|
| | JOIN (THD *thd_arg, Query_block *select) |
| |
| | JOIN (const JOIN &rhs)=delete |
| |
| JOIN & | operator= (const JOIN &rhs)=delete |
| |
| Query_expression * | query_expression () const |
| | Query expression referring this query block. More...
|
| |
| bool | plan_is_const () const |
| | True if plan is const, ie it will return zero or one rows. More...
|
| |
| bool | plan_is_single_table () |
| | True if plan contains one non-const primary table (ie not including tables taking part in semi-join materialization). More...
|
| |
| bool | contains_non_aggregated_fts () const |
| | Returns true if any of the items in JOIN::fields contains a call to the full-text search function MATCH, which is not wrapped in an aggregation function. More...
|
| |
| bool | optimize (bool finalize_access_paths) |
| | Optimizes one query block into a query execution plan (QEP.) More...
|
| |
| void | reset () |
| | Reset the state of this join object so that it is ready for a new execution. More...
|
| |
| bool | prepare_result () |
| | Prepare join result. More...
|
| |
| void | destroy () |
| | Clean up and destroy join object. More...
|
| |
| bool | alloc_func_list () |
| | Make an array of pointers to sum_functions to speed up sum_func calculation. More...
|
| |
| bool | make_sum_func_list (const mem_root_deque< Item * > &fields, bool before_group_by, bool recompute=false) |
| | Initialize 'sum_funcs' array with all Item_sum objects. More...
|
| |
| void | copy_ref_item_slice (uint dst_slice, uint src_slice) |
| | Overwrites one slice of ref_items with the contents of another slice. More...
|
| |
| void | copy_ref_item_slice (Ref_item_array dst_arr, Ref_item_array src_arr) |
| |
| bool | alloc_ref_item_slice (THD *thd_arg, int sliceno) |
| | Allocate a ref_item slice, assume that slice size is in ref_items[0]. More...
|
| |
| void | set_ref_item_slice (uint sliceno) |
| | Overwrite the base slice of ref_items with the slice supplied as argument. More...
|
| |
| uint | get_ref_item_slice () const |
| |
| mem_root_deque< Item * > * | get_current_fields () |
| | Returns the clone of fields_list which is appropriate for evaluating expressions at the current stage of execution; which stage is denoted by the value of current_ref_item_slice. More...
|
| |
| bool | optimize_rollup () |
| | Optimize rollup specification. More...
|
| |
| bool | finalize_table_conditions (THD *thd) |
| | Remove redundant predicates and cache constant expressions. More...
|
| |
| void | join_free () |
| | Release memory and, if possible, the open tables held by this execution plan (and nested plans). More...
|
| |
| void | cleanup () |
| | Cleanup this JOIN. More...
|
| |
| bool | clear_fields (table_map *save_nullinfo) |
| | Set all column values from all input tables to NULL. More...
|
| |
| void | restore_fields (table_map save_nullinfo) |
| | Restore all result fields for all tables specified in save_nullinfo. More...
|
| |
| bool | generate_derived_keys () |
| | Add keys to derived tables'/views' result tables in a list. More...
|
| |
| void | finalize_derived_keys () |
| | For each materialized derived table/view, informs every TABLE of the key it will (not) use, segregates used keys from unused keys in TABLE::key_info, and eliminates unused keys. More...
|
| |
| bool | get_best_combination () |
| | Set up JOIN_TAB structs according to the picked join order in best_positions. More...
|
| |
| bool | attach_join_conditions (plan_idx last_tab) |
| | Attach outer join conditions to generated table conditions in an optimal way. More...
|
| |
| bool | update_equalities_for_sjm () |
| | Update equalities and keyuse references after semi-join materialization strategy is chosen. More...
|
| |
| bool | add_sorting_to_table (uint idx, ORDER_with_src *order, bool sort_before_group) |
| | Add Filesort object to the given table to sort if with filesort. More...
|
| |
| bool | decide_subquery_strategy () |
| | Decides between EXISTS and materialization; performs last steps to set up the chosen strategy. More...
|
| |
| void | refine_best_rowcount () |
| | Refine the best_rowcount estimation based on what happens after tables have been joined: LIMIT and type of result sink. More...
