diff options
Diffstat (limited to 'myisam/mi_unique.c')
| -rw-r--r-- | myisam/mi_unique.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/myisam/mi_unique.c b/myisam/mi_unique.c new file mode 100644 index 00000000000..e598fbeedb4 --- /dev/null +++ b/myisam/mi_unique.c @@ -0,0 +1,188 @@ +/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB + + 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; either version 2 of the License, or + (at your option) any later version. + + 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 */ + +/* Functions to check if a row is unique */ + +#include "myisamdef.h" +#include <m_ctype.h> + +my_bool mi_check_unique(MI_INFO *info, MI_UNIQUEDEF *def, byte *record, + ha_checksum unique_hash, my_off_t disk_pos) +{ + my_off_t lastpos=info->lastpos; + MI_KEYDEF *key= &info->s->keyinfo[def->key]; + uchar *key_buff=info->lastkey+info->s->base.max_key_length; + DBUG_ENTER("mi_check_unique"); + + mi_unique_store(record+key->seg->start, unique_hash); + _mi_make_key(info,def->key,key_buff,record,0); + + if (_mi_search(info,info->s->keyinfo+def->key,key_buff,MI_UNIQUE_HASH_LENGTH, + SEARCH_FIND,info->s->state.key_root[def->key])) + { + info->page_changed=1; /* Can't optimize read next */ + info->lastpos= lastpos; + DBUG_RETURN(0); /* No matching rows */ + } + + for (;;) + { + if (info->lastpos != disk_pos && + !(*info->s->compare_unique)(info,def,record,info->lastpos)) + { + my_errno=HA_ERR_FOUND_DUPP_UNIQUE; + info->errkey= (int) def->key; + info->dupp_key_pos= info->lastpos; + info->page_changed=1; /* Can't optimize read next */ + info->lastpos=lastpos; + DBUG_PRINT("info",("Found duplicate")); + DBUG_RETURN(1); /* Found identical */ + } + if (_mi_search_next(info,info->s->keyinfo+def->key, info->lastkey, + MI_UNIQUE_HASH_LENGTH, SEARCH_BIGGER, + info->s->state.key_root[def->key]) || + bcmp(info->lastkey, key_buff, MI_UNIQUE_HASH_LENGTH)) + { + info->page_changed=1; /* Can't optimize read next */ + info->lastpos=lastpos; + DBUG_RETURN(0); /* end of tree */ + } + } +} + + +/* Calculate a hash for a row */ + +ha_checksum mi_unique_hash(MI_UNIQUEDEF *def, const byte *record) +{ + const byte *pos, *end; + ha_checksum crc=0; + MI_KEYSEG *keyseg; + + for (keyseg=def->seg ; keyseg < def->end ; keyseg++) + { + enum ha_base_keytype type=(enum ha_base_keytype) keyseg->type; + uint length=keyseg->length; + + if (keyseg->null_bit) + { + if (record[keyseg->null_pos] & keyseg->null_bit) + continue; + } + pos= record+keyseg->start; + if (keyseg->flag & HA_VAR_LENGTH) + { + uint tmp_length=uint2korr(pos); + pos+=2; /* Skip VARCHAR length */ + set_if_smaller(length,tmp_length); + } + else if (keyseg->flag & HA_BLOB_PART) + { + uint tmp_length=_mi_calc_blob_length(keyseg->bit_start,pos); + memcpy_fixed((byte*) &pos,pos+keyseg->bit_start,sizeof(char*)); + if (!length || length > tmp_length) + length=tmp_length; /* The whole blob */ + } + end= pos+length; + if (type == HA_KEYTYPE_TEXT || type == HA_KEYTYPE_VARTEXT) + { + uchar *sort_order=keyseg->charset->sort_order; + while (pos != end) + crc=((crc << 8) + + (((uchar) sort_order[*(uchar*) pos++]))) + + (crc >> (8*sizeof(ha_checksum)-8)); + } + else + while (pos != end) + crc=((crc << 8) + + (((uchar) *(uchar*) pos++))) + + (crc >> (8*sizeof(ha_checksum)-8)); + } + return crc; +} + + /* + Returns 0 if both rows have equal unique value + */ + +int mi_unique_comp(MI_UNIQUEDEF *def, const byte *a, const byte *b, + my_bool null_are_equal) +{ + const byte *pos_a, *pos_b, *end; + MI_KEYSEG *keyseg; + + for (keyseg=def->seg ; keyseg < def->end ; keyseg++) + { + enum ha_base_keytype type=(enum ha_base_keytype) keyseg->type; + uint length=keyseg->length; + + /* If part is NULL it's regarded as different */ + if (keyseg->null_bit) + { + uint tmp; + if ((tmp=(a[keyseg->null_pos] & keyseg->null_bit)) != + (uint) (b[keyseg->null_pos] & keyseg->null_bit)) + return 1; + if (tmp) + { + if (!null_are_equal) + return 1; + continue; + } + } + pos_a= a+keyseg->start; + pos_b= b+keyseg->start; + if (keyseg->flag & HA_VAR_LENGTH) + { + uint tmp_length=uint2korr(pos_a); + if (tmp_length != uint2korr(pos_b)) + return 1; + pos_a+=2; /* Skip VARCHAR length */ + pos_b+=2; + set_if_smaller(length,tmp_length); + } + else if (keyseg->flag & HA_BLOB_PART) + { + /* Only compare 'length' characters if length<> 0 */ + uint a_length= _mi_calc_blob_length(keyseg->bit_start,pos_a); + uint b_length= _mi_calc_blob_length(keyseg->bit_start,pos_b); + /* Check that a and b are of equal length */ + if (length && a_length > length) + a_length=length; + if (!length || length > b_length) + length=b_length; + if (length != a_length) + return 1; + /* Both strings are at least 'length' long */ + memcpy_fixed((byte*) &pos_a,pos_a+keyseg->bit_start,sizeof(char*)); + memcpy_fixed((byte*) &pos_b,pos_b+keyseg->bit_start,sizeof(char*)); + } + end= pos_a+length; + if (type == HA_KEYTYPE_TEXT || type == HA_KEYTYPE_VARTEXT) + { + uchar *sort_order=keyseg->charset->sort_order; + while (pos_a != end) + if (sort_order[*(uchar*) pos_a++] != + sort_order[*(uchar*) pos_b++]) + return 1; + } + else + while (pos_a != end) + if (*pos_a++ != *pos_b++) + return 1; + } + return 0; +} |