diff options
Diffstat (limited to 'sql/sql_cte.cc')
| -rw-r--r-- | sql/sql_cte.cc | 422 |
1 files changed, 289 insertions, 133 deletions
diff --git a/sql/sql_cte.cc b/sql/sql_cte.cc index ad4a37d0fbe..396b3f2c8a9 100644 --- a/sql/sql_cte.cc +++ b/sql/sql_cte.cc @@ -84,7 +84,7 @@ void st_select_lex_unit::set_with_clause(With_clause *with_cl) true on failure */ -bool check_dependencies_in_with_clauses(With_clause *with_clauses_list) +bool LEX::check_dependencies_in_with_clauses() { for (With_clause *with_clause= with_clauses_list; with_clause; @@ -102,6 +102,201 @@ bool check_dependencies_in_with_clauses(With_clause *with_clauses_list) /** @brief + Resolve references to CTE in specification of hanging CTE + + @details + A CTE to which there are no references in the query is called hanging CTE. + Although such CTE is not used for execution its specification must be + subject to context analysis. All errors concerning references to + non-existing tables or fields occurred in the specification must be + reported as well as all other errors caught at the prepare stage. + The specification of a hanging CTE might contain references to other + CTE outside of the specification and within it if the specification + contains a with clause. This function resolves all such references for + all hanging CTEs encountered in the processed query. + + @retval + false on success + true on failure +*/ + +bool +LEX::resolve_references_to_cte_in_hanging_cte() +{ + for (With_clause *with_clause= with_clauses_list; + with_clause; with_clause= with_clause->next_with_clause) + { + for (With_element *with_elem= with_clause->with_list.first; + with_elem; with_elem= with_elem->next) + { + if (!with_elem->is_referenced()) + { + TABLE_LIST *first_tbl= + with_elem->spec->first_select()->table_list.first; + TABLE_LIST **with_elem_end_pos= with_elem->head->tables_pos.end_pos; + if (first_tbl && resolve_references_to_cte(first_tbl, with_elem_end_pos)) + return true; + } + } + } + return false; +} + + +/** + @brief + Resolve table references to CTE from a sub-chain of table references + + @param tables Points to the beginning of the sub-chain + @param tables_last Points to the address with the sub-chain barrier + + @details + The method resolves tables references to CTE from the chain of + table references specified by the parameters 'tables' and 'tables_last'. + It resolves the references against the CTE definition occurred in a query + or the specification of a CTE whose parsing tree is represented by + this LEX structure. The method is always called right after the process + of parsing the query or of the specification of a CTE has been finished, + thus the chain of table references used in the parsed fragment has been + already built. It is assumed that parameters of the method specify a + a sub-chain of this chain. + If a table reference can be potentially a table reference to a CTE and it + has not been resolved yet then the method tries to find the definition + of the CTE against which the reference can be resolved. If it succeeds + it sets the field TABLE_LIST::with to point to the found definition. + It also sets the field TABLE_LIST::derived to point to the specification + of the found CTE and sets TABLE::db.str to empty_c_string. This will + allow to handle this table reference like a reference to a derived handle. + If another table reference has been already resolved against this CTE + and this CTE is not recursive then a clone of the CTE specification is + constructed using the function With_element::clone_parsed_spec() and + TABLE_LIST::derived is set to point to this clone rather than to the + original specification. + If the method does not find a matched CTE definition in the parsed fragment + then in the case when the flag this->only_cte_resolution is set to true + it just moves to the resolution of the next table reference from the + specified sub-chain while in the case when this->only_cte_resolution is set + to false the method additionally sets an mdl request for this table + reference. + + @notes + The flag this->only_cte_resolution is set to true in the cases when + the failure to resolve a table reference as a CTE reference within + the fragment associated with this LEX structure does not imply that + this table reference cannot be resolved as such at all. + + @retval false On success: no errors reported, no memory allocations failed + @retval true Otherwise +*/ + +bool LEX::resolve_references_to_cte(TABLE_LIST *tables, + TABLE_LIST **tables_last) +{ + With_element *with_elem= 0; + + for (TABLE_LIST *tbl= tables; tbl != *tables_last; tbl= tbl->next_global) + { + if (tbl->derived) + continue; + if (!tbl->db.str && !tbl->with) + tbl->with= tbl->select_lex->find_table_def_in_with_clauses(tbl); + if (!tbl->with) // no CTE matches table reference tbl + { + if (only_cte_resolution) + continue; + if (!tbl->db.str) // no database specified in table reference tbl + { + if (!thd->db.str) // no default database is set + { + my_message(ER_NO_DB_ERROR, ER(ER_NO_DB_ERROR), MYF(0)); + return true; + } + if (copy_db_to(&tbl->db)) + return true; + if (!