/******************************************************
SQL parser

(c) 1996 Innobase Oy

Created 11/19/1996 Heikki Tuuri
*******************************************************/

/* Historical note: Innobase executed its first SQL string (CREATE TABLE)
on 1/27/1998 */

#include "pars0pars.h"

#ifdef UNIV_NONINL
#include "pars0pars.ic"
#endif

#include "row0sel.h"
#include "row0ins.h"
#include "row0upd.h"
#include "dict0dict.h"
#include "dict0mem.h"
#include "dict0crea.h"
#include "que0que.h"
#include "pars0grm.h"
#include "pars0opt.h"
#include "data0data.h"
#include "data0type.h"
#include "trx0trx.h"
#include "trx0roll.h"
#include "lock0lock.h"
#include "eval0eval.h"

#ifdef UNIV_SQL_DEBUG
/* If the following is set TRUE, the lexer will print the SQL string
as it tokenizes it */

ibool	pars_print_lexed	= FALSE;
#endif /* UNIV_SQL_DEBUG */

/* Global variable used while parsing a single procedure or query : the code is
NOT re-entrant */
sym_tab_t*	pars_sym_tab_global;

/* Global variables used to denote certain reserved words, used in
constructing the parsing tree */

pars_res_word_t	pars_to_char_token = {PARS_TO_CHAR_TOKEN};
pars_res_word_t	pars_to_number_token = {PARS_TO_NUMBER_TOKEN};
pars_res_word_t	pars_to_binary_token = {PARS_TO_BINARY_TOKEN};
pars_res_word_t	pars_binary_to_number_token = {PARS_BINARY_TO_NUMBER_TOKEN};
pars_res_word_t	pars_substr_token = {PARS_SUBSTR_TOKEN};
pars_res_word_t	pars_replstr_token = {PARS_REPLSTR_TOKEN};
pars_res_word_t	pars_concat_token = {PARS_CONCAT_TOKEN};
pars_res_word_t	pars_instr_token = {PARS_INSTR_TOKEN};
pars_res_word_t	pars_length_token = {PARS_LENGTH_TOKEN};
pars_res_word_t	pars_sysdate_token = {PARS_SYSDATE_TOKEN};
pars_res_word_t	pars_printf_token = {PARS_PRINTF_TOKEN};
pars_res_word_t	pars_assert_token = {PARS_ASSERT_TOKEN};
pars_res_word_t	pars_rnd_token = {PARS_RND_TOKEN};
pars_res_word_t	pars_rnd_str_token = {PARS_RND_STR_TOKEN};
pars_res_word_t	pars_count_token = {PARS_COUNT_TOKEN};
pars_res_word_t	pars_sum_token = {PARS_SUM_TOKEN};
pars_res_word_t	pars_distinct_token = {PARS_DISTINCT_TOKEN};
pars_res_word_t	pars_int_token = {PARS_INT_TOKEN};
pars_res_word_t	pars_char_token = {PARS_CHAR_TOKEN};
pars_res_word_t	pars_float_token = {PARS_FLOAT_TOKEN};
pars_res_word_t	pars_update_token = {PARS_UPDATE_TOKEN};
pars_res_word_t	pars_asc_token = {PARS_ASC_TOKEN};
pars_res_word_t	pars_desc_token = {PARS_DESC_TOKEN};
pars_res_word_t	pars_open_token = {PARS_OPEN_TOKEN};
pars_res_word_t	pars_close_token = {PARS_CLOSE_TOKEN};
pars_res_word_t	pars_consistent_token = {PARS_CONSISTENT_TOKEN};
pars_res_word_t	pars_unique_token = {PARS_UNIQUE_TOKEN};
pars_res_word_t	pars_clustered_token = {PARS_CLUSTERED_TOKEN};

/* Global variable used to denote the '*' in SELECT * FROM.. */
#define PARS_STAR_DENOTER	12345678
ulint	pars_star_denoter	= PARS_STAR_DENOTER;


/*************************************************************************
Determines the class of a function code. */
static
ulint
pars_func_get_class(
/*================*/
			/* out: function class: PARS_FUNC_ARITH, ... */
	int	func)	/* in: function code: '=', PARS_GE_TOKEN, ... */
{
	if ((func == '+') || (func == '-') || (func == '*') || (func == '/')) {

		return(PARS_FUNC_ARITH);

	} else if ((func == '=') || (func == '<') || (func == '>')
		   || (func == PARS_GE_TOKEN) || (func == PARS_LE_TOKEN)
		   || (func == PARS_NE_TOKEN)) {

		return(PARS_FUNC_CMP);

	} else if ((func == PARS_AND_TOKEN) || (func == PARS_OR_TOKEN)
		   || (func == PARS_NOT_TOKEN)) {

		return(PARS_FUNC_LOGICAL);

	} else if ((func == PARS_COUNT_TOKEN) || (func == PARS_SUM_TOKEN)) {

		return(PARS_FUNC_AGGREGATE);

	} else if ((func == PARS_TO_CHAR_TOKEN)
		   || (func == PARS_TO_NUMBER_TOKEN)
		   || (func == PARS_TO_BINARY_TOKEN)
		   || (func == PARS_BINARY_TO_NUMBER_TOKEN)
		   || (func == PARS_SUBSTR_TOKEN)
		   || (func == PARS_CONCAT_TOKEN)
		   || (func == PARS_LENGTH_TOKEN)
		   || (func == PARS_INSTR_TOKEN)
		   || (func == PARS_SYSDATE_TOKEN)
		   || (func == PARS_NOTFOUND_TOKEN)
		   || (func == PARS_PRINTF_TOKEN)
		   || (func == PARS_ASSERT_TOKEN)
		   || (func == PARS_RND_TOKEN)
		   || (func == PARS_RND_STR_TOKEN)
		   || (func == PARS_REPLSTR_TOKEN)) {

		return(PARS_FUNC_PREDEFINED);
	} else {
		return(PARS_FUNC_OTHER);
	}
}
	
/*************************************************************************
Parses an operator or predefined function expression. */
static
func_node_t*
pars_func_low(
/*==========*/
				/* out, own: function node in a query tree */
	int		func,	/* in: function token code */
	que_node_t*	arg)	/* in: first argument in the argument list */
{
	func_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(func_node_t));

	node->common.type = QUE_NODE_FUNC;
	dfield_set_data(&(node->common.val), NULL, 0);
	node->common.val_buf_size = 0;
	
	node->func = func;

	node->class = pars_func_get_class(func);

	node->args = arg;

