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Adjust cost for re-creating a row from the JOIN CACHE

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Creating a record from the join cache is faster than getting a row from
the engine (less and simpler code to execute).

Added JOIN_CACHE_ROW_COPY_COST_FACTOR (0.5 for now) as the factor to
take this into account. This is multiplied with ROW_COPY_COST.

Other things:
- Added cost of copying rows to hash join, similar to join_cache joins.
This commit is contained in:
Monty
2022-06-30 15:43:58 +03:00
committed by Sergei Petrunia
parent 4515a89814
commit 07df2029a3
15 changed files with 424 additions and 414 deletions
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6
sql/sql_select.cc
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@@ -8786,7 +8786,8 @@ best_access_path(JOIN *join,
row combinations, only a HASH_FANOUT (10%) rows in the cache.
*/
cmp_time= (rnd_records * record_count * HASH_FANOUT *
WHERE_COST_THD(thd));
(ROW_COPY_COST_THD(thd) * JOIN_CACHE_ROW_COPY_COST_FACTOR +
WHERE_COST_THD(thd)));
tmp= COST_ADD(tmp, cmp_time);
best_cost= tmp;
@@ -9018,7 +9019,8 @@ best_access_path(JOIN *join,
row.
*/
cmp_time= (rnd_records * record_count *
(ROW_COPY_COST_THD(thd) * (idx - join->const_tables) +
(ROW_COPY_COST_THD(thd) * (idx - join->const_tables) *
JOIN_CACHE_ROW_COPY_COST_FACTOR +
WHERE_COST_THD(thd)));
tmp= COST_ADD(tmp, cmp_time);
}