mariadb/innobase/row/row0mysql.c

/******************************************************
Interface between Innobase row operations and MySQL.
Contains also create table and other data dictionary operations.

(c) 2000 Innobase Oy

Created 9/17/2000 Heikki Tuuri
*******************************************************/

#include "row0mysql.h"

#ifdef UNIV_NONINL
#include "row0mysql.ic"
#endif

#include "row0ins.h"
#include "row0sel.h"
#include "row0upd.h"
#include "row0row.h"
#include "que0que.h"
#include "pars0pars.h"
#include "dict0dict.h"
#include "dict0crea.h"
#include "trx0roll.h"
#include "trx0purge.h"
#include "lock0lock.h"

/***********************************************************************
Reads a MySQL format variable-length field (like VARCHAR) length and
returns pointer to the field data. */

byte*
row_mysql_read_var_ref_noninline(
/*=============================*/
			/* out: field + 2 */
	ulint*	len,	/* out: variable-length field length */
	byte*	field)	/* in: field */
{
	return(row_mysql_read_var_ref(len, field));
}

/***********************************************************************
Stores a reference to a BLOB in the MySQL format. */

void
row_mysql_store_blob_ref(
/*=====================*/
	byte*	dest,		/* in: where to store */
	ulint	col_len,	/* in: dest buffer size: determines into
				how many bytes the BLOB length is stored,
				this may vary from 1 to 4 bytes */
	byte*	data,		/* in: BLOB data */
	ulint	len)		/* in: BLOB length */
{
	/* In dest there are 1 - 4 bytes reserved for the BLOB length,
	and after that 8 bytes reserved for the pointer to the data.
	In 32-bit architectures we only use the first 4 bytes of the pointer
	slot. */

	mach_write_to_n_little_endian(dest, col_len - 8, len);

	ut_memcpy(dest + col_len - 8, (byte*)&data, sizeof(byte*));	
}

/***********************************************************************
Reads a reference to a BLOB in the MySQL format. */

byte*
row_mysql_read_blob_ref(
/*====================*/
				/* out: pointer to BLOB data */
	ulint*	len,		/* out: BLOB length */
	byte*	ref,		/* in: BLOB reference in the MySQL format */
	ulint	col_len)	/* in: BLOB reference length (not BLOB
				length) */
{
	byte*	data;

	*len = mach_read_from_n_little_endian(ref, col_len - 8);

	ut_memcpy((byte*)&data, ref + col_len - 8, sizeof(byte*));

	return(data);
}

/******************************************************************
Convert a row in the MySQL format to a row in the Innobase format. */
static
void
row_mysql_convert_row_to_innobase(
/*==============================*/
	dtuple_t*	row,		/* in/out: Innobase row where the
					field type information is already
					copied there, or will be copied
					later */
	row_prebuilt_t*	prebuilt,	/* in: prebuilt struct where template
					must be of type ROW_MYSQL_WHOLE_ROW */
	byte*		mysql_rec)	/* in: row in the MySQL format;
					NOTE: do not discard as long as
					row is used, as row may contain
					pointers to this record! */
{
	mysql_row_templ_t*	templ;	
	dfield_t*		dfield;
	ulint			i;
	
	ut_ad(prebuilt->template_type == ROW_MYSQL_WHOLE_ROW);
	ut_ad(prebuilt->mysql_template);

	for (i = 0; i < prebuilt->n_template; i++) {

		templ = prebuilt->mysql_template + i;
		dfield = dtuple_get_nth_field(row, i);

		if (templ->mysql_null_bit_mask != 0) {
			/* Column may be SQL NULL */

			if (mysql_rec[templ->mysql_null_byte_offset] &
 					(byte) (templ->mysql_null_bit_mask)) {

				/* It is SQL NULL */

				dfield_set_data(dfield, NULL, UNIV_SQL_NULL);

				goto next_column;
			}
		}			
		
		row_mysql_store_col_in_innobase_format(dfield,
					prebuilt->ins_upd_rec_buff
						+ templ->mysql_col_offset,
					mysql_rec + templ->mysql_col_offset,
					templ->mysql_col_len,
					templ->type, templ->is_unsigned);
next_column:
		;
	} 
}

