mariadb/storage/innobase/include/dict0dict.ic

/*****************************************************************************

Copyright (c) 1996, 2009, Innobase Oy. All Rights Reserved.

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., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA

*****************************************************************************/

/******************************************************************//**
@file include/dict0dict.ic
Data dictionary system

Created 1/8/1996 Heikki Tuuri
***********************************************************************/

#include "data0type.h"
#ifndef UNIV_HOTBACKUP
#include "dict0load.h"
#include "rem0types.h"

/*********************************************************************//**
Gets the minimum number of bytes per character.
@return minimum multi-byte char size, in bytes */
UNIV_INLINE
ulint
dict_col_get_mbminlen(
/*==================*/
	const dict_col_t*	col)	/*!< in: column */
{
	return(DATA_MBMINLEN(col->mbminmaxlen));
}
/*********************************************************************//**
Gets the maximum number of bytes per character.
@return maximum multi-byte char size, in bytes */
UNIV_INLINE
ulint
dict_col_get_mbmaxlen(
/*==================*/
	const dict_col_t*	col)	/*!< in: column */
{
	return(DATA_MBMAXLEN(col->mbminmaxlen));
}
/*********************************************************************//**
Sets the minimum and maximum number of bytes per character. */
UNIV_INLINE
void
dict_col_set_mbminmaxlen(
/*=====================*/
	dict_col_t*	col,		/*!< in/out: column */
	ulint		mbminlen,	/*!< in: minimum multi-byte
					character size, in bytes */
	ulint		mbmaxlen)	/*!< in: minimum multi-byte
					character size, in bytes */
{
	ut_ad(mbminlen < DATA_MBMAX);
	ut_ad(mbmaxlen < DATA_MBMAX);
	ut_ad(mbminlen <= mbmaxlen);

	col->mbminmaxlen = DATA_MBMINMAXLEN(mbminlen, mbmaxlen);
}
/*********************************************************************//**
Gets the column data type. */
UNIV_INLINE
void
dict_col_copy_type(
/*===============*/
	const dict_col_t*	col,	/*!< in: column */
	dtype_t*		type)	/*!< out: data type */
{
	ut_ad(col && type);

	type->mtype = col->mtype;
	type->prtype = col->prtype;
	type->len = col->len;
	type->mbminmaxlen = col->mbminmaxlen;
}
#endif /* !UNIV_HOTBACKUP */

#ifdef UNIV_DEBUG
/*********************************************************************//**
Assert that a column and a data type match.
@return	TRUE */
UNIV_INLINE
ibool
dict_col_type_assert_equal(
/*=======================*/
	const dict_col_t*	col,	/*!< in: column */
	const dtype_t*		type)	/*!< in: data type */
{
	ut_ad(col);
	ut_ad(type);

	ut_ad(col->mtype == type->mtype);
	ut_ad(col->prtype == type->prtype);
	ut_ad(col->len == type->len);
# ifndef UNIV_HOTBACKUP
	ut_ad(col->mbminmaxlen == type->mbminmaxlen);
# endif /* !UNIV_HOTBACKUP */

	return(TRUE);
}
#endif /* UNIV_DEBUG */

#ifndef UNIV_HOTBACKUP
/***********************************************************************//**
Returns the minimum size of the column.
@return	minimum size */
UNIV_INLINE
ulint
dict_col_get_min_size(
/*==================*/
	const dict_col_t*	col)	/*!< in: column */
{
	return(dtype_get_min_size_low(col->mtype, col->prtype, col->len,
				      col->mbminmaxlen));
}
/***********************************************************************//**
Returns the maximum size of the column.
@return	maximum size */
UNIV_INLINE
ulint
dict_col_get_max_size(
/*==================*/
	const dict_col_t*	col)	/*!< in: column */
{
	return(dtype_get_max_size_low(col->mtype, col->len));
}
#endif /* !UNIV_HOTBACKUP */
/***********************************************************************//**
Returns the size of a fixed size column, 0 if not a fixed size column.
@return	fixed size, or 0 */
UNIV_INLINE
ulint
dict_col_get_fixed_size(
/*====================*/
	const dict_col_t*	col,	/*!< in: column */
	ulint			comp)	/*!< in: nonzero=ROW_FORMAT=COMPACT  */
{
	return(dtype_get_fixed_size_low(col->mtype, col->prtype, col->len,
					col->mbminmaxlen, comp));
}
/***********************************************************************//**
Returns the ROW_FORMAT=REDUNDANT stored SQL NULL size of a column.
For fixed length types it is the fixed length of the type, otherwise 0.
@return	SQL null storage size in ROW_FORMAT=REDUNDANT */
UNIV_INLINE
ulint
dict_col_get_sql_null_size(
/*=======================*/
	const dict_col_t*	col,	/*!< in: column */
	ulint			comp)	/*!< in: nonzero=ROW_FORMAT=COMPACT  */
{
	return(dict_col_get_fixed_size(col, comp));
}

