/* 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 handle keys and fields in forms */ #include "mysql_priv.h" /* ** Search after with key field is. If no key starts with field test ** if field is part of some key. ** ** returns number of key. keylength is set to length of key before ** (not including) field ** Used when calculating key for NEXT_NUMBER */ int find_ref_key(KEY *key, uint key_count, Field *field, uint *key_length) { reg2 int i; reg3 KEY *key_info; uint fieldpos; fieldpos= field->offset(); /* Test if some key starts as fieldpos */ for (i= 0, key_info= key ; i < (int) key_count ; i++, key_info++) { if (key_info->key_part[0].offset == fieldpos) { /* Found key. Calc keylength */ *key_length=0; return(i); /* Use this key */ } } /* Test if some key contains fieldpos */ for (i= 0, key_info= key; i < (int) key_count ; i++, key_info++) { uint j; KEY_PART_INFO *key_part; *key_length=0; for (j=0, key_part=key_info->key_part ; j < key_info->key_parts ; j++, key_part++) { if (key_part->offset == fieldpos) return(i); /* Use this key */ *key_length+=key_part->store_length; } } return(-1); /* No key is ok */ } /* Copy part of a record that forms a key or key prefix to a buffer. SYNOPSIS key_copy() to_key buffer that will be used as a key from_record full record to be copied from key_info descriptor of the index key_length specifies length of all keyparts that will be copied DESCRIPTION The function takes a complete table record (as e.g. retrieved by handler::index_read()), and a description of an index on the same table, and extracts the first key_length bytes of the record which are part of a key into to_key. If length == 0 then copy all bytes from the record that form a key. RETURN None */ void key_copy(byte *to_key, byte *from_record, KEY *key_info, uint key_length) { uint length; KEY_PART_INFO *key_part; if (key_length == 0) key_length= key_info->key_length; for (key_part= key_info->key_part; (int) key_length > 0; key_part++) { if (key_part->null_bit) { *to_key++= test(from_record[key_part->null_offset] & key_part->null_bit); key_length--; } if (key_part->type == HA_KEYTYPE_BIT) { Field_bit *field= (Field_bit *) (key_part->field); if (field->bit_len) { uchar bits= get_rec_bits((uchar*) from_record + key_part->null_offset + (key_part->null_bit == 128), field->bit_ofs, field->bit_len); *to_key++= bits; key_length--; } } if (key_part->key_part_flag & HA_BLOB_PART) { char *pos; ulong blob_length= ((Field_blob*) key_part->field)->get_length(); key_length-= HA_KEY_BLOB_LENGTH; ((Field_blob*) key_part->field)->get_ptr(&pos); length=min(key_length, key_part->length); set_if_smaller(blob_length, length); int2store(to_key, (uint) blob_length); to_key+= HA_KEY_BLOB_LENGTH; // Skip length info memcpy(to_key, pos, blob_length); } else if (key_part->key_part_flag & HA_VAR_LENGTH_PART) { key_length-= HA_KEY_BLOB_LENGTH; length= min(key_length, key_part->length); key_part->field->get_key_image((char *) to_key, length, Field::itRAW); to_key+= HA_KEY_BLOB_LENGTH; } else { length= min(key_length, key_part->length); memcpy(to_key, from_record + key_part->offset, (size_t) length); } to_key+= length; key_length-= length; } } /* Restore a key from some buffer to record. SYNOPSIS key_restore() to_record record buffer where the key will be restored to from_key buffer that contains a key key_info descriptor of the index key_length specifies length of all keyparts that will be restored DESCRIPTION This function converts a key into record format. It can be used in cases when we want to return a key as a result row. RETURN None */ void key_restore(byte *to_record, byte *from_key, KEY *key_info, uint key_length) { uint length; KEY_PART_INFO *key_part; if (key_length == 0) { key_length= key_info->key_length; } for (key_part= key_info->key_part ; (int) key_length > 0 ; key_part++) { if (key_part->null_bit) { if (*from_key++) to_record[key_part->null_offset]|= key_part->null_bit; else