mariadb/include/row0sel.h

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

Copyright (c) 1997, 2009, Innobase Oy. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA

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

/**************************************************//**
@file include/row0sel.h
Select

Created 12/19/1997 Heikki Tuuri
*******************************************************/

#ifndef row0sel_h
#define row0sel_h

#include "univ.i"
#include "data0data.h"
#include "que0types.h"
#include "dict0types.h"
#include "trx0types.h"
#include "row0types.h"
#include "que0types.h"
#include "pars0sym.h"
#include "btr0pcur.h"
#include "read0read.h"
#include "row0mysql.h"

/*********************************************************************//**
Creates a select node struct.
@return	own: select node struct */
UNIV_INTERN
sel_node_t*
sel_node_create(
/*============*/
	mem_heap_t*	heap);	/*!< in: memory heap where created */
/*********************************************************************//**
Frees the memory private to a select node when a query graph is freed,
does not free the heap where the node was originally created. */
UNIV_INTERN
void
sel_node_free_private(
/*==================*/
	sel_node_t*	node);	/*!< in: select node struct */
/*********************************************************************//**
Frees a prefetch buffer for a column, including the dynamically allocated
memory for data stored there. */
UNIV_INTERN
void
sel_col_prefetch_buf_free(
/*======================*/
	sel_buf_t*	prefetch_buf);	/*!< in, own: prefetch buffer */
/*********************************************************************//**
Gets the plan node for the nth table in a join.
@return	plan node */
UNIV_INLINE
plan_t*
sel_node_get_nth_plan(
/*==================*/
	sel_node_t*	node,	/*!< in: select node */
	ulint		i);	/*!< in: get ith plan node */
/**********************************************************************//**
Performs a select step. This is a high-level function used in SQL execution
graphs.
@return	query thread to run next or NULL */
UNIV_INTERN
que_thr_t*
row_sel_step(
/*=========*/
	que_thr_t*	thr);	/*!< in: query thread */
/**********************************************************************//**
Performs an execution step of an open or close cursor statement node.
@return	query thread to run next or NULL */
UNIV_INLINE
que_thr_t*
open_step(
/*======*/
	que_thr_t*	thr);	/*!< in: query thread */
/**********************************************************************//**
Performs a fetch for a cursor.
@return	query thread to run next or NULL */
UNIV_INTERN
que_thr_t*
fetch_step(
/*=======*/
	que_thr_t*	thr);	/*!< in: query thread */
/****************************************************************//**
Sample callback function for fetch that prints each row.
@return	always returns non-NULL */
UNIV_INTERN
void*
row_fetch_print(
/*============*/
	void*	row,		/*!< in:  sel_node_t* */
	void*	user_arg);	/*!< in:  not used */
/***********************************************************//**
Prints a row in a select result.
@return	query thread to run next or NULL */
UNIV_INTERN
que_thr_t*
row_printf_step(
/*============*/
	que_thr_t*	thr);	/*!< in: query thread */
/****************************************************************//**
Converts a key value stored in MySQL format to an Innobase dtuple. The last
field of the key value may be just a prefix of a fixed length field: hence
the parameter key_len. But currently we do not allow search keys where the
last field is only a prefix of the full key field len and print a warning if
such appears. */
UNIV_INTERN
void
row_sel_convert_mysql_key_to_innobase(
/*==================================*/
	dtuple_t*	tuple,		/*!< in/out: tuple where to build;
					NOTE: we assume that the type info
					in the tuple is already according
					to index! */
	byte*		buf,		/*!< in: buffer to use in field
					conversions */
	ulint		buf_len,	/*!< in: buffer length */
	dict_index_t*	index,		/*!< in: index of the key value */
	const byte*	key_ptr,	/*!< in: MySQL key value */
	ulint		key_len,	/*!< in: MySQL key value length */
	trx_t*		trx);		/*!< in: transaction */
/********************************************************************//**
Searches for rows in the database. This is used in the interface to
MySQL. This function opens a cursor, and also implements fetch next
and fetch prev. NOTE that if we do a search with a full key value
from a unique index (ROW_SEL_EXACT), then we will not store the cursor
position and fetch next or fetch prev must not be tried to the cursor!
@return DB_SUCCESS, DB_RECORD_NOT_FOUND, DB_END_OF_INDEX, DB_DEADLOCK,
DB_LOCK_TABLE_FULL, or DB_TOO_BIG_RECORD */
UNIV_INTERN
ulint
row_search_for_mysql(
/*=================*/
	byte*		buf,		/*!< in/out: buffer for the fetched
					row in the MySQL format */
	ulint		mode,		/*!< in: search mode PAGE_CUR_L, ... */
	row_prebuilt_t*	prebuilt,	/*!< in: prebuilt struct for the
					table handle; this contains the info
					of search_tuple, index; if search
					tuple contains 0 fields then we
					position the cursor at the start or
					the end of the index, depending on
					'mode' */
	ulint		match_mode,	/*!< in: 0 or ROW_SEL_EXACT or
					ROW_SEL_EXACT_PREFIX */
	ulint		direction);	/*!< in: 0 or ROW_SEL_NEXT or
					ROW_SEL_PREV; NOTE: if this is != 0,
					then prebuilt must have a pcur
					with stored position! In opening of a
					cursor 'direction' should be 0. */
/*******************************************************************//**
Checks if MySQL at the moment is allowed for this table to retrieve a
consistent read result, or store it to the query cache.
@return	TRUE if storing or retrieving from the query cache is permitted */
UNIV_INTERN
ibool
row_search_check_if_query_cache_permitted(
/*======================================*/
	trx_t*		trx,		/*!< in: transaction object */
	const char*	norm_name);	/*!< in: concatenation of database name,
					'/' char, table name */
/*******************************************************************//**
Read the max AUTOINC value from an index.
@return	DB_SUCCESS if all OK else error code */
UNIV_INTERN
ulint
row_search_max_autoinc(
/*===================*/
	dict_index_t*	index,		/*!< in: index to search */
	const char*	col_name,	/*!< in: autoinc column name */
	ib_uint64_t*	value);		/*!< out: AUTOINC value read */

