mariadb/storage/innobase/rem/rem0cmp.cc

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

Copyright (c) 1994, 2019, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2020, MariaDB Corporation.

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
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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, Fifth Floor, Boston, MA 02110-1335 USA

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

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

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

#include "rem0cmp.h"
#include "rem0rec.h"
#include "page0page.h"
#include "dict0mem.h"
#include "handler0alter.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. */

/** Compare two data fields.
@param[in] prtype precise type
@param[in] a data field
@param[in] a_length length of a, in bytes (not UNIV_SQL_NULL)
@param[in] b data field
@param[in] b_length length of b, in bytes (not UNIV_SQL_NULL)
@return positive, 0, negative, if a is greater, equal, less than b,
respectively */
UNIV_INLINE
int
innobase_mysql_cmp(
	ulint		prtype,
	const byte*	a,
	unsigned int	a_length,
	const byte*	b,
	unsigned int	b_length)
{
#ifdef UNIV_DEBUG
	switch (prtype & DATA_MYSQL_TYPE_MASK) {
	case MYSQL_TYPE_BIT:
	case MYSQL_TYPE_STRING:
	case MYSQL_TYPE_VAR_STRING:
	case MYSQL_TYPE_TINY_BLOB:
	case MYSQL_TYPE_MEDIUM_BLOB:
	case MYSQL_TYPE_BLOB:
	case MYSQL_TYPE_LONG_BLOB:
	case MYSQL_TYPE_VARCHAR:
		break;
	default:
		ut_error;
	}
#endif /* UNIV_DEBUG */

	uint cs_num = (uint) dtype_get_charset_coll(prtype);

	if (CHARSET_INFO* cs = get_charset(cs_num, MYF(MY_WME))) {
		return(cs->coll->strnncollsp(
			       cs, a, a_length, b, b_length));
	}

	ib::fatal() << "Unable to find charset-collation " << cs_num;
	return(0);
}

/*************************************************************//**
Returns TRUE if two columns are equal for comparison purposes.
@return TRUE if the columns are considered equal in comparisons */
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);
}

/** Compare two DATA_DECIMAL (MYSQL_TYPE_DECIMAL) fields.
TODO: Remove this function. Everything should use MYSQL_TYPE_NEWDECIMAL.
@param[in] a data field
@param[in] a_length length of a, in bytes (not UNIV_SQL_NULL)
@param[in] b data field
@param[in] b_length length of b, in bytes (not UNIV_SQL_NULL)
@return positive, 0, negative, if a is greater, equal, less than b,
respectively */
static ATTRIBUTE_COLD
int
cmp_decimal(
	const byte*	a,
	unsigned int	a_length,
	const byte*	b,
	unsigned int	b_length)
{
	int	swap_flag;

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

	if (*a == '-') {
		swap_flag = -1;

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

		a++; b++;
		a_length--;
		b_length--;
	} else {
		swap_flag = 1;

		if (*b == '-') {
			return(swap_flag);
		}
	}

	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) {
		swap_flag = -swap_flag;
	}

	return(swap_flag);
}

/*************************************************************//**
Innobase uses this function to compare two geometry data fields
@return	1, 0, -1, if a is greater, equal, less than b, respectively */
static
int
cmp_geometry_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 */
{
	double		x1, x2;
	double		y1, y2;

	ut_ad(prtype & DATA_GIS_MBR);

	if (a_length < sizeof(double) || b_length < sizeof(double)) {
		return(0);
	}

	/* Try to compare mbr left lower corner (xmin, ymin) */
	x1 = mach_double_read(a);
	x2 = mach_double_read(b);
	y1 = mach_double_read(a + sizeof(double) * SPDIMS);
	y2 = mach_double_read(b + sizeof(double) * SPDIMS);

