mirror of
https://github.com/MariaDB/server.git
synced 2026-02-14 14:48:40 +01:00
4cff562f3f
They were based on the maximum possible key tuple length, which can be much larger than the real data size. The return value is used by handler::keyread_time(), which is used to estimate the cost of range access. This could cause range access not to be picked, even if it uses the clustered PK and reads about 8% of the table. The fix is to add KEY::stat_storage_length (next to KEY::rec_per_key) and have the storage engine fill it in handler::info(HA_STATUS_CONST). Currently, only InnoDB fills this based on its internal statistics: index->stat_index_size and ib_table->stat_n_rows. Also changed: - In handler::calculate_costs(), use ha_keyread_clustered_time() when computing clustered PK read cost, not ha_keyread_time(). The fix is OFF by default and enabled by setting FIX_INDEX_LOOKUP_COST flag in @@new_mode. |
||
|---|---|---|
| .. | ||
| inc | ||
| r | ||
| t | ||
| disabled.def | ||