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Diffstat (limited to 'sql/sql_tvc.cc')
| -rw-r--r-- | sql/sql_tvc.cc | 859 |
1 files changed, 859 insertions, 0 deletions
diff --git a/sql/sql_tvc.cc b/sql/sql_tvc.cc new file mode 100644 index 00000000000..0af5ad3cd11 --- /dev/null +++ b/sql/sql_tvc.cc @@ -0,0 +1,859 @@ +/* Copyright (c) 2017, 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 St, Fifth Floor, Boston, MA 02110-1301 USA */ + +#include "mariadb.h" +#include "sql_list.h" +#include "sql_tvc.h" +#include "sql_class.h" +#include "opt_range.h" +#include "sql_select.h" +#include "sql_explain.h" +#include "sql_parse.h" +#include "sql_cte.h" + +/** + @brief + Fix fields for TVC values + + @param + @param thd The context of the statement + @param li The iterator on the list of lists + + @details + Call fix_fields procedure for TVC values. + + @retval + true if an error was reported + false otherwise +*/ + +bool fix_fields_for_tvc(THD *thd, List_iterator_fast<List_item> &li) +{ + DBUG_ENTER("fix_fields_for_tvc"); + List_item *lst; + li.rewind(); + + while ((lst= li++)) + { + List_iterator_fast<Item> it(*lst); + Item *item; + + while ((item= it++)) + { + if (item->fix_fields(thd, 0)) + DBUG_RETURN(true); + } + } + DBUG_RETURN(false); +} + + +/** + @brief + Defines types of matrix columns elements where matrix rows are defined by + some lists of values. + + @param + @param thd The context of the statement + @param li The iterator on the list of lists + @param holders The structure where types of matrix columns are stored + @param first_list_el_count Count of the list values. It should be the same + for each list of lists elements. It contains + number of elements of the first list from list of + lists. + + @details + For each list list_a from list of lists the procedure gets its elements + types and aggregates them with the previous ones stored in holders. If + list_a is the first one in the list of lists its elements types are put in + holders. The errors can be reported when count of list_a elements is + different from the first_list_el_count. Also error can be reported whe + n aggregation can't be made. + + @retval + true if an error was reported + false otherwise +*/ + +bool join_type_handlers_for_tvc(THD *thd, List_iterator_fast<List_item> &li, + Type_holder *holders, uint first_list_el_count) +{ + DBUG_ENTER("join_type_handlers_for_tvc"); + List_item *lst; + li.rewind(); + bool first= true; + + while ((lst= li++)) + { + List_iterator_fast<Item> it(*lst); + Item *item; + + if (first_list_el_count != lst->elements) + { + my_message(ER_WRONG_NUMBER_OF_VALUES_IN_TVC, + ER_THD(thd, ER_WRONG_NUMBER_OF_VALUES_IN_TVC), + MYF(0)); + DBUG_RETURN(true); + } + for (uint pos= 0; (item=it++); pos++) + { + const Type_handler *item_type_handler= item->real_type_handler(); + if (first) + holders[pos].set_handler(item_type_handler); + else if (holders[pos].aggregate_for_result(item_type_handler)) + { + my_error(ER_ILLEGAL_PARAMETER_DATA_TYPES2_FOR_OPERATION, MYF(0), + holders[pos].type_handler()->name().ptr(), + item_type_handler->name().ptr(), + "TABLE VALUE CONSTRUCTOR"); + DBUG_RETURN(true); + } + } + first= false; + } + DBUG_RETURN(false); +} + + +/** + @brief + Define attributes of matrix columns elements where matrix rows are defined + by some lists of values. + + @param + @param thd The context of the statement + @param li The iterator on the list of lists + @param holders The structure where names of matrix columns are stored + @param count_of_lists Count of list of lists elements + @param first_list_el_count