	UT_LIST_ADD_LAST(func_node_list, pars_sym_tab_global->func_node_list,
								node);
	return(node);
}

/*************************************************************************
Parses a function expression. */

func_node_t*
pars_func(
/*======*/
				/* out, own: function node in a query tree */
	que_node_t* 	res_word,/* in: function name reserved word */
	que_node_t*	arg)	/* in: first argument in the argument list */
{
	return(pars_func_low(((pars_res_word_t*)res_word)->code, arg));
}

/*************************************************************************
Parses an operator expression. */

func_node_t*
pars_op(
/*====*/
				/* out, own: function node in a query tree */
	int		func,	/* in: operator token code */
	que_node_t*	arg1,	/* in: first argument */
	que_node_t*	arg2)	/* in: second argument or NULL for an unary
				operator */
{
	que_node_list_add_last(NULL, arg1);

	if (arg2) {
		que_node_list_add_last(arg1, arg2);
	}

	return(pars_func_low(func, arg1));
}

/*************************************************************************
Parses an ORDER BY clause. Order by a single column only is supported. */

order_node_t*
pars_order_by(
/*==========*/
				/* out, own: order-by node in a query tree */
	sym_node_t*	column,	/* in: column name */
	pars_res_word_t* asc)	/* in: &pars_asc_token or pars_desc_token */
{
	order_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(order_node_t));

	node->common.type = QUE_NODE_ORDER;
	
	node->column = column;

	if (asc == &pars_asc_token) {
		node->asc = TRUE;
	} else {
		ut_a(asc == &pars_desc_token);
		node->asc = FALSE;
	}

	return(node);
}

/*************************************************************************
Resolves the data type of a function in an expression. The argument data
types must already be resolved. */
static
void
pars_resolve_func_data_type(
/*========================*/
	func_node_t*	node)	/* in: function node */
{
	que_node_t*	arg;
	ulint		func;

	ut_a(que_node_get_type(node) == QUE_NODE_FUNC);
	
	arg = node->args;

	func = node->func;

	if ((func == PARS_SUM_TOKEN)
	    		|| (func == '+') || (func == '-') || (func == '*')
			|| (func == '/') || (func == '+')) {
	
		/* Inherit the data type from the first argument (which must
		not be the SQL null literal whose type is DATA_ERROR) */

		dtype_copy(que_node_get_data_type(node),
					que_node_get_data_type(arg));

		ut_a(dtype_get_mtype(que_node_get_data_type(node))
								== DATA_INT);
	} else if (func == PARS_COUNT_TOKEN) {
		ut_a(arg);
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);
		
	} else if (func == PARS_TO_CHAR_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg)) == DATA_INT);
		dtype_set(que_node_get_data_type(node), DATA_VARCHAR,
							DATA_ENGLISH, 0, 0);
	} else if (func == PARS_TO_BINARY_TOKEN) {
		if (dtype_get_mtype(que_node_get_data_type(arg)) == DATA_INT) {
			dtype_set(que_node_get_data_type(node), DATA_VARCHAR,
							DATA_ENGLISH, 0, 0);
		} else {
			dtype_set(que_node_get_data_type(node), DATA_BINARY,
								0, 0, 0);
		}
	} else if (func == PARS_TO_NUMBER_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg))
							== DATA_VARCHAR);
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if (func == PARS_BINARY_TO_NUMBER_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg))
							== DATA_VARCHAR);
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if (func == PARS_LENGTH_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg))
							== DATA_VARCHAR);
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if (func == PARS_INSTR_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg))
							== DATA_VARCHAR);
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if (func == PARS_SYSDATE_TOKEN) {
		ut_a(arg == NULL);
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if ((func == PARS_SUBSTR_TOKEN)
			|| (func == PARS_CONCAT_TOKEN)) {

		ut_a(dtype_get_mtype(que_node_get_data_type(arg))
							== DATA_VARCHAR);
		dtype_set(que_node_get_data_type(node), DATA_VARCHAR,
							DATA_ENGLISH, 0, 0);

	} else if ((func == '>') || (func == '<') || (func == '=')
		   || (func == PARS_GE_TOKEN)
		   || (func == PARS_LE_TOKEN)
		   || (func == PARS_NE_TOKEN)
		   || (func == PARS_AND_TOKEN)
		   || (func == PARS_OR_TOKEN)
		   || (func == PARS_NOT_TOKEN)
		   || (func == PARS_NOTFOUND_TOKEN)) {

		/* We currently have no iboolean type: use integer type */
		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if (func == PARS_RND_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg)) == DATA_INT);

		dtype_set(que_node_get_data_type(node), DATA_INT, 0, 4, 0);

	} else if (func == PARS_RND_STR_TOKEN) {
		ut_a(dtype_get_mtype(que_node_get_data_type(arg)) == DATA_INT);

		dtype_set(que_node_get_data_type(node), DATA_VARCHAR,
							DATA_ENGLISH, 0, 0);
	} else {
		ut_error;
	}
}

/*************************************************************************
Resolves the meaning of variables in an expression and the data types of
functions. It is an error if some identifier cannot be resolved here. */
static
void
pars_resolve_exp_variables_and_types(
/*=================================*/
	sel_node_t*	select_node,	/* in: select node or NULL; if
					this is not NULL then the variable
					sym nodes are added to the
					copy_variables list of select_node */
	que_node_t*	exp_node)	/* in: expression */
{
	func_node_t*	func_node;
	que_node_t*	arg;
	sym_node_t*	sym_node;
	sym_node_t*	node;

	ut_a(exp_node);

	if (que_node_get_type(exp_node) == QUE_NODE_FUNC) {
		func_node = exp_node;

		arg = func_node->args;

		while (arg) {
			pars_resolve_exp_variables_and_types(select_node, arg);

			arg = que_node_get_next(arg);
		}

		pars_resolve_func_data_type(func_node);

		return;
	}
		
	ut_a(que_node_get_type(exp_node) == QUE_NODE_SYMBOL);

	sym_node = exp_node;

	if (sym_node->resolved) {

		return;
	}
		
	/* Not resolved yet: look in the symbol table for a variable
	or a cursor with the same name */

	node = UT_LIST_GET_FIRST(pars_sym_tab_global->sym_list);

	while (node) {
		if (node->resolved
			&& ((node->token_type == SYM_VAR)
					|| (node->token_type == SYM_CURSOR))
			&& node->name
			&& (sym_node->name_len == node->name_len)
			&& (ut_memcmp(sym_node->name, node->name,
						node->name_len) == 0)) {