/********************************************************************
Handles user errors and lock waits detected by the database engine. */

ibool
row_mysql_handle_errors(
/*====================*/
				/* out: TRUE if it was a lock wait and
				we should continue running the query thread */
	ulint*		new_err,/* out: possible new error encountered in
				rollback, or the old error which was
				during the function entry */
	trx_t*		trx,	/* in: transaction */
	que_thr_t*	thr,	/* in: query thread */
	trx_savept_t*	savept)	/* in: savepoint */
{
	ibool	timeout_expired;
	ulint	err;

handle_new_error:
	err = trx->error_state;
	
	ut_a(err != DB_SUCCESS);
	
	trx->error_state = DB_SUCCESS;

	if (err == DB_DUPLICATE_KEY) {
		if (savept) {
			/* Roll back the latest, possibly incomplete
			insertion or update */

			trx_general_rollback_for_mysql(trx, TRUE, savept);
		}			
	} else if (err == DB_TOO_BIG_RECORD) {
		if (savept) {
			/* Roll back the latest, possibly incomplete
			insertion or update */

			trx_general_rollback_for_mysql(trx, TRUE, savept);
		}			
	} else if (err == DB_LOCK_WAIT) {

		timeout_expired = srv_suspend_mysql_thread(thr);

		if (timeout_expired) {
			trx->error_state = DB_DEADLOCK;

			que_thr_stop_for_mysql(thr);

			goto handle_new_error;
		}

		*new_err = err;

		return(TRUE);

	} else if (err == DB_DEADLOCK) {

		/* Roll back the whole transaction */

		trx_general_rollback_for_mysql(trx, FALSE, NULL);

	} else if (err == DB_OUT_OF_FILE_SPACE) {

		/* Roll back the whole transaction */

		trx_general_rollback_for_mysql(trx, FALSE, NULL);
	} else if (err == DB_MUST_GET_MORE_FILE_SPACE) {

		ut_a(0); /* TODO: print something to MySQL error log */
	} else {
		ut_a(0);
	}		

	if (trx->error_state != DB_SUCCESS) {
		*new_err = trx->error_state;
	} else {
		*new_err = err;
	}
	
	trx->error_state = DB_SUCCESS;

	return(FALSE);
}

/************************************************************************
Create a prebuilt struct for a MySQL table handle. */

row_prebuilt_t*
row_create_prebuilt(
/*================*/
				/* out, own: a prebuilt struct */
	dict_table_t*	table)	/* in: Innobase table handle */
{
	row_prebuilt_t*	prebuilt;
	mem_heap_t*	heap;
	dict_index_t*	clust_index;
	dtuple_t*	ref;
	ulint		ref_len;
	ulint		i;
	
	heap = mem_heap_create(128);

	prebuilt = mem_heap_alloc(heap, sizeof(row_prebuilt_t));

	prebuilt->table = table;

	prebuilt->trx = NULL;

	prebuilt->sql_stat_start = TRUE;

	prebuilt->index = NULL;
	prebuilt->n_template = 0;
	prebuilt->mysql_template = NULL;

	prebuilt->heap = heap;
	prebuilt->ins_node = NULL;

	prebuilt->ins_upd_rec_buff = NULL;
	
	prebuilt->upd_node = NULL;
	prebuilt->ins_graph = NULL;
	prebuilt->upd_graph = NULL;

  	prebuilt->pcur = btr_pcur_create_for_mysql();
  	prebuilt->clust_pcur = btr_pcur_create_for_mysql();

	prebuilt->select_lock_type = LOCK_NONE;

	prebuilt->sel_graph = NULL;

	prebuilt->search_tuple = dtuple_create(heap,
						dict_table_get_n_cols(table));
	
	clust_index = dict_table_get_first_index(table);

	ref_len = dict_index_get_n_unique(clust_index);

	ref = dtuple_create(heap, ref_len);

	dict_index_copy_types(ref, clust_index, ref_len);

	prebuilt->clust_ref = ref;