Count of the list values. It should be the same + for each list of lists elements. It contains + number of elements of the first list from list + of lists. + + @details + For each list list_a from list of lists the procedure gets its elements + attributes and aggregates them with the previous ones stored in holders. + The errors can be reported when aggregation can't be made. + + @retval + true if an error was reported + false otherwise +*/ + +bool get_type_attributes_for_tvc(THD *thd, + List_iterator_fast<List_item> &li, + Type_holder *holders, uint count_of_lists, + uint first_list_el_count) +{ + DBUG_ENTER("get_type_attributes_for_tvc"); + List_item *lst; + li.rewind(); + + for (uint pos= 0; pos < first_list_el_count; pos++) + { + if (holders[pos].alloc_arguments(thd, count_of_lists)) + DBUG_RETURN(true); + } + + while ((lst= li++)) + { + List_iterator_fast<Item> it(*lst); + Item *item; + for (uint holder_pos= 0 ; (item= it++); holder_pos++) + { + DBUG_ASSERT(item->fixed); + holders[holder_pos].add_argument(item); + } + } + + for (uint pos= 0; pos < first_list_el_count; pos++) + { + if (holders[pos].aggregate_attributes(thd)) + DBUG_RETURN(true); + } + DBUG_RETURN(false); +} + + +/** + @brief + Prepare of TVC + + @param + @param thd The context of the statement + @param sl The select where this TVC is defined + @param tmp_result Structure that contains the information + about where to send the result of the query + @param unit_arg The union where sl is defined + + @details + Gets types and attributes of values of this TVC that will be used + for temporary table creation for this TVC. It creates Item_type_holders + for each element of the first list from list of lists (VALUES from tvc), + using its elements name, defined type and attribute. + + @retval + true if an error was reported + false otherwise +*/ + +bool table_value_constr::prepare(THD *thd, SELECT_LEX *sl, + select_result *tmp_result, + st_select_lex_unit *unit_arg) +{ + DBUG_ENTER("table_value_constr::prepare"); + select_lex->in_tvc= true; + List_iterator_fast<List_item> li(lists_of_values); + + List_item *first_elem= li++; + uint cnt= first_elem->elements; + Type_holder *holders; + + if (fix_fields_for_tvc(thd, li)) + DBUG_RETURN(true); + + if (!(holders= new (thd->mem_root) + Type_holder[cnt]) || + join_type_handlers_for_tvc(thd, li, holders, + cnt) || + get_type_attributes_for_tvc(thd, li, holders, + lists_of_values.elements, cnt)) + DBUG_RETURN(true); + + List_iterator_fast<Item> it(*first_elem); + Item *item; + + sl->item_list.empty(); + for (uint pos= 0; (item= it++); pos++) + { + /* Error's in 'new' will be detected after loop */ + Item_type_holder *new_holder= new (thd->mem_root) + Item_type_holder(thd, + item, + holders[pos].type_handler(), + &holders[pos]/*Type_all_attributes*/, + holders[pos].get_maybe_null()); + new_holder->fix_fields(thd, 0); + sl->item_list.push_back(new_holder); + } + + if (thd->is_fatal_error) + DBUG_RETURN(true); // out of memory + + result= tmp_result; + + if (result && result->prepare(sl->item_list, unit_arg)) + DBUG_RETURN(true); + + select_lex->in_tvc= false; + DBUG_RETURN(false); +} + + +/** + Save Query Plan Footprint +*/ + +int table_value_constr::save_explain_data_intern(THD *thd, + Explain_query *output) +{ + const char *message= "No tables used"; + DBUG_ENTER("table_value_constr::save_explain_data_intern"); + DBUG_PRINT("info", ("Select %p, type %s, message %s", + select_lex, select_lex->type, + message)); + DBUG_ASSERT(have_query_plan == QEP_AVAILABLE); + + /* There should be no attempts to