				/* Found a variable or a cursor declared with
				the same name */
				
				break;
		}

		node = UT_LIST_GET_NEXT(sym_list, node);
	}

	if (!node) {
		fprintf(stderr, "PARSER ERROR: Unresolved identifier %s\n",
							sym_node->name);
	}
	
	ut_a(node);

	sym_node->resolved = TRUE;
	sym_node->token_type = SYM_IMPLICIT_VAR;
	sym_node->alias = node;		
	sym_node->indirection = node;

	if (select_node) {
		UT_LIST_ADD_LAST(col_var_list, select_node->copy_variables,
								sym_node);
	}

	dfield_set_type(que_node_get_val(sym_node),
					que_node_get_data_type(node));
}

/*************************************************************************
Resolves the meaning of variables in an expression list. It is an error if
some identifier cannot be resolved here. Resolves also the data types of
functions. */
static
void
pars_resolve_exp_list_variables_and_types(
/*======================================*/
	sel_node_t*	select_node,	/* in: select node or NULL */
	que_node_t*	exp_node)	/* in: expression list first node, or
					NULL */
{
	while (exp_node) {
		pars_resolve_exp_variables_and_types(select_node, exp_node);

		exp_node = que_node_get_next(exp_node);
	}
}

/*************************************************************************
Resolves the columns in an expression. */
static
void
pars_resolve_exp_columns(
/*=====================*/
	sym_node_t*	table_node,	/* in: first node in a table list */
	que_node_t*	exp_node)	/* in: expression */
{
	func_node_t*	func_node;
	que_node_t*	arg;
	sym_node_t*	sym_node;
	dict_table_t*	table;
	sym_node_t*	t_node;
	dict_col_t*	col;
	ulint		n_cols;
	ulint		i;

	ut_a(exp_node);

	if (que_node_get_type(exp_node) == QUE_NODE_FUNC) {
		func_node = exp_node;

		arg = func_node->args;

		while (arg) {
			pars_resolve_exp_columns(table_node, arg);

			arg = que_node_get_next(arg);
		}

		return;
	}
		
	ut_a(que_node_get_type(exp_node) == QUE_NODE_SYMBOL);

	sym_node = exp_node;

	if (sym_node->resolved) {

		return;
	}
		
	/* Not resolved yet: look in the table list for a column with the
	same name */

	t_node = table_node;

	while (t_node) {
		table = t_node->table;

		n_cols = dict_table_get_n_user_cols(table);

		for (i = 0; i < n_cols; i++) {
			col = dict_table_get_nth_col(table, i);

			if ((sym_node->name_len == ut_strlen(col->name))
			    && (0 == ut_memcmp(sym_node->name, col->name,
			    			sym_node->name_len))) {
			    	/* Found */
				sym_node->resolved = TRUE;
				sym_node->token_type = SYM_COLUMN;
				sym_node->table = table;
				sym_node->col_no = i;
				sym_node->prefetch_buf = NULL;
				
				dfield_set_type(&(sym_node->common.val),
						dict_col_get_type(col));
				return;
			}
		}

		t_node = que_node_get_next(t_node);
	}
}

/*************************************************************************
Resolves the meaning of columns in an expression list. */
static
void
pars_resolve_exp_list_columns(
/*==========================*/
	sym_node_t*	table_node,	/* in: first node in a table list */
	que_node_t*	exp_node)	/* in: expression list first node, or
					NULL */
{
	while (exp_node) {
		pars_resolve_exp_columns(table_node, exp_node);

		exp_node = que_node_get_next(exp_node);
	}
}

/*************************************************************************
Retrieves the table definition for a table name id. */
static
void
pars_retrieve_table_def(
/*====================*/
	sym_node_t*	sym_node)	/* in: table node */
{
	const char*	table_name;

	ut_a(sym_node);
	ut_a(que_node_get_type(sym_node) == QUE_NODE_SYMBOL);

	sym_node->resolved = TRUE;
	sym_node->token_type = SYM_TABLE;

	table_name = (const char*) sym_node->name;
	
	sym_node->table = dict_table_get_low(table_name);

	ut_a(sym_node->table);
}

/*************************************************************************
Retrieves the table definitions for a list of table name ids. */
static
ulint
pars_retrieve_table_list_defs(
/*==========================*/
					/* out: number of tables */
	sym_node_t*	sym_node)	/* in: first table node in list */
{
	ulint		count		= 0;
	
	if (sym_node == NULL) {

		return(count);
	}

	while (sym_node) {
		pars_retrieve_table_def(sym_node);

		count++;

		sym_node = que_node_get_next(sym_node);
	}

	return(count);
}

/*************************************************************************
Adds all columns to the select list if the query is SELECT * FROM ... */
static
void
pars_select_all_columns(
/*====================*/
	sel_node_t*	select_node)	/* in: select node already containing
					the table list */
{
	sym_node_t*	col_node;
	sym_node_t*	table_node;
	dict_table_t*	table;
	dict_col_t*	col;
	ulint		i;

	select_node->select_list = NULL;
	
	table_node = select_node->table_list;

	while (table_node) {
		table = table_node->table;

		for (i = 0; i < dict_table_get_n_user_cols(table); i++) {

			col = dict_table_get_nth_col(table, i);

			col_node = sym_tab_add_id(pars_sym_tab_global,
						(byte*)col->name,
						ut_strlen(col->name));
			select_node->select_list
					= que_node_list_add_last(
						select_node->select_list,
								col_node);
		}

		table_node = que_node_get_next(table_node);
	}
}

/*************************************************************************
Parses a select list; creates a query graph node for the whole SELECT
statement. */

