mariadb/storage/innobase/rem/rem0cmp.cc

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

Copyright (c) 1994, 2011, Oracle and/or its affiliates. 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.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA

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

/*******************************************************************//**
@file rem/rem0cmp.cc
Comparison services for records

Created 7/1/1994 Heikki Tuuri
************************************************************************/

#include "rem0cmp.h"

#ifdef UNIV_NONINL
#include "rem0cmp.ic"
#endif

#include "ha_prototypes.h"
#include "srv0srv.h"

/*		ALPHABETICAL ORDER
		==================

The records are put into alphabetical order in the following
way: let F be the first field where two records disagree.
If there is a character in some position n where the
records disagree, the order is determined by comparison of
the characters at position n, possibly after
collating transformation. If there is no such character,
but the corresponding fields have different lengths, then
if the data type of the fields is paddable,
shorter field is padded with a padding character. If the
data type is not paddable, longer field is considered greater.
Finally, the SQL null is bigger than any other value.

At the present, the comparison functions return 0 in the case,
where two records disagree only in the way that one
has more fields than the other. */

#ifdef UNIV_DEBUG
/*************************************************************//**
Used in debug checking of cmp_dtuple_... .
This function is used to compare a data tuple to a physical record. If
dtuple has n fields then rec must have either m >= n fields, or it must
differ from dtuple in some of the m fields rec has.
@return 1, 0, -1, if dtuple is greater, equal, less than rec,
respectively, when only the common first fields are compared */
static
int
cmp_debug_dtuple_rec_with_match(
/*============================*/
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	const rec_t*	rec,	/*!< in: physical record which differs from
				dtuple in some of the common fields, or which
				has an equal number or more fields than
				dtuple */
	const ulint*	offsets,/*!< in: array returned by rec_get_offsets() */
	ulint*		matched_fields);/*!< in/out: number of already
				completely  matched fields; when function
				returns, contains the value for current
				comparison */
#endif /* UNIV_DEBUG */
/*************************************************************//**
This function is used to compare two data fields for which the data type
is such that we must use MySQL code to compare them. The prototype here
must be a copy of the one in ha_innobase.cc!
@return	1, 0, -1, if a is greater, equal, less than b, respectively */
extern
int
innobase_mysql_cmp(
/*===============*/
	int		mysql_type,	/*!< in: MySQL type */
	uint		charset_number,	/*!< in: number of the charset */
	const unsigned char* a,		/*!< in: data field */
	unsigned int	a_length,	/*!< in: data field length,
					not UNIV_SQL_NULL */
	const unsigned char* b,		/*!< in: data field */
	unsigned int	b_length);	/*!< in: data field length,
					not UNIV_SQL_NULL */
/*************************************************************//**
This function is used to compare two data fields for which the data type
is such that we must use MySQL code to compare them. The prototype here
must be a copy of the one in ha_innobase.cc!
@return	1, 0, -1, if a is greater, equal, less than b, respectively */
extern
int
innobase_mysql_cmp_prefix(
/*======================*/
	int		mysql_type,	/*!< in: MySQL type */
	uint		charset_number,	/*!< in: number of the charset */
	const unsigned char* a,		/*!< in: data field */
	unsigned int	a_length,	/*!< in: data field length,
					not UNIV_SQL_NULL */
	const unsigned char* b,		/*!< in: data field */
	unsigned int	b_length);	/*!< in: data field length,
					not UNIV_SQL_NULL */
/*********************************************************************//**
Transforms the character code so that it is ordered appropriately for the
language. This is only used for the latin1 char set. MySQL does the
comparisons for other char sets.
@return	collation order position */
UNIV_INLINE
ulint
cmp_collate(
/*========*/
	ulint	code)	/*!< in: code of a character stored in database record */
{
	return((ulint) srv_latin1_ordering[code]);
}

/*************************************************************//**
Returns TRUE if two columns are equal for comparison purposes.
@return	TRUE if the columns are considered equal in comparisons */
UNIV_INTERN
ibool
cmp_cols_are_equal(
/*===============*/
	const dict_col_t*	col1,	/*!< in: column 1 */
	const dict_col_t*	col2,	/*!< in: column 2 */
	ibool			check_charsets)
					/*!< in: whether to check charsets */
{
	if (dtype_is_non_binary_string_type(col1->mtype, col1->prtype)
	    && dtype_is_non_binary_string_type(col2->mtype, col2->prtype)) {

		/* Both are non-binary string types: they can be compared if
		and only if the charset-collation is the same */

		if (check_charsets) {
			return(dtype_get_charset_coll(col1->prtype)
			       == dtype_get_charset_coll(col2->prtype));
		} else {
			return(TRUE);
		}
	}

	if (dtype_is_binary_string_type(col1->mtype, col1->prtype)
	    && dtype_is_binary_string_type(col2->mtype, col2->prtype)) {

		/* Both are binary string types: they can be compared */

		return(TRUE);
	}

	if (col1->mtype != col2->mtype) {

		return(FALSE);
	}

	if (col1->mtype == DATA_INT
	    && (col1->prtype & DATA_UNSIGNED)
	    != (col2->prtype & DATA_UNSIGNED)) {

