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Fixed LP bug#672497.

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Miscalculation of the minimum possible buffer size could trigger
an assert in JOIN_CACHE_HASHED::put_record when if join_buffer_size
was set to the values that is less than the length of one record to
stored in the join buffer.
It happened due to the following mistakes:
- underestimation of space needed for a key in the hash table
  (we have to take into account that hash table can have more
  buckets than the expected number of records).
- the value of maximum total length of all records stored in
  the join buffer was not saved in the field max_used_fieldlength
  by the function calc_used_field_length.
This commit is contained in:
Igor Babaev
2010-11-11 15:35:11 -08:00
parent 74d18e93c6
commit 92772d6d46
4 changed files with 125 additions and 6 deletions
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9
sql/sql_join_cache.cc
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@@ -731,7 +731,7 @@ ulong JOIN_CACHE::get_min_join_buffer_size()
ulong len= 0;
for (JOIN_TAB *tab= join_tab-tables; tab < join_tab; tab++)
len+= tab->get_max_used_fieldlength();
len+= get_record_max_affix_length() + get_max_key_addon_space_per_record();
len+= get_record_max_affix_length() + get_max_key_addon_space_per_record();
ulong min_sz= len*min_records;
ulong add_sz= 0;
for (uint i=0; i < min_records; i++)
@@ -2633,10 +2633,15 @@ uint JOIN_CACHE_HASHED::get_max_key_addon_space_per_record()
{
ulong len;
TABLE_REF *ref= &join_tab->ref;
/*
The total number of hash entries in the hash tables is bounded by
ceiling(N/0.7) where N is the maximum number of records in the buffer.
That's why the multiplier 2 is used in the formula below.
*/
len= (use_emb_key ? get_size_of_rec_offset() : ref->key_length) +
size_of_rec_ofs + // size of the key chain header
size_of_rec_ofs + // >= size of the reference to the next key
size_of_rec_ofs; // >= size of hash table entry
2*size_of_rec_ofs; // >= 2*( size of hash table entry)
return len;
}