sel_node_t*
pars_select_list(
/*=============*/
					/* out, own: select node in a query
					tree */
	que_node_t*	select_list,	/* in: select list */
	sym_node_t*	into_list)	/* in: variables list or NULL */
{
	sel_node_t*	node;

	node = sel_node_create(pars_sym_tab_global->heap);
	
	node->select_list = select_list;
	node->into_list = into_list;

	pars_resolve_exp_list_variables_and_types(NULL, into_list);

	return(node);
}

/*************************************************************************
Checks if the query is an aggregate query, in which case the selct list must
contain only aggregate function items. */
static
void
pars_check_aggregate(
/*=================*/
	sel_node_t*	select_node)	/* in: select node already containing
					the select list */
{
	que_node_t*	exp_node;
	func_node_t*	func_node;
	ulint		n_nodes			= 0;
	ulint		n_aggregate_nodes	= 0;

	exp_node = select_node->select_list;

	while (exp_node) {

		n_nodes++;
	
		if (que_node_get_type(exp_node) == QUE_NODE_FUNC) {

			func_node = exp_node;

			if (func_node->class == PARS_FUNC_AGGREGATE) {

				n_aggregate_nodes++;
			}
		}

		exp_node = que_node_get_next(exp_node);
	}

	if (n_aggregate_nodes > 0) {
		ut_a(n_nodes == n_aggregate_nodes);

		select_node->is_aggregate = TRUE;
	} else {
		select_node->is_aggregate = FALSE;
	}
}

/*************************************************************************
Parses a select statement. */

sel_node_t*
pars_select_statement(
/*==================*/
					/* out, own: select node in a query
					tree */
	sel_node_t*	select_node,	/* in: select node already containing
					the select list */
	sym_node_t*	table_list,	/* in: table list */
	que_node_t*	search_cond,	/* in: search condition or NULL */
	pars_res_word_t* for_update,	/* in: NULL or &pars_update_token */
	pars_res_word_t* consistent_read,/* in: NULL or
						&pars_consistent_token */
	order_node_t*	order_by)	/* in: NULL or an order-by node */
{
	select_node->state = SEL_NODE_OPEN;

	select_node->table_list = table_list;
	select_node->n_tables = pars_retrieve_table_list_defs(table_list);

	if (select_node->select_list == &pars_star_denoter) {

		/* SELECT * FROM ... */
		pars_select_all_columns(select_node);
	}
	
	if (select_node->into_list) {
		ut_a(que_node_list_get_len(select_node->into_list)
			== que_node_list_get_len(select_node->select_list));
	}

	UT_LIST_INIT(select_node->copy_variables);

	pars_resolve_exp_list_columns(table_list, select_node->select_list);
	pars_resolve_exp_list_variables_and_types(select_node,
						select_node->select_list);
	pars_check_aggregate(select_node);

	select_node->search_cond = search_cond;

	if (search_cond) {
		pars_resolve_exp_columns(table_list, search_cond);
		pars_resolve_exp_variables_and_types(select_node, search_cond);
	}

	if (for_update) {
		ut_a(!consistent_read);
		select_node->set_x_locks = TRUE;
		select_node->row_lock_mode = LOCK_X;
	} else {
		select_node->set_x_locks = FALSE;
		select_node->row_lock_mode = LOCK_S;
	}

	if (consistent_read) {
		select_node->consistent_read = TRUE;
	} else {
		select_node->consistent_read = FALSE;
		select_node->read_view = NULL;
	}

	select_node->order_by = order_by;

	if (order_by) {
		pars_resolve_exp_columns(table_list, order_by->column);
	}
	
	/* The final value of the following fields depend on the environment
	where the select statement appears: */

	select_node->can_get_updated = FALSE;
	select_node->explicit_cursor = NULL;

	opt_search_plan(select_node);

	return(select_node);
}

/*************************************************************************
Parses a cursor declaration. */

que_node_t*
pars_cursor_declaration(
/*====================*/
					/* out: sym_node */
	sym_node_t*	sym_node,	/* in: cursor id node in the symbol
					table */
	sel_node_t*	select_node)	/* in: select node */
{
	sym_node->resolved = TRUE;
	sym_node->token_type = SYM_CURSOR;
	sym_node->cursor_def = select_node;

	select_node->state = SEL_NODE_CLOSED;
	select_node->explicit_cursor = sym_node;

	return(sym_node);	
}

/*************************************************************************
Parses a delete or update statement start. */

upd_node_t*
pars_update_statement_start(
/*========================*/
					/* out, own: update node in a query
					tree */
	ibool		is_delete,	/* in: TRUE if delete */
	sym_node_t*	table_sym,	/* in: table name node */
	col_assign_node_t* col_assign_list)/* in: column assignment list, NULL
					if delete */	
{
	upd_node_t*	node;
	
	node = upd_node_create(pars_sym_tab_global->heap);

	node->is_delete = is_delete;

	node->table_sym = table_sym;
	node->col_assign_list = col_assign_list;

	return(node);
}
	
/*************************************************************************
Parses a column assignment in an update. */

col_assign_node_t*
pars_column_assignment(
/*===================*/
				/* out: column assignment node */
	sym_node_t*	column,	/* in: column to assign */
	que_node_t*	exp)	/* in: value to assign */
{
	col_assign_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap,
						sizeof(col_assign_node_t));
	node->common.type = QUE_NODE_COL_ASSIGNMENT;

	node->col = column;
	node->val = exp;

	return(node);
}

/*************************************************************************
Processes an update node assignment list. */
static
void
pars_process_assign_list(
/*=====================*/
	upd_node_t*	node)	/* in: update node */
{
	col_assign_node_t*	col_assign_list;
	sym_node_t*		table_sym;
	col_assign_node_t*	assign_node;
	upd_field_t*		upd_field;
	dict_index_t*		clust_index;
	sym_node_t*		col_sym;
	ulint			changes_ord_field;
	ulint			changes_field_size;
	ulint			n_assigns;
	ulint			i;

	table_sym = node->table_sym;
	col_assign_list = node->col_assign_list;
	clust_index = dict_table_get_first_index(node->table);
	
	assign_node = col_assign_list;
	n_assigns = 0;

	while (assign_node) {
		pars_resolve_exp_columns(table_sym, assign_node->col);
		pars_resolve_exp_columns(table_sym, assign_node->val);
		pars_resolve_exp_variables_and_types(NULL, assign_node->val);