		/* The storage format of an unsigned integer is different
		from a signed integer: in a signed integer we OR
		0x8000... to the value of positive integers. */

		return(FALSE);
	}

	return(col1->mtype != DATA_INT || col1->len == col2->len);
}

/*************************************************************//**
Innobase uses this function to compare two data fields for which the data type
is such that we must compare whole fields or call MySQL to do the comparison
@return	1, 0, -1, if a is greater, equal, less than b, respectively */
static
int
cmp_whole_field(
/*============*/
	ulint		mtype,		/*!< in: main type */
	ulint		prtype,		/*!< in: precise type */
	const byte*	a,		/*!< in: data field */
	unsigned int	a_length,	/*!< in: data field length,
					not UNIV_SQL_NULL */
	const byte*	b,		/*!< in: data field */
	unsigned int	b_length)	/*!< in: data field length,
					not UNIV_SQL_NULL */
{
	float		f_1;
	float		f_2;
	double		d_1;
	double		d_2;
	int		swap_flag	= 1;

	switch (mtype) {

	case DATA_DECIMAL:
		/* Remove preceding spaces */
		for (; a_length && *a == ' '; a++, a_length--) { }
		for (; b_length && *b == ' '; b++, b_length--) { }

		if (*a == '-') {
			if (*b != '-') {
				return(-1);
			}

			a++; b++;
			a_length--;
			b_length--;

			swap_flag = -1;

		} else if (*b == '-') {

			return(1);
		}

		while (a_length > 0 && (*a == '+' || *a == '0')) {
			a++; a_length--;
		}

		while (b_length > 0 && (*b == '+' || *b == '0')) {
			b++; b_length--;
		}

		if (a_length != b_length) {
			if (a_length < b_length) {
				return(-swap_flag);
			}

			return(swap_flag);
		}

		while (a_length > 0 && *a == *b) {

			a++; b++; a_length--;
		}

		if (a_length == 0) {

			return(0);
		}

		if (*a > *b) {
			return(swap_flag);
		}

		return(-swap_flag);
	case DATA_DOUBLE:
		d_1 = mach_double_read(a);
		d_2 = mach_double_read(b);

		if (d_1 > d_2) {
			return(1);
		} else if (d_2 > d_1) {
			return(-1);
		}

		return(0);

	case DATA_FLOAT:
		f_1 = mach_float_read(a);
		f_2 = mach_float_read(b);

		if (f_1 > f_2) {
			return(1);
		} else if (f_2 > f_1) {
			return(-1);
		}

		return(0);
	case DATA_BLOB:
		if (prtype & DATA_BINARY_TYPE) {

			ut_print_timestamp(stderr);
			fprintf(stderr,
				"  InnoDB: Error: comparing a binary BLOB"
				" with a character set sensitive\n"
				"InnoDB: comparison!\n");
		}
		/* fall through */
	case DATA_VARMYSQL:
	case DATA_MYSQL:
		return(innobase_mysql_cmp(
			       (int)(prtype & DATA_MYSQL_TYPE_MASK),
			       (uint) dtype_get_charset_coll(prtype),
			       a, a_length, b, b_length));
	default:
		fprintf(stderr,
			"InnoDB: unknown type number %lu\n",
			(ulong) mtype);
		ut_error;
	}

	return(0);
}

/*****************************************************************
This function is used to compare two dfields where at least the first
has its data type field set. */
UNIV_INTERN
int
cmp_dfield_dfield_like_prefix(
/*==========================*/
				/* out: 1, 0, -1, if dfield1 is greater, equal,
				less than dfield2, respectively */
	dfield_t*	dfield1,/* in: data field; must have type field set */
	dfield_t*	dfield2)/* in: data field */
{
	const dtype_t*  type;
	ulint           ret;

	ut_ad(dfield_check_typed(dfield1));

	type = dfield_get_type(dfield1);

	if (type->mtype >= DATA_FLOAT) {
		ret = innobase_mysql_cmp_prefix(
			(int)(type->prtype & DATA_MYSQL_TYPE_MASK),
			(uint) dtype_get_charset_coll(type->prtype),
			static_cast<byte*>(dfield_get_data(dfield1)),
			dfield_get_len(dfield1),
                        static_cast<byte*>(dfield_get_data(dfield2)),
                        dfield_get_len(dfield2));
        } else {
                ret = (cmp_data_data_like_prefix(
                        static_cast<byte*>(dfield_get_data(dfield1)),
                        dfield_get_len(dfield1),
                        static_cast<byte*>(dfield_get_data(dfield2)),
                        dfield_get_len(dfield2)));
        }

        return(ret);
}

/*************************************************************//**
This function is used to compare two data fields for which we know the
data type.
@return	1, 0, -1, if data1 is greater, equal, less than data2, respectively */
UNIV_INTERN
int
cmp_data_data_slow(
/*===============*/
	ulint		mtype,	/*!< in: main type */
	ulint		prtype,	/*!< in: precise type */
	const byte*	data1,	/*!< in: data field (== a pointer to a memory
				buffer) */
	ulint		len1,	/*!< in: data field length or UNIV_SQL_NULL */
	const byte*	data2,	/*!< in: data field (== a pointer to a memory
				buffer) */
	ulint		len2)	/*!< in: data field length or UNIV_SQL_NULL */
{
	ulint	data1_byte;
	ulint	data2_byte;
	ulint	cur_bytes;

	if (len1 == UNIV_SQL_NULL || len2 == UNIV_SQL_NULL) {

		if (len1 == len2) {

			return(0);
		}

		if (len1 == UNIV_SQL_NULL) {
			/* We define the SQL null to be the smallest possible
			value of a field in the alphabetical order */

			return(-1);
		}

		return(1);
	}

	if (mtype >= DATA_FLOAT
	    || (mtype == DATA_BLOB
		&& 0 == (prtype & DATA_BINARY_TYPE)
		&& dtype_get_charset_coll(prtype)
		!= DATA_MYSQL_LATIN1_SWEDISH_CHARSET_COLL)) {

		return(cmp_whole_field(mtype, prtype,
				       data1, (unsigned) len1,
				       data2, (unsigned) len2));
	}