	if (x1 > x2) {
		return(1);
	} else if (x2 > x1) {
		return(-1);
	}

	if (y1 > y2) {
		return(1);
	} else if (y2 > y1) {
		return(-1);
	}

	/* left lower corner (xmin, ymin) overlaps, now right upper corner */
	x1 = mach_double_read(a + sizeof(double));
	x2 = mach_double_read(b + sizeof(double));
	y1 = mach_double_read(a + sizeof(double) * SPDIMS + sizeof(double));
	y2 = mach_double_read(b + sizeof(double) * SPDIMS + sizeof(double));

	if (x1 > x2) {
		return(1);
	} else if (x2 > x1) {
		return(-1);
	}

	if (y1 > y2) {
		return(1);
	} else if (y2 > y1) {
		return(-1);
	}

	return(0);
}
/*************************************************************//**
Innobase uses this function to compare two gis data fields
@return	1, 0, -1, if mode == PAGE_CUR_MBR_EQUAL. And return
1, 0 for rest compare modes, depends on a and b qualifies the
relationship (CONTAINT, WITHIN etc.) */
static
int
cmp_gis_field(
/*============*/
	page_cur_mode_t	mode,		/*!< in: compare mode */
	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 */
{
	if (mode == PAGE_CUR_MBR_EQUAL) {
		/* TODO: Since the DATA_GEOMETRY is not used in compare
		function, we could pass it instead of a specific type now */
		return(cmp_geometry_field(DATA_GEOMETRY, DATA_GIS_MBR,
					  a, a_length, b, b_length));
	} else {
		return(rtree_key_cmp(mode, a, a_length, b, b_length));
	}
}

/** Compare two data fields.
@param[in] mtype main type
@param[in] prtype precise type
@param[in] a data field
@param[in] a_length length of a, in bytes (not UNIV_SQL_NULL)
@param[in] b data field
@param[in] b_length length of b, in bytes (not UNIV_SQL_NULL)
@return positive, 0, negative, if a is greater, equal, less than b,
respectively */
static
int
cmp_whole_field(
	ulint		mtype,
	ulint		prtype,
	const byte*	a,
	unsigned int	a_length,
	const byte*	b,
	unsigned int	b_length)
{
	float		f_1;
	float		f_2;
	double		d_1;
	double		d_2;

	switch (mtype) {
	case DATA_DECIMAL:
		return(cmp_decimal(a, a_length, b, b_length));
	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_VARCHAR:
	case DATA_CHAR:
		return(my_charset_latin1.coll->strnncollsp(
			       &my_charset_latin1,
			       a, a_length, b, b_length));
	case DATA_BLOB:
		if (prtype & DATA_BINARY_TYPE) {
			ib::error() << "Comparing a binary BLOB"
				" using a character set collation!";
			ut_ad(0);
		}
		/* fall through */
	case DATA_VARMYSQL:
	case DATA_MYSQL:
		return(innobase_mysql_cmp(prtype,
					  a, a_length, b, b_length));
	case DATA_GEOMETRY:
		return(cmp_geometry_field(mtype, prtype, a, a_length, b,
				b_length));
	default:
		ib::fatal() << "Unknown data type number " << mtype;
	}

	return(0);
}

/** Compare two data fields.
@param[in] mtype main type
@param[in] prtype precise type
@param[in] data1 data field
@param[in] len1 length of data1 in bytes, or UNIV_SQL_NULL
@param[in] data2 data field
@param[in] len2 length of data2 in bytes, or UNIV_SQL_NULL
@return the comparison result of data1 and data2
@retval 0 if data1 is equal to data2
@retval negative if data1 is less than data2
@retval positive if data1 is greater than data2 */
inline
int
cmp_data(
	ulint		mtype,
	ulint		prtype,
	const byte*	data1,
	ulint		len1,
	const byte*	data2,
	ulint		len2)
{
	if (len1 == UNIV_SQL_NULL || len2 == UNIV_SQL_NULL) {
		if (len1 == len2) {
			return(0);
		}