|
| |
| table_map | calculate_deps_of_remaining_lateral_derived_tables (table_map plan_tables, uint idx) const |
| | Finds the dependencies of the remaining lateral derived tables. More...
|
| |
| bool | clear_sj_tmp_tables () |
| | Remove all rows from all temp tables used by NL-semijoin runtime. More...
|
| |
| bool | clear_corr_derived_tmp_tables () |
| | Empties all correlated materialized derived tables. More...
|
| |
| void | clear_hash_tables () |
| |
| void | mark_const_table (JOIN_TAB *table, Key_use *key) |
| | Move const tables first in the position array. More...
|
| |
| enum_plan_state | get_plan_state () const |
| | See enum_plan_state. More...
|
| |
| bool | is_optimized () const |
| |
| void | set_optimized () |
| |
| bool | is_executed () const |
| |
| void | set_executed () |
| |
| const Cost_model_server * | cost_model () const |
| | Retrieve the cost model object to be used for this join. More...
|
| |
| bool | fts_index_access (JOIN_TAB *tab) |
| | Check if FTS index only access is possible. More...
|
| |
| QEP_TAB::enum_op_type | get_end_select_func () |
| |
| bool | propagate_dependencies () |
| | Propagate dependencies between tables due to outer join relations. More...
|
| |
| bool | push_to_engines () |
| | Handle offloading of query parts to the underlying engines, when such is supported by their implementation. More...
|
| |
| AccessPath * | root_access_path () const |
| |
| void | set_root_access_path (AccessPath *path) |
| |
| void | change_to_access_path_without_in2exists () |
| | If this query block was planned twice, once with and once without conditions added by in2exists, changes the root access path to the one without in2exists. More...
|
| |
| void | refresh_base_slice () |
| | In the case of rollup (only): After the base slice list was made, we may have modified the field list to add rollup group items and sum switchers, but there may be Items with refs that refer to the base slice. More...
|
| |
| AccessPath * | create_access_paths_for_zero_rows () const |
| | Create access paths with the knowledge that there are going to be zero rows coming from tables (before aggregation); typically because we know that all of them would be filtered away by WHERE (e.g. More...
|
| |
|
| Query_block *const | query_block |
| | Query block that is optimized and executed using this JOIN. More...
|
| |
| THD *const | thd |
| | Thread handler. More...
|
| |
| JOIN_TAB * | join_tab {nullptr} |
| | Optimal query execution plan. More...
|
| |
| QEP_TAB * | qep_tab {nullptr} |
| | Array of QEP_TABs. More...
|
| |
| JOIN_TAB ** | best_ref {nullptr} |
| | Array of plan operators representing the current (partial) best plan. More...
|
| |
| JOIN_TAB ** | map2table {nullptr} |
| | mapping between table indexes and JOIN_TABs More...
|
| |
| TABLE * | sort_by_table {nullptr} |
| |
| Prealloced_array< TemporaryTableToCleanup, 1 > | temp_tables |
| |
| Prealloced_array< Filesort *, 1 > | filesorts_to_cleanup {PSI_NOT_INSTRUMENTED} |
| |
| uint | tables {0} |
| | Before plan has been created, "tables" denote number of input tables in the query block and "primary_tables" is equal to "tables". More...
|
| |
| uint | primary_tables {0} |
| | Number of primary input tables in query block. More...
|
| |
| uint | const_tables {0} |
| | Number of primary tables deemed constant. More...
|
| |
| uint | tmp_tables {0} |
| | Number of temporary tables used by query. More...
|
| |
| uint | send_group_parts {0} |
| |
| bool | streaming_aggregation {false} |
| | Indicates that the data will be aggregated (typically GROUP BY), and that it is already processed in an order that is compatible with the grouping in use (e.g. More...
|
| |
| bool | grouped |
| | If query contains GROUP BY clause. More...
|
| |
| bool | do_send_rows {true} |
| | If true, send produced rows using query_result. More...
|
| |
| table_map | all_table_map {0} |
| | Set of tables contained in query. More...
|
| |
| table_map | const_table_map |
| | Set of tables found to be const. More...