	/* Compare then the fields */

	cur_bytes = 0;

	for (;;) {
		if (len1 <= cur_bytes) {
			if (len2 <= cur_bytes) {

				return(0);
			}

			data1_byte = dtype_get_pad_char(mtype, prtype);

			if (data1_byte == ULINT_UNDEFINED) {

				return(-1);
			}
		} else {
			data1_byte = *data1;
		}

		if (len2 <= cur_bytes) {
			data2_byte = dtype_get_pad_char(mtype, prtype);

			if (data2_byte == ULINT_UNDEFINED) {

				return(1);
			}
		} else {
			data2_byte = *data2;
		}

		if (data1_byte == data2_byte) {
			/* If the bytes are equal, they will remain such even
			after the collation transformation below */

			goto next_byte;
		}

		if (mtype <= DATA_CHAR
		    || (mtype == DATA_BLOB
			&& 0 == (prtype & DATA_BINARY_TYPE))) {

			data1_byte = cmp_collate(data1_byte);
			data2_byte = cmp_collate(data2_byte);
		}

		if (data1_byte > data2_byte) {

			return(1);
		} else if (data1_byte < data2_byte) {

			return(-1);
		}
next_byte:
		/* Next byte */
		cur_bytes++;
		data1++;
		data2++;
	}

	return(0);		/* Not reached */
}

/*****************************************************************
This function is used to compare two data fields for which we know the
data type to be VARCHAR */

int
cmp_data_data_slow_varchar(
/*=======================*/
				/* out: 1, 0, -1, if lhs is greater, equal,
				less than rhs, respectively */
	const byte*	lhs,	/* in: data field (== a pointer to a memory
				buffer) */
	ulint		lhs_len,/* in: data field length or UNIV_SQL_NULL */
	const byte*	rhs,	/* in: data field (== a pointer to a memory
				buffer) */
	ulint		rhs_len)/* in: data field length or UNIV_SQL_NULL */
{
	ulint	i;

	ut_a(rhs_len != UNIV_SQL_NULL);

	if (lhs_len == UNIV_SQL_NULL) {

		/* We define the SQL null to be the smallest possible
		value of a field in the alphabetical order */

		return(-1);
	}

	/* Compare the values.*/

	for (i = 0; i < lhs_len && i < rhs_len; ++i, ++rhs, ++lhs) {
		ulint	lhs_byte = *lhs;
		ulint	rhs_byte = *rhs;

		if (lhs_byte != rhs_byte) {
			/* If the bytes are equal, they will remain such even
			after the collation transformation below */

			lhs_byte = cmp_collate(lhs_byte);
			rhs_byte = cmp_collate(rhs_byte);

			if (lhs_byte > rhs_byte) {

				return(1);
			} else if (lhs_byte < rhs_byte) {

				return(-1);
			}
		}
	}

	return(i == lhs_len && i == rhs_len) ? 0 : rhs_len - lhs_len;
}

/*****************************************************************
This function is used to compare two data fields for which we know the
data type. The comparison is done for the LIKE operator.*/

int
cmp_data_data_slow_like_prefix(
/*===========================*/
				/* out: 1, 0, -1, if lhs is greater, equal,
				less than rhs, respectively */
	const byte*	lhs,	/* in: data field (== a pointer to a memory
				buffer) */
	ulint		len1,	/* in: data field length or UNIV_SQL_NULL */
	const byte*	rhs,	/* in: data field (== a pointer to a memory
				buffer) */
	ulint		len2)	/* in: data field length or UNIV_SQL_NULL */
{
	ulint	i;

	ut_a(len2 != UNIV_SQL_NULL);

	if (len1 == UNIV_SQL_NULL) {

		/* We define the SQL null to be the smallest possible
		value of a field in the alphabetical order */

		return(-1);
	}

	/* Compare the values.*/

	for (i = 0; i < len1 && i < len2; ++i, ++rhs, ++lhs) {
		ulint	lhs_byte = *lhs;
		ulint	rhs_byte = *rhs;

		if (lhs_byte != rhs_byte) {
			/* If the bytes are equal, they will remain such even
			after the collation transformation below */

			lhs_byte = cmp_collate(lhs_byte);
			rhs_byte = cmp_collate(rhs_byte);

			if (lhs_byte > rhs_byte) {

				return(1);
			} else if (lhs_byte < rhs_byte) {

				return(-1);
			}
		}
	}

	return(i == len2 ? 0 : 1);
}

/*****************************************************************
This function is used to compare two data fields for which we know the
data type. The comparison is done for the LIKE operator.*/

int
cmp_data_data_slow_like_suffix(
/*===========================*/
				/* out: 1, 0, -1, if data1 is greater, equal,
				less than data2, respectively */
				/* in: data field (== a pointer to a
				memory buffer) */
	const byte*	data1 UNIV_UNUSED,
				/* in: data field length or UNIV_SQL_NULL */
	ulint		len1 UNIV_UNUSED,
				/* in: data field (== a pointer to a memory
				buffer) */
	const byte*	data2 UNIV_UNUSED,
				/* in: data field length or UNIV_SQL_NULL */
	ulint		len2 UNIV_UNUSED)