		/* We define the SQL null to be the smallest possible
		value of a field. */
		return(len1 == UNIV_SQL_NULL ? -1 : 1);
	}

	ulint	pad;

	switch (mtype) {
	case DATA_FIXBINARY:
	case DATA_BINARY:
		if (dtype_get_charset_coll(prtype)
		    != DATA_MYSQL_BINARY_CHARSET_COLL) {
			pad = 0x20;
			break;
		}
		/* fall through */
	case DATA_INT:
	case DATA_SYS_CHILD:
	case DATA_SYS:
		pad = ULINT_UNDEFINED;
		break;
	case DATA_GEOMETRY:
		ut_ad(prtype & DATA_BINARY_TYPE);
		pad = ULINT_UNDEFINED;
		if (prtype & DATA_GIS_MBR) {
			return(cmp_whole_field(mtype, prtype,
					       data1, (unsigned) len1,
					       data2, (unsigned) len2));
		}
		break;
	case DATA_BLOB:
		if (prtype & DATA_BINARY_TYPE) {
			pad = ULINT_UNDEFINED;
			break;
		}
		/* fall through */
	default:
		return(cmp_whole_field(mtype, prtype,
				       data1, (unsigned) len1,
				       data2, (unsigned) len2));
	}

	ulint	len;
	int	cmp;

	if (len1 < len2) {
		len = len1;
		len2 -= len;
		len1 = 0;
	} else {
		len = len2;
		len1 -= len;
		len2 = 0;
	}

	if (len) {
#if defined __i386__ || defined __x86_64__ || defined _M_IX86 || defined _M_X64
		/* Compare the first bytes with a loop to avoid the call
		overhead of memcmp(). On x86 and x86-64, the GCC built-in
		(repz cmpsb) seems to be very slow, so we will be calling the
		libc version. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43052
		tracks the slowness of the GCC built-in memcmp().

		We compare up to the first 4..7 bytes with the loop.
		The (len & 3) is used for "normalizing" or
		"quantizing" the len parameter for the memcmp() call,
		in case the whole prefix is equal. On x86 and x86-64,
		the GNU libc memcmp() of equal strings is faster with
		len=4 than with len=3.

		On other architectures than the IA32 or AMD64, there could
		be a built-in memcmp() that is faster than the loop.
		We only use the loop where we know that it can improve
		the performance. */
		for (ulint i = 4 + (len & 3); i > 0; i--) {
			cmp = int(*data1++) - int(*data2++);
			if (cmp) {
				return(cmp);
			}

			if (!--len) {
				break;
			}
		}

		if (len) {
#endif /* IA32 or AMD64 */
			cmp = memcmp(data1, data2, len);

			if (cmp) {
				return(cmp);
			}

			data1 += len;
			data2 += len;
#if defined __i386__ || defined __x86_64__ || defined _M_IX86 || defined _M_X64
		}
#endif /* IA32 or AMD64 */
	}

	cmp = (int) (len1 - len2);

	if (!cmp || pad == ULINT_UNDEFINED) {
		return(cmp);
	}

	len = 0;

	if (len1) {
		do {
			cmp = static_cast<int>(
				mach_read_from_1(&data1[len++]) - pad);
		} while (cmp == 0 && len < len1);
	} else {
		ut_ad(len2 > 0);

		do {
			cmp = static_cast<int>(
				pad - mach_read_from_1(&data2[len++]));
		} while (cmp == 0 && len < len2);
	}

	return(cmp);
}

/** Compare a GIS data tuple to a physical record.
@param[in] dtuple data tuple
@param[in] rec R-tree record
@param[in] offsets rec_get_offsets(rec)
@param[in] mode compare mode
@retval negative if dtuple is less than rec */
int
cmp_dtuple_rec_with_gis(
/*====================*/
	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 offset_t*	offsets,/*!< in: array returned by rec_get_offsets() */
	page_cur_mode_t	mode)	/*!< in: compare mode */
{
	const dfield_t*	dtuple_field;	/* current field in logical record */
	ulint		dtuple_f_len;	/* the length of the current field
					in the logical record */
	ulint		rec_f_len;	/* length of current field in rec */
	const byte*	rec_b_ptr;	/* pointer to the current byte in
					rec field */
	int		ret = 0;	/* return value */

