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307 lines
9.7 KiB
307 lines
9.7 KiB
/* Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef QUERY_RESULT_INCLUDED
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#define QUERY_RESULT_INCLUDED
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#include <stddef.h>
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#include <sys/types.h>
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#include "m_ctype.h"
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#include "my_base.h"
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#include "my_dbug.h"
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#include "my_inttypes.h"
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#include "my_io.h"
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#include "my_sys.h"
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#include "mysqld_error.h" // ER_*
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#include "sql/sql_list.h"
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class Item;
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class Item_subselect;
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class PT_select_var;
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class SELECT_LEX_UNIT;
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class THD;
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/*
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This is used to get result from a query
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*/
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class Query_result {
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protected:
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SELECT_LEX_UNIT *unit;
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public:
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/**
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Number of records estimated in this result.
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Valid only for materialized derived tables/views.
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*/
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ha_rows estimated_rowcount;
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/**
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Cost to execute the subquery which produces this result.
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Valid only for materialized derived tables/views.
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*/
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double estimated_cost;
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Query_result() : unit(NULL), estimated_rowcount(0), estimated_cost(0) {}
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virtual ~Query_result() {}
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virtual bool needs_file_privilege() const { return false; }
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/**
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Change wrapped Query_result.
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Replace the wrapped query result object with new_result and call
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prepare() on new_result.
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This base class implementation doesn't wrap other Query_results.
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@retval false Success
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@retval true Error
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*/
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virtual bool change_query_result(THD *, Query_result *) { return false; }
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/// @return true if an interceptor object is needed for EXPLAIN
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virtual bool need_explain_interceptor() const { return false; }
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/**
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Perform preparation specific to the query expression or DML statement.
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@returns false if success, true if error
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*/
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virtual bool prepare(THD *, List<Item> &, SELECT_LEX_UNIT *u) {
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unit = u;
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return false;
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}
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/**
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Optimize the result processing of a query expression, applicable to
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data change operation (not simple select queries).
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@returns false if success, true if error
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*/
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virtual bool optimize() { return false; }
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/**
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Prepare for execution of the query expression or DML statement.
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Generally, this will have an implementation only for outer-most
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SELECT_LEX objects, such as data change statements (for preparation
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of the target table(s)) or dump statements (for preparation of target file).
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@returns false if success, true if error
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*/
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virtual bool start_execution(THD *) { return false; }
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/*
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Because of peculiarities of prepared statements protocol
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we need to know number of columns in the result set (if
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there is a result set) apart from sending columns metadata.
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*/
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virtual uint field_count(List<Item> &fields) const { return fields.elements; }
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virtual bool send_result_set_metadata(THD *thd, List<Item> &list,
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uint flags) = 0;
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virtual bool send_data(THD *thd, List<Item> &items) = 0;
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virtual void send_error(THD *, uint errcode, const char *err) {
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my_message(errcode, err, MYF(0));
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}
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virtual bool send_eof(THD *thd) = 0;
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/**
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Check if this query returns a result set and therefore is allowed in
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cursors and set an error message if it is not the case.
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@retval false success
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@retval true error, an error message is set
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*/
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virtual bool check_simple_select() const {
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my_error(ER_SP_BAD_CURSOR_QUERY, MYF(0));
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return true;
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}
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virtual void abort_result_set(THD *) {}
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/**
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Cleanup after one execution of the unit, to be ready for a next execution
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inside the same statement.
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@returns true if error
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*/
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virtual bool reset() {
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DBUG_ASSERT(0);
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return false;
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}
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/**
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Cleanup after this execution. Completes the execution and resets object
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before next execution of a prepared statement/stored procedure.
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*/
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virtual void cleanup(THD *) { /* do nothing */
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}
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void begin_dataset() {}
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/// @returns Pointer to count of rows retained by this result.
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virtual const ha_rows *row_count() const /* purecov: inspected */
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{
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DBUG_ASSERT(false);
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return nullptr;
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} /* purecov: inspected */
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/**
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Checks if this Query_result intercepts and transforms the result set.
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@return true if it is an interceptor, false otherwise
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*/
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virtual bool is_interceptor() const { return false; }
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};
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/*
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Base class for Query_result descendands which intercept and
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transform result set rows. As the rows are not sent to the client,
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sending of result set metadata should be suppressed as well.
