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Fixed LP bug #801536.

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Ensured valid calculations of the estimates stored in JOIN_TAB::used_fieldlength.
This commit is contained in:
Igor Babaev 2011-06-26 21:55:32 -07:00
parent 77f8874c8b
commit cb164640be
1 changed files with 7 additions and 4 deletions
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11
sql/sql_select.cc
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@ -6492,7 +6492,8 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
void JOIN_TAB::calc_used_field_length(bool max_fl)
{
uint null_fields,blobs,fields,rec_length;
uint null_fields,blobs,fields;
ulong rec_length;
Field **f_ptr,*field;
uint uneven_bit_fields;
MY_BITMAP *read_set= table->read_set;
@ -6523,9 +6524,11 @@ void JOIN_TAB::calc_used_field_length(bool max_fl)
// TODO: to improve this estimate for max expected length
if (blobs)
{
uint blob_length=(uint) (table->file->stats.mean_rec_length-
(table->s->reclength-rec_length));
rec_length+=(uint) max(sizeof(void*) * blobs, blob_length);
ulong blob_length= table->file->stats.mean_rec_length;
if (ULONG_MAX - rec_length > blob_length)
rec_length+= blob_length;
else
rec_length= ULONG_MAX;
}
max_used_fieldlength= rec_length;
}