save query plans for merged selects */ + DBUG_ASSERT(!select_lex->master_unit()->derived || + select_lex->master_unit()->derived->is_materialized_derived() || + select_lex->master_unit()->derived->is_with_table()); + + explain= new (output->mem_root) Explain_select(output->mem_root, + thd->lex->analyze_stmt); + if (!explain) + DBUG_RETURN(1); + + select_lex->set_explain_type(true); + + explain->select_id= select_lex->select_number; + explain->select_type= select_lex->type; + explain->linkage= select_lex->linkage; + explain->using_temporary= false; + explain->using_filesort= false; + /* Setting explain->message means that all other members are invalid */ + explain->message= message; + + if (select_lex->master_unit()->derived) + explain->connection_type= Explain_node::EXPLAIN_NODE_DERIVED; + + output->add_node(explain); + + if (select_lex->is_top_level_node()) + output->query_plan_ready(); + + DBUG_RETURN(0); +} + + +/** + Optimization of TVC +*/ + +bool table_value_constr::optimize(THD *thd) +{ + create_explain_query_if_not_exists(thd->lex, thd->mem_root); + have_query_plan= QEP_AVAILABLE; + + if (select_lex->select_number != UINT_MAX && + select_lex->select_number != INT_MAX /* this is not a UNION's "fake select */ && + have_query_plan != QEP_NOT_PRESENT_YET && + thd->lex->explain && // for "SET" command in SPs. + (!thd->lex->explain->get_select(select_lex->select_number))) + { + return save_explain_data_intern(thd, thd->lex->explain); + } + return 0; +} + + +/** + Execute of TVC +*/ + +bool table_value_constr::exec(SELECT_LEX *sl) +{ + DBUG_ENTER("table_value_constr::exec"); + List_iterator_fast<List_item> li(lists_of_values); + List_item *elem; + + if (select_options & SELECT_DESCRIBE) + DBUG_RETURN(false); + + if (result->send_result_set_metadata(sl->item_list, + Protocol::SEND_NUM_ROWS | + Protocol::SEND_EOF)) + { + DBUG_RETURN(true); + } + + while ((elem= li++)) + { + result->send_data(*elem); + } + + if (result->send_eof()) + DBUG_RETURN(true); + + DBUG_RETURN(false); +} + + +/** + @brief + Print list + + @param str The reference on the string representation of the list + @param list The list that needed to be print + @param query_type The mode of printing + + @details + The method saves a string representation of list in the + string str. +*/ + +void print_list_item(String *str, List_item *list, + enum_query_type query_type) +{ + bool is_first_elem= true; + List_iterator_fast<Item> it(*list); + Item *item; + + str->append('('); + + while ((item= it++)) + { + if (is_first_elem) + is_first_elem= false; + else + str->append(','); + + item->print(str, query_type); + } + + str->append(')'); +} + + +/** + @brief + Print this TVC + + @param thd The context of the statement + @param str The reference on the string representation of this TVC + @param query_type The mode of printing + + @details + The method saves a string representation of this TVC in the + string str. +*/ + +void table_value_constr::print(THD *thd, String *str, + enum_query_type query_type) +{ + DBUG_ASSERT(thd); + + str->append(STRING_WITH_LEN("values ")); + + bool is_first_elem= true; + List_iterator_fast<List_item> li(lists_of_values); + List_item *list; + + while ((list= li++)) + { + if (is_first_elem) + is_first_elem= false; + else + str->append(','); + + print_list_item(str, list, query_type); + } +} + + +/** + @brief + Create list of lists for TVC from the list of this IN predicate + + @param thd The context of the statement + @param values TVC list of values + + @details + The method uses the list of values of this IN predicate to build + an equivalent list of values that can be used in TVC. + + E.g.: + + <value_list> = 5,2,7 + <transformed_value_list> = (5),(2),(7) + + <value_list> = (5,2),(7,1) + <transformed_value_list> = (5,2),(7,1) + + @retval + false if the method succeeds + true otherwise +*/ + +bool Item_func_in::create_value_list_for_tvc(THD *thd, + List< List<Item> > *values) +{ + bool is_list_of_rows= args[1]->type() == Item::ROW_ITEM; + + for (uint i=1; i < arg_count; i++) + { + List<Item> *tvc_value; + if (!