	for (i = 0; i < MYSQL_FETCH_CACHE_SIZE; i++) {
		prebuilt->fetch_cache[i] = NULL;
	}

	prebuilt->n_fetch_cached = 0;

	prebuilt->blob_heap = NULL;

	prebuilt->old_vers_heap = NULL;
	
	return(prebuilt);
}

/************************************************************************
Free a prebuilt struct for a MySQL table handle. */

void
row_prebuilt_free(
/*==============*/
	row_prebuilt_t*	prebuilt)	/* in, own: prebuilt struct */
{
	ulint	i;

	btr_pcur_free_for_mysql(prebuilt->pcur);
	btr_pcur_free_for_mysql(prebuilt->clust_pcur);

	if (prebuilt->mysql_template) {
		mem_free(prebuilt->mysql_template);
	}

	if (prebuilt->ins_graph) {
		que_graph_free_recursive(prebuilt->ins_graph);
	}

	if (prebuilt->sel_graph) {
		que_graph_free_recursive(prebuilt->sel_graph);
	}
	
	if (prebuilt->upd_graph) {
		que_graph_free_recursive(prebuilt->upd_graph);
	}
	
	if (prebuilt->blob_heap) {
		mem_heap_free(prebuilt->blob_heap);
	}

	if (prebuilt->old_vers_heap) {
		mem_heap_free(prebuilt->old_vers_heap);
	}
	
	for (i = 0; i < MYSQL_FETCH_CACHE_SIZE; i++) {
		if (prebuilt->fetch_cache[i] != NULL) {
			mem_free(prebuilt->fetch_cache[i]);
		}
	}

	mem_heap_free(prebuilt->heap);
}

/*************************************************************************
Updates the transaction pointers in query graphs stored in the prebuilt
struct. */

void
row_update_prebuilt_trx(
/*====================*/
					/* out: prebuilt dtuple */
	row_prebuilt_t*	prebuilt,	/* in: prebuilt struct in MySQL
					handle */
	trx_t*		trx)		/* in: transaction handle */
{	
	prebuilt->trx = trx;

	if (prebuilt->ins_graph) {
		prebuilt->ins_graph->trx = trx;
	}

	if (prebuilt->upd_graph) {
		prebuilt->upd_graph->trx = trx;
	}

	if (prebuilt->sel_graph) {
		prebuilt->sel_graph->trx = trx;
	}	
}

/*************************************************************************
Gets pointer to a prebuilt dtuple used in insertions. If the insert graph
has not yet been built in the prebuilt struct, then this function first
builds it. */
static
dtuple_t*
row_get_prebuilt_insert_row(
/*========================*/
					/* out: prebuilt dtuple */
	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct in MySQL
					handle */
{
	ins_node_t*	node;
	dtuple_t*	row;
	dict_table_t*	table	= prebuilt->table;

	ut_ad(prebuilt && table && prebuilt->trx);
	
	if (prebuilt->ins_node == NULL) {

		/* Not called before for this handle: create an insert node
		and query graph to the prebuilt struct */

		node = ins_node_create(INS_DIRECT, table, prebuilt->heap);
		
		prebuilt->ins_node = node;

		if (prebuilt->ins_upd_rec_buff == NULL) {
			prebuilt->ins_upd_rec_buff = mem_heap_alloc(
						prebuilt->heap,
						prebuilt->mysql_row_len);
		}
		
		row = dtuple_create(prebuilt->heap,
					dict_table_get_n_cols(table));

		dict_table_copy_types(row, table);

		ins_node_set_new_row(node, row);

		prebuilt->ins_graph =
			que_node_get_parent(
				pars_complete_graph_for_exec(node,
							prebuilt->trx,
							prebuilt->heap));
		prebuilt->ins_graph->state = QUE_FORK_ACTIVE;
	}

	return(prebuilt->ins_node->row);	
}

/*************************************************************************
Updates the table modification counter and calculates new estimates
for table and index statistics if necessary. */
UNIV_INLINE
void
row_update_statistics_if_needed(
/*============================*/
	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct */
{
	ulint	counter;
	ulint	old_counter;
	