	dtuple_field = dtuple_get_nth_field(dtuple, 0);
	dtuple_f_len = dfield_get_len(dtuple_field);

	rec_b_ptr = rec_get_nth_field(rec, offsets, 0, &rec_f_len);
	ret = cmp_gis_field(
		mode, static_cast<const byte*>(dfield_get_data(dtuple_field)),
		(unsigned) dtuple_f_len, rec_b_ptr, (unsigned) rec_f_len);

	return(ret);
}

/** Compare a GIS data tuple to a physical record in rtree non-leaf node.
We need to check the page number field, since we don't store pk field in
rtree non-leaf node.
@param[in]	dtuple		data tuple
@param[in]	rec		R-tree record
@param[in]	offsets		rec_get_offsets(rec)
@retval negative if dtuple is less than rec */
int
cmp_dtuple_rec_with_gis_internal(
	const dtuple_t*	dtuple,
	const rec_t*	rec,
	const offset_t*	offsets)
{
	const dfield_t*	dtuple_field;	/* current field in logical record */
	ulint		dtuple_f_len;	/* the length of the current field
					in the logical record */
	ulint		rec_f_len;	/* length of current field in rec */
	const byte*	rec_b_ptr;	/* pointer to the current byte in
					rec field */
	int		ret = 0;	/* return value */

	dtuple_field = dtuple_get_nth_field(dtuple, 0);
	dtuple_f_len = dfield_get_len(dtuple_field);

	rec_b_ptr = rec_get_nth_field(rec, offsets, 0, &rec_f_len);
	ret = cmp_gis_field(
		PAGE_CUR_WITHIN,
		static_cast<const byte*>(dfield_get_data(dtuple_field)),
		(unsigned) dtuple_f_len, rec_b_ptr, (unsigned) rec_f_len);
	if (ret != 0) {
		return(ret);
	}

	dtuple_field = dtuple_get_nth_field(dtuple, 1);
	dtuple_f_len = dfield_get_len(dtuple_field);
	rec_b_ptr = rec_get_nth_field(rec, offsets, 1, &rec_f_len);

	return(cmp_data(dtuple_field->type.mtype,
			dtuple_field->type.prtype,
			static_cast<const byte*>(dtuple_field->data),
			dtuple_f_len,
			rec_b_ptr,
			rec_f_len));
}

/** Compare two data fields.
@param[in] mtype main type
@param[in] prtype precise type
@param[in] data1 data field
@param[in] len1 length of data1 in bytes, or UNIV_SQL_NULL
@param[in] data2 data field
@param[in] len2 length of data2 in bytes, or UNIV_SQL_NULL
@return the comparison result of data1 and data2
@retval 0 if data1 is equal to data2
@retval negative if data1 is less than data2
@retval positive if data1 is greater than data2 */
int
cmp_data_data(
	ulint		mtype,
	ulint		prtype,
	const byte*	data1,
	ulint		len1,
	const byte*	data2,
	ulint		len2)
{
	return(cmp_data(mtype, prtype, data1, len1, data2, len2));
}

/** Compare a data tuple to a physical record.
@param[in] dtuple data tuple
@param[in] rec B-tree record
@param[in] offsets rec_get_offsets(rec)
@param[in] n_cmp number of fields to compare
@param[in,out] matched_fields number of completely matched fields
@return the comparison result of dtuple and rec
@retval 0 if dtuple is equal to rec
@retval negative if dtuple is less than rec
@retval positive if dtuple is greater than rec */
int
cmp_dtuple_rec_with_match_low(
	const dtuple_t*	dtuple,
	const rec_t*	rec,
	const offset_t*	offsets,
	ulint		n_cmp,
	ulint*		matched_fields)
{
	ulint		cur_field;	/* current field number */
	int		ret;		/* return value */