|
| |
| table_map | found_const_table_map |
| | Const tables which are either: More...
|
| |
| table_map | deps_of_remaining_lateral_derived_tables {0} |
| | This is the bitmap of all tables which are dependencies of lateral derived tables which are not (yet) part of the partial plan. More...
|
| |
| ha_rows | send_records {0} |
| |
| ha_rows | found_records {0} |
| |
| ha_rows | examined_rows {0} |
| |
| ha_rows | row_limit {0} |
| |
| ha_rows | m_select_limit {0} |
| |
| ha_rows | fetch_limit {HA_POS_ERROR} |
| | Used to fetch no more than given amount of rows per one fetch operation of server side cursor. More...
|
| |
| POSITION * | best_positions {nullptr} |
| | This is the result of join optimization. More...
|
| |
| POSITION * | positions {nullptr} |
| |
| Override_executor_func | override_executor_func = nullptr |
| |
| double | best_read {0.0} |
| | The cost of best complete join plan found so far during optimization, after optimization phase - cost of picked join order (not taking into account the changes made by test_if_skip_sort_order()). More...
|
| |
| ha_rows | best_rowcount {0} |
| | The estimated row count of the plan with best read time (see above). More...
|
| |
| double | sort_cost {0.0} |
| | Expected cost of filesort. More...
|
| |
| double | windowing_cost {0.0} |
| | Expected cost of windowing;. More...
|
| |
| mem_root_deque< Item * > * | fields |
| |
| List< Cached_item > | group_fields {} |
| |
| List< Cached_item > | group_fields_cache {} |
| |
| List< Cached_item > | semijoin_deduplication_fields {} |
| |
| Item_sum ** | sum_funcs {nullptr} |
| |
| Temp_table_param | tmp_table_param |
| | Describes a temporary table. More...
|
| |
| MYSQL_LOCK * | lock |
| |
| RollupState | rollup_state |
| |
| bool | implicit_grouping |
| | True if aggregated but no GROUP BY. More...
|
| |
| bool | select_distinct |
| | At construction time, set if SELECT DISTINCT. More...
|
| |
| bool | group_optimized_away {false} |
| | If we have the GROUP BY statement in the query, but the group_list was emptied by optimizer, this flag is true. More...
|
| |
| bool | simple_order {false} |
| |
| bool | simple_group {false} |
| |
| enum JOIN:: { ... } | ORDERED_INDEX_VOID |
| |
| bool | skip_sort_order {false} |
| | Is set if we have a GROUP BY and we have ORDER BY on a constant or when sorting isn't required. More...
|
| |
| bool | need_tmp_before_win {false} |
| | If true we need a temporary table on the result set before any windowing steps, e.g. More...
|
| |
| bool | has_lateral {false} |
| | If JOIN has lateral derived tables (is set at start of planning) More...
|
| |
| Key_use_array | keyuse_array |
| | Used and updated by JOIN::make_join_plan() and optimize_keyuse() More...
|
| |
| mem_root_deque< Item * > * | tmp_fields = nullptr |
| | Array of pointers to lists of expressions. More...
|
| |
| int | error {0} |
| | set in optimize(), exec(), prepare_result() More...
|
| |
| uint64_t | hash_table_generation {0} |
| | Incremented each time clear_hash_tables() is run, signaling to HashJoinIterators that they cannot keep their hash tables anymore (since outer references may have changed). More...
|
| |
| ORDER_with_src | order |
| | ORDER BY and GROUP BY lists, to transform with prepare,optimize and exec. More...
|
| |
| ORDER_with_src | group_list |
| |
| Prealloced_array< Item_rollup_group_item *, 4 > | rollup_group_items |
| |
| Prealloced_array< Item_rollup_sum_switcher *, 4 > | rollup_sums |
| |
| List< Window > | m_windows |
| | Any window definitions. More...
|
| |
| bool | m_windows_sort {false} |
| | True if a window requires a certain order of rows, which implies that any order of rows coming out of the pre-window join will be disturbed. More...
|
| |
| bool | m_windowing_steps {false} |
| | If we have set up tmp tables for windowing,. More...