	counter = prebuilt->table->stat_modif_counter;

	counter += prebuilt->mysql_row_len;
	prebuilt->table->stat_modif_counter = counter;

	old_counter = prebuilt->table->stat_last_estimate_counter;

	if (counter - old_counter >= DICT_STAT_CALCULATE_INTERVAL
	    || counter - old_counter >=
		(UNIV_PAGE_SIZE
			* prebuilt->table->stat_clustered_index_size / 2)) {

		dict_update_statistics(prebuilt->table);
	}	
}

/*************************************************************************
Does an insert for MySQL. */

int
row_insert_for_mysql(
/*=================*/
					/* out: error code or DB_SUCCESS */
	byte*		mysql_rec,	/* in: row in the MySQL format */
	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct in MySQL
					handle */
{
	trx_savept_t	savept;
	que_thr_t*	thr;
	ulint		err;
	ibool		was_lock_wait;
	trx_t*		trx 		= prebuilt->trx;
	ins_node_t*	node		= prebuilt->ins_node;
	
	ut_ad(trx);
	ut_ad(trx->mysql_thread_id == os_thread_get_curr_id());
	
	if (node == NULL) {
		row_get_prebuilt_insert_row(prebuilt);
		node = prebuilt->ins_node;
	}

	row_mysql_convert_row_to_innobase(node->row, prebuilt, mysql_rec);
	
	savept = trx_savept_take(trx);
	
	thr = que_fork_get_first_thr(prebuilt->ins_graph);

	if (prebuilt->sql_stat_start) {
		node->state = INS_NODE_SET_IX_LOCK;
		prebuilt->sql_stat_start = FALSE;
	} else {
		node->state = INS_NODE_ALLOC_ROW_ID;
	}
	
	que_thr_move_to_run_state_for_mysql(thr, trx);

run_again:
	thr->run_node = node;
	thr->prev_node = node;

	row_ins_step(thr);
	
	err = trx->error_state;

	if (err != DB_SUCCESS) {
		que_thr_stop_for_mysql(thr);

		was_lock_wait = row_mysql_handle_errors(&err, trx, thr,
								&savept);
		if (was_lock_wait) {
			goto run_again;
		}

		return(err);
	}

	que_thr_stop_for_mysql_no_error(thr, trx);
	
	prebuilt->table->stat_n_rows++;

	if (prebuilt->table->stat_n_rows == 0) {
		/* Avoid wrap-over */
		prebuilt->table->stat_n_rows--;
	}	

	row_update_statistics_if_needed(prebuilt);

	return((int) err);
}

/*************************************************************************
Builds a dummy query graph used in selects. */

void
row_prebuild_sel_graph(
/*===================*/
	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct in MySQL
					handle */
{
	sel_node_t*	node;

	ut_ad(prebuilt && prebuilt->trx);
	
	if (prebuilt->sel_graph == NULL) {

		node = sel_node_create(prebuilt->heap);
				
		prebuilt->sel_graph =
			que_node_get_parent(
				pars_complete_graph_for_exec(node,
							prebuilt->trx,
							prebuilt->heap));

		prebuilt->sel_graph->state = QUE_FORK_ACTIVE;
	}
}

/*************************************************************************
Gets pointer to a prebuilt update vector used in updates. If the update
graph has not yet been built in the prebuilt struct, then this function
first builds it. */

upd_t*
row_get_prebuilt_update_vector(
/*===========================*/
					/* out: prebuilt update vector */
	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct in MySQL
					handle */
{
	dict_table_t*	table	= prebuilt->table;
	upd_node_t*	node;

	ut_ad(prebuilt && table && prebuilt->trx);
	
	if (prebuilt->upd_node == NULL) {

		/* Not called before for this handle: create an update node
		and query graph to the prebuilt struct */

		node = upd_node_create(prebuilt->heap);
		
		prebuilt->upd_node = node;

		node->in_mysql_interface = TRUE;
		node->is_delete = FALSE;
		node->searched_update = FALSE;
		node->select_will_do_update = FALSE;
		node->select = NULL;
		node->pcur = btr_pcur_create_for_mysql();
		node->table = table;

