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115 lines
4.5 KiB
115 lines
4.5 KiB
5 months ago
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/* Copyright (c) 2015, 2019, 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 DEFAULT_VALUES_INCLUDED
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#define DEFAULT_VALUES_INCLUDED
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#include <stddef.h>
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#include "my_inttypes.h"
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/** Forward declarations. */
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class Create_field;
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class THD;
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template <class T>
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class List;
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namespace dd {
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class Column;
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class Table;
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} // namespace dd
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struct TABLE;
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struct TABLE_SHARE;
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/**
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Find the largest field among a list of create fields.
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Iterates over the list of create fields and find the largest one, i.e.
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the field with largest pack length.
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@param create_fields List of create fields.
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@return Size of the largest field, as number of bytes.
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*/
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size_t max_pack_length(const List<Create_field> &create_fields);
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/**
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Prepare the default value of a single column.
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This function creates a fake field using the submitted fake table
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object, which also has assigned a fake table share. The field is
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create in order to use existing code to store the default value. The
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value is stored into the submitted buffer, which has been allocated
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in advance (and will be deleted afterwards). The fake table and
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share are required by the field infrastructure.
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After storing the default value into the buffer, the value is read back
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and copied into the column object's default value field. For bit fields
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with leftover bits in the preamble, these bits are copied and appended
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onto the default value as the last byte.
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@param thd Thread context.
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@param buf Buffer to store the default value into. The buffer
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size must be at least two bytes.
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@param table Fake table to use when storing the default value.
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@param field Create_field corresponding to the column object.
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@param [in,out] col_obj Column for which to prepare the default value.
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@retval true Failure.
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@retval false Success.
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*/
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bool prepare_default_value(THD *thd, uchar *buf, TABLE *table,
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const Create_field &field, dd::Column *col_obj);
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/**
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Prepare the default value buffer for an empty record.
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This function prepares the buffer based on the objects retrieved from the
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data dictionary. The function will scan the columns of the submitted table
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objects and calculate the length of the record, the number of null bits,
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etc. The empty buffer is allocated, and all bits are set to 0, including
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used null bits, the actual field values, etc. Afterwards, the unused bits
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in the preamble, up to the next full byte border, are set to 1. Finally,
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the buffer is assigned to the 'TABLE_SHARE::default_values' field.
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@note This function does not fill in the actual default values, it just
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allocates and prepares the buffer.
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@param thd Thread context.
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@param table Table for which the default value buffer should
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be prepared.
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@param [in,out] share Table share for the table. The default value
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buffer is assigned to the appropriate table
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share field.
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@retval true Failure.
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@retval false Success.
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*/
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bool prepare_default_value_buffer_and_table_share(THD *thd,
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const dd::Table &table,
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TABLE_SHARE *share);
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#endif /* DEFAULT_VALUES_INCLUDED */
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