/* Copyright (C) 2000-2006 MySQL 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; 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 */ /* Functions to check if a row is unique */ #include "myisamdef.h" #include my_bool mi_check_unique(MI_INFO *info, MI_UNIQUEDEF *def, uchar *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->lastkey2; DBUG_ENTER("mi_check_unique"); mi_unique_store(record+key->seg->start, unique_hash); _mi_make_key(info,def->key,key_buff,record,0); /* The above changed info->lastkey2. Inform mi_rnext_same(). */ info->update&= ~HA_STATE_RNEXT_SAME; 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]) || memcmp(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 TODO Add support for bit fields */ ha_checksum mi_unique_hash(MI_UNIQUEDEF *def, const uchar *record) { const uchar *pos, *end; ha_checksum crc= 0; ulong seed1=0, seed2= 4; HA_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) { /* Change crc in a way different from an empty string or 0. (This is an optimisation; The code will work even if this isn't done) */ crc=((crc << 8) + 511+ (crc >> (8*sizeof(ha_checksum)-8))); continue; } } pos= record+keyseg->start; if (keyseg->flag & HA_VAR_LENGTH_PART) { uint pack_length= keyseg->bit_start; uint tmp_length= (pack_length == 1 ? (uint) *(uchar*) pos : uint2korr(pos)); pos+= pack_length; /* 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((uchar*) &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_VARTEXT1 || type == HA_KEYTYPE_VARTEXT2) { keyseg->charset->coll->hash_sort(keyseg->charset, (const uchar*) pos, length, &seed1, &seed2); crc^= seed1; } else while (pos != end) crc=((crc << 8) + (((uchar) *(uchar*) pos++))) + (crc >> (8*sizeof(ha_checksum)-8)); } return crc; } /* compare unique key for two rows TODO Add support for bit fields RETURN 0 if both rows have equal unique value # Rows are different */ int mi_unique_comp(MI_UNIQUEDEF *def, const uchar *a, const uchar *b, my_bool null_are_equal) { const uchar *pos_a, *pos_b, *end; HA_KEYSEG *keyseg; for (keyseg=def->seg ; keyseg < def->end ; keyseg++) { enum ha_base_keytype type=(enum ha_base_keytype) keyseg->type; uint a_length, b_length; a_length= b_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_PART) { uint pack_length= keyseg->bit_start; if (pack_length == 1) { a_length= (uint) *(uchar*) pos_a++; b_length= (uint) *(uchar*) pos_b++; } else { a_length= uint2korr(pos_a); b_length= uint2korr(pos_b); pos_a+= 2; /* Skip VARCHAR length */ pos_b+= 2; } set_if_smaller(a_length, keyseg->length); /* Safety */ set_if_smaller(b_length, keyseg->length); /* safety */ } else if (keyseg->flag & HA_BLOB_PART) { /* Only compare 'length' characters if length != 0 */ a_length= _mi_calc_blob_length(keyseg->bit_start,pos_a); b_length= _mi_calc_blob_length(keyseg->bit_start,pos_b); /* Check that a and b are of equal length */ if (keyseg->length) { /* This is used in some cases when we are not interested in comparing the whole length of the blob. */ set_if_smaller(a_length, keyseg->length); set_if_smaller(b_length, keyseg->length); } memcpy_fixed((uchar*) &pos_a,pos_a+keyseg->bit_start,sizeof(char*)); memcpy_fixed((uchar*) &pos_b,pos_b+keyseg->bit_start,sizeof(char*)); } if (type == HA_KEYTYPE_TEXT || type == HA_KEYTYPE_VARTEXT1 || type == HA_KEYTYPE_VARTEXT2) { if (ha_compare_text(keyseg->charset, (uchar *) pos_a, a_length, (uchar *) pos_b, b_length, 0, 1)) return 1; } else { if (a_length != b_length) return 1; end= pos_a+a_length; while (pos_a != end) { if (*pos_a++ != *pos_b++) return 1; } } } return 0; }