && s->emb_sj_nest &&                        // (1)
        s->emb_sj_nest->sj_in_exprs < 64 && 
        ((remaining_tables & s->emb_sj_nest->sj_inner_tables) ==        // (2)
         s->emb_sj_nest->sj_inner_tables) &&                            // (2)
        join->cur_sj_inner_tables == 0 &&                               // (3)
        !(remaining_tables & 
          s->emb_sj_nest->nested_join->sj_corr_tables) &&               // (4)
        remaining_tables & s->emb_sj_nest->nested_join->sj_depends_on &&// (5)
        optimizer_flag(join->thd, OPTIMIZER_SWITCH_LOOSE_SCAN))
    {
      /* This table is an LooseScan scan candidate */
      bound_sj_equalities= get_bound_sj_equalities(s->emb_sj_nest, 
                                                   remaining_tables);
      try_loosescan= TRUE;
      DBUG_PRINT("info", ("Will try LooseScan scan, bound_map=%llx",
                          (longlong)bound_sj_equalities));
    }
  }

void next_ref_key()
  {
    handled_sj_equalities=0;
    loose_scan_keyparts= 0;
    max_loose_keypart= 0;
    part1_conds_met= FALSE;
  }
  
  void add_keyuse(table_map remaining_tables, KEYUSE *keyuse)
  {
    if (try_loosescan && keyuse->sj_pred_no != UINT_MAX &&
        (keyuse->table->file->index_flags(keyuse->key, 0, 1 ) & HA_READ_ORDER))

{
      if (!(remaining_tables & keyuse->used_tables))
      {
        /* 
          This allows to use equality propagation to infer that some 
          sj-equalities are bound.
        */
        bound_sj_equalities |= 1ULL << keyuse->sj_pred_no;
      }
      else
      {
        handled_sj_equalities |= 1ULL << keyuse->sj_pred_no;
        loose_scan_keyparts |= ((key_part_map)1) << keyuse->keypart;
        set_if_bigger(max_loose_keypart, keyuse->keypart);
      }
    }
  }

bool have_a_case() { return MY_TEST(handled_sj_equalities); }

void check_ref_access_part1(JOIN_TAB *s, uint key, KEYUSE *start_key, 
                              table_map found_part)
  {
    /*
      Check if we can use LooseScan semi-join strategy. We can if
      1. This is the right table at right location
      2. All IN-equalities are either
         - "bound", ie. the outer_expr part refers to the preceding tables
         - "handled", ie. covered by the index we're considering
      3. Index order allows to enumerate subquery's duplicate groups in
         order. This happens when the index definition matches this
         pattern:

(handled_col|bound_col)* (other_col|bound_col)

*/
    if (try_loosescan &&                                       // (1)
        (handled_sj_equalities | bound_sj_equalities) ==       // (2)
        PREV_BITS(ulonglong, s->emb_sj_nest->sj_in_exprs) &&   // (2)
        (PREV_BITS(key_part_map, max_loose_keypart+1) &        // (3)
         (found_part | loose_scan_keyparts)) ==                // (3)
        PREV_BITS(key_part_map, max_loose_keypart+1) &&        // (3)
        !key_uses_partial_cols(s->table->s, key))
    {
      if (s->quick && s->quick->index == key && 
          s->quick->get_type() == QUICK_SELECT_I::QS_TYPE_RANGE)
      {
        quick_uses_applicable_index= TRUE;
        quick_max_loose_keypart= max_loose_keypart;
      }
      DBUG_PRINT("info", ("Can use LooseScan scan"));

if (found_part & 1)
      {
        /* Can use LooseScan on ref access if the first key part is bound */
        part1_conds_met= TRUE;
      }

/* 
        Check if this is a special case where there are no usable bound
        IN-equalities, i.e. we have

outer_expr IN (SELECT innertbl.key FROM ...) 
        
        and outer_expr cannot be evaluated yet, so it's actually full
        index scan and not a ref access.
        We can do full index scan if it uses index-only.
      */
      if (!(found_part & 1 ) && /* no usable ref access for 1st key part */
          s->table->covering_keys.is_set(key))
      {
        part1_conds_met= TRUE;
        DBUG_PRINT("info", ("Can use full index scan for LooseScan"));
        
        /* Calculate the cost of complete loose index scan.  */
        double records= rows2double(s->table->file->stats.records);

/* The cost is entire index scan cost (divided by 2) */
        double read_time= s->table->file->keyread_time(key, 1,
                                                       (ha_rows) records);

/*
          Now find out how many different keys we will get (for now we
          ignore the fact that we have "keypart_i=const" restriction for
          some key components, that may make us think think that loose
          scan will produce more distinct records than it actually will)
        */
        ulong rpc;
        if ((rpc= s->table->key_info[key].rec_per_key[max_loose_keypart]))
          records= records / rpc;