/** A structure for caching column values for prefetched rows */
struct sel_buf_struct{
	byte*		data;	/*!< data, or NULL; if not NULL, this field
				has allocated memory which must be explicitly
				freed; can be != NULL even when len is
				UNIV_SQL_NULL */
	ulint		len;	/*!< data length or UNIV_SQL_NULL */
	ulint		val_buf_size;
				/*!< size of memory buffer allocated for data:
				this can be more than len; this is defined
				when data != NULL */
};

/** Query plan */
struct plan_struct{
	dict_table_t*	table;		/*!< table struct in the dictionary
					cache */
	dict_index_t*	index;		/*!< table index used in the search */
	btr_pcur_t	pcur;		/*!< persistent cursor used to search
					the index */
	ibool		asc;		/*!< TRUE if cursor traveling upwards */
	ibool		pcur_is_open;	/*!< TRUE if pcur has been positioned
					and we can try to fetch new rows */
	ibool		cursor_at_end;	/*!< TRUE if the cursor is open but
					we know that there are no more
					qualifying rows left to retrieve from
					the index tree; NOTE though, that
					there may still be unprocessed rows in
					the prefetch stack; always FALSE when
					pcur_is_open is FALSE */
	ibool		stored_cursor_rec_processed;
					/*!< TRUE if the pcur position has been
					stored and the record it is positioned
					on has already been processed */
	que_node_t**	tuple_exps;	/*!< array of expressions
					which are used to calculate
					the field values in the search
					tuple: there is one expression
					for each field in the search
					tuple */
	dtuple_t*	tuple;		/*!< search tuple */
	ulint		mode;		/*!< search mode: PAGE_CUR_G, ... */
	ulint		n_exact_match;	/*!< number of first fields in
					the search tuple which must be
					exactly matched */
	ibool		unique_search;	/*!< TRUE if we are searching an
					index record with a unique key */
	ulint		n_rows_fetched;	/*!< number of rows fetched using pcur
					after it was opened */
	ulint		n_rows_prefetched;/*!< number of prefetched rows cached
					for fetch: fetching several rows in
					the same mtr saves CPU time */
	ulint		first_prefetched;/*!< index of the first cached row in
					select buffer arrays for each column */
	ibool		no_prefetch;	/*!< no prefetch for this table */
	sym_node_list_t	columns;	/*!< symbol table nodes for the columns
					to retrieve from the table */
	UT_LIST_BASE_NODE_T(func_node_t)
			end_conds;	/*!< conditions which determine the
					fetch limit of the index segment we
					have to look at: when one of these
					fails, the result set has been
					exhausted for the cursor in this
					index; these conditions are normalized
					so that in a comparison the column
					for this table is the first argument */
	UT_LIST_BASE_NODE_T(func_node_t)
			other_conds;	/*!< the rest of search conditions we can
					test at this table in a join */
	ibool		must_get_clust;	/*!< TRUE if index is a non-clustered
					index and we must also fetch the
					clustered index record; this is the
					case if the non-clustered record does
					not contain all the needed columns, or
					if this is a single-table explicit
					cursor, or a searched update or
					delete */
	ulint*		clust_map;	/*!< map telling how clust_ref is built
					from the fields of a non-clustered
					record */
	dtuple_t*	clust_ref;	/*!< the reference to the clustered
					index entry is built here if index is
					a non-clustered index */
	btr_pcur_t	clust_pcur;	/*!< if index is non-clustered, we use
					this pcur to search the clustered
					index */
	mem_heap_t*	old_vers_heap;	/*!< memory heap used in building an old
					version of a row, or NULL */
};

