mariadb/innobase/dict/dict0load.c

/******************************************************
Loads to the memory cache database object definitions
from dictionary tables

(c) 1996 Innobase Oy

Created 4/24/1996 Heikki Tuuri
*******************************************************/

#include "dict0load.h"

#ifdef UNIV_NONINL
#include "dict0load.ic"
#endif

#include "btr0pcur.h"
#include "btr0btr.h"
#include "page0page.h"
#include "mach0data.h"
#include "dict0dict.h"
#include "dict0boot.h"

/************************************************************************
Loads definitions for table columns. */
static
void
dict_load_columns(
/*==============*/
	dict_table_t*	table,	/* in: table */
	mem_heap_t*	heap);	/* in: memory heap for temporary storage */
/************************************************************************
Loads definitions for table indexes. */
static
void
dict_load_indexes(
/*==============*/
	dict_table_t*	table,	/* in: table */
	mem_heap_t*	heap);	/* in: memory heap for temporary storage */
/************************************************************************
Loads definitions for index fields. */
static
void
dict_load_fields(
/*=============*/
	dict_table_t*	table,	/* in: table */
	dict_index_t*	index,	/* in: index whose fields to load */
	mem_heap_t*	heap);	/* in: memory heap for temporary storage */


/************************************************************************
Finds the first table name in the given database. */

char*
dict_get_first_table_name_in_db(
/*============================*/
			/* out, own: table name, NULL if does not exist;
			the caller must free the memory in the string! */
	char*	name)	/* in: database name which ends to '/' */
{
	dict_table_t*	sys_tables;
	btr_pcur_t	pcur;
	dict_index_t*	sys_index;
	dtuple_t*	tuple;
	mem_heap_t*	heap;
	dfield_t*	dfield;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	char*		table_name;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	heap = mem_heap_create(1000);
	
	mtr_start(&mtr);

	sys_tables = dict_table_get_low((char *) "SYS_TABLES");
	sys_index = UT_LIST_GET_FIRST(sys_tables->indexes);

	tuple = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(dfield, name, ut_strlen(name));
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
					BTR_SEARCH_LEAF, &pcur, &mtr);
loop:
	rec = btr_pcur_get_rec(&pcur);

	if (!btr_pcur_is_on_user_rec(&pcur, &mtr)) {
		/* Not found */

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(NULL);
	}	

	field = rec_get_nth_field(rec, 0, &len);

	if (len < strlen(name)
	    || ut_memcmp(name, field, strlen(name)) != 0) {
		/* Not found */

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(NULL);
	}

	if (!rec_get_deleted_flag(rec)) {

		/* We found one */

		table_name = mem_alloc(len + 1);
		ut_memcpy(table_name, field, len);
		table_name[len] = '\0';
		
		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(table_name);
	}
	
	btr_pcur_move_to_next_user_rec(&pcur, &mtr);

	goto loop;
}

/************************************************************************
Prints to the standard output information on all tables found in the data
dictionary system table. */

void
dict_print(void)
/*============*/
{
	dict_table_t*	sys_tables;
	dict_index_t*	sys_index;
	dict_table_t*	table;
	btr_pcur_t	pcur;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	char		table_name[10000];
	mtr_t		mtr;
	
	mutex_enter(&(dict_sys->mutex));

	mtr_start(&mtr);

	sys_tables = dict_table_get_low((char *) "SYS_TABLES");
	sys_index = UT_LIST_GET_FIRST(sys_tables->indexes);

	btr_pcur_open_at_index_side(TRUE, sys_index, BTR_SEARCH_LEAF, &pcur,
								TRUE, &mtr);
loop:
	btr_pcur_move_to_next_user_rec(&pcur, &mtr);

	rec = btr_pcur_get_rec(&pcur);

	if (!btr_pcur_is_on_user_rec(&pcur, &mtr)) {
		/* end of index */

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		
		mutex_exit(&(dict_sys->mutex));

		return;
	}	

	field = rec_get_nth_field(rec, 0, &len);

	if (!rec_get_deleted_flag(rec)) {

		/* We found one */

		ut_memcpy(table_name, field, len);
		table_name[len] = '\0';
			
		btr_pcur_store_position(&pcur, &mtr);

		mtr_commit(&mtr);
		
