rem0cmp.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

/***********************************************************************
Comparison services for records

(c) 1994-1996 Innobase Oy

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

#include "rem0cmp.h"

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

#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 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. */
static
int
cmp_debug_dtuple_rec_with_match(
/*============================*/	
				/* out: 1, 0, -1, if dtuple is greater, equal, 
				less than rec, respectively, when only the 
				common first fields are compared */
	dtuple_t*	dtuple,	/* in: data tuple */
	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 the one in ha_innobase.cc! */
extern
int
innobase_mysql_cmp(
/*===============*/
					/* out: 1, 0, -1, if a is greater,
					equal, less than b, respectively */
	int		mysql_type,	/* in: MySQL type */
	uint		charset_number,	/* in: number of the charset */
	unsigned char*	a,		/* in: data field */
	unsigned int	a_length,	/* in: data field length,
					not UNIV_SQL_NULL */
	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. */
UNIV_INLINE
ulint
cmp_collate(
/*========*/
			/* out: collation order position */
	ulint	code)	/* in: code of a character stored in database record */
{	
	return((ulint) srv_latin1_ordering[code]);
}

/*****************************************************************
Returns TRUE if two types are equal for comparison purposes. */

ibool
cmp_types_are_equal(
/*================*/
				/* out: TRUE if the types are considered
				equal in comparisons */
	dtype_t*	type1,	/* in: type 1 */
	dtype_t*	type2,	/* in: type 2 */
	ibool		check_charsets) /* in: whether to check charsets */
{
	if (dtype_is_non_binary_string_type(type1->mtype, type1->prtype)
	    && dtype_is_non_binary_string_type(type2->mtype, type2->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(type1->prtype)
			    == dtype_get_charset_coll(type2->prtype));
		} else {
			return(TRUE);
		}
        }

	if (dtype_is_binary_string_type(type1->mtype, type1->prtype)
	    && dtype_is_binary_string_type(type2->mtype, type2->prtype)) {

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

		return(TRUE);
	}
	
        if (type1->mtype != type2->mtype) {

		return(FALSE);
	}

        if (type1->mtype == DATA_INT
	    && (type1->prtype & DATA_UNSIGNED)
		!= (type2->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);
	}

        if (type1->mtype == DATA_INT && type1->len != type2->len) {
	
		return(FALSE);
	}

	return(TRUE);
}

/*****************************************************************
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 */
static
int
cmp_whole_field(
/*============*/	
					/* out: 1, 0, -1, if a is greater,
					equal, less than b, respectively */
	dtype_t*	type,		/* in: data type */
	unsigned char*	a,		/* in: data field */
	unsigned int	a_length,	/* in: data field length,
					not UNIV_SQL_NULL */
	unsigned char*	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;
	ulint		data_type;

	data_type = type->mtype;

	switch (data_type) {

    	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_VARMYSQL:
	case DATA_MYSQL:
	case DATA_BLOB:
		if (data_type == DATA_BLOB
		    && 0 != (type->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");
		}		   

		return(innobase_mysql_cmp(
				(int)(type->prtype & DATA_MYSQL_TYPE_MASK),
				(uint)dtype_get_charset_coll(type->prtype),
				a, a_length, b, b_length));
	default:
	        fprintf(stderr,
			"InnoDB: unknown type number %lu\n",
			(ulong) data_type);
	        ut_error;
	}

	return(0);
}

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

int
cmp_data_data_slow(
/*===============*/	
				/* out: 1, 0, -1, if data1 is greater, equal, 
				less than data2, respectively */
	dtype_t*	cur_type,/* in: data type of the fields */
	byte*		data1,	/* in: data field (== a pointer to a memory
				buffer) */
	ulint		len1,	/* in: data field length or UNIV_SQL_NULL */
	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;

	ut_ad(dtype_validate(cur_type));

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

		return(cmp_whole_field(cur_type,
					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(cur_type);

			if (data1_byte == ULINT_UNDEFINED) {

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

		if (len2 <= cur_bytes) {
			data2_byte = dtype_get_pad_char(cur_type);

			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 (cur_type->mtype <= DATA_CHAR
		    || (cur_type->mtype == DATA_BLOB
		        && 0 == (cur_type->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 a data tuple to a physical record.
Only dtuple->n_fields_cmp first fields are taken into account for
the 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. */

int
cmp_dtuple_rec_with_match(
/*======================*/	
				/* out: 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 */
	dtuple_t*	dtuple,	/* in: data tuple */
	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 */
{
	dtype_t*	cur_type;	/* pointer to type of the current
					field in dtuple */
	dfield_t*	dtuple_field;	/* current field in logical record */
	ulint		dtuple_f_len;	/* the length of the current field 
					in the logical record */
	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 */
	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 (rec_info & REC_INFO_MIN_REC_FLAG) {
			ret = !(tup_info & REC_INFO_MIN_REC_FLAG);
			goto order_resolved;
		} else if (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)) {

		dtuple_field = dtuple_get_nth_field(dtuple, cur_field);
		cur_type = dfield_get_type(dtuple_field);

		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;
			}
		}