(tvc_value= new (thd->mem_root) List<Item>())) + return true; + + if (is_list_of_rows) + { + Item_row *row_list= (Item_row *)(args[i]); + + for (uint j=0; j < row_list->cols(); j++) + { + if (tvc_value->push_back(row_list->element_index(j), + thd->mem_root)) + return true; + } + } + else if (tvc_value->push_back(args[i])) + return true; + + if (values->push_back(tvc_value, thd->mem_root)) + return true; + } + return false; +} + + +/** + @brief + Create name for the derived table defined by TVC + + @param thd The context of the statement + @param parent_select The SELECT where derived table is used + @param alias The returned created name + + @details + Create name for the derived table using current TVC number + for this parent_select stored in parent_select + + @retval + true if creation fails + false otherwise +*/ + +static bool create_tvc_name(THD *thd, st_select_lex *parent_select, + LEX_CSTRING *alias) +{ + char buff[6]; + + alias->length= my_snprintf(buff, sizeof(buff), + "tvc_%u", parent_select->curr_tvc_name); + alias->str= thd->strmake(buff, alias->length); + if (!alias->str) + return true; + + return false; +} + + +bool Item_subselect::wrap_tvc_in_derived_table(THD *thd, + st_select_lex *tvc_sl) +{ + LEX *lex= thd->lex; + /* SELECT_LEX object where the transformation is performed */ + SELECT_LEX *parent_select= lex->current_select; + uint8 save_derived_tables= lex->derived_tables; + + Query_arena backup; + Query_arena *arena= thd->activate_stmt_arena_if_needed(&backup); + + /* + Create SELECT_LEX of the subquery SQ used in the result of transformation + */ + lex->current_select= tvc_sl; + if (mysql_new_select(lex, 0, NULL)) + goto err; + mysql_init_select(lex); + /* Create item list as '*' for the subquery SQ */ + Item *item; + SELECT_LEX *sq_select; // select for IN subquery; + sq_select= lex->current_select; + sq_select->linkage= tvc_sl->linkage; + sq_select->parsing_place= SELECT_LIST; + item= new (thd->mem_root) Item_field(thd, &sq_select->context, + NULL, NULL, &star_clex_str); + if (item == NULL || add_item_to_list(thd, item)) + goto err; + (sq_select->with_wild)++; + + /* Exclude SELECT with TVC */ + tvc_sl->exclude(); + /* + Create derived table DT that will wrap TVC in the result of transformation + */ + SELECT_LEX *tvc_select; // select for tvc + SELECT_LEX_UNIT *derived_unit; // unit for tvc_select + if (mysql_new_select(lex, 1, tvc_sl)) + goto err; + tvc_select= lex->current_select; + derived_unit= tvc_select->master_unit(); + tvc_select->linkage= DERIVED_TABLE_TYPE; + + lex->current_select= sq_select; + + /* + Create the name of the wrapping derived table and + add it to the FROM list of the subquery SQ + */ + Table_ident *ti; + LEX_CSTRING alias; + TABLE_LIST *derived_tab; + if (!(ti= new (thd->mem_root) Table_ident(derived_unit)) || + create_tvc_name(thd, parent_select, &alias)) + goto err; + if (!