{
	ut_error;	// FIXME:
	return(1);
}

/*****************************************************************
This function is used to compare two data fields for which we know the
data type. The comparison is done for the LIKE operator.*/

int
cmp_data_data_slow_like_substr(
/*===========================*/
				/* out: 1, 0, -1, if data1 is greater, equal,
				less than data2, respectively */
				/* in: data field (== a pointer to a
				memory buffer) */
	const byte*	data1 UNIV_UNUSED,
				/* in: data field length or UNIV_SQL_NULL */
	ulint		len1 UNIV_UNUSED,
				/* in: data field (== a pointer to a memory
				buffer) */
	const byte*	data2 UNIV_UNUSED,
				/* in: data field length or UNIV_SQL_NULL */
	ulint		len2 UNIV_UNUSED)
{
	ut_error;	// FIXME:
	return(1);
}
/*************************************************************//**
This function is used to compare a data tuple to a physical record.
Only dtuple->n_fields_cmp first fields are taken into account for
the data tuple! If we denote by n = n_fields_cmp, then rec must
have either m >= n fields, or it must differ from dtuple in some of
the m fields rec has. If rec has an externally stored field we do not
compare it but return with value 0 if such a comparison should be
made.
@return 1, 0, -1, if dtuple is greater, equal, less than rec,
respectively, when only the common first fields are compared, or until
the first externally stored field in rec */
UNIV_INTERN
int
cmp_dtuple_rec_with_match(
/*======================*/
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	const rec_t*	rec,	/*!< in: physical record which differs from
				dtuple in some of the common fields, or which
				has an equal number or more fields than
				dtuple */
	const ulint*	offsets,/*!< in: array returned by rec_get_offsets() */
	ulint*		matched_fields, /*!< in/out: number of already completely
				matched fields; when function returns,
				contains the value for current comparison */
	ulint*		matched_bytes) /*!< in/out: number of already matched
				bytes within the first field not completely
				matched; when function returns, contains the
				value for current comparison */
{
	const dfield_t*	dtuple_field;	/* current field in logical record */
	ulint		dtuple_f_len;	/* the length of the current field
					in the logical record */
	const byte*	dtuple_b_ptr;	/* pointer to the current byte in
					logical field data */
	ulint		dtuple_byte;	/* value of current byte to be compared
					in dtuple*/
	ulint		rec_f_len;	/* length of current field in rec */
	const byte*	rec_b_ptr;	/* pointer to the current byte in
					rec field */
	ulint		rec_byte;	/* value of current byte to be
					compared in rec */
	ulint		cur_field;	/* current field number */
	ulint		cur_bytes;	/* number of already matched bytes
					in current field */
	int		ret = 3333;	/* return value */

	ut_ad(dtuple && rec && matched_fields && matched_bytes);
	ut_ad(dtuple_check_typed(dtuple));
	ut_ad(rec_offs_validate(rec, NULL, offsets));

	cur_field = *matched_fields;
	cur_bytes = *matched_bytes;

	ut_ad(cur_field <= dtuple_get_n_fields_cmp(dtuple));
	ut_ad(cur_field <= rec_offs_n_fields(offsets));

	if (cur_bytes == 0 && cur_field == 0) {
		ulint	rec_info = rec_get_info_bits(rec,
						     rec_offs_comp(offsets));
		ulint	tup_info = dtuple_get_info_bits(dtuple);

		if (UNIV_UNLIKELY(rec_info & REC_INFO_MIN_REC_FLAG)) {
			ret = !(tup_info & REC_INFO_MIN_REC_FLAG);
			goto order_resolved;
		} else if (UNIV_UNLIKELY(tup_info & REC_INFO_MIN_REC_FLAG)) {
			ret = -1;
			goto order_resolved;
		}
	}

	/* Match fields in a loop; stop if we run out of fields in dtuple
	or find an externally stored field */

	while (cur_field < dtuple_get_n_fields_cmp(dtuple)) {

		ulint	mtype;
		ulint	prtype;

		dtuple_field = dtuple_get_nth_field(dtuple, cur_field);
		{
			const dtype_t*	type
				= dfield_get_type(dtuple_field);

			mtype = type->mtype;
			prtype = type->prtype;
		}

		dtuple_f_len = dfield_get_len(dtuple_field);

		rec_b_ptr = rec_get_nth_field(rec, offsets,
					      cur_field, &rec_f_len);