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

	cur_field = *matched_fields;

	ut_ad(n_cmp > 0);
	ut_ad(n_cmp <= dtuple_get_n_fields(dtuple));
	ut_ad(cur_field <= n_cmp);
	ut_ad(cur_field <= rec_offs_n_fields(offsets));

	if (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 */

	for (; cur_field < n_cmp; cur_field++) {
		const byte*	rec_b_ptr;
		const dfield_t*	dtuple_field
			= dtuple_get_nth_field(dtuple, cur_field);
		const byte*	dtuple_b_ptr
			= static_cast<const byte*>(
				dfield_get_data(dtuple_field));
		const dtype_t*	type
			= dfield_get_type(dtuple_field);
		ulint		dtuple_f_len
			= dfield_get_len(dtuple_field);
		ulint		rec_f_len;

		/* We should never compare against an externally
		stored field.  Only clustered index records can
		contain externally stored fields, and the first fields
		(primary key fields) should already differ. */
		ut_ad(!rec_offs_nth_extern(offsets, cur_field));

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

		ut_ad(!dfield_is_ext(dtuple_field));

		ret = cmp_data(type->mtype, type->prtype,
			       dtuple_b_ptr, dtuple_f_len,
			       rec_b_ptr, rec_f_len);
		if (ret) {
			goto order_resolved;
		}
	}

	ret = 0;	/* If we ran out of fields, dtuple was equal to rec
			up to the common fields */
order_resolved:
	*matched_fields = cur_field;
	return(ret);
}

/** Get the pad character code point for a type.
@param[in]	type
@return		pad character code point
@retval		ULINT_UNDEFINED if no padding is specified */
UNIV_INLINE
ulint
cmp_get_pad_char(
	const dtype_t*	type)
{
	switch (type->mtype) {
	case DATA_FIXBINARY:
	case DATA_BINARY:
		if (dtype_get_charset_coll(type->prtype)
		    == DATA_MYSQL_BINARY_CHARSET_COLL) {
			/* Starting from 5.0.18, do not pad
			VARBINARY or BINARY columns. */
			return(ULINT_UNDEFINED);
		}
		/* Fall through */
	case DATA_CHAR:
	case DATA_VARCHAR:
	case DATA_MYSQL:
	case DATA_VARMYSQL:
		/* Space is the padding character for all char and binary
		strings, and starting from 5.0.3, also for TEXT strings. */
		return(0x20);
	case DATA_GEOMETRY:
                /* DATA_GEOMETRY is binary data, not ASCII-based. */
	        return(ULINT_UNDEFINED);
	case DATA_BLOB:
		if (!(type->prtype & DATA_BINARY_TYPE)) {
			return(0x20);
		}
		/* Fall through */
	default:
		/* No padding specified */
		return(ULINT_UNDEFINED);
	}
}

/** Compare a data tuple to a physical record.
@param[in]	dtuple		data tuple
@param[in]	rec		B-tree or R-tree index record
@param[in]	index		index tree
@param[in]	offsets		rec_get_offsets(rec)
@param[in,out]	matched_fields	number of completely matched fields
@param[in,out]	matched_bytes	number of matched bytes in the first
field that is not matched
@return the comparison result of dtuple and rec
@retval 0 if dtuple is equal to rec
@retval negative if dtuple is less than rec
@retval positive if dtuple is greater than rec */
int
cmp_dtuple_rec_with_match_bytes(
	const dtuple_t*		dtuple,
	const rec_t*		rec,
	const dict_index_t*	index,
	const offset_t*		offsets,
	ulint*			matched_fields,
	ulint*			matched_bytes)
{
	ulint		n_cmp	= dtuple_get_n_fields_cmp(dtuple);
	ulint		cur_field;	/* current field number */
	ulint		cur_bytes;
	int		ret;		/* return value */

	ut_ad(dtuple_check_typed(dtuple));
	ut_ad(rec_offs_validate(rec, index, offsets));
	ut_ad(!(REC_INFO_MIN_REC_FLAG
		& dtuple_get_info_bits(dtuple)));
	ut_ad(!(REC_INFO_MIN_REC_FLAG
		& rec_get_info_bits(rec, rec_offs_comp(offsets))));

	cur_field = *matched_fields;
	cur_bytes = *matched_bytes;

	ut_ad(n_cmp <= dtuple_get_n_fields(dtuple));
	ut_ad(cur_field <= n_cmp);
	ut_ad(cur_field + (cur_bytes > 0) <= rec_offs_n_fields(offsets));