/*********************************************************************//**
Gets the column number.
@return	col->ind, table column position (starting from 0) */
UNIV_INLINE
ulint
dict_col_get_no(
/*============*/
	const dict_col_t*	col)	/*!< in: column */
{
	ut_ad(col);

	return(col->ind);
}

/*********************************************************************//**
Gets the column position in the clustered index. */
UNIV_INLINE
ulint
dict_col_get_clust_pos(
/*===================*/
	const dict_col_t*	col,		/*!< in: table column */
	const dict_index_t*	clust_index)	/*!< in: clustered index */
{
	ulint	i;

	ut_ad(col);
	ut_ad(clust_index);
	ut_ad(dict_index_is_clust(clust_index));

	for (i = 0; i < clust_index->n_def; i++) {
		const dict_field_t*	field = &clust_index->fields[i];

		if (!field->prefix_len && field->col == col) {
			return(i);
		}
	}

	return(ULINT_UNDEFINED);
}

#ifndef UNIV_HOTBACKUP
#ifdef UNIV_DEBUG
/********************************************************************//**
Gets the first index on the table (the clustered index).
@return	index, NULL if none exists */
UNIV_INLINE
dict_index_t*
dict_table_get_first_index(
/*=======================*/
	const dict_table_t*	table)	/*!< in: table */
{
	ut_ad(table);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);

	return(UT_LIST_GET_FIRST(((dict_table_t*) table)->indexes));
}

/********************************************************************//**
Gets the next index on the table.
@return	index, NULL if none left */
UNIV_INLINE
dict_index_t*
dict_table_get_next_index(
/*======================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(UT_LIST_GET_NEXT(indexes, (dict_index_t*) index));
}
#endif /* UNIV_DEBUG */
#endif /* !UNIV_HOTBACKUP */

/********************************************************************//**
Check whether the index is the clustered index.
@return	nonzero for clustered index, zero for other indexes */
UNIV_INLINE
ulint
dict_index_is_clust(
/*================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(UNIV_UNLIKELY(index->type & DICT_CLUSTERED));
}
/********************************************************************//**
Check whether the index is unique.
@return	nonzero for unique index, zero for other indexes */
UNIV_INLINE
ulint
dict_index_is_unique(
/*=================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(UNIV_UNLIKELY(index->type & DICT_UNIQUE));
}

/********************************************************************//**
Check whether the index is the insert buffer tree.
@return	nonzero for insert buffer, zero for other indexes */
UNIV_INLINE
ulint
dict_index_is_ibuf(
/*===============*/
	const dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(UNIV_UNLIKELY(index->type & DICT_IBUF));
}

/********************************************************************//**
Check whether the index is a secondary index or the insert buffer tree.
@return	nonzero for insert buffer, zero for other indexes */
UNIV_INLINE
ulint
dict_index_is_sec_or_ibuf(
/*======================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ulint	type;

