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MDEV-6838: Using too big key for internal temp tables

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This bug manifests due to wrong computation and evaluation of
keyinfo->key_length. The issues were:
* Using table->file->max_key_length() as an absolute value that must not be
  reached for a key, while it represents the maximum number of bytes
  possible for a table key.
* Incorrectly computing the keyinfo->key_length size during
  KEY_PART_INFO creation. The metadata information regarding the key
  such the field length (for strings) was added twice.
This commit is contained in:
Vicențiu Ciorbaru
2015-02-28 23:44:55 +02:00
parent fa87fc733d
commit 45b6edb158
6 changed files with 62 additions and 12 deletions
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34
sql/table.cc
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@@ -5968,18 +5968,32 @@ bool TABLE::alloc_keys(uint key_count)
}
void TABLE::create_key_part_by_field(KEY *keyinfo,
KEY_PART_INFO *key_part_info,
/**
@brief
Populate a KEY_PART_INFO structure with the data related to a field entry.
@param key_part_info The structure to fill.
@param field The field entry that represents the key part.
@param fleldnr The number of the field, count starting from 1.
TODO: This method does not make use of any table specific fields. It
could be refactored to act as a constructor for KEY_PART_INFO instead.
*/
void TABLE::create_key_part_by_field(KEY_PART_INFO *key_part_info,
Field *field, uint fieldnr)
{
{
key_part_info->null_bit= field->null_bit;
key_part_info->null_offset= (uint) (field->null_ptr -
(uchar*) record[0]);
key_part_info->field= field;
key_part_info->fieldnr= fieldnr;
key_part_info->offset= field->offset(record[0]);
key_part_info->length= (uint16) field->pack_length();
keyinfo->key_length+= key_part_info->length;
/*
field->key_length() accounts for the raw length of the field, excluding
any metadata such as length of field or the NULL flag.
*/
key_part_info->length= (uint16) field->key_length();
key_part_info->key_part_flag= 0;
/* TODO:
The below method of computing the key format length of the
@@ -5991,17 +6005,20 @@ void TABLE::create_key_part_by_field(KEY *keyinfo,
*/
key_part_info->store_length= key_part_info->length;
/*
The total store length of the key part is the raw length of the field +
any metadata information, such as its length for strings and/or the null
flag.
*/
if (field->real_maybe_null())
{
key_part_info->store_length+= HA_KEY_NULL_LENGTH;
keyinfo->key_length+= HA_KEY_NULL_LENGTH;
}
if (field->type() == MYSQL_TYPE_BLOB ||
field->type() == MYSQL_TYPE_GEOMETRY ||
field->real_type() == MYSQL_TYPE_VARCHAR)
{
key_part_info->store_length+= HA_KEY_BLOB_LENGTH;
keyinfo->key_length+= HA_KEY_BLOB_LENGTH; // ???
key_part_info->key_part_flag|=
field->type() == MYSQL_TYPE_BLOB ? HA_BLOB_PART: HA_VAR_LENGTH_PART;
}
@@ -6124,7 +6141,8 @@ bool TABLE::add_tmp_key(uint key, uint key_parts,
if (key_start)
(*reg_field)->key_start.set_bit(key);
(*reg_field)->part_of_key.set_bit(key);
create_key_part_by_field(keyinfo, key_part_info, *reg_field, fld_idx+1);
create_key_part_by_field(key_part_info, *reg_field, fld_idx+1);
keyinfo->key_length += key_part_info->store_length;
(*reg_field)->flags|= PART_KEY_FLAG;
key_start= FALSE;
key_part_info++;