(tbl->table_options & TL_OPTION_ALIAS)) + MDL_REQUEST_INIT(&tbl->mdl_request, MDL_key::TABLE, + tbl->db.str, tbl->table_name.str, + tbl->mdl_type, MDL_TRANSACTION); + tbl->mdl_request.set_type((tbl->lock_type >= TL_WRITE_ALLOW_WRITE) ? + MDL_SHARED_WRITE : MDL_SHARED_READ); + } + continue; + } + with_elem= tbl->with; + if (tbl->is_recursive_with_table() && + !tbl->is_with_table_recursive_reference()) + { + tbl->with->rec_outer_references++; + while ((with_elem= with_elem->get_next_mutually_recursive()) != + tbl->with) + with_elem->rec_outer_references++; + } + if (!with_elem->is_used_in_query || with_elem->is_recursive) + { + tbl->derived= with_elem->spec; + if (tbl->derived != tbl->select_lex->master_unit() && + !with_elem->is_recursive && + !tbl->is_with_table_recursive_reference()) + { + tbl->derived->move_as_slave(tbl->select_lex); + } + with_elem->is_used_in_query= true; + } + else + { + if (!(tbl->derived= tbl->with->clone_parsed_spec(thd->lex, tbl))) + return true; + } + tbl->db.str= empty_c_string; + tbl->db.length= 0; + tbl->schema_table= 0; + if (tbl->derived) + { + tbl->derived->first_select()->set_linkage(DERIVED_TABLE_TYPE); + tbl->select_lex->add_statistics(tbl->derived); + } + if (tbl->with->is_recursive && tbl->is_with_table_recursive_reference()) + continue; + with_elem->inc_references(); + } + return false; +} + + +/** + @brief + Find out dependencies between CTEs, resolve references to them + + @details + The function can be called in two modes. With this->with_cte_resolution + set to false the function only finds out all dependencies between CTEs + used in a query expression with a WITH clause whose parsing has been + just finished. Based on these dependencies recursive CTEs are detected. + If this->with_cte_resolution is set to true the function additionally + resolves all references to CTE occurred in this query expression. + + @retval + true on failure + false on success +*/ + +bool +LEX::check_cte_dependencies_and_resolve_references() +{ + if (check_dependencies_in_with_clauses()) + return true; + if (!with_cte_resolution) + return false; + if (resolve_references_to_cte(query_tables, query_tables_last)) + return true; + if (resolve_references_to_cte_in_hanging_cte()) + return true; + return false; +} + + +/** + @brief Check dependencies between tables defined in this with clause @details @@ -138,10 +333,11 @@ bool With_clause::check_dependencies() elem != with_elem; elem= elem->next) { - if (lex_string_cmp(system_charset_info, with_elem->query_name, - elem->query_name) == 0) + if (lex_string_cmp(system_charset_info, with_elem->get_name(), + elem->get_name()) == 0) { - my_error(ER_DUP_QUERY_NAME, MYF(0), with_elem->query_name->str); + my_error(ER_DUP_QUERY_NAME, MYF(0), + with_elem->get_name_str()); return true; } } @@ -248,13 +444,12 @@ With_element *With_clause::find_table_def(TABLE_LIST *table, with_elem != barrier; with_elem= with_elem->next) { - if (my_strcasecmp(system_charset_info, with_elem->query_name->str, - table->table_name.str) == 0 && + if (my_strcasecmp(system_charset_info, with_elem->get_name_str(), + table->table_name.str) == 0 && !table->is_fqtn) { table->set_derived(); - table->db.str= empty_c_string; - table->db.length= 0; + with_elem->referenced= true; return with_elem; } } @@ -611,7 +806,7 @@ bool With_clause::check_anchors() if (elem == with_elem) { my_error(ER_RECURSIVE_WITHOUT_ANCHORS, MYF(0), - with_elem->query_name->str); + with_elem->get_name_str()); return true; } } @@ -644,7 +839,7 @@ bool With_clause::check_anchors() if (elem->work_dep_map & elem->get_elem_map()) { my_error(ER_UNACCEPTABLE_MUTUAL_RECURSION, MYF(0), - with_elem->query_name->str); + with_elem->get_name_str()); return true; } } @@ -798,7 +993,8 @@ bool With_element::set_unparsed_spec(THD *thd, @brief Create a clone of the specification for the given with table - @param thd The context of the statement containing this with element + @param old_lex The LEX structure created for the query or CTE specification + where this With_element is defined @param with_table The reference to the table defined in this element for which the clone is created. @@ -808,12 +1004,13 @@ bool With_element::set_unparsed_spec(THD *thd, this element. The clone is created when the string with the specification saved in unparsed_spec is fed into the parser as an input string. The parsing - this string a unit object representing the specification is build. + this string a unit object representing the specification is built. A chain of all table references occurred in the specification is also formed. The method includes the new unit and its sub-unit into hierarchy of the units of the main query. I also insert the constructed chain of the table references into the chain of all table references of the main query. + The method resolves all references to CTE in the clone. @note Clones is created only for not first references to tables defined in @@ -829,116 +1026,128 @@ bool With_element::set_unparsed_spec(THD *thd, NULL - otherwise */ -st_select_lex_unit *With_element::clone_parsed_spec(THD *thd, +st_select_lex_unit *With_element::clone_parsed_spec(LEX *old_lex, TABLE_LIST *with_table) { + THD *thd= old_lex->thd; LEX *lex; - st_select_lex_unit *res= NULL; - Query_arena backup; - Query_arena *arena= thd->activate_stmt_arena_if_needed(&backup); - bool has_tmp_tables; + st_select_lex_unit *res= NULL; if (!(lex= (LEX*) new(thd->mem_root) st_lex_local)) - { - if (arena) - thd->restore_active_arena(arena, &backup); return res; - } - LEX *old_lex= thd->lex; thd->lex= lex; bool parse_status= false; - Parser_state parser_state; - TABLE_LIST *spec_tables; - TABLE_LIST *spec_tables_tail; st_select_lex *with_select; char save_end= unparsed_spec.str[unparsed_spec.length]; ((char*) &unparsed_spec.str[unparsed_spec.length])[0]= '\0'; - if (parser_state.init(thd, (char*) unparsed_spec.str, (unsigned int)unparsed_spec.length)) - goto err; - parser_state.m_lip.stmt_prepare_mode= stmt_prepare_mode; - parser_state.m_lip.multi_statements= false; - parser_state.m_lip.m_digest= NULL; lex_start(thd); lex->clone_spec_offset= unparsed_spec_offset; - lex->param_list= old_lex->param_list; - lex->sphead= old_lex->sphead; - lex->spname= old_lex->spname; - lex->spcont= old_lex->spcont; - lex->sp_chistics= old_lex->sp_chistics; - - lex->stmt_lex= old_lex; - parse_status= parse_sql(thd, &parser_state, 0); + lex->with_cte_resolution= true; + + /* + The specification of a CTE is to be parsed as a regular query. + At the very end of the parsing query the function + check_cte_dependencies_and_resolve_references() will be called. + It will check the dependencies between CTEs that are defined + within the query and will resolve CTE references in this query. + If a table reference is not resolved as a CTE reference within + this query it still can be resolved as a reference to a CTE defined + in the same clause as the CTE whose specification is to be parsed + or defined in an embedding CTE definition. + + Example: + with + cte1 as ( ... ), + cte2 as ([WITH ...] select ... from cte1 ...) + select ... from cte2 as r, ..., cte2 as s ... + + Here the specification of cte2 has be cloned for table reference + with alias s1. The specification contains a reference to cte1 + that is defined outside this specification. If the reference to + cte1 cannot be resolved within the specification of cte2 it's + not necessarily has to be a reference to a non-CTE table. That's + why the flag lex->only_cte_resolution has to be set to true + before parsing of the specification of cte2 invoked by this + function starts. Otherwise an mdl_lock would be requested for s + and this would not be correct. + */ + + lex->only_cte_resolution= true; + + lex->stmt_lex= old_lex->stmt_lex ? old_lex->stmt_lex : old_lex; + + parse_status= thd->sql_parser(old_lex, lex, + (char*) unparsed_spec.str, + (unsigned int)unparsed_spec.length, + stmt_prepare_mode); + ((char*) &unparsed_spec.str[unparsed_spec.length])[0]= save_end; - with_select= lex->first_select_lex(); + with_select= lex->unit.first_select(); if (parse_status) goto err; - if (check_dependencies_in_with_clauses(lex->with_clauses_list)) - goto err; - - spec_tables= lex->query_tables; - spec_tables_tail= 0; - has_tmp_tables= thd->has_temporary_tables(); - for (TABLE_LIST *tbl= spec_tables; - tbl; - tbl= tbl->next_global) - { - if (has_tmp_tables && !tbl->derived && !tbl->schema_table && - thd->open_temporary_table(tbl)) - goto err; - spec_tables_tail= tbl; - } - if (spec_tables) + /* + The global chain of TABLE_LIST objects created for the specification that + just has been parsed is added to such chain that contains the reference + to the CTE whose specification is parsed right after the TABLE_LIST object + created for the reference. + */ + if (lex->query_tables) { - if (with_table->next_global) + head->tables_pos.set_start_pos(&with_table->next_global); + head->tables_pos.set_end_pos(lex->query_tables_last); + TABLE_LIST *next_tbl= with_table->next_global; + if (next_tbl) { - spec_tables_tail->next_global= with_table->next_global; - with_table->next_global->prev_global= &spec_tables_tail->next_global; + *(lex->query_tables->prev_global= next_tbl->prev_global)= + lex->query_tables; + *(next_tbl->prev_global= lex->query_tables_last)= next_tbl; } else { - old_lex->query_tables_last= &spec_tables_tail->next_global; + *(lex->query_tables->prev_global= old_lex->query_tables_last)= + lex->query_tables; + old_lex->query_tables_last= lex->query_tables_last; } - spec_tables->prev_global= &with_table->next_global; - with_table->next_global= spec_tables; } res= &lex->unit; res->with_element= this; + /* + The unit of the specification that just has been parsed is included + as a slave of the select that contained in its from list the table + reference for which the unit has been created. + */ lex->unit.include_down(with_table->select_lex); - lex->unit.set_slave(with_select); + lex->unit.set_slave(with_select); + lex->unit.cloned_from= spec; old_lex->all_selects_list= (st_select_lex*) (lex->all_selects_list-> insert_chain_before( (st_select_lex_node **) &(old_lex->all_selects_list), with_select)); - if (check_dependencies_in_with_clauses(lex->with_clauses_list)) - res= NULL; + /* - Resolve references to CTE from the spec_tables list that has not - been resolved yet. + Now all references to the CTE defined outside of the cloned specification + has to be resolved. Additionally if old_lex->only_cte_resolution == false + for the table references that has not been resolved requests for mdl_locks + has to be set. */ - for (TABLE_LIST *tbl= spec_tables; - tbl; - tbl= tbl->next_global) + lex->only_cte_resolution= old_lex->only_cte_resolution; + if (lex->resolve_references_to_cte(lex->query_tables, + lex->query_tables_last)) { - if (!tbl->with) - tbl->with= with_select->find_table_def_in_with_clauses(tbl); - if (tbl == spec_tables_tail) - break; - } - if (check_table_access(thd, SELECT_ACL, spec_tables, FALSE, UINT_MAX, FALSE)) + res= NULL; goto err; + } - lex->sphead= NULL; // in order not to delete lex->sphead + lex->sphead= NULL; // in order not to delete lex->sphead lex_end(lex); err: - if (arena) - thd->restore_active_arena(arena, &backup); thd->lex= old_lex; return res; } @@ -1145,59 +1354,6 @@ With_element *st_select_lex::find_table_def_in_with_clauses(TABLE_LIST *table) } -/** - @brief - Set the specifying unit in this reference to a with table - - @details - The method assumes that the given element with_elem defines the table T - this table reference refers to. - If this is the first reference to T the method just sets its specification - in the field 'derived' as the unit that yields T. Otherwise the method - first creates a clone specification and sets rather this clone in this field. - - @retval - false on success - true on failure -*/ - -bool TABLE_LIST::set_as_with_table(THD *thd, With_element *with_elem) -{ - if (table) - { - /* - This table was prematurely identified as a temporary table. - We correct it here, but it's not a nice solution in the case - when the temporary table with this name is not used anywhere - else in the query. - */ - thd->mark_tmp_table_as_free_for_reuse(table); - table= 0; - } - with= with_elem; - schema_table= NULL; - if (!with_elem->is_referenced() || with_elem->is_recursive) - { - derived= with_elem->spec; - if (derived != select_lex->master_unit() && - !with_elem->is_recursive && - !is_with_table_recursive_reference()) - { - derived->move_as_slave(select_lex); - } - } - else - { - if(!(derived= with_elem->clone_parsed_spec(thd, this))) - return true; - } - derived->first_select()->set_linkage(DERIVED_TABLE_TYPE); - select_lex->add_statistics(derived); - with_elem->inc_references(); - return false; -} - - bool TABLE_LIST::is_recursive_with_table() { return with && with->is_recursive; @@ -1297,7 +1453,7 @@ bool st_select_lex::check_unrestricted_recursive(bool only_standard_compliant) if (only_standard_compliant && with_elem->is_unrestricted()) { my_error(ER_NOT_STANDARD_COMPLIANT_RECURSIVE, - MYF(0), with_elem->query_name->str); + MYF(0), with_elem->get_name_str()); return true; } @@ -1514,7 +1670,7 @@ static void list_strlex_print(THD *thd, String *str, List<Lex_ident_sys> *list) void With_element::print(THD *thd, String *str, enum_query_type query_type) { - str->append(query_name); + str->append(get_name()); if (column_list.elements) { List_iterator_fast<Lex_ident_sys> li(column_list); |