		node->update = upd_create(dict_table_get_n_cols(table),
							prebuilt->heap);
		UT_LIST_INIT(node->columns);
		node->has_clust_rec_x_lock = TRUE;
		node->cmpl_info = 0;

		node->table_sym = NULL;
		node->col_assign_list = NULL;
		
		prebuilt->upd_graph =
			que_node_get_parent(
				pars_complete_graph_for_exec(node,
							prebuilt->trx,
							prebuilt->heap));
		prebuilt->upd_graph->state = QUE_FORK_ACTIVE;
	}

	return(prebuilt->upd_node->update);
}

/*************************************************************************
Does an update or delete of a row for MySQL. */

int
row_update_for_mysql(
/*=================*/
					/* out: error code or DB_SUCCESS */
	byte*		mysql_rec,	/* in: the row to be updated, in
					the MySQL format */
	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct in MySQL
					handle */
{
	trx_savept_t	savept;
	ulint		err;
	que_thr_t*	thr;
	ibool		was_lock_wait;
	dict_index_t*	clust_index; 
/*	ulint		ref_len; */
	upd_node_t*	node;
	dict_table_t*	table		= prebuilt->table;
	trx_t*		trx		= prebuilt->trx;
/*	mem_heap_t*	heap;
	dtuple_t*	search_tuple;
	dtuple_t*	row_tuple;
	mtr_t		mtr; */
	
	ut_ad(prebuilt && trx);
	ut_ad(trx->mysql_thread_id == os_thread_get_curr_id());

	node = prebuilt->upd_node;

	clust_index = dict_table_get_first_index(table);

	if (prebuilt->pcur->btr_cur.index == clust_index) {
		btr_pcur_copy_stored_position(node->pcur, prebuilt->pcur);
	} else {
		btr_pcur_copy_stored_position(node->pcur, prebuilt->clust_pcur);
	}
		
	ut_a(node->pcur->rel_pos == BTR_PCUR_ON);
	 	
	/* MySQL seems to call rnd_pos before updating each row it
	has cached: we can get the correct cursor position from
	prebuilt->pcur; NOTE that we cannot build the row reference
	from mysql_rec if the clustered index was automatically
	generated for the table: MySQL does not know anything about
	the row id used as the clustered index key */

#ifdef notdefined
	/* We have to search for the correct cursor position */

	ref_len = dict_index_get_n_unique(clust_index);

	heap = mem_heap_create(450);

	row_tuple = dtuple_create(heap, dict_table_get_n_cols(table));
	dict_table_copy_types(row_tuple, table);

	if (prebuilt->ins_upd_rec_buff == NULL) {
		prebuilt->ins_upd_rec_buff = mem_heap_alloc(prebuilt->heap,
						prebuilt->mysql_row_len);
	}
		
	row_mysql_convert_row_to_innobase(row_tuple, prebuilt, mysql_rec);

	search_tuple = dtuple_create(heap, ref_len);

	row_build_row_ref_from_row(search_tuple, table, row_tuple);

	mtr_start(&mtr);
	
	btr_pcur_open_with_no_init(clust_index, search_tuple, PAGE_CUR_LE,
					BTR_SEARCH_LEAF, node->pcur, 0, &mtr);	

	btr_pcur_store_position(node->pcur, &mtr);
	
	mtr_commit(&mtr);

	mem_heap_free(heap);
#endif
	savept = trx_savept_take(trx);
	
	thr = que_fork_get_first_thr(prebuilt->upd_graph);

	node->state = UPD_NODE_UPDATE_CLUSTERED;

	ut_ad(!prebuilt->sql_stat_start);

	que_thr_move_to_run_state_for_mysql(thr, trx);
run_again:
	thr->run_node = node;
	thr->prev_node = node;

	row_upd_step(thr);

	err = trx->error_state;

	if (err != DB_SUCCESS) {
		que_thr_stop_for_mysql(thr);
		