	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	type = index->type;

	return(UNIV_LIKELY(!(type & DICT_CLUSTERED) || (type & DICT_IBUF)));
}

/********************************************************************//**
Gets the number of user-defined columns in a table in the dictionary
cache.
@return	number of user-defined (e.g., not ROW_ID) columns of a table */
UNIV_INLINE
ulint
dict_table_get_n_user_cols(
/*=======================*/
	const dict_table_t*	table)	/*!< in: table */
{
	ut_ad(table);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);

	return(table->n_cols - DATA_N_SYS_COLS);
}

/********************************************************************//**
Gets the number of system columns in a table in the dictionary cache.
@return	number of system (e.g., ROW_ID) columns of a table */
UNIV_INLINE
ulint
dict_table_get_n_sys_cols(
/*======================*/
	const dict_table_t*	table __attribute__((unused)))	/*!< in: table */
{
	ut_ad(table);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);
	ut_ad(table->cached);

	return(DATA_N_SYS_COLS);
}

/********************************************************************//**
Gets the number of all columns (also system) in a table in the dictionary
cache.
@return	number of columns of a table */
UNIV_INLINE
ulint
dict_table_get_n_cols(
/*==================*/
	const dict_table_t*	table)	/*!< in: table */
{
	ut_ad(table);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);

	return(table->n_cols);
}

#ifdef UNIV_DEBUG
/********************************************************************//**
Gets the nth column of a table.
@return	pointer to column object */
UNIV_INLINE
dict_col_t*
dict_table_get_nth_col(
/*===================*/
	const dict_table_t*	table,	/*!< in: table */
	ulint			pos)	/*!< in: position of column */
{
	ut_ad(table);
	ut_ad(pos < table->n_def);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);

	return((dict_col_t*) (table->cols) + pos);
}

/********************************************************************//**
Gets the given system column of a table.
@return	pointer to column object */
UNIV_INLINE
dict_col_t*
dict_table_get_sys_col(
/*===================*/
	const dict_table_t*	table,	/*!< in: table */
	ulint			sys)	/*!< in: DATA_ROW_ID, ... */
{
	dict_col_t*	col;

	ut_ad(table);
	ut_ad(sys < DATA_N_SYS_COLS);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);

	col = dict_table_get_nth_col(table, table->n_cols
				     - DATA_N_SYS_COLS + sys);
	ut_ad(col->mtype == DATA_SYS);
	ut_ad(col->prtype == (sys | DATA_NOT_NULL));

	return(col);
}
#endif /* UNIV_DEBUG */

/********************************************************************//**
Gets the given system column number of a table.
@return	column number */
UNIV_INLINE
ulint
dict_table_get_sys_col_no(
/*======================*/
	const dict_table_t*	table,	/*!< in: table */
	ulint			sys)	/*!< in: DATA_ROW_ID, ... */
{
	ut_ad(table);
	ut_ad(sys < DATA_N_SYS_COLS);
	ut_ad(table->magic_n == DICT_TABLE_MAGIC_N);

	return(table->n_cols - DATA_N_SYS_COLS + sys);
}

/********************************************************************//**
Check whether the table uses the compact page format.
@return	TRUE if table uses the compact page format */
UNIV_INLINE
ibool
dict_table_is_comp(
/*===============*/
	const dict_table_t*	table)	/*!< in: table */
{
	ut_ad(table);

#if DICT_TF_COMPACT != TRUE
#error
#endif

	return(UNIV_LIKELY(table->flags & DICT_TF_COMPACT));
}

/********************************************************************//**
Determine the file format of a table.
@return	file format version */
UNIV_INLINE
ulint
dict_table_get_format(
/*==================*/
	const dict_table_t*	table)	/*!< in: table */
{
	ut_ad(table);

	return((table->flags & DICT_TF_FORMAT_MASK) >> DICT_TF_FORMAT_SHIFT);
}

/********************************************************************//**
Determine the file format of a table. */
UNIV_INLINE
void
dict_table_set_format(
/*==================*/
	dict_table_t*	table,	/*!< in/out: table */
	ulint		format)	/*!< in: file format version */
{
	ut_ad(table);

	table->flags = (table->flags & ~DICT_TF_FORMAT_MASK)
		| (format << DICT_TF_FORMAT_SHIFT);
}