		/* ut_a(dtype_get_mtype(dfield_get_type(
				que_node_get_val(assign_node->col)))
		     == dtype_get_mtype(dfield_get_type(
				que_node_get_val(assign_node->val)))); */

		/* Add to the update node all the columns found in assignment
		values as columns to copy: therefore, TRUE */

		opt_find_all_cols(TRUE, clust_index, &(node->columns), NULL,
							assign_node->val);
		n_assigns++;

		assign_node = que_node_get_next(assign_node);
	}

	node->update = upd_create(n_assigns, pars_sym_tab_global->heap);

	assign_node = col_assign_list;

	changes_field_size = UPD_NODE_NO_SIZE_CHANGE;

	for (i = 0; i < n_assigns; i++) {
		upd_field = upd_get_nth_field(node->update, i);

		col_sym = assign_node->col;

		upd_field_set_field_no(upd_field,
				dict_index_get_nth_col_pos(clust_index,
							col_sym->col_no),
							clust_index, NULL);
		upd_field->exp = assign_node->val;

		if (!dtype_is_fixed_size(
			dict_index_get_nth_type(clust_index,
						upd_field->field_no))) {
			changes_field_size = 0;
		}					
		
		assign_node = que_node_get_next(assign_node);
	}

	/* Find out if the update can modify an ordering field in any index */

	changes_ord_field = UPD_NODE_NO_ORD_CHANGE;

	if (row_upd_changes_some_index_ord_field_binary(node->table,
							node->update)) {
		changes_ord_field = 0;
	}
	
	node->cmpl_info = changes_ord_field | changes_field_size;
}
	
/*************************************************************************
Parses an update or delete statement. */

upd_node_t*
pars_update_statement(
/*==================*/
					/* out, own: update node in a query
					tree */
	upd_node_t*	node,		/* in: update node */
	sym_node_t*	cursor_sym,	/* in: pointer to a cursor entry in
					the symbol table or NULL */
	que_node_t*	search_cond)	/* in: search condition or NULL */
{
	sym_node_t*	table_sym;
	sel_node_t*	sel_node;
	plan_t*		plan;

	table_sym = node->table_sym;
	
	pars_retrieve_table_def(table_sym);
	node->table = table_sym->table;

	UT_LIST_INIT(node->columns);
	
	/* Make the single table node into a list of table nodes of length 1 */
	
	que_node_list_add_last(NULL, table_sym);

	if (cursor_sym) {
		pars_resolve_exp_variables_and_types(NULL, cursor_sym);

		sel_node = cursor_sym->alias->cursor_def;

		node->searched_update = FALSE;
	} else {
		sel_node = pars_select_list(NULL, NULL);

		pars_select_statement(sel_node, table_sym, search_cond, NULL,
								NULL, NULL);
		node->searched_update = TRUE;
		sel_node->common.parent = node;
	}
	
	node->select = sel_node;

	ut_a(!node->is_delete || (node->col_assign_list == NULL));
	ut_a(node->is_delete || (node->col_assign_list != NULL));

	if (node->is_delete) {
		node->cmpl_info = 0;
	} else {
		pars_process_assign_list(node);
	}

	if (node->searched_update) {
		node->has_clust_rec_x_lock = TRUE;
		sel_node->set_x_locks = TRUE;
		sel_node->row_lock_mode = LOCK_X;
	} else {
		node->has_clust_rec_x_lock = sel_node->set_x_locks;
	}

	ut_a(sel_node->n_tables == 1);
	ut_a(sel_node->consistent_read == FALSE);
	ut_a(sel_node->order_by == NULL);
	ut_a(sel_node->is_aggregate == FALSE);

	sel_node->can_get_updated = TRUE;
	
	node->state = UPD_NODE_UPDATE_CLUSTERED;
	
	plan = sel_node_get_nth_plan(sel_node, 0);

	plan->no_prefetch = TRUE;

	if (!((plan->index)->type & DICT_CLUSTERED)) {

		plan->must_get_clust = TRUE;

		node->pcur = &(plan->clust_pcur);
	} else {
		node->pcur = &(plan->pcur);
	}

	if (!node->is_delete && node->searched_update
			&& (node->cmpl_info & UPD_NODE_NO_SIZE_CHANGE)
			&& (node->cmpl_info & UPD_NODE_NO_ORD_CHANGE)) {

		/* The select node can perform the update in-place */

		ut_a(plan->asc);

		node->select_will_do_update = TRUE;
		sel_node->select_will_do_update = TRUE;
		sel_node->latch_mode = BTR_MODIFY_LEAF;
	}

	return(node);
}

/*************************************************************************
Parses an insert statement. */

ins_node_t*
pars_insert_statement(
/*==================*/
					/* out, own: update node in a query
					tree */
	sym_node_t*	table_sym,	/* in: table name node */
	que_node_t* 	values_list,	/* in: value expression list or NULL */
	sel_node_t*	select)		/* in: select condition or NULL */
{
	ins_node_t*	node;
	dtuple_t*	row;
	ulint		ins_type;

	ut_a(values_list || select);
	ut_a(!values_list || !select);

	if (values_list) {
		ins_type = INS_VALUES;
	} else {
		ins_type = INS_SEARCHED;
	}

	pars_retrieve_table_def(table_sym);

	node = ins_node_create(ins_type, table_sym->table,
						pars_sym_tab_global->heap);

	row = dtuple_create(pars_sym_tab_global->heap,
					dict_table_get_n_cols(node->table));

	dict_table_copy_types(row, table_sym->table);

	ins_node_set_new_row(node, row);

	node->select = select;

	if (select) {
		select->common.parent = node;

		ut_a(que_node_list_get_len(select->select_list)
			== dict_table_get_n_user_cols(table_sym->table));
	}
	
	node->values_list = values_list;

	if (node->values_list) {
		pars_resolve_exp_list_variables_and_types(NULL, values_list);

		ut_a(que_node_list_get_len(values_list)
			== dict_table_get_n_user_cols(table_sym->table));
	}

	return(node);
}

/*************************************************************************
Set the type of a dfield. */
static
void
pars_set_dfield_type(
/*=================*/
	dfield_t*	dfield,	/* in: dfield */
	pars_res_word_t* type)	/* in: pointer to a type token */
{
	if (type == &pars_int_token) {

		dtype_set(dfield_get_type(dfield), DATA_INT, 0, 4, 0);