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*/
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class Query_result_interceptor : public Query_result {
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public:
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Query_result_interceptor() : Query_result() {}
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uint field_count(List<Item> &) const override { return 0; }
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bool send_result_set_metadata(THD *, List<Item> &, uint) override {
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return false;
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}
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bool is_interceptor() const override final { return true; }
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};
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class Query_result_send : public Query_result {
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/**
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True if we have sent result set metadata to the client.
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In this case the client always expects us to end the result
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set with an eof or error packet
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*/
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bool is_result_set_started;
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public:
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Query_result_send() : Query_result(), is_result_set_started(false) {}
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bool send_result_set_metadata(THD *thd, List<Item> &list,
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uint flags) override;
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bool send_data(THD *thd, List<Item> &items) override;
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bool send_eof(THD *thd) override;
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bool check_simple_select() const override { return false; }
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void abort_result_set(THD *thd) override;
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void cleanup(THD *) override { is_result_set_started = false; }
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};
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class sql_exchange;
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class Query_result_to_file : public Query_result_interceptor {
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protected:
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sql_exchange *exchange;
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File file;
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IO_CACHE cache;
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ha_rows row_count;
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char path[FN_REFLEN];
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public:
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explicit Query_result_to_file(sql_exchange *ex)
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: Query_result_interceptor(), exchange(ex), file(-1), row_count(0L) {
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path[0] = 0;
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}
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~Query_result_to_file() override { DBUG_ASSERT(file < 0); }
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bool needs_file_privilege() const override { return true; }
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void send_error(THD *thd, uint errcode, const char *err) override;
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bool send_eof(THD *thd) override;
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void cleanup(THD *thd) override;
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};
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#define ESCAPE_CHARS "ntrb0ZN" // keep synchronous with READ_INFO::unescape
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/*
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List of all possible characters of a numeric value text representation.
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*/
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#define NUMERIC_CHARS ".0123456789e+-"
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class Query_result_export final : public Query_result_to_file {
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size_t field_term_length;
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int field_sep_char, escape_char, line_sep_char;
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int field_term_char; // first char of FIELDS TERMINATED BY or MAX_INT
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/*
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The is_ambiguous_field_sep field is true if a value of the field_sep_char
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field is one of the 'n', 't', 'r' etc characters
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(see the READ_INFO::unescape method and the ESCAPE_CHARS constant value).
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*/
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bool is_ambiguous_field_sep;
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/*
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The is_ambiguous_field_term is true if field_sep_char contains the first
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char of the FIELDS TERMINATED BY (ENCLOSED BY is empty), and items can
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contain this character.
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*/
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bool is_ambiguous_field_term;
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/*
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The is_unsafe_field_sep field is true if a value of the field_sep_char
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field is one of the '0'..'9', '+', '-', '.' and 'e' characters
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(see the NUMERIC_CHARS constant value).
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*/
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bool is_unsafe_field_sep;
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bool fixed_row_size;
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const CHARSET_INFO *write_cs; // output charset
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public:
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explicit Query_result_export(sql_exchange *ex) : Query_result_to_file(ex) {}
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bool prepare(THD *thd, List<Item> &list, SELECT_LEX_UNIT *u) override;
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bool start_execution(THD *thd) override;
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bool send_data(THD *thd, List<Item> &items) override;
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void cleanup(THD *thd) override;
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};
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class Query_result_dump : public Query_result_to_file {
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public:
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explicit Query_result_dump(sql_exchange *ex) : Query_result_to_file(ex) {}
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bool prepare(THD *thd, List<Item> &list, SELECT_LEX_UNIT *u) override;
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bool start_execution(THD *thd) override;
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bool send_data(THD *thd, List<Item> &items) override;
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};
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class Query_dumpvar final : public Query_result_interceptor {
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ha_rows row_count;
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public:
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List<PT_select_var> var_list;
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Query_dumpvar() : Query_result_interceptor(), row_count(0) {
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var_list.empty();
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}
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bool prepare(THD *thd, List<Item> &list, SELECT_LEX_UNIT *u) override;
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bool send_data(THD *thd, List<Item> &items) override;
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bool send_eof(THD *thd) override;
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bool check_simple_select() const override;
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void cleanup(THD *) override { row_count = 0; }
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};
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/**
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Base class for result from a subquery.
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*/
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class Query_result_subquery : public Query_result_interceptor {
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protected:
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Item_subselect *item;
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public:
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explicit Query_result_subquery(Item_subselect *item_arg)
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: Query_result_interceptor(), item(item_arg) {}
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bool send_data(THD *thd, List<Item> &items) override = 0;
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bool send_eof(THD *) override { return false; }
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};
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#endif // QUERY_RESULT_INCLUDED
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