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

	while (cur_field < n_cmp) {
		const dfield_t*	dfield		= dtuple_get_nth_field(
			dtuple, cur_field);
		const dtype_t*	type		= dfield_get_type(dfield);
		ulint		dtuple_f_len	= dfield_get_len(dfield);
		const byte*	dtuple_b_ptr;
		const byte*	rec_b_ptr;
		ulint		rec_f_len;

		dtuple_b_ptr = static_cast<const byte*>(
			dfield_get_data(dfield));
		rec_b_ptr = rec_get_nth_field(rec, offsets,
					      cur_field, &rec_f_len);
		ut_ad(!rec_offs_nth_extern(offsets, cur_field));

		/* 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. */
		if (cur_bytes == 0) {
			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;
			}
		}

		switch (type->mtype) {
		case DATA_FIXBINARY:
		case DATA_BINARY:
		case DATA_INT:
		case DATA_SYS_CHILD:
		case DATA_SYS:
			break;
		case DATA_BLOB:
			if (type->prtype & DATA_BINARY_TYPE) {
				break;
			}
			/* fall through */
		default:
			ret = cmp_data(type->mtype, type->prtype,
				       dtuple_b_ptr, dtuple_f_len,
				       rec_b_ptr, rec_f_len);

			if (!ret) {
				goto next_field;
			}

			cur_bytes = 0;
			goto order_resolved;
		}

		/* Set the pointers at the current byte */

		rec_b_ptr += cur_bytes;
		dtuple_b_ptr += cur_bytes;
		/* Compare then the fields */

		for (const ulint pad = cmp_get_pad_char(type);;
		     cur_bytes++) {
			ulint	rec_byte = pad;
			ulint	dtuple_byte = pad;

			if (rec_f_len <= cur_bytes) {
				if (dtuple_f_len <= cur_bytes) {

					goto next_field;
				}

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

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

			if (dtuple_f_len <= cur_bytes) {
				if (dtuple_byte == ULINT_UNDEFINED) {
					ret = -1;

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

			if (dtuple_byte < rec_byte) {
				ret = -1;
				goto order_resolved;
			} else if (dtuple_byte > rec_byte) {
				ret = 1;
				goto order_resolved;
			}
		}

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:
	*matched_fields = cur_field;
	*matched_bytes = cur_bytes;

	return(ret);
}

/** Compare a data tuple to a physical record.
@see cmp_dtuple_rec_with_match
@param[in] dtuple data tuple
@param[in] rec B-tree record
@param[in] offsets rec_get_offsets(rec); may be NULL
for ROW_FORMAT=REDUNDANT
@return the comparison result of dtuple and rec
@retval 0 if dtuple is equal to rec
@retval negative if dtuple is less than rec
@retval positive if dtuple is greater than rec */
int
cmp_dtuple_rec(
	const dtuple_t*	dtuple,
	const rec_t*	rec,
	const offset_t*	offsets)
{
	ulint	matched_fields	= 0;

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

/**************************************************************//**
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 */
ibool
cmp_dtuple_is_prefix_of_rec(
/*========================*/
	const dtuple_t*	dtuple,	/*!< in: data tuple */
	const rec_t*	rec,	/*!< in: physical record */
	const offset_t*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	ulint	n_fields;
	ulint	matched_fields	= 0;

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

	if (n_fields > rec_offs_n_fields(offsets)) {
		ut_ad(0);
		return(FALSE);
	}

	cmp_dtuple_rec_with_match(dtuple, rec, offsets, &matched_fields);
	return(matched_fields == n_fields);
}