// TODO: previous version also did /2
        if (read_time < best_loose_scan_cost)
        {
          best_loose_scan_key= key;
          best_loose_scan_cost= read_time;
          best_loose_scan_records= records;
          best_max_loose_keypart= max_loose_keypart;
          best_loose_scan_start_key= start_key;
          best_ref_depend_map= 0;
        }
      }
    }
  }
  
  void check_ref_access_part2(uint key, KEYUSE *start_key, double records, 
                              double read_time, table_map ref_depend_map_arg)
  {
    if (part1_conds_met && read_time < best_loose_scan_cost)
    {
      /* TODO use rec-per-key-based fanout calculations */
      best_loose_scan_key= key;
      best_loose_scan_cost= read_time;
      best_loose_scan_records= records;
      best_max_loose_keypart= max_loose_keypart;
      best_loose_scan_start_key= start_key;
      best_ref_depend_map= ref_depend_map_arg;
    }
  }

void check_range_access(JOIN *join, uint idx, QUICK_SELECT_I *quick)
  {
    /* TODO: this the right part restriction: */
    if (quick_uses_applicable_index && idx == join->const_tables && 
        quick->read_time < best_loose_scan_cost)
    {
      best_loose_scan_key= quick->index;
      best_loose_scan_cost= quick->read_time;
      /* this is ok because idx == join->const_tables */
      best_loose_scan_records= rows2double(quick->records);
      best_max_loose_keypart= quick_max_loose_keypart;
      best_loose_scan_start_key= NULL;
      best_ref_depend_map= 0;
    }
  }

void save_to_position(JOIN_TAB *tab, POSITION *pos)
  {
    pos->read_time=       best_loose_scan_cost;
    if (best_loose_scan_cost != DBL_MAX)
    {
      pos->records_read=    best_loose_scan_records;
      pos->key=             best_loose_scan_start_key;
      pos->cond_selectivity= 1.0;
      pos->loosescan_picker.loosescan_key=   best_loose_scan_key;
      pos->loosescan_picker.loosescan_parts= best_max_loose_keypart + 1;
      pos->use_join_buffer= FALSE;
      pos->table=           tab;
      pos->range_rowid_filter_info= tab->range_rowid_filter_info;
      pos->ref_depend_map=  best_ref_depend_map;
      DBUG_PRINT("info", ("Produced a LooseScan plan, key %s, %s",
                          tab->table->key_info[best_loose_scan_key].name.str,
                          best_loose_scan_start_key? "(ref access)":
                                                     "(range/index access)"));
    }
  }
};

void optimize_semi_joins(JOIN *join, table_map remaining_tables, uint idx,
                         double *current_record_count,
                         double *current_read_time, POSITION *loose_scan_pos);
void update_sj_state(JOIN *join, const JOIN_TAB *new_tab,
                     uint idx, table_map remaining_tables);
void restore_prev_sj_state(const table_map remaining_tables, 
                                  const JOIN_TAB *tab, uint idx);

void fix_semijoin_strategies_for_picked_join_order(JOIN *join);

bool setup_sj_materialization_part1(JOIN_TAB *sjm_tab);
bool setup_sj_materialization_part2(JOIN_TAB *sjm_tab);
uint get_number_of_tables_at_top_level(JOIN *join);

/*
  Temporary table used by semi-join DuplicateElimination strategy

This consists of the temptable itself and data needed to put records
  into it. The table's DDL is as follows:

CREATE TABLE tmptable (col VARCHAR(n) BINARY, PRIMARY KEY(col));

where the primary key can be replaced with unique constraint if n exceeds
  the limit (as it is always done for query execution-time temptables).

The record value is a concatenation of rowids of tables from the join we're
  executing. If a join table is on the inner side of the outer join, we
  assume that its rowid can be NULL and provide means to store this rowid in
  the tuple.
*/

class SJ_TMP_TABLE : public Sql_alloc
{
public:
  /*
    Array of pointers to tables whose rowids compose the temporary table
    record.
  */
  class TAB
  {
  public:
    JOIN_TAB *join_tab;
    uint rowid_offset;
    ushort null_byte;
    uchar null_bit;
  };
  TAB *tabs;
  TAB *tabs_end;
  
  /* 
    is_degenerate==TRUE means this is a special case where the temptable record
    has zero length (and presence of a unique key means that the temptable can
    have either 0 or 1 records). 
    In this case we don't create the physical temptable but instead record
    its state in SJ_TMP_TABLE::have_degenerate_row.
  */
  bool is_degenerate;

/* 
    When is_degenerate==TRUE: the contents of the table (whether it has the
    record or not).
  */
  bool have_degenerate_row;
  
  /* table record parameters */
  uint null_bits;
  uint null_bytes;
  uint rowid_len;

/* The temporary table itself (NULL means not created yet) */
  TABLE *tmp_table;
  
  /*
    These are the members we got from temptable creation code. We'll need
    them if we'll need to convert table from HEAP to MyISAM/Maria.
  */
  TMP_ENGINE_COLUMNDEF *start_recinfo;
  TMP_ENGINE_COLUMNDEF *recinfo;

SJ_TMP_TABLE *next_flush_table;

int sj_weedout_delete_rows();
  int sj_weedout_check_row(THD *thd);
  bool create_sj_weedout_tmp_table(THD *thd);
};

int setup_semijoin_loosescan(JOIN *join);
int setup_semijoin_dups_elimination(JOIN *join, ulonglong options, 
                                    uint no_jbuf_after);
void destroy_sj_tmp_tables(JOIN *join);
int clear_sj_tmp_tables(JOIN *join);
int rewrite_to_index_subquery_engine(JOIN *join);

void get_delayed_table_estimates(TABLE *table,
                                 ha_rows *out_rows, 
                                 double *scan_time,
                                 double *startup_cost);

enum_nested_loop_state join_tab_execution_startup(JOIN_TAB *tab);

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