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/* Copyright (C) 2000-2006 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Functions to handle keys and fields in forms */
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#include <drizzled/server_includes.h>
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Search after a key that starts with 'field'
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key First key to check
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key_count How many keys to check
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record Start of record
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field Field to search after
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key_length On partial match, contains length of fields before
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keypart key part # of a field
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Used when calculating key for NEXT_NUMBER
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If no key starts with field test if field is part of some key. If we find
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one, then return first key and set key_length to the number of bytes
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-1 field is not part of the key
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# Key part for key matching key.
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key_length is set to length of key before (not including) field
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int find_ref_key(KEY *key, uint32_t key_count, unsigned char *record, Field *field,
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uint32_t *key_length, uint32_t *keypart)
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register KEY *key_info;
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fieldpos= field->offset(record);
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/* Test if some key starts as fieldpos */
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for (i= 0, key_info= key ;
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if (key_info->key_part[0].offset == fieldpos)
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{ /* Found key. Calc keylength */
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*key_length= *keypart= 0;
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return i; /* Use this key */
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/* Test if some key contains fieldpos */
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for (i= 0, key_info= key;
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KEY_PART_INFO *key_part;
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for (j=0, key_part=key_info->key_part ;
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j < key_info->key_parts ;
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if (key_part->offset == fieldpos)
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return i; /* Use this key */
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*key_length+= key_part->store_length;
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return(-1); /* No key is ok */
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Copy part of a record that forms a key or key prefix to a buffer.
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The function takes a complete table record (as e.g. retrieved by
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handler::index_read()), and a description of an index on the same table,
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and extracts the first key_length bytes of the record which are part of a
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key into to_key. If length == 0 then copy all bytes from the record that
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@param to_key buffer that will be used as a key
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@param from_record full record to be copied from
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@param key_info descriptor of the index
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@param key_length specifies length of all keyparts that will be copied
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void key_copy(unsigned char *to_key, unsigned char *from_record, KEY *key_info,
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unsigned int key_length)
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KEY_PART_INFO *key_part;
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key_length= key_info->key_length;
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for (key_part= key_info->key_part; (int) key_length > 0; key_part++)
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if (key_part->null_bit)
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*to_key++= test(from_record[key_part->null_offset] &
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if (key_part->key_part_flag & HA_BLOB_PART ||
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key_part->key_part_flag & HA_VAR_LENGTH_PART)
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key_length-= HA_KEY_BLOB_LENGTH;
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length= cmin((uint16_t)key_length, key_part->length);
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key_part->field->get_key_image(to_key, length, Field::itRAW);
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to_key+= HA_KEY_BLOB_LENGTH;
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length= cmin((uint16_t)key_length, key_part->length);
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Field *field= key_part->field;
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const CHARSET_INFO * const cs= field->charset();
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uint32_t bytes= field->get_key_image(to_key, length, Field::itRAW);
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cs->cset->fill(cs, (char*) to_key + bytes, length - bytes, ' ');
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Zero the null components of key tuple.
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void key_zero_nulls(unsigned char *tuple, KEY *key_info)
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KEY_PART_INFO *key_part= key_info->key_part;
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KEY_PART_INFO *key_part_end= key_part + key_info->key_parts;
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for (; key_part != key_part_end; key_part++)
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if (key_part->null_bit && *tuple)
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memset(tuple+1, 0, key_part->store_length-1);
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tuple+= key_part->store_length;
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Restore a key from some buffer to record.
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This function converts a key into record format. It can be used in cases
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when we want to return a key as a result row.
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@param to_record record buffer where the key will be restored to
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@param from_key buffer that contains a key
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@param key_info descriptor of the index
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@param key_length specifies length of all keyparts that will be restored
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void key_restore(unsigned char *to_record, unsigned char *from_key, KEY *key_info,
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KEY_PART_INFO *key_part;
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key_length= key_info->key_length;
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for (key_part= key_info->key_part ; (int) key_length > 0 ; key_part++)
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unsigned char used_uneven_bits= 0;
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if (key_part->null_bit)
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to_record[key_part->null_offset]|= key_part->null_bit;
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to_record[key_part->null_offset]&= ~key_part->null_bit;
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if (key_part->key_part_flag & HA_BLOB_PART)
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This in fact never happens, as we have only partial BLOB
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keys yet anyway, so it's difficult to find any sence to
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restore the part of a record.