		if (err == DB_RECORD_NOT_FOUND) {
			trx->error_state = DB_SUCCESS;

			return((int) err);
		}
	
		was_lock_wait = row_mysql_handle_errors(&err, trx, thr,
								&savept);
		if (was_lock_wait) {
			goto run_again;
		}

		return(err);
	}

	que_thr_stop_for_mysql_no_error(thr, trx);

	if (prebuilt->upd_node->is_delete) {
		if (prebuilt->table->stat_n_rows > 0) {
			prebuilt->table->stat_n_rows--;
		}
	}	

	row_update_statistics_if_needed(prebuilt);

	return((int) err);
}

/*************************************************************************
Checks if a table is such that we automatically created a clustered
index on it (on row id). */

ibool
row_table_got_default_clust_index(
/*==============================*/
	dict_table_t*	table)
{
	dict_index_t*	clust_index;

	clust_index = dict_table_get_first_index(table);

	if (dtype_get_mtype(dict_index_get_nth_type(clust_index, 0))
	 							== DATA_SYS) {
	 	return(TRUE);
	}

	return(FALSE);
}

/*************************************************************************
Calculates the key number used inside MySQL for an Innobase index. We have
to take into account if we generated a default clustered index for the table */

ulint
row_get_mysql_key_number_for_index(
/*===============================*/
	dict_index_t*	index)
{
	dict_index_t*	ind;
	ulint		i;

	ut_a(index);

	i = 0;
	ind = dict_table_get_first_index(index->table);

	while (index != ind) {
		ind = dict_table_get_next_index(ind);
		i++;
	}

	if (row_table_got_default_clust_index(index->table)) {
		ut_a(i > 0);
		i--;
	}

	return(i);
}

/*************************************************************************
Does a table creation operation for MySQL. */

int
row_create_table_for_mysql(
/*=======================*/
				/* out: error code or DB_SUCCESS */
	dict_table_t*	table,	/* in: table definition */
	trx_t*		trx)	/* in: transaction handle */
{
	tab_node_t*	node;
	mem_heap_t*	heap;
	que_thr_t*	thr;
	ulint		err;

	ut_ad(trx->mysql_thread_id == os_thread_get_curr_id());
	
	/* Serialize data dictionary operations with dictionary mutex:
	no deadlocks can occur then in these operations */

	mutex_enter(&(dict_sys->mutex));

	heap = mem_heap_create(512);

	trx->dict_operation = TRUE;
	
	node = tab_create_graph_create(table, heap);

	thr = pars_complete_graph_for_exec(node, trx, heap);

	ut_a(thr == que_fork_start_command(que_node_get_parent(thr),
						SESS_COMM_EXECUTE, 0));
	que_run_threads(thr);

	err = trx->error_state;

	if (err != DB_SUCCESS) {
		/* We have special error handling here */
		
		trx->error_state = DB_SUCCESS;
		
		trx_general_rollback_for_mysql(trx, FALSE, NULL);

		if (err == DB_OUT_OF_FILE_SPACE) {
		         row_drop_table_for_mysql(table->name, trx, TRUE);
		} else {
		         assert(err == DB_DUPLICATE_KEY);
			 fprintf(stderr, 
     "Innobase: error: table %s already exists in Innobase data dictionary\n",
				 table->name);
		}

		trx->error_state = DB_SUCCESS;
	}

	mutex_exit(&(dict_sys->mutex));
	que_graph_free((que_t*) que_node_get_parent(thr));
	
	return((int) err);
}

/*************************************************************************
Does an index creation operation for MySQL. TODO: currently failure
to create an index results in dropping the whole table! This is no problem
currently as all indexes must be created at the same time as the table. */

int
row_create_index_for_mysql(
/*=======================*/
					/* out: error number or DB_SUCCESS */
	dict_index_t*	index,		/* in: index defintion */
	trx_t*		trx)		/* in: transaction handle */
{
	ind_node_t*	node;
	mem_heap_t*	heap;
	que_thr_t*	thr;
	ulint		err;
	
	ut_ad(trx->mysql_thread_id == os_thread_get_curr_id());
	