		table = dict_table_get_low(table_name);

		if (table == NULL) {
			fprintf(stderr, "InnoDB: Failed to load table %s\n",
								table_name);
		} else {
			dict_update_statistics_low(table, TRUE);

			dict_table_print_low(table);
		}

		mtr_start(&mtr);

		btr_pcur_restore_position(BTR_SEARCH_LEAF, &pcur, &mtr);
	}

	goto loop;
}

/************************************************************************
Loads a table definition and also all its index definitions, and also
the cluster definition if the table is a member in a cluster. Also loads
all foreign key constraints where the foreign key is in the table or where
a foreign key references columns in this table. Adds all these to the data
dictionary cache. */

dict_table_t*
dict_load_table(
/*============*/
			/* out: table, NULL if does not exist */
	char*	name)	/* in: table name */
{
	dict_table_t*	table;
	dict_table_t*	sys_tables;
	btr_pcur_t	pcur;
	dict_index_t*	sys_index;
	dtuple_t*	tuple;
	mem_heap_t*	heap;
	dfield_t*	dfield;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	char*		buf;
	ulint		space;
	ulint		n_cols;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	heap = mem_heap_create(1000);
	
	mtr_start(&mtr);

	sys_tables = dict_table_get_low((char *) "SYS_TABLES");
	sys_index = UT_LIST_GET_FIRST(sys_tables->indexes);

	tuple = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(dfield, name, ut_strlen(name));
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
					BTR_SEARCH_LEAF, &pcur, &mtr);
	rec = btr_pcur_get_rec(&pcur);

	if (!btr_pcur_is_on_user_rec(&pcur, &mtr)
					|| rec_get_deleted_flag(rec)) {
		/* Not found */

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(NULL);
	}	

	field = rec_get_nth_field(rec, 0, &len);

	/* Check if the table name in record is the searched one */
	if (len != ut_strlen(name) || ut_memcmp(name, field, len) != 0) {

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(NULL);
	}

	ut_a(0 == ut_strcmp((char *) "SPACE",
		dict_field_get_col(
		dict_index_get_nth_field(
			dict_table_get_first_index(sys_tables), 9))->name));
	
	field = rec_get_nth_field(rec, 9, &len);
	space = mach_read_from_4(field);

	ut_a(0 == ut_strcmp((char *) "N_COLS",
		dict_field_get_col(
		dict_index_get_nth_field(
			dict_table_get_first_index(sys_tables), 4))->name));

	field = rec_get_nth_field(rec, 4, &len);
	n_cols = mach_read_from_4(field);

	table = dict_mem_table_create(name, space, n_cols);

	ut_a(0 == ut_strcmp((char *) "ID",
		dict_field_get_col(
		dict_index_get_nth_field(
			dict_table_get_first_index(sys_tables), 3))->name));

	field = rec_get_nth_field(rec, 3, &len);
	table->id = mach_read_from_8(field);

	field = rec_get_nth_field(rec, 5, &len);
	table->type = mach_read_from_4(field);

	if (table->type == DICT_TABLE_CLUSTER_MEMBER) {
		ut_a(0);
	
		field = rec_get_nth_field(rec, 6, &len);
		table->mix_id = mach_read_from_8(field);

		field = rec_get_nth_field(rec, 8, &len);
		buf = mem_heap_alloc(heap, len);
		ut_memcpy(buf, field, len);

		table->cluster_name = buf;
	}

	if ((table->type == DICT_TABLE_CLUSTER)
	    || (table->type == DICT_TABLE_CLUSTER_MEMBER)) {
		
		field = rec_get_nth_field(rec, 7, &len);
		table->mix_len = mach_read_from_4(field);
	}

	btr_pcur_close(&pcur);
	mtr_commit(&mtr);

	if (table->type == DICT_TABLE_CLUSTER_MEMBER) {
		/* Load the cluster table definition if not yet in
		memory cache */
		dict_table_get_low(table->cluster_name);
	}

	dict_load_columns(table, heap);

	dict_table_add_to_cache(table);

	dict_load_indexes(table, heap);
	
	ut_a(DB_SUCCESS == dict_load_foreigns(table->name));

	mem_heap_free(heap);

	return(table);
}

/***************************************************************************
Loads a table object based on the table id. */