/********************************************************************//**
Extract the compressed page size from table flags.
@return	compressed page size, or 0 if not compressed */
UNIV_INLINE
ulint
dict_table_flags_to_zip_size(
/*=========================*/
	ulint	flags)	/*!< in: flags */
{
	ulint	zip_size = flags & DICT_TF_ZSSIZE_MASK;

	if (UNIV_UNLIKELY(zip_size)) {
		zip_size = ((PAGE_ZIP_MIN_SIZE >> 1)
			 << (zip_size >> DICT_TF_ZSSIZE_SHIFT));

		ut_ad(zip_size <= UNIV_PAGE_SIZE);
	}

	return(zip_size);
}

/********************************************************************//**
Check whether the table uses the compressed compact page format.
@return	compressed page size, or 0 if not compressed */
UNIV_INLINE
ulint
dict_table_zip_size(
/*================*/
	const dict_table_t*	table)	/*!< in: table */
{
	ut_ad(table);

	return(dict_table_flags_to_zip_size(table->flags));
}

/*********************************************************************//**
Obtain exclusive locks on all index trees of the table. This is to prevent
accessing index trees while InnoDB is updating internal metadata for
operations such as truncate tables. */
UNIV_INLINE
void
dict_table_x_lock_indexes(
/*======================*/
	dict_table_t*	table)	/*!< in: table */
{
	dict_index_t*   index;

	ut_a(table);
	ut_ad(mutex_own(&(dict_sys->mutex)));

	/* Loop through each index of the table and lock them */
	for (index = dict_table_get_first_index(table);
	     index != NULL;
	     index = dict_table_get_next_index(index)) {
		rw_lock_x_lock(dict_index_get_lock(index));
	}
}

/*********************************************************************//**
Release the exclusive locks on all index tree. */
UNIV_INLINE
void
dict_table_x_unlock_indexes(
/*========================*/
	dict_table_t*	table)	/*!< in: table */
{
	dict_index_t*   index;

	ut_a(table);
	ut_ad(mutex_own(&(dict_sys->mutex)));

	for (index = dict_table_get_first_index(table);
	     index != NULL;
	     index = dict_table_get_next_index(index)) {
		rw_lock_x_unlock(dict_index_get_lock(index));
	}
}
/********************************************************************//**
Gets the number of fields in the internal representation of an index,
including fields added by the dictionary system.
@return	number of fields */
UNIV_INLINE
ulint
dict_index_get_n_fields(
/*====================*/
	const dict_index_t*	index)	/*!< in: an internal
					representation of index (in
					the dictionary cache) */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(index->n_fields);
}

/********************************************************************//**
Gets the number of fields in the internal representation of an index
that uniquely determine the position of an index entry in the index, if
we do not take multiversioning into account: in the B-tree use the value
returned by dict_index_get_n_unique_in_tree.
@return	number of fields */
UNIV_INLINE
ulint
dict_index_get_n_unique(
/*====================*/
	const dict_index_t*	index)	/*!< in: an internal representation
					of index (in the dictionary cache) */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
	ut_ad(index->cached);

	return(index->n_uniq);
}

/********************************************************************//**
Gets the number of fields in the internal representation of an index
which uniquely determine the position of an index entry in the index, if
we also take multiversioning into account.
@return	number of fields */
UNIV_INLINE
ulint
dict_index_get_n_unique_in_tree(
/*============================*/
	const dict_index_t*	index)	/*!< in: an internal representation
					of index (in the dictionary cache) */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
	ut_ad(index->cached);

	if (dict_index_is_clust(index)) {

		return(dict_index_get_n_unique(index));
	}

	return(dict_index_get_n_fields(index));
}

/********************************************************************//**
Gets the number of user-defined ordering fields in the index. In the internal
representation of clustered indexes we add the row id to the ordering fields
to make a clustered index unique, but this function returns the number of
fields the user defined in the index as ordering fields.
@return	number of fields */
UNIV_INLINE
ulint
dict_index_get_n_ordering_defined_by_user(
/*======================================*/
	const dict_index_t*	index)	/*!< in: an internal representation
					of index (in the dictionary cache) */
{
	return(index->n_user_defined_cols);
}