|
| |
| Explain_format_flags | explain_flags {} |
| | Buffer to gather GROUP BY, ORDER BY and DISTINCT QEP details for EXPLAIN. More...
|
| |
| Item * | where_cond |
| | JOIN::having_cond is initially equal to query_block->having_cond, but may later be changed by optimizations performed by JOIN. More...
|
| |
| Item * | having_cond |
| | Optimized HAVING clause item tree (valid for one single execution). More...
|
| |
| Item * | having_for_explain |
| | Saved optimized HAVING for EXPLAIN. More...
|
| |
| Table_ref * | tables_list |
| | Pointer set to query_block->get_table_list() at the start of optimization. More...
|
| |
| COND_EQUAL * | cond_equal {nullptr} |
| |
| plan_idx | return_tab {0} |
| |
| Ref_item_array * | ref_items |
| | ref_items is an array of 4+ slices, each containing an array of Item pointers. More...
|
| |
| uint | current_ref_item_slice |
| | The slice currently stored in ref_items[0]. More...
|
| |
| uint | recursive_iteration_count {0} |
| | Used only if this query block is recursive. More...
|
| |
| const char * | zero_result_cause {nullptr} |
| | <> NULL if optimization has determined that execution will produce an empty result before aggregation, contains a textual explanation on why result is empty. More...
|
| |
| bool | child_subquery_can_materialize {false} |
| | True if, at this stage of processing, subquery materialization is allowed for children subqueries of this JOIN (those in the SELECT list, in WHERE, etc). More...
|
| |
| bool | allow_outer_refs {false} |
| | True if plan search is allowed to use references to expressions outer to this JOIN (for example may set up a 'ref' access looking up an outer expression in the index, etc). More...
|
| |
| List< TABLE > | sj_tmp_tables {} |
| |
| List< Semijoin_mat_exec > | sjm_exec_list {} |
| |
| bool | group_sent {false} |
| | Exec time only: true <=> current group has been sent. More...
|
| |
| bool | calc_found_rows {false} |
| | If true, calculate found rows for this query block. More...
|
| |
| bool | with_json_agg |
| | This will force tmp table to NOT use index + update for group operation as it'll cause [de]serialization for each json aggregated value and is very ineffective (times worse). More...
|
| |
| bool | needs_finalize {false} |
| | Whether this query block needs finalization (see FinalizePlanForQueryBlock()) before it can be actually used. More...
|
| |
| bool | select_count {false} |
| |
|
| bool | send_row_on_empty_set () const |
| | Return whether the caller should send a row even if the join produced no rows if: More...
|
| |
| bool | attach_join_condition_to_nest (plan_idx first_inner, plan_idx last_tab, Item *join_cond, bool is_sj_mat_cond) |
| | Helper for JOIN::attach_join_conditions(). More...
|
| |
| bool | create_intermediate_table (QEP_TAB *tab, const mem_root_deque< Item * > &tmp_table_fields, ORDER_with_src &tmp_table_group, bool save_sum_fields) |
| | Create a temporary table to be used for processing DISTINCT/ORDER BY/GROUP BY. More...
|
| |
| void | optimize_distinct () |
| | Optimize distinct when used on a subset of the tables. More...
|
| |
| bool | optimize_fts_query () |
| | Function sets FT hints, initializes FT handlers and checks if FT index can be used as covered. More...
|
| |
| bool | check_access_path_with_fts () const |
| | Checks if the chosen plan suffers from a problem related to full-text search and streaming aggregation, which is likely to cause wrong results or make the query misbehave in other ways, and raises an error if so. More...
|
| |
| bool | prune_table_partitions () |
| | Prune partitions for all tables of a join (query block). More...
|
| |
| void | init_key_dependencies () |
| | Initialize key dependencies for join tables. More...
|
| |
| void | set_prefix_tables () |
| | Assign set of available (prefix) tables to all tables in query block. More...
|
| |
| void | cleanup_item_list (const mem_root_deque< Item * > &items) const |
| |
| void | set_semijoin_embedding () |
| | Set semi-join embedding join nest pointers. More...
|
| |
| bool | make_join_plan () |
| | Calculate best possible join order and initialize the join structure. More...