dict_table_t*
dict_load_table_on_id(
/*==================*/
				/* out: table; NULL if table does not exist */
	dulint	table_id)	/* in: table id */	
{
	byte		id_buf[8];
	btr_pcur_t	pcur;
	mem_heap_t* 	heap;
	dtuple_t*	tuple;
	dfield_t*	dfield;
	dict_index_t*	sys_table_ids;
	dict_table_t*	sys_tables;
	rec_t*		rec;
	byte*		field;
	ulint		len;	
	dict_table_t*	table;
	char*		name;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	/* NOTE that the operation of this function is protected by
	the dictionary mutex, and therefore no deadlocks can occur
	with other dictionary operations. */

	mtr_start(&mtr);	
	/*---------------------------------------------------*/
	/* Get the secondary index based on ID for table SYS_TABLES */	
	sys_tables = dict_sys->sys_tables;
	sys_table_ids = dict_table_get_next_index(
				dict_table_get_first_index(sys_tables));
	heap = mem_heap_create(256);

	tuple  = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	/* Write the table id in byte format to id_buf */
	mach_write_to_8(id_buf, table_id);
	
	dfield_set_data(dfield, id_buf, 8);
	dict_index_copy_types(tuple, sys_table_ids, 1);

	btr_pcur_open_on_user_rec(sys_table_ids, tuple, PAGE_CUR_GE,
						BTR_SEARCH_LEAF, &pcur, &mtr);
	rec = btr_pcur_get_rec(&pcur);
	
	if (!btr_pcur_is_on_user_rec(&pcur, &mtr)
					|| rec_get_deleted_flag(rec)) {
		/* Not found */

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(NULL);
	}

	/*---------------------------------------------------*/
	/* Now we have the record in the secondary index containing the
	table ID and NAME */

	rec = btr_pcur_get_rec(&pcur);
	field = rec_get_nth_field(rec, 0, &len);
	ut_ad(len == 8);

	/* Check if the table id in record is the one searched for */
	if (ut_dulint_cmp(table_id, mach_read_from_8(field)) != 0) {

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap);
		
		return(NULL);
	}
		
	/* Now we get the table name from the record */
	field = rec_get_nth_field(rec, 1, &len);

	name = mem_heap_alloc(heap, len + 1);
	ut_memcpy(name, field, len);
	name[len] = '\0';
	
	/* Load the table definition to memory */
	table = dict_load_table(name);

	ut_a(table);
	
	btr_pcur_close(&pcur);
	mtr_commit(&mtr);
	mem_heap_free(heap);

	return(table);
}

/************************************************************************
This function is called when the database is booted. Loads system table
index definitions except for the clustered index which is added to the
dictionary cache at booting before calling this function. */

void
dict_load_sys_table(
/*================*/
	dict_table_t*	table)	/* in: system table */
{
	mem_heap_t*	heap;

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

	heap = mem_heap_create(1000);

	dict_load_indexes(table, heap);
	
	mem_heap_free(heap);
}

/************************************************************************
Loads definitions for table columns. */
static
void
dict_load_columns(
/*==============*/
	dict_table_t*	table,	/* in: table */
	mem_heap_t*	heap)	/* in: memory heap for temporary storage */
{
	dict_table_t*	sys_columns;
	dict_index_t*	sys_index;
	btr_pcur_t	pcur;
	dtuple_t*	tuple;
	dfield_t*	dfield;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	byte*		buf;
	char*		name_buf;
	char*		name;
	ulint		mtype;
	ulint		prtype;
	ulint		col_len;
	ulint		prec;
	ulint		i;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	mtr_start(&mtr);

	sys_columns = dict_table_get_low((char *) "SYS_COLUMNS");
	sys_index = UT_LIST_GET_FIRST(sys_columns->indexes);

	tuple = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	buf = mem_heap_alloc(heap, 8);
	mach_write_to_8(buf, table->id);

	dfield_set_data(dfield, buf, 8);
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
						BTR_SEARCH_LEAF, &pcur, &mtr);
   	for (i = 0; i < table->n_cols - DATA_N_SYS_COLS; i++) {

		rec = btr_pcur_get_rec(&pcur);

		ut_a(btr_pcur_is_on_user_rec(&pcur, &mtr));

		ut_a(!rec_get_deleted_flag(rec));
		