	/* Serialize data dictionary operations with dictionary mutex:
	no deadlocks can occur then in these operations */

	mutex_enter(&(dict_sys->mutex));

	heap = mem_heap_create(512);

	trx->dict_operation = TRUE;

	node = ind_create_graph_create(index, heap);

	thr = pars_complete_graph_for_exec(node, trx, heap);

	ut_a(thr == que_fork_start_command(que_node_get_parent(thr),
						SESS_COMM_EXECUTE, 0));
	que_run_threads(thr);

	err = trx->error_state;

	if (err != DB_SUCCESS) {
		/* We have special error handling here */
		ut_a(err == DB_OUT_OF_FILE_SPACE);
		
		trx->error_state = DB_SUCCESS;

		trx_general_rollback_for_mysql(trx, FALSE, NULL);

		row_drop_table_for_mysql(index->table_name, trx, TRUE);

		trx->error_state = DB_SUCCESS;
	}

	mutex_exit(&(dict_sys->mutex));

	que_graph_free((que_t*) que_node_get_parent(thr));
	
	return((int) err);
}

/*************************************************************************
Drops a table for MySQL. */

int
row_drop_table_for_mysql(
/*=====================*/
				/* out: error code or DB_SUCCESS */
	char*	name,		/* in: table name */
	trx_t*	trx,		/* in: transaction handle */
	ibool	has_dict_mutex)	/* in: TRUE if the caller already owns the
				dictionary system mutex */
{
	dict_table_t*	table;
	que_thr_t*	thr;
	que_t*		graph;
	ulint		err;
	char*		str1;
	char*		str2;
	ulint		len;
	char		buf[10000];
retry:
	ut_ad(trx->mysql_thread_id == os_thread_get_curr_id());
	ut_a(name != NULL);
	
	/* We use the private SQL parser of Innobase to generate the
	query graphs needed in deleting the dictionary data from system
	tables in Innobase. Deleting a row from SYS_INDEXES table also
	frees the file segments of the B-tree associated with the index. */

	str1 =
	"PROCEDURE DROP_TABLE_PROC () IS\n"
	"table_id CHAR;\n"
	"index_id CHAR;\n"
	"found INT;\n"
	"BEGIN\n"
	"SELECT ID INTO table_id\n"
	"FROM SYS_TABLES\n"
	"WHERE NAME ='";

	str2 = 
	"';\n"
	"IF (SQL % NOTFOUND) THEN\n"
	"	COMMIT WORK;\n"
	"	RETURN;\n"
	"END IF;\n"
	"found := 1;\n"
	"WHILE found = 1 LOOP\n"
	"	SELECT ID INTO index_id\n"
	"	FROM SYS_INDEXES\n"
	"	WHERE TABLE_ID = table_id;\n"	
	"	IF (SQL % NOTFOUND) THEN\n"
	"		found := 0;\n"
	"	ELSE"
	"		DELETE FROM SYS_FIELDS WHERE INDEX_ID = index_id;\n"
	"		DELETE FROM SYS_INDEXES WHERE ID = index_id;\n"
	"	END IF;\n"
	"END LOOP;\n"
	"DELETE FROM SYS_COLUMNS WHERE TABLE_ID = table_id;\n"
	"DELETE FROM SYS_TABLES WHERE ID = table_id;\n"
	"COMMIT WORK;\n"
	"END;\n";

	len = ut_strlen(str1);

	ut_memcpy(buf, str1, len);
	ut_memcpy(buf + len, name, ut_strlen(name));

	len += ut_strlen(name);

	ut_memcpy(buf + len, str2, ut_strlen(str2) + 1);

	/* Serialize data dictionary operations with dictionary mutex:
	no deadlocks can occur then in these operations */

	if (!has_dict_mutex) {
		mutex_enter(&(dict_sys->mutex));
	}

	graph = pars_sql(buf);

	ut_a(graph);

	graph->trx = trx;
	trx->graph = NULL;

	graph->fork_type = QUE_FORK_MYSQL_INTERFACE;