	} else if (type == &pars_char_token) {

		dtype_set(dfield_get_type(dfield), DATA_VARCHAR,
							DATA_ENGLISH, 0, 0);
	} else {
		ut_error;
	}
}

/*************************************************************************
Parses a variable declaration. */

sym_node_t*
pars_variable_declaration(
/*======================*/
				/* out, own: symbol table node of type
				SYM_VAR */
	sym_node_t*	node,	/* in: symbol table node allocated for the
				id of the variable */
	pars_res_word_t* type)	/* in: pointer to a type token */
{
	node->resolved = TRUE;
	node->token_type = SYM_VAR;

	node->param_type = PARS_NOT_PARAM;

	pars_set_dfield_type(que_node_get_val(node), type);
	
	return(node);
}

/*************************************************************************
Parses a procedure parameter declaration. */

sym_node_t*
pars_parameter_declaration(
/*=======================*/
				/* out, own: symbol table node of type
				SYM_VAR */
	sym_node_t*	node,	/* in: symbol table node allocated for the
				id of the parameter */
	ulint		param_type,
				/* in: PARS_INPUT or PARS_OUTPUT */
	pars_res_word_t* type)	/* in: pointer to a type token */
{	
	ut_a((param_type == PARS_INPUT) || (param_type == PARS_OUTPUT));

	pars_variable_declaration(node, type);

	node->param_type = param_type;

	return(node);
}

/*************************************************************************
Sets the parent field in a query node list. */
static
void
pars_set_parent_in_list(
/*====================*/
	que_node_t*	node_list,	/* in: first node in a list */
	que_node_t*	parent)		/* in: parent value to set in all
					nodes of the list */
{
	que_common_t*	common;

	common = node_list;

	while (common) {
		common->parent = parent;

		common = que_node_get_next(common);
	}
}	

/*************************************************************************
Parses an elsif element. */

elsif_node_t*
pars_elsif_element(
/*===============*/
					/* out: elsif node */
	que_node_t*	cond,		/* in: if-condition */
	que_node_t*	stat_list)	/* in: statement list */
{
	elsif_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(elsif_node_t));

	node->common.type = QUE_NODE_ELSIF;

	node->cond = cond;

	pars_resolve_exp_variables_and_types(NULL, cond);
	
	node->stat_list = stat_list;

	return(node);
}

/*************************************************************************
Parses an if-statement. */

if_node_t*
pars_if_statement(
/*==============*/
					/* out: if-statement node */
	que_node_t*	cond,		/* in: if-condition */
	que_node_t*	stat_list,	/* in: statement list */
	que_node_t*	else_part)	/* in: else-part statement list
					or elsif element list */
{
	if_node_t*	node;
	elsif_node_t*	elsif_node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(if_node_t));

	node->common.type = QUE_NODE_IF;

	node->cond = cond;

	pars_resolve_exp_variables_and_types(NULL, cond);
	
	node->stat_list = stat_list;

	if (else_part && (que_node_get_type(else_part) == QUE_NODE_ELSIF)) {

		/* There is a list of elsif conditions */

		node->else_part = NULL;
		node->elsif_list = else_part;

		elsif_node = else_part;

		while (elsif_node) {
			pars_set_parent_in_list(elsif_node->stat_list, node);

			elsif_node = que_node_get_next(elsif_node);
		}
	} else {
		node->else_part = else_part;
		node->elsif_list = NULL;

		pars_set_parent_in_list(else_part, node);
	}

	pars_set_parent_in_list(stat_list, node);
	
	return(node);
}

/*************************************************************************
Parses a while-statement. */

while_node_t*
pars_while_statement(
/*=================*/
					/* out: while-statement node */
	que_node_t*	cond,		/* in: while-condition */
	que_node_t*	stat_list)	/* in: statement list */
{
	while_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(while_node_t));

	node->common.type = QUE_NODE_WHILE;

	node->cond = cond;

	pars_resolve_exp_variables_and_types(NULL, cond);

	node->stat_list = stat_list;

	pars_set_parent_in_list(stat_list, node);
	
	return(node);
}

/*************************************************************************
Parses a for-loop-statement. */

for_node_t*
pars_for_statement(
/*===============*/
					/* out: for-statement node */
	sym_node_t*	loop_var,	/* in: loop variable */
	que_node_t*	loop_start_limit,/* in: loop start expression */
	que_node_t*	loop_end_limit,	/* in: loop end expression */
	que_node_t*	stat_list)	/* in: statement list */
{
	for_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(for_node_t));

	node->common.type = QUE_NODE_FOR;

	pars_resolve_exp_variables_and_types(NULL, loop_var);
	pars_resolve_exp_variables_and_types(NULL, loop_start_limit);
	pars_resolve_exp_variables_and_types(NULL, loop_end_limit);

	node->loop_var = loop_var->indirection;

	ut_a(loop_var->indirection);

	node->loop_start_limit = loop_start_limit;
	node->loop_end_limit = loop_end_limit;

	node->stat_list = stat_list;

	pars_set_parent_in_list(stat_list, node);
	
	return(node);
}

/*************************************************************************
Parses a return-statement. */

return_node_t*
pars_return_statement(void)
/*=======================*/
					/* out: return-statement node */
{
	return_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap,
						sizeof(return_node_t));
	node->common.type = QUE_NODE_RETURN;

	return(node);
}

/*************************************************************************
Parses an assignment statement. */

assign_node_t*
pars_assignment_statement(
/*======================*/
				/* out: assignment statement node */
	sym_node_t*	var,	/* in: variable to assign */
	que_node_t*	val)	/* in: value to assign */
{
	assign_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap,
						sizeof(assign_node_t));
	node->common.type = QUE_NODE_ASSIGNMENT;

	node->var = var;
	node->val = val;