(derived_tab= + sq_select->add_table_to_list(thd, + ti, &alias, 0, + TL_READ, MDL_SHARED_READ))) + goto err; + sq_select->add_joined_table(derived_tab); + sq_select->add_where_field(derived_unit->first_select()); + sq_select->context.table_list= sq_select->table_list.first; + sq_select->context.first_name_resolution_table= sq_select->table_list.first; + sq_select->table_list.first->derived_type= DTYPE_TABLE | DTYPE_MATERIALIZE; + lex->derived_tables|= DERIVED_SUBQUERY; + + sq_select->where= 0; + sq_select->set_braces(false); + derived_unit->set_with_clause(0); + + if (engine->engine_type() == subselect_engine::SINGLE_SELECT_ENGINE) + ((subselect_single_select_engine *) engine)->change_select(sq_select); + + if (arena) + thd->restore_active_arena(arena, &backup); + lex->current_select= sq_select; + return false; + +err: + if (arena) + thd->restore_active_arena(arena, &backup); + lex->derived_tables= save_derived_tables; + lex->current_select= parent_select; + return true; +} + + +/** + @brief + Transform IN predicate into IN subquery + + @param thd The context of the statement + @param arg Not used + + @details + The method transforms this IN predicate into in equivalent IN subquery: + + <left_expr> IN (<value_list>) + => + <left_expr> IN (SELECT * FROM (VALUES <transformed_value_list>) AS tvc_#) + + E.g.: + + <value_list> = 5,2,7 + <transformed_value_list> = (5),(2),(7) + + <value_list> = (5,2),(7,1) + <transformed_value_list> = (5,2),(7,1) + + If the transformation succeeds the method returns the result IN subquery, + otherwise this IN predicate is returned. + + @retval + pointer to the result of transformation if succeeded + pointer to this IN predicate otherwise +*/ + +Item *Item_func_in::in_predicate_to_in_subs_transformer(THD *thd, + uchar *arg) +{ + if (!transform_into_subq) + return this; + + transform_into_subq= false; + + List<List_item> values; + + LEX *lex= thd->lex; + /* SELECT_LEX object where the transformation is performed */ + SELECT_LEX *parent_select= lex->current_select; + uint8 save_derived_tables= lex->derived_tables; + + for (uint i=1; i < arg_count; i++) + { + if (!args[i]->const_item()) + return this; + } + + Query_arena backup; + Query_arena *arena= thd->activate_stmt_arena_if_needed(&backup); + + /* + Create SELECT_LEX of the subquery SQ used in the result of transformation + */ + if (mysql_new_select(lex, 1, NULL)) + goto err; + mysql_init_select(lex); + /* Create item list as '*' for the subquery SQ */ + Item *item; + SELECT_LEX *sq_select; // select for IN subquery; + sq_select= lex->current_select; + sq_select->parsing_place= SELECT_LIST; + item= new (thd->mem_root) Item_field(thd, &sq_select->context, + NULL, NULL, &star_clex_str); + if (item == NULL || add_item_to_list(thd, item)) + goto err; + (sq_select->with_wild)++; + /* + Create derived table DT that will wrap TVC in the result of transformation + */ + SELECT_LEX *tvc_select; // select for tvc + SELECT_LEX_UNIT *derived_unit; // unit for tvc_select + if (mysql_new_select(lex, 1, NULL)) + goto err; + mysql_init_select(lex); + tvc_select= lex->current_select; + derived_unit= tvc_select->master_unit(); + tvc_select->linkage= DERIVED_TABLE_TYPE; + + /* Create TVC used in the transformation */ + if (create_value_list_for_tvc(thd, &values)) + goto err; + if (!(tvc_select->tvc= + new (thd->mem_root) + table_value_constr(values, + tvc_select, + tvc_select->options))) + goto err; + + lex->current_select= sq_select; + + /* + Create the name of the wrapping derived table and + add it to the FROM list of the subquery SQ + */ + Table_ident *ti; + LEX_CSTRING alias; + TABLE_LIST *derived_tab; + if (!(ti= new (thd->mem_root) Table_ident(derived_unit)) || + create_tvc_name(thd, parent_select, &alias)) + goto err; + if (!