	/* Prevent purge from running while we are dropping the table */
	rw_lock_s_lock(&(purge_sys->purge_is_running));

	table = dict_table_get_low(name);

	if (!table) {
		err = DB_TABLE_NOT_FOUND;

		goto funct_exit;
	}

	/* Check if there are any locks on the table: if yes, it cannot
	be dropped: we have to wait for the locks to be released  */

	if (lock_is_on_table(table)) {

		err = DB_TABLE_IS_BEING_USED;

		goto funct_exit;
	}		

	/* TODO: check that MySQL prevents users from accessing the table
	after this function row_drop_table_for_mysql has been called:
	otherwise anyone with an open handle to the table could, for example,
	come to read the table! */

	trx->dict_operation = TRUE;
	trx->table_id = table->id;

	ut_a(thr = que_fork_start_command(graph, SESS_COMM_EXECUTE, 0));

	que_run_threads(thr);

	err = trx->error_state;

	if (err != DB_SUCCESS) {
		ut_a(err == DB_OUT_OF_FILE_SPACE);

		err = DB_MUST_GET_MORE_FILE_SPACE;
		
		row_mysql_handle_errors(&err, trx, thr, NULL);

		ut_a(0);
	} else {
		dict_table_remove_from_cache(table);
	}
funct_exit:	
	rw_lock_s_unlock(&(purge_sys->purge_is_running));

	if (!has_dict_mutex) {
		mutex_exit(&(dict_sys->mutex));
	}

	que_graph_free(graph);
	
	if (err == DB_TABLE_IS_BEING_USED) {
		os_thread_sleep(200000);

		goto retry;
	}

	return((int) err);
}

/*************************************************************************
Renames a table for MySQL. */

int
row_rename_table_for_mysql(
/*=======================*/
				/* out: error code or DB_SUCCESS */
	char*	old_name,	/* in: old table name */
	char*	new_name,	/* in: new table name */
	trx_t*	trx)		/* in: transaction handle */
{
	dict_table_t*	table;
	que_thr_t*	thr;
	que_t*		graph;
	ulint		err;
	char*		str1;
	char*		str2;
	char*		str3;
	ulint		len;
	char		buf[10000];

	ut_ad(trx->mysql_thread_id == os_thread_get_curr_id());
	ut_a(old_name != NULL);
	ut_a(new_name != NULL);

	str1 =
	"PROCEDURE RENAME_TABLE_PROC () IS\n"
	"BEGIN\n"
	"UPDATE SYS_TABLES SET NAME ='";

	str2 = 
	"' WHERE NAME = '";

	str3 =
	"';\n"
	"COMMIT WORK;\n"
	"END;\n";

	len = ut_strlen(str1);

	ut_memcpy(buf, str1, len);

	ut_memcpy(buf + len, new_name, ut_strlen(new_name));

	len += ut_strlen(new_name);

	ut_memcpy(buf + len, str2, ut_strlen(str2));

	len += ut_strlen(str2);

	ut_memcpy(buf + len, old_name, ut_strlen(old_name));

	len += ut_strlen(old_name);

	ut_memcpy(buf + len, str3, ut_strlen(str3) + 1);
	
	/* Serialize data dictionary operations with dictionary mutex:
	no deadlocks can occur then in these operations */

	mutex_enter(&(dict_sys->mutex));

	table = dict_table_get_low(old_name);

	graph = pars_sql(buf);

	ut_a(graph);

	graph->trx = trx;
	trx->graph = NULL;

	graph->fork_type = QUE_FORK_MYSQL_INTERFACE;

	if (!table) {
		err = DB_TABLE_NOT_FOUND;

		goto funct_exit;
	}

	ut_a(thr = que_fork_start_command(graph, SESS_COMM_EXECUTE, 0));

	que_run_threads(thr);

	err = trx->error_state;

	if (err != DB_SUCCESS) {
		row_mysql_handle_errors(&err, trx, thr, NULL);
	} else {
		ut_a(dict_table_rename_in_cache(table, new_name));
	}
funct_exit:	
	mutex_exit(&(dict_sys->mutex));

	que_graph_free(graph);
	
	return((int) err);
}