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merge

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monty@narttu.mysql.fi
2003-10-07 21:41:07 +03:00
parent 6112853cda 1f8e38d03a
commit 359d40f2f5
168 changed files with 2858 additions and 6744 deletions
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69
sql/sql_select.cc
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@ -2574,7 +2574,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
best=best_time=records=DBL_MAX;
KEYUSE *best_key=0;
uint best_max_key_part=0;
my_bool found_constrain= 0;
my_bool found_constraint= 0;
if (s->keyuse)
{ /* Use key if possible */
@ -2639,7 +2639,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
}
else
{
found_constrain= 1;
found_constraint= 1;
/*
Check if we found full key
*/
@ -2801,29 +2801,50 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
s->table->used_keys && best_key) &&
!(s->table->force_index && best_key))
{ // Check full join
ha_rows rnd_records= s->found_records;
if (s->on_expr)
{
tmp=rows2double(rnd_records); // Can't use read cache
}
else
{
tmp=(double) s->read_time;
/* Calculate time to read previous rows through cache */
tmp*=(1.0+floor((double) cache_record_length(join,idx)*
record_count /
(double) thd->variables.join_buff_size));
}
ha_rows rnd_records= s->found_records;
/* Estimate cost of reading table. */
tmp= s->table->file->scan_time();
/*
If there is a restriction on the table, assume that 25% of the
rows can be skipped on next part.
This is to force tables that this table depends on before this
table
*/
if (found_constraint)
rnd_records-= rnd_records/4;
/*
If there is a restriction on the table, assume that 25% of the
rows can be skipped on next part.
This is to force tables that this table depends on before this
table
*/
if (found_constrain)
rnd_records-= rnd_records/4;
if (s->on_expr) // Can't use join cache
{
tmp= record_count *
/* We have to read the whole table for each record */
(tmp +
/*
And we have to skip rows which does not satisfy join
condition for each record.
*/
(s->records - rnd_records)/(double) TIME_FOR_COMPARE);
}
else
{
/* We read the table as many times as join buffer becomes full. */
tmp*= (1.0 + floor((double) cache_record_length(join,idx) *
record_count /
(double) thd->variables.join_buff_size));
/*
We don't make full cartesian product between rows in the scanned
table and existing records because we skip all rows from the
scanned table, which does not satisfy join condition when
we read the table (see flush_cached_records for details). Here we
take into account cost to read and skip these records.
*/
tmp+= (s->records - rnd_records)/(double) TIME_FOR_COMPARE;
}
/*
We estimate the cost of evaluating WHERE clause for found records
as record_count * rnd_records + TIME_FOR_COMPARE. This cost plus
tmp give us total cost of using TABLE SCAN
*/
if (best == DBL_MAX ||
(tmp + record_count/(double) TIME_FOR_COMPARE*rnd_records <
best + record_count/(double) TIME_FOR_COMPARE*records))
@ -4453,6 +4474,8 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
new_field->field_name=item->name;
if (org_field->maybe_null())
new_field->flags&= ~NOT_NULL_FLAG; // Because of outer join
if (org_field->type()==FIELD_TYPE_VAR_STRING)
table->db_create_options|= HA_OPTION_PACK_RECORD;
}
return new_field;
}