		/* If we have matched yet 0 bytes, it may be that one or
		both the fields are SQL null, or the record or dtuple may be
		the predefined minimum record, or the field is externally
		stored */

		if (UNIV_LIKELY(cur_bytes == 0)) {
			if (rec_offs_nth_extern(offsets, cur_field)) {
				/* We do not compare to an externally
				stored field */

				ret = 0;

				goto order_resolved;
			}

			if (dtuple_f_len == UNIV_SQL_NULL) {
				if (rec_f_len == UNIV_SQL_NULL) {

					goto next_field;
				}

				ret = -1;
				goto order_resolved;
			} else if (rec_f_len == UNIV_SQL_NULL) {
				/* We define the SQL null to be the
				smallest possible value of a field
				in the alphabetical order */

				ret = 1;
				goto order_resolved;
			}
		}

		if (mtype >= DATA_FLOAT
		    || (mtype == DATA_BLOB
			&& 0 == (prtype & DATA_BINARY_TYPE)
			&& dtype_get_charset_coll(prtype)
			!= DATA_MYSQL_LATIN1_SWEDISH_CHARSET_COLL)) {

			ret = cmp_whole_field(
				mtype, prtype,
				static_cast<const byte*>(
					dfield_get_data(dtuple_field)),
				(unsigned) dtuple_f_len,
				rec_b_ptr, (unsigned) rec_f_len);

			if (ret != 0) {
				cur_bytes = 0;

				goto order_resolved;
			} else {
				goto next_field;
			}
		}

		/* Set the pointers at the current byte */

		rec_b_ptr = rec_b_ptr + cur_bytes;
		dtuple_b_ptr = (byte*) dfield_get_data(dtuple_field)
			+ cur_bytes;
		/* Compare then the fields */

		for (;;) {
			if (UNIV_UNLIKELY(rec_f_len <= cur_bytes)) {
				if (dtuple_f_len <= cur_bytes) {

					goto next_field;
				}

				rec_byte = dtype_get_pad_char(mtype, prtype);

				if (rec_byte == ULINT_UNDEFINED) {
					ret = 1;

					goto order_resolved;
				}
			} else {
				rec_byte = *rec_b_ptr;
			}

			if (UNIV_UNLIKELY(dtuple_f_len <= cur_bytes)) {
				dtuple_byte = dtype_get_pad_char(mtype,
								 prtype);

				if (dtuple_byte == ULINT_UNDEFINED) {
					ret = -1;

					goto order_resolved;
				}
			} else {
				dtuple_byte = *dtuple_b_ptr;
			}

			if (dtuple_byte == rec_byte) {
				/* If the bytes are equal, they will
				remain such even after the collation
				transformation below */

				goto next_byte;
			}

			if (mtype <= DATA_CHAR
			    || (mtype == DATA_BLOB
				&& !(prtype & DATA_BINARY_TYPE))) {

				rec_byte = cmp_collate(rec_byte);
				dtuple_byte = cmp_collate(dtuple_byte);
			}

			ret = (int) (dtuple_byte - rec_byte);
			if (UNIV_LIKELY(ret)) {
				if (ret < 0) {
					ret = -1;
					goto order_resolved;
				} else {
					ret = 1;
					goto order_resolved;
				}
			}
next_byte:
			/* Next byte */
			cur_bytes++;
			rec_b_ptr++;
			dtuple_b_ptr++;
		}

next_field:
		cur_field++;
		cur_bytes = 0;
	}

	ut_ad(cur_bytes == 0);

	ret = 0;	/* If we ran out of fields, dtuple was equal to rec
			up to the common fields */
order_resolved:
	ut_ad((ret >= - 1) && (ret <= 1));
	ut_ad(ret == cmp_debug_dtuple_rec_with_match(dtuple, rec, offsets,
						     matched_fields));
	ut_ad(*matched_fields == cur_field); /* In the debug version, the
					     above cmp_debug_... sets
					     *matched_fields to a value */
	*matched_fields = cur_field;
	*matched_bytes = cur_bytes;

	return(ret);
}

/**************************************************************//**
Compares a data tuple to a physical record.
@see cmp_dtuple_rec_with_match
@return 1, 0, -1, if dtuple is greater, equal, less than rec, respectively */
UNIV_INTERN
int
cmp_dtuple_rec(
/*===========*/
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	const rec_t*	rec,	/*!< in: physical record */
	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	ulint	matched_fields	= 0;
	ulint	matched_bytes	= 0;

	ut_ad(rec_offs_validate(rec, NULL, offsets));
	return(cmp_dtuple_rec_with_match(dtuple, rec, offsets,
					 &matched_fields, &matched_bytes));
}

/**************************************************************//**
Checks if a dtuple is a prefix of a record. The last field in dtuple
is allowed to be a prefix of the corresponding field in the record.
@return	TRUE if prefix */
UNIV_INTERN
ibool
cmp_dtuple_is_prefix_of_rec(
/*========================*/
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	const rec_t*	rec,	/*!< in: physical record */
	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	ulint	n_fields;
	ulint	matched_fields	= 0;
	ulint	matched_bytes	= 0;

	ut_ad(rec_offs_validate(rec, NULL, offsets));
	n_fields = dtuple_get_n_fields(dtuple);

	if (n_fields > rec_offs_n_fields(offsets)) {

		return(FALSE);
	}

	cmp_dtuple_rec_with_match(dtuple, rec, offsets,
				  &matched_fields, &matched_bytes);
	if (matched_fields == n_fields) {

		return(TRUE);
	}

	if (matched_fields == n_fields - 1
	    && matched_bytes == dfield_get_len(
		    dtuple_get_nth_field(dtuple, n_fields - 1))) {
		return(TRUE);
	}