to_record[key_part->null_offset]&= ~key_part->null_bit; key_length--; } if (key_part->type == HA_KEYTYPE_BIT) { Field_bit *field= (Field_bit *) (key_part->field); if (field->bit_len) { uchar bits= *(from_key + key_part->length - field->pack_length_in_rec() - 1); set_rec_bits(bits, to_record + key_part->null_offset + (key_part->null_bit == 128), field->bit_ofs, field->bit_len); } } if (key_part->key_part_flag & HA_BLOB_PART) { uint blob_length= uint2korr(from_key); from_key+= HA_KEY_BLOB_LENGTH; key_length-= HA_KEY_BLOB_LENGTH; ((Field_blob*) key_part->field)->set_ptr((ulong) blob_length, (char*) from_key); length= key_part->length; } else if (key_part->key_part_flag & HA_VAR_LENGTH_PART) { key_length-= HA_KEY_BLOB_LENGTH; length= min(key_length, key_part->length); key_part->field->set_key_image((char *) from_key, length); from_key+= HA_KEY_BLOB_LENGTH; } else { length= min(key_length, key_part->length); memcpy(to_record + key_part->offset, from_key, (size_t) length); } from_key+= length; key_length-= length; } } /* Compare if a key has changed SYNOPSIS key_cmp_if_same() table TABLE key key to compare to row idx Index used key_length Length of key NOTES In theory we could just call field->cmp() for all field types, but as we are only interested if a key has changed (not if the key is larger or smaller than the previous value) we can do things a bit faster by using memcmp() instead. RETURN 0 If key is equal 1 Key has changed */ bool key_cmp_if_same(TABLE *table,const byte *key,uint idx,uint key_length) { uint store_length; KEY_PART_INFO *key_part; const byte *key_end= key + key_length;; for (key_part=table->key_info[idx].key_part; key < key_end ; key_part++, key+= store_length) { uint length; store_length= key_part->store_length; if (key_part->null_bit) { if (*key != test(table->record[0][key_part->null_offset] & key_part->null_bit)) return 1; if (*key) continue; key++; store_length--; } if (key_part->key_part_flag & (HA_BLOB_PART | HA_VAR_LENGTH_PART | HA_BIT_PART)) { if (key_part->field->key_cmp(key, key_part->length)) return 1; continue; } length= min((uint) (key_end-key), store_length); if (!(key_part->key_type & (FIELDFLAG_NUMBER+FIELDFLAG_BINARY+ FIELDFLAG_PACK))) { CHARSET_INFO *cs= key_part->field->charset(); uint char_length= key_part->length / cs->mbmaxlen; const byte *pos= table->record[0] + key_part->offset; if (length > char_length) { char_length= my_charpos(cs, pos, pos + length, char_length); set_if_smaller(char_length, length); } if (cs->coll->strnncollsp(cs, (const uchar*) key, length, (const uchar*) pos, char_length, 0)) return 1; continue; } if (memcmp(key,table->record[0]+key_part->offset,length)) return 1; } return 0; } /* unpack key-fields from record to some buffer */ /* This is used to get a good error message */ void key_unpack(String *to,TABLE *table,uint idx) { KEY_PART_INFO *key_part,*key_part_end; Field *field; String tmp; DBUG_ENTER("key_unpack"); to->length(0); for (key_part=table->key_info[idx].key_part,key_part_end=key_part+ table->key_info[idx].key_parts ; key_part < key_part_end; key_part++) { if (to->length()) to->append('-'); if (key_part->null_bit) { if (table->record[0][key_part->null_offset] & key_part->null_bit) { to->append(STRING_WITH_LEN("NULL")); continue; } } if ((field=key_part->field)) { field->val_str(&tmp); if (key_part->length < field->pack_length()) tmp.length(min(tmp.length(),key_part->length)); to->append(tmp); } else to->append(STRING_WITH_LEN("???")); } DBUG_VOID_RETURN; } /* Return 1 if any field in a list is part of key or the key uses a field that is automaticly updated (like a timestamp) */ bool check_if_key_used(TABLE *table, uint idx, List &fields) { List_iterator_fast f(fields); KEY_PART_INFO *key_part,*key_part_end; for (key_part=table->key_info[idx].key_part,key_part_end=key_part+ table->key_info[idx].key_parts ; key_part < key_part_end; key_part++) { Item_field *field; if (key_part->field == table->timestamp_field) return 1; // Can't be used for update f.rewind(); while ((field=(Item_field*) f++)) { if (key_part->field->eq(field->field)) return 1; } } /* If table handler has primary key as part of the index, check that primary key is not updated */ if (idx != table->s->primary_key && table->s->primary_key < MAX_KEY && (table->file->table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX)) return check_if_key_used(table, table->s->primary_key, fields); return 0; } /* Compare key in row to a given key SYNOPSIS key_cmp() key_part Key part handler key Key to compare to value in table->record[0] key_length length of 'key' RETURN The return value is SIGN(key_in_row - range_key): 0 Key is equal to range or 'range' == 0 (no range) -1 Key is less than range 1 Key is larger than range */ int key_cmp(KEY_PART_INFO *key_part, const byte *key, uint key_length) { uint store_length; for (const byte *end=key + key_length; key < end; key+= store_length, key_part++) { int cmp; store_length= key_part->store_length; if (key_part->null_bit) { /* This key part allows null values; NULL is lower than everything */ register bool field_is_null= key_part->field->is_null(); if (*key) // If range key is null { /* the range is expecting a null value */ if (!field_is_null) return 1; // Found key is > range /* null -- exact match, go to next key part */ continue; } else if (field_is_null) return -1; // NULL is less than any value key++; // Skip null byte store_length--; } if ((cmp=key_part->field->key_cmp((byte*) key, key_part->length)) < 0) return -1; if (cmp > 0) return 1; } return 0; // Keys are equal } /* Compare two records in index order SYNOPSIS key_rec_cmp() key Index information rec0 Pointer to table->record[0] first_rec Pointer to record compare with second_rec Pointer to record compare against first_rec DESCRIPTION This method is set-up such that it can be called directly from the priority queue and it is attempted to be optimised as much as possible since this will be called O(N * log N) times while performing a merge sort in various places in the code. We retrieve the pointer to table->record[0] using the fact that key_parts have an offset making it possible to calculate the start of the record. We need to get the diff to the compared record since none of the records being compared are stored in table->record[0]. We first check for NULL values, if there are no NULL values we use a compare method that gets two field pointers and a max length and return the result of the comparison. */ int key_rec_cmp(void *key, byte *first_rec, byte *second_rec) { KEY *key_info= (KEY*)key; uint key_parts= key_info->key_parts, i= 0; KEY_PART_INFO *key_part= key_info->key_part; char *rec0= key_part->field->ptr - key_part->offset; my_ptrdiff_t first_diff= first_rec - (byte*)rec0, sec_diff= second_rec - (byte*)rec0; int result= 0; DBUG_ENTER("key_rec_cmp"); do { Field *field= key_part->field; if (key_part->null_bit) { /* The key_part can contain NULL values */ bool first_is_null= field->is_null_in_record_with_offset(first_diff); bool sec_is_null= field->is_null_in_record_with_offset(sec_diff); /* NULL is smaller then everything so if first is NULL and the other not then we know that we should return -1 and for the opposite we should return +1. If both are NULL then we call it equality although it is a strange form of equality, we have equally little information of the real value. */ if (!first_is_null) { if (!sec_is_null) ; /* Fall through, no NULL fields */ else { DBUG_RETURN(+1); } } else if (!sec_is_null) { DBUG_RETURN(-1); } else goto next_loop; /* Both were NULL */ } /* No null values in the fields We use the virtual method cmp_max with a max length parameter. For most field types this translates into a cmp without max length. The exceptions are the BLOB and VARCHAR field types that take the max length into account. */ result= field->cmp_max(field->ptr+first_diff, field->ptr+sec_diff, key_part->length); next_loop: key_part++; } while (!result && ++i < key_parts); DBUG_RETURN(result); }