		field = rec_get_nth_field(rec, 0, &len);
		ut_ad(len == 8);
		ut_a(ut_dulint_cmp(table->id, mach_read_from_8(field)) == 0);

		field = rec_get_nth_field(rec, 1, &len);
		ut_ad(len == 4);
		ut_a(i == mach_read_from_4(field));

		ut_a(0 == ut_strcmp((char *) "NAME",
			dict_field_get_col(
			dict_index_get_nth_field(
			dict_table_get_first_index(sys_columns), 4))->name));

		field = rec_get_nth_field(rec, 4, &len);

		name_buf = mem_heap_alloc(heap, len + 1);
		ut_memcpy(name_buf, field, len);
		name_buf[len] = '\0';

		name = name_buf;

		field = rec_get_nth_field(rec, 5, &len);
		mtype = mach_read_from_4(field);

		field = rec_get_nth_field(rec, 6, &len);
		prtype = mach_read_from_4(field);

		field = rec_get_nth_field(rec, 7, &len);
		col_len = mach_read_from_4(field);

		ut_a(0 == ut_strcmp((char *) "PREC",
			dict_field_get_col(
			dict_index_get_nth_field(
			dict_table_get_first_index(sys_columns), 8))->name));

		field = rec_get_nth_field(rec, 8, &len);
		prec = mach_read_from_4(field);

		dict_mem_table_add_col(table, name, mtype, prtype, col_len,
									prec);
		btr_pcur_move_to_next_user_rec(&pcur, &mtr);
	} 

	btr_pcur_close(&pcur);
	mtr_commit(&mtr);
}

/************************************************************************
Loads definitions for table indexes. Adds them to the data dictionary cache.
*/
static
void
dict_load_indexes(
/*==============*/
	dict_table_t*	table,	/* in: table */
	mem_heap_t*	heap)	/* in: memory heap for temporary storage */
{
	dict_table_t*	sys_indexes;
	dict_index_t*	sys_index;
	dict_index_t*	index;
	btr_pcur_t	pcur;
	dtuple_t*	tuple;
	dfield_t*	dfield;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	ulint		name_len;
	char*		name_buf;
	ulint		type;
	ulint		space;
	ulint		page_no;
	ulint		n_fields;
	byte*		buf;
	ibool		is_sys_table;
	dulint		id;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	if ((ut_dulint_get_high(table->id) == 0)
	    && (ut_dulint_get_low(table->id) < DICT_HDR_FIRST_ID)) {
		is_sys_table = TRUE;
	} else {
		is_sys_table = FALSE;
	}
	
	mtr_start(&mtr);

	sys_indexes = dict_table_get_low((char *) "SYS_INDEXES");
	sys_index = UT_LIST_GET_FIRST(sys_indexes->indexes);

	tuple = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	buf = mem_heap_alloc(heap, 8);
	mach_write_to_8(buf, table->id);

	dfield_set_data(dfield, buf, 8);
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
						BTR_SEARCH_LEAF, &pcur, &mtr);
   	for (;;) {
		if (!btr_pcur_is_on_user_rec(&pcur, &mtr)) {

			break;
		}

		rec = btr_pcur_get_rec(&pcur);
		
		field = rec_get_nth_field(rec, 0, &len);
		ut_ad(len == 8);

		if (ut_memcmp(buf, field, len) != 0) {
			break;
		}

		ut_a(!rec_get_deleted_flag(rec));

		field = rec_get_nth_field(rec, 1, &len);
		ut_ad(len == 8);
		id = mach_read_from_8(field);

		ut_a(0 == ut_strcmp((char *) "NAME",
			dict_field_get_col(
			dict_index_get_nth_field(
			dict_table_get_first_index(sys_indexes), 4))->name));
		
		field = rec_get_nth_field(rec, 4, &name_len);

		name_buf = mem_heap_alloc(heap, name_len + 1);
		ut_memcpy(name_buf, field, name_len);
		name_buf[name_len] = '\0';

		field = rec_get_nth_field(rec, 5, &len);
		n_fields = mach_read_from_4(field);

		field = rec_get_nth_field(rec, 6, &len);
		type = mach_read_from_4(field);

		field = rec_get_nth_field(rec, 7, &len);
		space = mach_read_from_4(field);

		ut_a(0 == ut_strcmp((char *) "PAGE_NO",
			dict_field_get_col(
			dict_index_get_nth_field(
			dict_table_get_first_index(sys_indexes), 8))->name));

		field = rec_get_nth_field(rec, 8, &len);
		page_no = mach_read_from_4(field);

		if (is_sys_table
		    && ((type & DICT_CLUSTERED)
		        || ((table == dict_sys->sys_tables)
		            && (name_len == ut_strlen((char *) "ID_IND"))
			    && (0 == ut_memcmp(name_buf, (char *) "ID_IND",
							name_len))))) {