	return(FALSE);
}

/*************************************************************//**
Compare two physical records that contain the same number of columns,
none of which are stored externally.
@return	1, 0, -1 if rec1 is greater, equal, less, respectively, than rec2 */
UNIV_INTERN
int
cmp_rec_rec_simple(
/*===============*/
	const rec_t*		rec1,	/*!< in: physical record */
	const rec_t*		rec2,	/*!< in: physical record */
	const ulint*		offsets1,/*!< in: rec_get_offsets(rec1, ...) */
	const ulint*		offsets2,/*!< in: rec_get_offsets(rec2, ...) */
	const dict_index_t*	index,	/*!< in: data dictionary index */
	ibool*			null_eq)/*!< out: set to TRUE if
					found matching null values */
{
	ulint		rec1_f_len;	/*!< length of current field in rec1 */
	const byte*	rec1_b_ptr;	/*!< pointer to the current byte
					in rec1 field */
	ulint		rec1_byte;	/*!< value of current byte to be
					compared in rec1 */
	ulint		rec2_f_len;	/*!< length of current field in rec2 */
	const byte*	rec2_b_ptr;	/*!< pointer to the current byte
					in rec2 field */
	ulint		rec2_byte;	/*!< value of current byte to be
					compared in rec2 */
	ulint		cur_field;	/*!< current field number */
	ulint		n_uniq;

	n_uniq = dict_index_get_n_unique(index);
	ut_ad(rec_offs_n_fields(offsets1) >= n_uniq);
	ut_ad(rec_offs_n_fields(offsets2) >= n_uniq);

	ut_ad(rec_offs_comp(offsets1) == rec_offs_comp(offsets2));

	for (cur_field = 0; cur_field < n_uniq; cur_field++) {

		ulint	cur_bytes;
		ulint	mtype;
		ulint	prtype;

		{
			const dict_col_t*	col
				= dict_index_get_nth_col(index, cur_field);

			mtype = col->mtype;
			prtype = col->prtype;
		}

		ut_ad(!rec_offs_nth_extern(offsets1, cur_field));
		ut_ad(!rec_offs_nth_extern(offsets2, cur_field));

		rec1_b_ptr = rec_get_nth_field(rec1, offsets1,
					       cur_field, &rec1_f_len);
		rec2_b_ptr = rec_get_nth_field(rec2, offsets2,
					       cur_field, &rec2_f_len);

		if (rec1_f_len == UNIV_SQL_NULL
		    || rec2_f_len == UNIV_SQL_NULL) {

			if (rec1_f_len == rec2_f_len) {
				if (null_eq) {
					*null_eq = TRUE;
				}

				goto next_field;

			} else if (rec2_f_len == UNIV_SQL_NULL) {

				/* We define the SQL null to be the
				smallest possible value of a field
				in the alphabetical order */

				return(1);
			} else {
				return(-1);
			}
		}

		if (mtype >= DATA_FLOAT
		    || (mtype == DATA_BLOB
			&& 0 == (prtype & DATA_BINARY_TYPE)
			&& dtype_get_charset_coll(prtype)
			!= DATA_MYSQL_LATIN1_SWEDISH_CHARSET_COLL)) {
			int ret = cmp_whole_field(mtype, prtype,
						  rec1_b_ptr,
						  (unsigned) rec1_f_len,
						  rec2_b_ptr,
						  (unsigned) rec2_f_len);
			if (ret) {
				return(ret);
			}

			goto next_field;
		}

		/* Compare the fields */
		for (cur_bytes = 0;; cur_bytes++, rec1_b_ptr++, rec2_b_ptr++) {
			if (rec2_f_len <= cur_bytes) {

				if (rec1_f_len <= cur_bytes) {

					goto next_field;
				}

				rec2_byte = dtype_get_pad_char(mtype, prtype);

				if (rec2_byte == ULINT_UNDEFINED) {
					return(1);
				}
			} else {
				rec2_byte = *rec2_b_ptr;
			}

			if (rec1_f_len <= cur_bytes) {
				rec1_byte = dtype_get_pad_char(mtype, prtype);

				if (rec1_byte == ULINT_UNDEFINED) {
					return(-1);
				}
			} else {
				rec1_byte = *rec1_b_ptr;
			}

			if (rec1_byte == rec2_byte) {
				/* If the bytes are equal, they will remain
				such even after the collation transformation
				below */

				continue;
			}

			if (mtype <= DATA_CHAR
			    || (mtype == DATA_BLOB
				&& !(prtype & DATA_BINARY_TYPE))) {

				rec1_byte = cmp_collate(rec1_byte);
				rec2_byte = cmp_collate(rec2_byte);
			}

			if (rec1_byte < rec2_byte) {
				return(-1);
			} else if (rec1_byte > rec2_byte) {
				return(1);
			}
		}
next_field:
		continue;
	}