/*************************************************************//**
Compare two physical record fields.
@retval positive if rec1 field is greater than rec2
@retval negative if rec1 field is less than rec2
@retval 0 if rec1 field equals to rec2 */
static MY_ATTRIBUTE((nonnull, warn_unused_result))
int
cmp_rec_rec_simple_field(
/*=====================*/
	const rec_t*		rec1,	/*!< in: physical record */
	const rec_t*		rec2,	/*!< in: physical record */
	const offset_t*		offsets1,/*!< in: rec_get_offsets(rec1, ...) */
	const offset_t*		offsets2,/*!< in: rec_get_offsets(rec2, ...) */
	const dict_index_t*	index,	/*!< in: data dictionary index */
	ulint			n)	/*!< in: field to compare */
{
	const byte*	rec1_b_ptr;
	const byte*	rec2_b_ptr;
	ulint		rec1_f_len;
	ulint		rec2_f_len;
	const dict_col_t*	col	= dict_index_get_nth_col(index, n);

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

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

	return(cmp_data(col->mtype, col->prtype,
			rec1_b_ptr, rec1_f_len, rec2_b_ptr, rec2_f_len));
}

/** Compare two physical records that contain the same number of columns,
none of which are stored externally.
@retval positive if rec1 (including non-ordering columns) is greater than rec2
@retval negative if rec1 (including non-ordering columns) is less than rec2
@retval 0 if rec1 is a duplicate of rec2 */
int
cmp_rec_rec_simple(
/*===============*/
	const rec_t*		rec1,	/*!< in: physical record */
	const rec_t*		rec2,	/*!< in: physical record */
	const offset_t*		offsets1,/*!< in: rec_get_offsets(rec1, ...) */
	const offset_t*		offsets2,/*!< in: rec_get_offsets(rec2, ...) */
	const dict_index_t*	index,	/*!< in: data dictionary index */
	struct TABLE*		table)	/*!< in: MySQL table, for reporting
					duplicate key value if applicable,
					or NULL */
{
	ulint		n;
	ulint		n_uniq	= dict_index_get_n_unique(index);
	bool		null_eq	= false;

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

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

	for (n = 0; n < n_uniq; n++) {
		int cmp = cmp_rec_rec_simple_field(
			rec1, rec2, offsets1, offsets2, index, n);

		if (cmp) {
			return(cmp);
		}

		/* If the fields are internally equal, they must both
		be NULL or non-NULL. */
		ut_ad(rec_offs_nth_sql_null(offsets1, n)
		      == rec_offs_nth_sql_null(offsets2, n));

		if (rec_offs_nth_sql_null(offsets1, n)) {
			ut_ad(!(dict_index_get_nth_col(index, n)->prtype
				& DATA_NOT_NULL));
			null_eq = true;
		}
	}

	/* If we ran out of fields, the ordering columns of rec1 were
	equal to rec2. Issue a duplicate key error if needed. */

	if (!null_eq && table && dict_index_is_unique(index)) {
		/* Report erroneous row using new version of table. */
		innobase_rec_to_mysql(table, rec1, index, offsets1);
		return(0);
	}

	/* Else, keep comparing so that we have the full internal
	order. */
	for (; n < dict_index_get_n_fields(index); n++) {
		int cmp = cmp_rec_rec_simple_field(
			rec1, rec2, offsets1, offsets2, index, n);

		if (cmp) {
			return(cmp);
		}

		/* If the fields are internally equal, they must both
		be NULL or non-NULL. */
		ut_ad(rec_offs_nth_sql_null(offsets1, n)
		      == rec_offs_nth_sql_null(offsets2, n));
	}

	/* This should never be reached. Internally, an index must
	never contain duplicate entries. */
	ut_ad(0);
	return(0);
}