			/* The index was created in memory already in
			booting */
		} else {
 			index = dict_mem_index_create(table->name, name_buf,
						space, type, n_fields);
			index->page_no = page_no;
			index->id = id;
		
			dict_load_fields(table, index, heap);

			dict_index_add_to_cache(table, index);
		}

		btr_pcur_move_to_next_user_rec(&pcur, &mtr);
	} 

	btr_pcur_close(&pcur);
	mtr_commit(&mtr);
}

/************************************************************************
Loads definitions for index fields. */
static
void
dict_load_fields(
/*=============*/
	dict_table_t*	table,	/* in: table */
	dict_index_t*	index,	/* in: index whose fields to load */
	mem_heap_t*	heap)	/* in: memory heap for temporary storage */
{
	dict_table_t*	sys_fields;
	dict_index_t*	sys_index;
	btr_pcur_t	pcur;
	dtuple_t*	tuple;
	dfield_t*	dfield;
	char*		col_name;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	byte*		buf;
	ulint		i;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	UT_NOT_USED(table);

	mtr_start(&mtr);

	sys_fields = dict_table_get_low((char *) "SYS_FIELDS");
	sys_index = UT_LIST_GET_FIRST(sys_fields->indexes);

	tuple = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	buf = mem_heap_alloc(heap, 8);
	mach_write_to_8(buf, index->id);

	dfield_set_data(dfield, buf, 8);
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
						BTR_SEARCH_LEAF, &pcur, &mtr);
   	for (i = 0; i < index->n_fields; i++) {

		rec = btr_pcur_get_rec(&pcur);

		ut_a(btr_pcur_is_on_user_rec(&pcur, &mtr));
		ut_a(!rec_get_deleted_flag(rec));
		
		field = rec_get_nth_field(rec, 0, &len);
		ut_ad(len == 8);
		ut_a(ut_memcmp(buf, field, len) == 0);

		field = rec_get_nth_field(rec, 1, &len);
		ut_ad(len == 4);
		ut_a(i == mach_read_from_4(field));

		ut_a(0 == ut_strcmp((char *) "COL_NAME",
			dict_field_get_col(
			dict_index_get_nth_field(
			dict_table_get_first_index(sys_fields), 4))->name));

		field = rec_get_nth_field(rec, 4, &len);

		col_name = mem_heap_alloc(heap, len + 1);
		ut_memcpy(col_name, field, len);
		col_name[len] = '\0';
		
		dict_mem_index_add_field(index, col_name, 0);

		btr_pcur_move_to_next_user_rec(&pcur, &mtr);
	} 

	btr_pcur_close(&pcur);
	mtr_commit(&mtr);
}

/************************************************************************
Loads foreign key constraint col names (also for the referenced table). */
static
void
dict_load_foreign_cols(
/*===================*/
	char*		id,	/* in: foreign constraint id as a null-
				terminated string */
	dict_foreign_t*	foreign)/* in: foreign constraint object */
{
	dict_table_t*	sys_foreign_cols;
	dict_index_t*	sys_index;
	btr_pcur_t	pcur;
	dtuple_t*	tuple;
	dfield_t*	dfield;
	char*		col_name;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	ulint		i;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	foreign->foreign_col_names = mem_heap_alloc(foreign->heap,
					foreign->n_fields * sizeof(void*));

	foreign->referenced_col_names = mem_heap_alloc(foreign->heap,
					foreign->n_fields * sizeof(void*));
	mtr_start(&mtr);

	sys_foreign_cols = dict_table_get_low((char *) "SYS_FOREIGN_COLS");
	sys_index = UT_LIST_GET_FIRST(sys_foreign_cols->indexes);