	/* If we ran out of fields, rec1 was equal to rec2. */
	return(0);
}

/*************************************************************//**
This function is used to compare two physical records. Only the common
first fields are compared, and if an externally stored field is
encountered, then 0 is returned.
@return 1, 0, -1 if rec1 is greater, equal, less, respectively */
UNIV_INTERN
int
cmp_rec_rec_with_match(
/*===================*/
	const rec_t*	rec1,	/*!< in: physical record */
	const rec_t*	rec2,	/*!< in: physical record */
	const ulint*	offsets1,/*!< in: rec_get_offsets(rec1, index) */
	const ulint*	offsets2,/*!< in: rec_get_offsets(rec2, index) */
	dict_index_t*	index,	/*!< in: data dictionary index */
	ibool		nulls_unequal,
				/* in: TRUE if this is for index statistics
				cardinality estimation, and innodb_stats_method
				is "nulls_unequal" or "nulls_ignored" */
	ulint*		matched_fields, /*!< in/out: number of already completely
				matched fields; when the function returns,
				contains the value the for current
				comparison */
	ulint*		matched_bytes) /*!< in/out: number of already matched
				bytes within the first field not completely
				matched; when the function returns, contains
				the value for the current comparison */
{
	ulint		rec1_n_fields;	/* the number of fields in rec */
	ulint		rec1_f_len;	/* length of current field in rec */
	const byte*	rec1_b_ptr;	/* pointer to the current byte
					in rec field */
	ulint		rec1_byte;	/* value of current byte to be
					compared in rec */
	ulint		rec2_n_fields;	/* the number of fields in rec */
	ulint		rec2_f_len;	/* length of current field in rec */
	const byte*	rec2_b_ptr;	/* pointer to the current byte
					in rec field */
	ulint		rec2_byte;	/* value of current byte to be
					compared in rec */
	ulint		cur_field;	/* current field number */
	ulint		cur_bytes;	/* number of already matched
					bytes in current field */
	int		ret = 0;	/* return value */
	ulint		comp;

	ut_ad(rec1 && rec2 && index);
	ut_ad(rec_offs_validate(rec1, index, offsets1));
	ut_ad(rec_offs_validate(rec2, index, offsets2));
	ut_ad(rec_offs_comp(offsets1) == rec_offs_comp(offsets2));

	comp = rec_offs_comp(offsets1);
	rec1_n_fields = rec_offs_n_fields(offsets1);
	rec2_n_fields = rec_offs_n_fields(offsets2);

	cur_field = *matched_fields;
	cur_bytes = *matched_bytes;

	/* Match fields in a loop */

	while ((cur_field < rec1_n_fields) && (cur_field < rec2_n_fields)) {

		ulint	mtype;
		ulint	prtype;

		if (dict_index_is_univ(index)) {
			/* This is for the insert buffer B-tree. */
			mtype = DATA_BINARY;
			prtype = 0;
		} else {
			const dict_col_t*	col
				= dict_index_get_nth_col(index, cur_field);

			mtype = col->mtype;
			prtype = col->prtype;
		}

		rec1_b_ptr = rec_get_nth_field(rec1, offsets1,
					       cur_field, &rec1_f_len);
		rec2_b_ptr = rec_get_nth_field(rec2, offsets2,
					       cur_field, &rec2_f_len);

		if (cur_bytes == 0) {
			if (cur_field == 0) {
				/* Test if rec is the predefined minimum
				record */
				if (UNIV_UNLIKELY(rec_get_info_bits(rec1, comp)
						  & REC_INFO_MIN_REC_FLAG)) {

					if (!(rec_get_info_bits(rec2, comp)
					      & REC_INFO_MIN_REC_FLAG)) {
						ret = -1;
					}

					goto order_resolved;

				} else if (UNIV_UNLIKELY
					   (rec_get_info_bits(rec2, comp)
					    & REC_INFO_MIN_REC_FLAG)) {

					ret = 1;

					goto order_resolved;
				}
			}

			if (rec_offs_nth_extern(offsets1, cur_field)
			    || rec_offs_nth_extern(offsets2, cur_field)) {
				/* We do not compare to an externally
				stored field */

				goto order_resolved;
			}

			if (rec1_f_len == UNIV_SQL_NULL
			    || rec2_f_len == UNIV_SQL_NULL) {

				if (rec1_f_len == rec2_f_len) {
					/* This is limited to stats collection,
					cannot use it for regular search */
					if (nulls_unequal) {
						ret = -1;
					} else {
						goto next_field;
					}
				} else if (rec2_f_len == UNIV_SQL_NULL) {

					/* We define the SQL null to be the
					smallest possible value of a field
					in the alphabetical order */

					ret = 1;
				} else {
					ret = -1;
				}

				goto order_resolved;
			}
		}

		if (mtype >= DATA_FLOAT
		    || (mtype == DATA_BLOB
			&& 0 == (prtype & DATA_BINARY_TYPE)
			&& dtype_get_charset_coll(prtype)
			!= DATA_MYSQL_LATIN1_SWEDISH_CHARSET_COLL)) {

			ret = cmp_whole_field(mtype, prtype,
					      rec1_b_ptr,
					      (unsigned) rec1_f_len,
					      rec2_b_ptr,
					      (unsigned) rec2_f_len);
			if (ret != 0) {
				cur_bytes = 0;

				goto order_resolved;
			} else {
				goto next_field;
			}
		}

		/* Set the pointers at the current byte */
		rec1_b_ptr = rec1_b_ptr + cur_bytes;
		rec2_b_ptr = rec2_b_ptr + cur_bytes;