#ifdef UNIV_DEBUG
/********************************************************************//**
Gets the nth field of an index.
@return	pointer to field object */
UNIV_INLINE
dict_field_t*
dict_index_get_nth_field(
/*=====================*/
	const dict_index_t*	index,	/*!< in: index */
	ulint			pos)	/*!< in: position of field */
{
	ut_ad(index);
	ut_ad(pos < index->n_def);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return((dict_field_t*) (index->fields) + pos);
}
#endif /* UNIV_DEBUG */

/********************************************************************//**
Returns the position of a system column in an index.
@return	position, ULINT_UNDEFINED if not contained */
UNIV_INLINE
ulint
dict_index_get_sys_col_pos(
/*=======================*/
	const dict_index_t*	index,	/*!< in: index */
	ulint			type)	/*!< in: DATA_ROW_ID, ... */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
	ut_ad(!(index->type & DICT_UNIVERSAL));

	if (dict_index_is_clust(index)) {

		return(dict_col_get_clust_pos(
			       dict_table_get_sys_col(index->table, type),
			       index));
	}

	return(dict_index_get_nth_col_pos(
		       index, dict_table_get_sys_col_no(index->table, type)));
}

/*********************************************************************//**
Gets the field column.
@return	field->col, pointer to the table column */
UNIV_INLINE
const dict_col_t*
dict_field_get_col(
/*===============*/
	const dict_field_t*	field)	/*!< in: index field */
{
	ut_ad(field);

	return(field->col);
}

/********************************************************************//**
Gets pointer to the nth column in an index.
@return	column */
UNIV_INLINE
const dict_col_t*
dict_index_get_nth_col(
/*===================*/
	const dict_index_t*	index,	/*!< in: index */
	ulint			pos)	/*!< in: position of the field */
{
	return(dict_field_get_col(dict_index_get_nth_field(index, pos)));
}

/********************************************************************//**
Gets the column number the nth field in an index.
@return	column number */
UNIV_INLINE
ulint
dict_index_get_nth_col_no(
/*======================*/
	const dict_index_t*	index,	/*!< in: index */
	ulint			pos)	/*!< in: position of the field */
{
	return(dict_col_get_no(dict_index_get_nth_col(index, pos)));
}

#ifndef UNIV_HOTBACKUP
/********************************************************************//**
Returns the minimum data size of an index record.
@return	minimum data size in bytes */
UNIV_INLINE
ulint
dict_index_get_min_size(
/*====================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ulint	n	= dict_index_get_n_fields(index);
	ulint	size	= 0;

	while (n--) {
		size += dict_col_get_min_size(dict_index_get_nth_col(index,
								     n));
	}

	return(size);
}

/*********************************************************************//**
Gets the space id of the root of the index tree.
@return	space id */
UNIV_INLINE
ulint
dict_index_get_space(
/*=================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(index->space);
}

/*********************************************************************//**
Sets the space id of the root of the index tree. */
UNIV_INLINE
void
dict_index_set_space(
/*=================*/
	dict_index_t*	index,	/*!< in/out: index */
	ulint		space)	/*!< in: space id */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	index->space = space;
}

/*********************************************************************//**
Gets the page number of the root of the index tree.
@return	page number */
UNIV_INLINE
ulint
dict_index_get_page(
/*================*/
	const dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(index->page);
}

/*********************************************************************//**
Sets the page number of the root of index tree. */
UNIV_INLINE
void
dict_index_set_page(
/*================*/
	dict_index_t*	index,	/*!< in/out: index */
	ulint		page)	/*!< in: page number */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	index->page = page;
}

/*********************************************************************//**
Gets the read-write lock of the index tree.
@return	read-write lock */
UNIV_INLINE
rw_lock_t*
dict_index_get_lock(
/*================*/
	dict_index_t*	index)	/*!< in: index */
{
	ut_ad(index);
	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);

	return(&(index->lock));
}

/********************************************************************//**
Returns free space reserved for future updates of records. This is
relevant only in the case of many consecutive inserts, as updates
which make the records bigger might fragment the index.
@return	number of free bytes on page, reserved for updates */
UNIV_INLINE
ulint
dict_index_get_space_reserve(void)
/*==============================*/
{
	return(UNIV_PAGE_SIZE / 16);
}