	tuple = dtuple_create(foreign->heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(dfield, id, ut_strlen(id));
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
						BTR_SEARCH_LEAF, &pcur, &mtr);
   	for (i = 0; i < foreign->n_fields; i++) {

		rec = btr_pcur_get_rec(&pcur);

		ut_a(btr_pcur_is_on_user_rec(&pcur, &mtr));
		ut_a(!rec_get_deleted_flag(rec));
		
		field = rec_get_nth_field(rec, 0, &len);
		ut_a(len == ut_strlen(id));
		ut_a(ut_memcmp(id, field, len) == 0);

		field = rec_get_nth_field(rec, 1, &len);
		ut_a(len == 4);
		ut_a(i == mach_read_from_4(field));

		field = rec_get_nth_field(rec, 4, &len);

		col_name = mem_heap_alloc(foreign->heap, len + 1);
		ut_memcpy(col_name, field, len);
		col_name[len] = '\0';

		foreign->foreign_col_names[i] = col_name;

		field = rec_get_nth_field(rec, 5, &len);

		col_name = mem_heap_alloc(foreign->heap, len + 1);
		ut_memcpy(col_name, field, len);
		col_name[len] = '\0';

		foreign->referenced_col_names[i] = col_name;
		
		btr_pcur_move_to_next_user_rec(&pcur, &mtr);
	} 

	btr_pcur_close(&pcur);
	mtr_commit(&mtr);
}

/***************************************************************************
Loads a foreign key constraint to the dictionary cache. */
static
ulint
dict_load_foreign(
/*==============*/
			/* out: DB_SUCCESS or error code */
	char*	id)	/* in: foreign constraint id as a null-terminated
			string */
{	
	dict_foreign_t*	foreign;
	dict_table_t*	sys_foreign;
	btr_pcur_t	pcur;
	dict_index_t*	sys_index;
	dtuple_t*	tuple;
	mem_heap_t*	heap2;
	dfield_t*	dfield;
	rec_t*		rec;
	byte*		field;
	ulint		len;
	ulint		err;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	heap2 = mem_heap_create(1000);
	
	mtr_start(&mtr);

	sys_foreign = dict_table_get_low((char *) "SYS_FOREIGN");
	sys_index = UT_LIST_GET_FIRST(sys_foreign->indexes);

	tuple = dtuple_create(heap2, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(dfield, id, ut_strlen(id));
	dict_index_copy_types(tuple, sys_index, 1);

	btr_pcur_open_on_user_rec(sys_index, tuple, PAGE_CUR_GE,
					BTR_SEARCH_LEAF, &pcur, &mtr);
	rec = btr_pcur_get_rec(&pcur);

	if (!btr_pcur_is_on_user_rec(&pcur, &mtr)
					|| rec_get_deleted_flag(rec)) {
		/* Not found */

		fprintf(stderr,
		"InnoDB: Error A: cannot load foreign constraint %s\n", id);

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap2);
		
		return(DB_ERROR);
	}	

	field = rec_get_nth_field(rec, 0, &len);

	/* Check if the id in record is the searched one */
	if (len != ut_strlen(id) || ut_memcmp(id, field, len) != 0) {

		fprintf(stderr,
		"InnoDB: Error B: cannot load foreign constraint %s\n", id);

		btr_pcur_close(&pcur);
		mtr_commit(&mtr);
		mem_heap_free(heap2);
		
		return(DB_ERROR);
	}

	/* Read the table names and the number of columns associated
	with the constraint */

	mem_heap_free(heap2);
	
	foreign = dict_mem_foreign_create();

	foreign->n_fields = mach_read_from_4(rec_get_nth_field(rec, 5, &len));

	ut_a(len == 4);
	
	foreign->id = mem_heap_alloc(foreign->heap, ut_strlen(id) + 1);
				
	ut_memcpy(foreign->id, id, ut_strlen(id) + 1);

	field = rec_get_nth_field(rec, 3, &len);
							
	foreign->foreign_table_name = mem_heap_alloc(foreign->heap, 1 + len);
				
	ut_memcpy(foreign->foreign_table_name, field, len);
	foreign->foreign_table_name[len] = '\0';	
	
	field = rec_get_nth_field(rec, 4, &len);
							
	foreign->referenced_table_name = mem_heap_alloc(foreign->heap, 1 + len);
				
	ut_memcpy(foreign->referenced_table_name, field, len);
	foreign->referenced_table_name[len] = '\0';	

	btr_pcur_close(&pcur);
	mtr_commit(&mtr);

	dict_load_foreign_cols(id, foreign);