(derived_tab= + sq_select->add_table_to_list(thd, + ti, &alias, 0, + TL_READ, MDL_SHARED_READ))) + goto err; + sq_select->add_joined_table(derived_tab); + sq_select->add_where_field(derived_unit->first_select()); + sq_select->context.table_list= sq_select->table_list.first; + sq_select->context.first_name_resolution_table= sq_select->table_list.first; + sq_select->table_list.first->derived_type= DTYPE_TABLE | DTYPE_MATERIALIZE; + lex->derived_tables|= DERIVED_SUBQUERY; + + sq_select->where= 0; + sq_select->set_braces(false); + derived_unit->set_with_clause(0); + + /* Create IN subquery predicate */ + sq_select->parsing_place= parent_select->parsing_place; + Item_in_subselect *in_subs; + Item *sq; + if (!(in_subs= + new (thd->mem_root) Item_in_subselect(thd, args[0], sq_select))) + goto err; + sq= in_subs; + if (negated) + sq= negate_expression(thd, in_subs); + else + in_subs->emb_on_expr_nest= emb_on_expr_nest; + + if (arena) + thd->restore_active_arena(arena, &backup); + thd->lex->current_select= parent_select; + + if (sq->fix_fields(thd, (Item **)&sq)) + goto err; + + parent_select->curr_tvc_name++; + return sq; + +err: + if (arena) + thd->restore_active_arena(arena, &backup); + lex->derived_tables= save_derived_tables; + thd->lex->current_select= parent_select; + return NULL; +} + + +/** + @brief + Check if this IN-predicate can be transformed in IN-subquery + with TVC + + @param thd The context of the statement + + @details + Compare the number of elements in the list of + values in this IN-predicate with the + in_subquery_conversion_threshold special variable + + @retval + true if transformation can be made + false otherwise +*/ + +bool Item_func_in::to_be_transformed_into_in_subq(THD *thd) +{ + uint values_count= arg_count-1; + + if (args[1]->type() == Item::ROW_ITEM) + values_count*= ((Item_row *)(args[1]))->cols(); + + if (values_count < thd->variables.in_subquery_conversion_threshold) + return false; + + return true; +} + + +/** + @brief + Transform IN predicates into IN subqueries in WHERE and ON expressions + + @param thd The context of the statement + + @details + For each IN predicate from AND parts of the WHERE condition and/or + ON expressions of the SELECT for this join the method performs + the intransformation into an equivalent IN sunquery if it's needed. + + @retval + false always +*/ + +bool JOIN::transform_in_predicates_into_in_subq(THD *thd) +{ + DBUG_ENTER("JOIN::transform_in_predicates_into_in_subq"); + if (!select_lex->in_funcs.elements) + DBUG_RETURN(false); + + SELECT_LEX *save_current_select= thd->lex->current_select; + enum_parsing_place save_parsing_place= select_lex->parsing_place; + thd->lex->current_select= select_lex; + if (conds) + { + select_lex->parsing_place= IN_WHERE; + conds= + conds->transform(thd, + &Item::in_predicate_to_in_subs_transformer, + (uchar*) 0); + if (!conds) + DBUG_RETURN(true); + select_lex->prep_where= conds ? conds->copy_andor_structure(thd) : 0; + select_lex->where= conds; + } + + if (join_list) + { + TABLE_LIST *table; + List_iterator<TABLE_LIST> li(*join_list); + select_lex->parsing_place= IN_ON; + + while ((table= li++)) + { + if (table->on_expr) + { + table->on_expr= + table->on_expr->transform(thd, + &Item::in_predicate_to_in_subs_transformer, + (uchar*) 0); + if (!table->on_expr) + DBUG_RETURN(true); + table->prep_on_expr= table->on_expr ? + table->on_expr->copy_andor_structure(thd) : 0; + } + } + } + + select_lex->in_funcs.empty(); + select_lex->parsing_place= save_parsing_place; + thd->lex->current_select= save_current_select; + DBUG_RETURN(false); +} + |