	pars_resolve_exp_variables_and_types(NULL, var);
	pars_resolve_exp_variables_and_types(NULL, val);
	
	ut_a(dtype_get_mtype(dfield_get_type(que_node_get_val(var)))
	      == dtype_get_mtype(dfield_get_type(que_node_get_val(val))));

	return(node);
}

/*************************************************************************
Parses a procedure call. */

func_node_t*
pars_procedure_call(
/*================*/
				/* out: function node */
	que_node_t*	res_word,/* in: procedure name reserved word */
	que_node_t*	args)	/* in: argument list */
{
	func_node_t*	node;

	node = pars_func(res_word, args);

	pars_resolve_exp_list_variables_and_types(NULL, args);
	
	return(node);
}

/*************************************************************************
Parses a fetch statement. */

fetch_node_t*
pars_fetch_statement(
/*=================*/
					/* out: fetch statement node */
	sym_node_t*	cursor,		/* in: cursor node */
	sym_node_t*	into_list)	/* in: variables to set */
{
	sym_node_t*	cursor_decl;
	fetch_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(fetch_node_t));

	node->common.type = QUE_NODE_FETCH;	
	
	pars_resolve_exp_variables_and_types(NULL, cursor);
	pars_resolve_exp_list_variables_and_types(NULL, into_list);

	node->into_list = into_list;

	cursor_decl = cursor->alias;

	ut_a(cursor_decl->token_type == SYM_CURSOR);

	node->cursor_def = cursor_decl->cursor_def;

	ut_a(que_node_list_get_len(into_list)
		== que_node_list_get_len(node->cursor_def->select_list));

	return(node);
}

/*************************************************************************
Parses an open or close cursor statement. */

open_node_t*
pars_open_statement(
/*================*/
				/* out: fetch statement node */
	ulint		type,	/* in: ROW_SEL_OPEN_CURSOR
				or ROW_SEL_CLOSE_CURSOR */
	sym_node_t*	cursor)	/* in: cursor node */
{
	sym_node_t*	cursor_decl;
	open_node_t*	node;

	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(open_node_t));

	node->common.type = QUE_NODE_OPEN;	

	pars_resolve_exp_variables_and_types(NULL, cursor);

	cursor_decl = cursor->alias;

	ut_a(cursor_decl->token_type == SYM_CURSOR);

	node->op_type = type;
	node->cursor_def = cursor_decl->cursor_def;

	return(node);
}

/*************************************************************************
Parses a row_printf-statement. */

row_printf_node_t*
pars_row_printf_statement(
/*======================*/
					/* out: row_printf-statement node */
	sel_node_t*	sel_node)	/* in: select node */
{
	row_printf_node_t*	node;
	
	node = mem_heap_alloc(pars_sym_tab_global->heap,
						sizeof(row_printf_node_t));
	node->common.type = QUE_NODE_ROW_PRINTF;
	
	node->sel_node = sel_node;

	sel_node->common.parent = node;

	return(node);
}

/*************************************************************************
Parses a commit statement. */

commit_node_t*
pars_commit_statement(void)
/*=======================*/
{
	return(commit_node_create(pars_sym_tab_global->heap));
}

/*************************************************************************
Parses a rollback statement. */

roll_node_t*
pars_rollback_statement(void)
/*=========================*/
{
	return(roll_node_create(pars_sym_tab_global->heap));
}

/*************************************************************************
Parses a column definition at a table creation. */

sym_node_t*
pars_column_def(
/*============*/
					/* out: column sym table node */
	sym_node_t*	sym_node,	/* in: column node in the symbol
					table */
	pars_res_word_t* type)		/* in: data type */
{
	pars_set_dfield_type(que_node_get_val(sym_node), type);

	return(sym_node);
}

/*************************************************************************
Parses a table creation operation. */

tab_node_t*
pars_create_table(
/*==============*/
					/* out: table create subgraph */
	sym_node_t*	table_sym,	/* in: table name node in the symbol
					table */
	sym_node_t*	column_defs,	/* in: list of column names */
	void*		not_fit_in_memory)/* in: a non-NULL pointer means that
					this is a table which in simulations
					should be simulated as not fitting
					in memory; thread is put to sleep
					to simulate disk accesses; NOTE that
					this flag is not stored to the data
					dictionary on disk, and the database
					will forget about non-NULL value if
					it has to reload the table definition
					from disk */
{
	dict_table_t*	table;
	sym_node_t*	column;
	tab_node_t*	node;
	dtype_t*	dtype;
	ulint		n_cols;

	n_cols = que_node_list_get_len(column_defs);

	/* As the InnoDB SQL parser is for internal use only,
	for creating some system tables, this function will only
	create tables in the old (not compact) record format. */
	table = dict_mem_table_create(table_sym->name, 0, n_cols, FALSE);

	if (not_fit_in_memory != NULL) {
		table->does_not_fit_in_memory = TRUE;
	}

	column = column_defs;

	while (column) {
		dtype = dfield_get_type(que_node_get_val(column));
	
		dict_mem_table_add_col(table, column->name, dtype->mtype,
						dtype->prtype, dtype->len,
						dtype->prec);
		column->resolved = TRUE;
		column->token_type = SYM_COLUMN;

		column = que_node_get_next(column);
	}
	
	node = tab_create_graph_create(table, pars_sym_tab_global->heap);

	table_sym->resolved = TRUE;
	table_sym->token_type = SYM_TABLE;
	
	return(node);
}

/*************************************************************************
Parses an index creation operation. */

ind_node_t*
pars_create_index(
/*==============*/
					/* out: index create subgraph */
	pars_res_word_t* unique_def,	/* in: not NULL if a unique index */
	pars_res_word_t* clustered_def,	/* in: not NULL if a clustered index */
	sym_node_t*	index_sym,	/* in: index name node in the symbol
					table */
	sym_node_t*	table_sym,	/* in: table name node in the symbol
					table */
	sym_node_t*	column_list)	/* in: list of column names */
{
	dict_index_t*	index;
	sym_node_t*	column;
	ind_node_t*	node;
	ulint		n_fields;
	ulint		ind_type;

	n_fields = que_node_list_get_len(column_list);

	ind_type = 0;