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Maybe this branch is to be removed, but now we
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have to ignore GCov compaining.
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uint32_t blob_length= uint2korr(from_key);
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Field_blob *field= (Field_blob*) key_part->field;
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from_key+= HA_KEY_BLOB_LENGTH;
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key_length-= HA_KEY_BLOB_LENGTH;
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field->set_ptr_offset(to_record - field->table->record[0],
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(ulong) blob_length, from_key);
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length= key_part->length;
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else if (key_part->key_part_flag & HA_VAR_LENGTH_PART)
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Field *field= key_part->field;
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my_ptrdiff_t ptrdiff= to_record - field->table->record[0];
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field->move_field_offset(ptrdiff);
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key_length-= HA_KEY_BLOB_LENGTH;
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length= cmin(key_length, key_part->length);
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field->set_key_image(from_key, length);
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from_key+= HA_KEY_BLOB_LENGTH;
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field->move_field_offset(-ptrdiff);
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length= cmin(key_length, key_part->length);
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/* skip the byte with 'uneven' bits, if used */
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memcpy(to_record + key_part->offset, from_key + used_uneven_bits
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, (size_t) length - used_uneven_bits);
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Compare if a key has changed.
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@param key key to compare to row
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@param idx Index used
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@param key_length Length of key
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In theory we could just call field->cmp() for all field types,
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but as we are only interested if a key has changed (not if the key is
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larger or smaller than the previous value) we can do things a bit
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faster by using memcmp() instead.
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bool key_cmp_if_same(Table *table,const unsigned char *key,uint32_t idx,uint32_t key_length)
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uint32_t store_length;
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KEY_PART_INFO *key_part;
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const unsigned char *key_end= key + key_length;;
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for (key_part=table->key_info[idx].key_part;
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key_part++, key+= store_length)
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store_length= key_part->store_length;
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if (key_part->null_bit)
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if (*key != test(table->record[0][key_part->null_offset] &
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if (key_part->key_part_flag & (HA_BLOB_PART | HA_VAR_LENGTH_PART |
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if (key_part->field->key_cmp(key, key_part->length))
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length= cmin((uint) (key_end-key), store_length);
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if (!(key_part->key_type & (FIELDFLAG_NUMBER+FIELDFLAG_BINARY+
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const CHARSET_INFO * const cs= key_part->field->charset();
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uint32_t char_length= key_part->length / cs->mbmaxlen;
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const unsigned char *pos= table->record[0] + key_part->offset;
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if (length > char_length)
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char_length= my_charpos(cs, pos, pos + length, char_length);
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set_if_smaller(char_length, length);
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if (cs->coll->strnncollsp(cs,
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(const unsigned char*) key, length,
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(const unsigned char*) pos, char_length, 0))
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if (memcmp(key,table->record[0]+key_part->offset,length))
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unpack key-fields from record to some buffer.
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This is used mainly to get a good error message. We temporary
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change the column bitmap so that all columns are readable.
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to Store value here in an easy to read form
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void key_unpack(String *to,Table *table,uint32_t idx)
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KEY_PART_INFO *key_part,*key_part_end;
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for (key_part=table->key_info[idx].key_part,key_part_end=key_part+
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table->key_info[idx].key_parts ;
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key_part < key_part_end;
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if (key_part->null_bit)
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if (table->record[0][key_part->null_offset] & key_part->null_bit)
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to->append(STRING_WITH_LEN("NULL"));
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if ((field=key_part->field))
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const CHARSET_INFO * const cs= field->charset();
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field->val_str(&tmp);
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if (cs->mbmaxlen > 1 &&
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table->field[key_part->fieldnr - 1]->field_length !=
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Prefix key, multi-byte charset.
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For the columns of type CHAR(N), the above val_str()
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call will return exactly "key_part->length" bytes,
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which can break a multi-byte characters in the middle.
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Align, returning not more than "char_length" characters.
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uint32_t charpos, char_length= key_part->length / cs->mbmaxlen;
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if ((charpos= my_charpos(cs, tmp.ptr(),
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tmp.ptr() + tmp.length(),
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char_length)) < key_part->length)
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if (key_part->length < field->pack_length())
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tmp.length(cmin(tmp.length(),(uint32_t)key_part->length));
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to->append(STRING_WITH_LEN("???"));
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Check if key uses field that is marked in passed field bitmap.