|
| |
| bool | init_planner_arrays () |
| | Initialize scratch arrays for the join order optimization. More...
|
| |
| bool | extract_const_tables () |
| | Extract const tables based on row counts. More...
|
| |
| bool | extract_func_dependent_tables () |
| | Extract const tables based on functional dependencies. More...
|
| |
| void | update_sargable_from_const (SARGABLE_PARAM *sargables) |
| | Update info on indexes that can be used for search lookups as reading const tables may has added new sargable predicates. More...
|
| |
| bool | estimate_rowcount () |
| | Estimate the number of matched rows for each joined table. More...
|
| |
| void | optimize_keyuse () |
| | Update some values in keyuse for faster choose_table_order() loop. More...
|
| |
| void | set_semijoin_info () |
| | Set the first_sj_inner_tab and last_sj_inner_tab fields for all tables inside the semijoin nests of the query. More...
|
| |
| void | adjust_access_methods () |
| | An utility function - apply heuristics and optimize access methods to tables. More...
|
| |
| void | update_depend_map () |
| | Update the dependency map for the tables. More...
|
| |
| void | update_depend_map (ORDER *order) |
| | Update the dependency map for the sort order. More...
|
| |
| void | make_outerjoin_info () |
| | Fill in outer join related info for the execution plan structure. More...
|
| |
| bool | init_ref_access () |
| | Initialize ref access for all tables that use it. More...
|
| |
| bool | alloc_qep (uint n) |
| |
| void | unplug_join_tabs () |
| |
| bool | setup_semijoin_materialized_table (JOIN_TAB *tab, uint tableno, POSITION *inner_pos, POSITION *sjm_pos) |
| | Setup the materialized table for a semi-join nest. More...
|
| |
| bool | add_having_as_tmp_table_cond (uint curr_tmp_table) |
| | Add having condition as a filter condition, which is applied when reading from the temp table. More...
|
| |
| bool | make_tmp_tables_info () |
| | Init tmp tables usage info. More...
|
| |
| void | set_plan_state (enum_plan_state plan_state_arg) |
| | Sets the plan's state of the JOIN. More...
|
| |
| bool | compare_costs_of_subquery_strategies (Subquery_strategy *method) |
| | Tells what is the cheapest between IN->EXISTS and subquery materialization, in terms of cost, for the subquery's JOIN. More...
|
| |
| ORDER * | remove_const (ORDER *first_order, Item *cond, bool change_list, bool *simple_order, bool group_by) |
| | Remove all constants and check if ORDER only contains simple expressions. More...
|
| |
| int | replace_index_subquery () |
| | Check whether this is a subquery that can be evaluated by index look-ups. More...
|
| |
| bool | optimize_distinct_group_order () |
| | Optimize DISTINCT, GROUP BY, ORDER BY clauses. More...
|
| |
| void | test_skip_sort () |
| | Test if an index could be used to replace filesort for ORDER BY/GROUP BY. More...
|
| |
| bool | alloc_indirection_slices () |
| |
| void | create_access_paths () |
| | Convert the executor structures to a set of access paths, storing the result in m_root_access_path. More...
|
| |
| void | create_access_paths_for_index_subquery () |
| |
|
| AccessPath * | create_root_access_path_for_join () |
| |
| AccessPath * | attach_access_paths_for_having_and_limit (AccessPath *path) const |
| |
| AccessPath * | attach_access_path_for_update_or_delete (AccessPath *path) const |
| |
| bool JOIN::attach_join_conditions |
( |
plan_idx |
last_tab | ) |
|
Attach outer join conditions to generated table conditions in an optimal way.
- Parameters
-
| last_tab | - Last table that has been added to the current plan. Pre-condition: If this is the last inner table of an outer join operation, a join condition is attached to the first inner table of that outer join operation. |
- Returns
- false if success, true if error.
Outer join conditions are attached to individual tables, but we can analyze those conditions only when reaching the last inner table of an outer join operation. Notice also that a table can be last within several outer join nests, hence the outer for() loop of this function.
Example: SELECT * FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.a=t3.a) ON t1.a=t2.a
Table t3 is last both in the join nest (t2 - t3) and in (t1 - (t2 - t3)) Thus, join conditions for both join nests will be evaluated when reaching this table.