		/* Compare then the fields */
		for (;;) {
			if (rec2_f_len <= cur_bytes) {

				if (rec1_f_len <= cur_bytes) {

					goto next_field;
				}

				rec2_byte = dtype_get_pad_char(mtype, prtype);

				if (rec2_byte == ULINT_UNDEFINED) {
					ret = 1;

					goto order_resolved;
				}
			} else {
				rec2_byte = *rec2_b_ptr;
			}

			if (rec1_f_len <= cur_bytes) {
				rec1_byte = dtype_get_pad_char(mtype, prtype);

				if (rec1_byte == ULINT_UNDEFINED) {
					ret = -1;

					goto order_resolved;
				}
			} else {
				rec1_byte = *rec1_b_ptr;
			}

			if (rec1_byte == rec2_byte) {
				/* If the bytes are equal, they will remain
				such even after the collation transformation
				below */

				goto next_byte;
			}

			if (mtype <= DATA_CHAR
			    || (mtype == DATA_BLOB
				&& !(prtype & DATA_BINARY_TYPE))) {

				rec1_byte = cmp_collate(rec1_byte);
				rec2_byte = cmp_collate(rec2_byte);
			}

			if (rec1_byte < rec2_byte) {
				ret = -1;
				goto order_resolved;
			} else if (rec1_byte > rec2_byte) {
				ret = 1;
				goto order_resolved;
			}
next_byte:
			/* Next byte */

			cur_bytes++;
			rec1_b_ptr++;
			rec2_b_ptr++;
		}

next_field:
		cur_field++;
		cur_bytes = 0;
	}

	ut_ad(cur_bytes == 0);

	/* If we ran out of fields, rec1 was equal to rec2 up
	to the common fields */
	ut_ad(ret == 0);
order_resolved:

	ut_ad((ret >= - 1) && (ret <= 1));

	*matched_fields = cur_field;
	*matched_bytes = cur_bytes;

	return(ret);
}

#ifdef UNIV_DEBUG
/*************************************************************//**
Used in debug checking of cmp_dtuple_... .
This function is used to compare a data tuple to a physical record. If
dtuple has n fields then rec must have either m >= n fields, or it must
differ from dtuple in some of the m fields rec has. If encounters an
externally stored field, returns 0.
@return 1, 0, -1, if dtuple is greater, equal, less than rec,
respectively, when only the common first fields are compared */
static
int
cmp_debug_dtuple_rec_with_match(
/*============================*/
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	const rec_t*	rec,	/*!< in: physical record which differs from
				dtuple in some of the common fields, or which
				has an equal number or more fields than
				dtuple */
	const ulint*	offsets,/*!< in: array returned by rec_get_offsets() */
	ulint*		matched_fields) /*!< in/out: number of already
				completely matched fields; when function
				returns, contains the value for current
				comparison */
{
	const dfield_t*	dtuple_field;	/* current field in logical record */
	ulint		dtuple_f_len;	/* the length of the current field
					in the logical record */
	const byte*	dtuple_f_data;	/* pointer to the current logical
					field data */
	ulint		rec_f_len;	/* length of current field in rec */
	const byte*	rec_f_data;	/* pointer to the current rec field */
	int		ret = 3333;	/* return value */
	ulint		cur_field;	/* current field number */

	ut_ad(dtuple && rec && matched_fields);
	ut_ad(dtuple_check_typed(dtuple));
	ut_ad(rec_offs_validate(rec, NULL, offsets));

	ut_ad(*matched_fields <= dtuple_get_n_fields_cmp(dtuple));
	ut_ad(*matched_fields <= rec_offs_n_fields(offsets));

	cur_field = *matched_fields;

	if (cur_field == 0) {
		if (UNIV_UNLIKELY
		    (rec_get_info_bits(rec, rec_offs_comp(offsets))
		     & REC_INFO_MIN_REC_FLAG)) {

			ret = !(dtuple_get_info_bits(dtuple)
				& REC_INFO_MIN_REC_FLAG);

			goto order_resolved;
		}

		if (UNIV_UNLIKELY
		    (dtuple_get_info_bits(dtuple) & REC_INFO_MIN_REC_FLAG)) {
			ret = -1;

			goto order_resolved;
		}
	}

	/* Match fields in a loop; stop if we run out of fields in dtuple */

	while (cur_field < dtuple_get_n_fields_cmp(dtuple)) {

		ulint	mtype;
		ulint	prtype;

		dtuple_field = dtuple_get_nth_field(dtuple, cur_field);
		{
			const dtype_t*	type
				= dfield_get_type(dtuple_field);

			mtype = type->mtype;
			prtype = type->prtype;
		}

		dtuple_f_data = static_cast<const byte*>(
			dfield_get_data(dtuple_field));

		dtuple_f_len = dfield_get_len(dtuple_field);

		rec_f_data = rec_get_nth_field(rec, offsets,
					       cur_field, &rec_f_len);

		if (rec_offs_nth_extern(offsets, cur_field)) {
			/* We do not compare to an externally stored field */

			ret = 0;

			goto order_resolved;
		}

		ret = cmp_data_data(mtype, prtype, dtuple_f_data, dtuple_f_len,
				    rec_f_data, rec_f_len);
		if (ret != 0) {
			goto order_resolved;
		}

		cur_field++;
	}

	ret = 0;	/* If we ran out of fields, dtuple was equal to rec
			up to the common fields */
order_resolved:
	ut_ad((ret >= - 1) && (ret <= 1));

	*matched_fields = cur_field;

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