/**********************************************************************//**
Checks if a table is in the dictionary cache.
@return	table, NULL if not found */
UNIV_INLINE
dict_table_t*
dict_table_check_if_in_cache_low(
/*=============================*/
	const char*	table_name)	/*!< in: table name */
{
	dict_table_t*	table;
	ulint		table_fold;

	ut_ad(table_name);
	ut_ad(mutex_own(&(dict_sys->mutex)));

	/* Look for the table name in the hash table */
	table_fold = ut_fold_string(table_name);

	HASH_SEARCH(name_hash, dict_sys->table_hash, table_fold,
		    dict_table_t*, table, ut_ad(table->cached),
		    !strcmp(table->name, table_name));
	return(table);
}

/**********************************************************************//**
load a table into dictionary cache, ignore any error specified during load; 
@return	table, NULL if not found */
UNIV_INLINE
dict_table_t*
dict_table_get_low_ignore_err(
/*==========================*/
	const char*	table_name,	/*!< in: table name */
	dict_err_ignore_t
			ignore_err)	/*!< in: error to be ignored when
					loading a table definition */
{
	dict_table_t*	table;

	ut_ad(table_name);
	ut_ad(mutex_own(&(dict_sys->mutex)));

	table = dict_table_check_if_in_cache_low(table_name);

	if (table == NULL) {
		table = dict_load_table(table_name, TRUE, ignore_err);
	}

	ut_ad(!table || table->cached);

	return(table);
}

/**********************************************************************//**
Gets a table; loads it to the dictionary cache if necessary. A low-level
function.
@return	table, NULL if not found */
UNIV_INLINE
dict_table_t*
dict_table_get_low(
/*===============*/
	const char*	table_name)	/*!< in: table name */
{
	dict_table_t*	table;

	ut_ad(table_name);
	ut_ad(mutex_own(&(dict_sys->mutex)));

	table = dict_table_check_if_in_cache_low(table_name);

	if (table == NULL) {
		table = dict_load_table(table_name, TRUE, DICT_ERR_IGNORE_NONE);
	}

	ut_ad(!table || table->cached);

	return(table);
}

/**********************************************************************//**
Returns a table object based on table id.
@return	table, NULL if does not exist */
UNIV_INLINE
dict_table_t*
dict_table_get_on_id_low(
/*=====================*/
	table_id_t	table_id)	/*!< in: table id */
{
	dict_table_t*	table;
	ulint		fold;

	ut_ad(mutex_own(&(dict_sys->mutex)));

	/* Look for the table name in the hash table */
	fold = ut_fold_ull(table_id);

	HASH_SEARCH(id_hash, dict_sys->table_id_hash, fold,
		    dict_table_t*, table, ut_ad(table->cached),
		    table->id == table_id);
	if (table == NULL) {
		table = dict_load_table_on_id(table_id);
	}

	ut_ad(!table || table->cached);

	/* TODO: should get the type information from MySQL */

	return(table);
}

/**********************************************************************//**
Determine bytes of column prefix to be stored in the undo log. Please
note if the table format is UNIV_FORMAT_A (< DICT_TF_FORMAT_ZIP), no prefix
needs to be stored in the undo log.
@return bytes of column prefix to be stored in the undo log */
UNIV_INLINE
ulint
dict_max_field_len_store_undo(
/*==========================*/
	dict_table_t*		table,	/*!< in: table */
	const dict_col_t*	col)	/*!< in: column which index prefix
					is based on */
{
	ulint   prefix_len = 0;

	if (dict_table_get_format(table) >= DICT_TF_FORMAT_ZIP)
	{
		prefix_len = col->max_prefix
			? col->max_prefix
			: DICT_MAX_FIELD_LEN_BY_FORMAT(table);
	}

	return(prefix_len);
}

#endif /* !UNIV_HOTBACKUP */