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table Table object with which keys and fields are associated.
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idx Key to be checked.
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fields Bitmap of fields to be checked.
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This function uses Table::tmp_set bitmap so the caller should care
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about saving/restoring its state if it also uses this bitmap.
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TRUE Key uses field from bitmap
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bool is_key_used(Table *table, uint32_t idx, const MY_BITMAP *fields)
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bitmap_clear_all(&table->tmp_set);
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table->mark_columns_used_by_index_no_reset(idx, &table->tmp_set);
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if (bitmap_is_overlapping(&table->tmp_set, fields))
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If table handler has primary key as part of the index, check that primary
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if (idx != table->s->primary_key && table->s->primary_key < MAX_KEY &&
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(table->file->ha_table_flags() & HA_PRIMARY_KEY_IN_READ_INDEX))
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return is_key_used(table, table->s->primary_key, fields);
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Compare key in row to a given key.
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@param key_part Key part handler
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@param key Key to compare to value in table->record[0]
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@param key_length length of 'key'
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The return value is SIGN(key_in_row - range_key):
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- 0 Key is equal to range or 'range' == 0 (no range)
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- -1 Key is less than range
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- 1 Key is larger than range
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int key_cmp(KEY_PART_INFO *key_part, const unsigned char *key, uint32_t key_length)
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uint32_t store_length;
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for (const unsigned char *end=key + key_length;
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key+= store_length, key_part++)
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store_length= key_part->store_length;
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if (key_part->null_bit)
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/* This key part allows null values; NULL is lower than everything */
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register bool field_is_null= key_part->field->is_null();
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if (*key) // If range key is null
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/* the range is expecting a null value */
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return 1; // Found key is > range
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/* null -- exact match, go to next key part */
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else if (field_is_null)
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return -1; // NULL is less than any value
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key++; // Skip null byte
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if ((cmp=key_part->field->key_cmp(key, key_part->length)) < 0)
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return 0; // Keys are equal
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Compare two records in index order
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key Index information
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rec0 Pointer to table->record[0]
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first_rec Pointer to record compare with
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second_rec Pointer to record compare against first_rec
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This method is set-up such that it can be called directly from the
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priority queue and it is attempted to be optimised as much as possible
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since this will be called O(N * log N) times while performing a merge
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sort in various places in the code.
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We retrieve the pointer to table->record[0] using the fact that key_parts
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have an offset making it possible to calculate the start of the record.
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We need to get the diff to the compared record since none of the records
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being compared are stored in table->record[0].
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We first check for NULL values, if there are no NULL values we use
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a compare method that gets two field pointers and a max length
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and return the result of the comparison.
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int key_rec_cmp(void *key, unsigned char *first_rec, unsigned char *second_rec)
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KEY *key_info= (KEY*)key;
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uint32_t key_parts= key_info->key_parts, i= 0;
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KEY_PART_INFO *key_part= key_info->key_part;
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unsigned char *rec0= key_part->field->ptr - key_part->offset;
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my_ptrdiff_t first_diff= first_rec - rec0, sec_diff= second_rec - rec0;
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Field *field= key_part->field;
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if (key_part->null_bit)
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/* The key_part can contain NULL values */
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bool first_is_null= field->is_null_in_record_with_offset(first_diff);
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bool sec_is_null= field->is_null_in_record_with_offset(sec_diff);
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NULL is smaller then everything so if first is NULL and the other
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not then we know that we should return -1 and for the opposite
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we should return +1. If both are NULL then we call it equality
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although it is a strange form of equality, we have equally little
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information of the real value.
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; /* Fall through, no NULL fields */
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else if (!sec_is_null)
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goto next_loop; /* Both were NULL */
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No null values in the fields
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We use the virtual method cmp_max with a max length parameter.
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For most field types this translates into a cmp without
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max length. The exceptions are the BLOB and VARCHAR field types
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that take the max length into account.
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result= field->cmp_max(field->ptr+first_diff, field->ptr+sec_diff,
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} while (!result && ++i < key_parts);
added
removed
drizzled/key.cc