For each outer join operation processed, the join condition is split optimally over the inner tables of the outer join. The split-out conditions are later referred to as table conditions (but note that several table conditions stemming from different join operations may be combined into a composite table condition).
Example: Consider the above query once more. The predicate t1.a=t2.a can be evaluated when rows from t1 and t2 are ready, ie at table t2. The predicate t2.a=t3.a can be evaluated at table t3.
Each non-constant split-out table condition is guarded by a match variable that enables it only when a matching row is found for all the embedded outer join operations.
Each split-out table condition is guarded by a variable that turns the condition off just before a null-complemented row for the outer join operation is formed. Thus, the join condition will not be checked for the null-complemented row.
| void JOIN::make_outerjoin_info |
( |
| ) |
|
|
private |
Fill in outer join related info for the execution plan structure.
For each outer join operation left after simplification of the original query the function set up the following pointers in the linear structure join->join_tab representing the selected execution plan. The first inner table t0 for the operation is set to refer to the last inner table tk through the field t0->last_inner. Any inner table ti for the operation are set to refer to the first inner table ti->first_inner. The first inner table t0 for the operation is set to refer to the first inner table of the embedding outer join operation, if there is any, through the field t0->first_upper. The on expression for the outer join operation is attached to the corresponding first inner table through the field t0->on_expr_ref. Here ti are structures of the JOIN_TAB type.
EXAMPLE. For the query:
ON (t1.a=t2.a AND t1.b=t3.b)
Definition: sql_optimizer.h:133
JOIN(THD *thd_arg, Query_block *select)
Definition: sql_optimizer.cc:168
const std::string SELECT("SELECT")
Name of the static privileges.
@ WHERE
Definition: sql_yacc.h:687
@ FROM
Definition: sql_yacc.h:250
@ LEFT
Definition: sql_yacc.h:324
given the execution plan with the table order t1,t2,t3,t4 is selected, the following references will be set; t4->last_inner=[t4], t4->first_inner=[t4], t4->first_upper=[t2] t2->last_inner=[t4], t2->first_inner=t3->first_inner=[t2], on expression (t1.a=t2.a AND t1.b=t3.b) will be attached to t2->on_expr_ref, while t3.a=t4.a will be attached to *t4->on_expr_ref.
- Note
- The function assumes that the simplification procedure has been already applied to the join query (see simplify_joins). This function can be called only after the execution plan has been chosen.
| table_map JOIN::deps_of_remaining_lateral_derived_tables {0} |
This is the bitmap of all tables which are dependencies of lateral derived tables which are not (yet) part of the partial plan.
(The value is a logical 'or' of zero or more Table_ref.map() values.)
When we are building the join order, there is a partial plan (an ordered sequence of JOIN_TABs), and an unordered set of JOIN_TABs not yet added to the plan. Due to backtracking, the partial plan may both grow and shrink. When we add a new table to the plan, we may wish to set up join buffering, so that rows from the preceding table are buffered. If any of the remaining tables are derived tables that depends on any of the predecessors of the table we are adding (i.e. a lateral dependency), join buffering would be inefficient. (
- See also
- setup_join_buffering() for a detailed explanation of why this is so.)
For this reason we need to maintain this table_map of lateral dependencies of tables not yet in the plan. Whenever we add a new table to the plan, we update the map by calling Optimize_table_order::recalculate_lateral_deps_incrementally(). And when we remove a table, we restore the previous map value using a Tabel_map_restorer object.
As an example, assume that we join four tables, t1, t2, t3 and d1, where d1 is a derived table that depends on t1:
SELECT * FROM t1 JOIN t2 ON t1.a=t2.b JOIN t3 ON t2.c=t3.d JOIN LATERAL (SELECT DISTINCT e AS x FROM t4 WHERE t4.f=t1.c) AS d1 ON t3.e=d1.x;
Now, if our partial plan is t1->t2, the map (of lateral dependencies of the remaining tables) will contain t1. This tells us that we should not use join buffering when joining t1 with t2. But if the partial plan is t1->d2->t2, the map will be empty. We may thus use join buffering when joining d2 with t2.
1.9.2