/** Compare two B-tree or R-tree records.
Only the common first fields are compared, and externally stored field
are treated as equal.
@param[in]	rec1		record (possibly not on an index page)
@param[in]	rec2		B-tree or R-tree record in an index page
@param[in]	offsets1	rec_get_offsets(rec1, index)
@param[in]	offsets2	rec_get_offsets(rec2, index)
@param[in]	nulls_unequal	true if this is for index cardinality
				statistics estimation with
				innodb_stats_method=nulls_unequal
				or innodb_stats_method=nulls_ignored
@param[out]	matched_fields	number of completely matched fields
				within the first field not completely matched
@retval 0 if rec1 is equal to rec2
@retval negative if rec1 is less than rec2
@retval positive if rec1 is greater than rec2 */
int
cmp_rec_rec(
	const rec_t*		rec1,
	const rec_t*		rec2,
	const offset_t*		offsets1,
	const offset_t*		offsets2,
	const dict_index_t*	index,
	bool			nulls_unequal,
	ulint*			matched_fields)
{
	ulint		rec1_f_len;	/* length of current field in rec */
	const byte*	rec1_b_ptr;	/* pointer to the current byte
					in rec field */
	ulint		rec2_f_len;	/* length of current field in rec */
	const byte*	rec2_b_ptr;	/* pointer to the current byte
					in rec field */
	ulint		cur_field = 0;	/* current field number */
	int		ret = 0;	/* return value */

	ut_ad(rec1 != NULL);
	ut_ad(rec2 != NULL);
	ut_ad(index != NULL);
	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));
	ut_ad(fil_page_index_page_check(page_align(rec2)));
	ut_ad(!!dict_index_is_spatial(index)
	      == (fil_page_get_type(page_align(rec2)) == FIL_PAGE_RTREE));

	ulint comp = rec_offs_comp(offsets1);
	ulint n_fields;

	/* Test if rec is the predefined minimum record */
	if (UNIV_UNLIKELY(rec_get_info_bits(rec1, comp)
			  & REC_INFO_MIN_REC_FLAG)) {
		/* There should only be one such record. */
		ut_ad(!(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;
	}

	/* For non-leaf spatial index records, the
	dict_index_get_n_unique_in_tree() does include the child page
	number, because spatial index node pointers only contain
	the MBR (minimum bounding rectangle) and the child page number.

	For B-tree node pointers, the key alone (secondary index
	columns and PRIMARY KEY columns) must be unique, and there is
	no need to compare the child page number. */
	n_fields = std::min(rec_offs_n_fields(offsets1),
			    rec_offs_n_fields(offsets2));
	n_fields = std::min(n_fields, dict_index_get_n_unique_in_tree(index));

	for (; cur_field < n_fields; cur_field++) {
		ulint	mtype;
		ulint	prtype;

		if (UNIV_UNLIKELY(dict_index_is_ibuf(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;

			if (UNIV_LIKELY(!dict_index_is_spatial(index))) {
			} else if (cur_field == 0) {
				ut_ad(DATA_GEOMETRY_MTYPE(mtype));
				prtype |= DATA_GIS_MBR;
			} else if (!page_rec_is_leaf(rec2)) {
				/* Compare the child page number. */
				ut_ad(cur_field == 1);
				mtype = DATA_SYS_CHILD;
				prtype = 0;
			}
		}

		/* We should never encounter an externally stored field.
		Externally stored fields only exist in clustered index
		leaf page records. These fields should already differ
		in the primary key columns already, before DB_TRX_ID,
		DB_ROLL_PTR, and any externally stored columns. */
		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 (nulls_unequal
		    && rec1_f_len == UNIV_SQL_NULL
		    && rec2_f_len == UNIV_SQL_NULL) {
			ret = -1;
			goto order_resolved;
		}

		ret = cmp_data(mtype, prtype,
			       rec1_b_ptr, rec1_f_len,
			       rec2_b_ptr, rec2_f_len);
		if (ret) {
			goto order_resolved;
		}
	}

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

#ifdef UNIV_COMPILE_TEST_FUNCS

#ifdef HAVE_UT_CHRONO_T

void
test_cmp_data_data(ulint len)
{
	int		i;
	static byte	zeros[64];

	if (len > sizeof zeros) {
		len = sizeof zeros;
	}

	ut_chrono_t	ch(__func__);

	for (i = 1000000; i > 0; i--) {
		i += cmp_data(DATA_INT, 0, zeros, len, zeros, len);
	}
}

#endif /* HAVE_UT_CHRONO_T */

#endif /* UNIV_COMPILE_TEST_FUNCS */