	/* Note that there may already be a foreign constraint object in
	the dictionary cache for this constraint: then the following
	call only sets the pointers in it to point to the appropriate table
	and index objects and frees the newly created object foreign. */

	err = dict_foreign_add_to_cache(foreign);

	return(err); 
}

/***************************************************************************
Loads foreign key constraints where the table is either the foreign key
holder or where the table is referenced by a foreign key. Adds these
constraints to the data dictionary. Note that we know that the dictionary
cache already contains all constraints where the other relevant table is
already in the dictionary cache. */

ulint
dict_load_foreigns(
/*===============*/
				/* out: DB_SUCCESS or error code */
	char*	table_name)	/* in: table name */
{
	btr_pcur_t	pcur;
	mem_heap_t* 	heap;
	dtuple_t*	tuple;
	dfield_t*	dfield;
	dict_index_t*	sec_index;
	dict_table_t*	sys_foreign;
	rec_t*		rec;
	byte*		field;
	ulint		len;	
	char*		id ;
	ulint		err;
	mtr_t		mtr;
	
	ut_ad(mutex_own(&(dict_sys->mutex)));

	sys_foreign = dict_table_get_low((char *) "SYS_FOREIGN");

	if (sys_foreign == NULL) {
		/* No foreign keys defined yet in this database */

		fprintf(stderr,
	"InnoDB: Error: no foreign key system tables in the database\n");
		
		return(DB_ERROR);
	}

	mtr_start(&mtr);	

	/* Get the secondary index based on FOR_NAME from table
	SYS_FOREIGN */	

	sec_index = dict_table_get_next_index(
				dict_table_get_first_index(sys_foreign));
start_load:
	heap = mem_heap_create(256);

	tuple  = dtuple_create(heap, 1);
	dfield = dtuple_get_nth_field(tuple, 0);

	dfield_set_data(dfield, table_name, ut_strlen(table_name));
	dict_index_copy_types(tuple, sec_index, 1);

	btr_pcur_open_on_user_rec(sec_index, tuple, PAGE_CUR_GE,
						BTR_SEARCH_LEAF, &pcur, &mtr);
loop:
	rec = btr_pcur_get_rec(&pcur);
	
	if (!btr_pcur_is_on_user_rec(&pcur, &mtr)) {
		/* End of index */

		goto load_next_index;
	}

	/* Now we have the record in the secondary index containing a table
	name and a foreign constraint ID */

	rec = btr_pcur_get_rec(&pcur);
	field = rec_get_nth_field(rec, 0, &len);

	/* Check if the table name in record is the one searched for */
	if (len != ut_strlen(table_name)
	    || 0 != ut_memcmp(field, table_name, len)) {

		goto load_next_index;
	}
		
	if (rec_get_deleted_flag(rec)) {

		goto next_rec;
	}

	/* Now we get a foreign key constraint id */
	field = rec_get_nth_field(rec, 1, &len);

	id = mem_heap_alloc(heap, len + 1);
	ut_memcpy(id, field, len);
	id[len] = '\0';
	
	btr_pcur_store_position(&pcur, &mtr);

	mtr_commit(&mtr);

	/* Load the foreign constraint definition to the dictionary cache */
	
	err = dict_load_foreign(id);

	if (err != DB_SUCCESS) {
		btr_pcur_close(&pcur);
		mem_heap_free(heap);

		return(err);
	}

	mtr_start(&mtr);

	btr_pcur_restore_position(BTR_SEARCH_LEAF, &pcur, &mtr);
next_rec:
	btr_pcur_move_to_next_user_rec(&pcur, &mtr);

	goto loop;

load_next_index:
	btr_pcur_close(&pcur);
	mtr_commit(&mtr);
	mem_heap_free(heap);
	
	sec_index = dict_table_get_next_index(sec_index);

	if (sec_index != NULL) {

		mtr_start(&mtr);	

		goto start_load;
	}

	return(DB_SUCCESS);
}