	if (unique_def) {
		ind_type = ind_type | DICT_UNIQUE;
	}

	if (clustered_def) {
		ind_type = ind_type | DICT_CLUSTERED;
	}
	
	index = dict_mem_index_create(table_sym->name, index_sym->name, 0,
							ind_type, n_fields);
	column = column_list;

	while (column) {
		dict_mem_index_add_field(index, column->name, 0, 0);

		column->resolved = TRUE;
		column->token_type = SYM_COLUMN;

		column = que_node_get_next(column);
	}
	
	node = ind_create_graph_create(index, pars_sym_tab_global->heap);

	table_sym->resolved = TRUE;
	table_sym->token_type = SYM_TABLE;

	index_sym->resolved = TRUE;
	index_sym->token_type = SYM_TABLE;

	return(node);
}

/*************************************************************************
Parses a procedure definition. */

que_fork_t*
pars_procedure_definition(
/*======================*/
					/* out: query fork node */
	sym_node_t*	sym_node,	/* in: procedure id node in the symbol
					table */
	sym_node_t*	param_list,	/* in: parameter declaration list */
	que_node_t*	stat_list)	/* in: statement list */
{
	proc_node_t*	node;
	que_fork_t*	fork;
	que_thr_t*	thr;
	mem_heap_t*	heap;

	heap = pars_sym_tab_global->heap;

	fork = que_fork_create(NULL, NULL, QUE_FORK_PROCEDURE, heap);
	fork->trx = NULL;

	thr = que_thr_create(fork, heap);

	node = mem_heap_alloc(heap, sizeof(proc_node_t));

	node->common.type = QUE_NODE_PROC;
	node->common.parent = thr;

	sym_node->token_type = SYM_PROCEDURE_NAME;
	sym_node->resolved = TRUE;
	
	node->proc_id = sym_node;
	node->param_list = param_list;
	node->stat_list = stat_list;

	pars_set_parent_in_list(stat_list, node);

	node->sym_tab = pars_sym_tab_global;

	thr->child = node;

 	pars_sym_tab_global->query_graph = fork;

	return(fork);
}

/*****************************************************************
Parses a stored procedure call, when this is not within another stored
procedure, that is, the client issues a procedure call directly.
In MySQL/InnoDB, stored InnoDB procedures are invoked via the
parsed procedure tree, not via InnoDB SQL, so this function is not used. */

que_fork_t*
pars_stored_procedure_call(
/*=======================*/
					/* out: query graph */
	sym_node_t*	sym_node __attribute__((unused)))
					/* in: stored procedure name */
{
	ut_error;
	return(NULL);
}

/*****************************************************************
Retrieves characters to the lexical analyzer. */

void
pars_get_lex_chars(
/*===============*/
	char*	buf,		/* in/out: buffer where to copy */
	int*	result,		/* out: number of characters copied or EOF */
	int	max_size)	/* in: maximum number of characters which fit
				in the buffer */
{
	int	len;
	
	len = pars_sym_tab_global->string_len
				- pars_sym_tab_global->next_char_pos;
	if (len == 0) {
#ifdef YYDEBUG
		/* fputs("SQL string ends\n", stderr); */
#endif	
		*result = 0;

		return;
	}

	if (len > max_size) {
		len = max_size;
	}

#ifdef UNIV_SQL_DEBUG
	if (pars_print_lexed) {
		
		if (len >= 5) {
			len = 5;
		}

		fwrite(pars_sym_tab_global->sql_string +
			pars_sym_tab_global->next_char_pos,
			1, len, stderr);
	}
#endif /* UNIV_SQL_DEBUG */
	
	ut_memcpy(buf, pars_sym_tab_global->sql_string +
				pars_sym_tab_global->next_char_pos, len);
	*result = len;

	pars_sym_tab_global->next_char_pos += len;
}

/*****************************************************************
Called by yyparse on error. */

void
yyerror(
/*====*/
	const char*	s __attribute__((unused)))
				/* in: error message string */
{
	ut_ad(s);

	fputs("PARSER ERROR: Syntax error in SQL string\n", stderr);

	ut_error;
}

/*****************************************************************
Parses an SQL string returning the query graph. */

que_t*
pars_sql(
/*=====*/
				/* out, own: the query graph */
	const char*	str)	/* in: SQL string */
{
	sym_node_t*	sym_node;
	mem_heap_t*	heap;
	que_t*		graph;

	ut_ad(str);

	heap = mem_heap_create(256);

#ifdef UNIV_SYNC_DEBUG
	/* Currently, the parser is not reentrant: */
	ut_ad(mutex_own(&(dict_sys->mutex)));
#endif /* UNIV_SYNC_DEBUG */
	pars_sym_tab_global = sym_tab_create(heap);

	pars_sym_tab_global->sql_string = mem_heap_strdup(heap, str);
	pars_sym_tab_global->string_len = strlen(str);
	pars_sym_tab_global->next_char_pos = 0;
	
	yyparse();

	sym_node = UT_LIST_GET_FIRST(pars_sym_tab_global->sym_list);

	while (sym_node) {
		ut_a(sym_node->resolved);

		sym_node = UT_LIST_GET_NEXT(sym_list, sym_node);
	}

	graph = pars_sym_tab_global->query_graph;

	graph->sym_tab = pars_sym_tab_global;

	/* fprintf(stderr, "SQL graph size %lu\n", mem_heap_get_size(heap)); */

	return(graph);
}

/**********************************************************************
Completes a query graph by adding query thread and fork nodes
above it and prepares the graph for running. The fork created is of
type QUE_FORK_MYSQL_INTERFACE. */

que_thr_t*
pars_complete_graph_for_exec(
/*=========================*/
				/* out: query thread node to run */
	que_node_t*	node,	/* in: root node for an incomplete
				query graph */
	trx_t*		trx,	/* in: transaction handle */
	mem_heap_t*	heap)	/* in: memory heap from which allocated */
{
	que_fork_t*	fork;
	que_thr_t*	thr;
	
	fork = que_fork_create(NULL, NULL, QUE_FORK_MYSQL_INTERFACE, heap);
	fork->trx = trx;

	thr = que_thr_create(fork, heap);

	thr->child = node;

	que_node_set_parent(node, thr);

	trx->graph = NULL;
	
	return(thr);
}