/** Select node states */
enum sel_node_state {
	SEL_NODE_CLOSED,	/*!< it is a declared cursor which is not
				currently open */
	SEL_NODE_OPEN,		/*!< intention locks not yet set on tables */
	SEL_NODE_FETCH,		/*!< intention locks have been set */
	SEL_NODE_NO_MORE_ROWS	/*!< cursor has reached the result set end */
};

/** Select statement node */
struct sel_node_struct{
	que_common_t	common;		/*!< node type: QUE_NODE_SELECT */
	enum sel_node_state
			state;	/*!< node state */
	que_node_t*	select_list;	/*!< select list */
	sym_node_t*	into_list;	/*!< variables list or NULL */
	sym_node_t*	table_list;	/*!< table list */
	ibool		asc;		/*!< TRUE if the rows should be fetched
					in an ascending order */
	ibool		set_x_locks;	/*!< TRUE if the cursor is for update or
					delete, which means that a row x-lock
					should be placed on the cursor row */
	ulint		row_lock_mode;	/*!< LOCK_X or LOCK_S */
	ulint		n_tables;	/*!< number of tables */
	ulint		fetch_table;	/*!< number of the next table to access
					in the join */
	plan_t*		plans;		/*!< array of n_tables many plan nodes
					containing the search plan and the
					search data structures */
	que_node_t*	search_cond;	/*!< search condition */
	read_view_t*	read_view;	/*!< if the query is a non-locking
					consistent read, its read view is
					placed here, otherwise NULL */
	ibool		consistent_read;/*!< TRUE if the select is a consistent,
					non-locking read */
	order_node_t*	order_by;	/*!< order by column definition, or
					NULL */
	ibool		is_aggregate;	/*!< TRUE if the select list consists of
					aggregate functions */
	ibool		aggregate_already_fetched;
					/*!< TRUE if the aggregate row has
					already been fetched for the current
					cursor */
	ibool		can_get_updated;/*!< this is TRUE if the select
					is in a single-table explicit
					cursor which can get updated
					within the stored procedure,
					or in a searched update or
					delete; NOTE that to determine
					of an explicit cursor if it
					can get updated, the parser
					checks from a stored procedure
					if it contains positioned
					update or delete statements */
	sym_node_t*	explicit_cursor;/*!< not NULL if an explicit cursor */
	UT_LIST_BASE_NODE_T(sym_node_t)
			copy_variables; /*!< variables whose values we have to
					copy when an explicit cursor is opened,
					so that they do not change between
					fetches */
};

/** Fetch statement node */
struct fetch_node_struct{
	que_common_t	common;		/*!< type: QUE_NODE_FETCH */
	sel_node_t*	cursor_def;	/*!< cursor definition */
	sym_node_t*	into_list;	/*!< variables to set */

	pars_user_func_t*
			func;		/*!< User callback function or NULL.
					The first argument to the function
					is a sel_node_t*, containing the
					results of the SELECT operation for
					one row. If the function returns
					NULL, it is not interested in
					further rows and the cursor is
					modified so (cursor % NOTFOUND) is
					true. If it returns not-NULL,
					continue normally. See
					row_fetch_print() for an example
					(and a useful debugging tool). */
};

/** Open or close cursor operation type */
enum open_node_op {
	ROW_SEL_OPEN_CURSOR,	/*!< open cursor */
	ROW_SEL_CLOSE_CURSOR	/*!< close cursor */
};

/** Open or close cursor statement node */
struct open_node_struct{
	que_common_t	common;		/*!< type: QUE_NODE_OPEN */
	enum open_node_op
			op_type;	/*!< operation type: open or
					close cursor */
	sel_node_t*	cursor_def;	/*!< cursor definition */
};

/** Row printf statement node */
struct row_printf_node_struct{
	que_common_t	common;		/*!< type: QUE_NODE_ROW_PRINTF */
	sel_node_t*	sel_node;	/*!< select */
};

/** Search direction for the MySQL interface */
enum row_sel_direction {
	ROW_SEL_NEXT = 1,	/*!< ascending direction */
	ROW_SEL_PREV = 2	/*!< descending direction */
};

/** Match mode for the MySQL interface */
enum row_sel_match_mode {
	ROW_SEL_EXACT = 1,	/*!< search using a complete key value */
	ROW_SEL_EXACT_PREFIX	/*!< search using a key prefix which
				must match rows: the prefix may
				contain an incomplete field (the last
				field in prefix may be just a prefix
				of a fixed length column) */
};

#ifndef UNIV_NONINL
#include "row0sel.ic"
#endif

#endif