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-rw-r--r--storage/maria/ma_unique.c271
1 files changed, 271 insertions, 0 deletions
diff --git a/storage/maria/ma_unique.c b/storage/maria/ma_unique.c
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+++ b/storage/maria/ma_unique.c
@@ -0,0 +1,271 @@
+/* Copyright (C) 2006 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
+ Copyright (c) 2020, MariaDB Corporation.
+
+ 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
+
+/* Functions to check if a row is unique */
+
+#include "maria_def.h"
+#include <m_ctype.h>
+
+/**
+ Check if there exist a row with the same hash
+
+ @notes
+ This function is not versioning safe. For the moment this is not a problem
+ as it's only used for internal temporary tables in MySQL for which there
+ isn't any versioning information.
+*/
+
+my_bool _ma_check_unique(MARIA_HA *info, MARIA_UNIQUEDEF *def,
+ const uchar *record,
+ ha_checksum unique_hash, my_off_t disk_pos)
+{
+ my_off_t lastpos=info->cur_row.lastpos;
+ MARIA_KEYDEF *keyinfo= &info->s->keyinfo[def->key];
+ uchar *key_buff= info->lastkey_buff2;
+ MARIA_KEY key;
+ int error= 0;
+ DBUG_ENTER("_ma_check_unique");
+ DBUG_PRINT("enter",("unique_hash: %lu", (ulong) unique_hash));
+
+ /* We need to store the hash value as a key in the record, breaking const */
+ maria_unique_store(record+keyinfo->seg->start, unique_hash);
+ /* Can't be spatial so it's ok to call _ma_make_key directly here */
+ _ma_make_key(info, &key, def->key, key_buff, record, 0, 0);
+
+ /* The above changed info->lastkey_buff2. Inform maria_rnext_same(). */
+ info->update&= ~HA_STATE_RNEXT_SAME;
+
+ /* Setup that unique key is active key */
+ info->last_key.keyinfo= keyinfo;
+
+ /* any key pointer in data is destroyed */
+ info->lastinx= ~0;
+
+ DBUG_ASSERT(key.data_length == MARIA_UNIQUE_HASH_LENGTH);
+ if (_ma_search(info, &key, SEARCH_FIND | SEARCH_SAVE_BUFF,
+ info->s->state.key_root[def->key]))
+ {
+ info->page_changed=1; /* Can't optimize read next */
+ info->cur_row.lastpos= lastpos;
+ goto end;
+ }
+
+ for (;;)
+ {
+ if (info->cur_row.lastpos != disk_pos &&
+ !(*info->s->compare_unique)(info,def,record,info->cur_row.lastpos))
+ {
+ my_errno=HA_ERR_FOUND_DUPP_UNIQUE;
+ info->errkey= (int) def->key;
+ info->dup_key_pos= info->cur_row.lastpos;
+ info->page_changed= 1; /* Can't optimize read next */
+ info->cur_row.lastpos= lastpos;
+ DBUG_PRINT("info",("Found duplicate"));
+ error= 1; /* Found identical */
+ goto end;
+ }
+ DBUG_ASSERT(info->last_key.data_length == MARIA_UNIQUE_HASH_LENGTH);
+ if (_ma_search_next(info, &info->last_key, SEARCH_BIGGER,
+ info->s->state.key_root[def->key]) ||
+ bcmp(info->last_key.data, key_buff, MARIA_UNIQUE_HASH_LENGTH))
+ {
+ info->page_changed= 1; /* Can't optimize read next */
+ info->cur_row.lastpos= lastpos;
+ break; /* end of tree */
+ }
+ }
+
+end:
+ DBUG_RETURN(error);
+}
+
+
+/*
+ Calculate a hash for a row
+
+ TODO
+ Add support for bit fields
+*/
+
+ha_checksum _ma_unique_hash(MARIA_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) *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= _ma_calc_blob_length(keyseg->bit_start,pos);
+ memcpy((void*) &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)
+ {
+ my_ci_hash_sort(keyseg->charset,
+ (const uchar*) pos, length,
+ &seed1, &seed2);
+ crc+= seed1;
+ }
+ else
+ {
+ my_hash_sort_bin((CHARSET_INFO*) 0, pos, (size_t) (end-pos),
+ &seed1, &seed2);
+ crc+= seed1;
+ }
+ }
+ return crc;
+}
+
+
+/*
+ compare unique key for two rows
+
+ TODO
+ Add support for bit fields
+
+ RETURN
+ 0 if both rows have equal unique value
+ 1 Rows are different
+*/
+
+my_bool _ma_unique_comp(MARIA_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) *pos_a++;
+ b_length= (uint) *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= _ma_calc_blob_length(keyseg->bit_start,pos_a);
+ b_length= _ma_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((void*) &pos_a, pos_a+keyseg->bit_start, sizeof(char*));
+ memcpy((void*) &pos_b, pos_b+keyseg->bit_start, sizeof(char*));
+ }
+ if (type == HA_KEYTYPE_TEXT/* the CHAR data type*/)
+ {
+ if (ha_compare_char_fixed(keyseg->charset,
+ pos_a, a_length,
+ pos_b, b_length,
+ keyseg->length / keyseg->charset->mbmaxlen,
+ FALSE/*b_is_prefix*/))
+ return 1;
+ }
+ else if (type == HA_KEYTYPE_VARTEXT1 ||
+ type == HA_KEYTYPE_VARTEXT2)
+ {
+ if (ha_compare_char_varying(keyseg->charset,
+ pos_a, a_length,
+ pos_b, b_length,
+ FALSE/*b_is_prefix*/))
+ 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;
+}
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