diff options
Diffstat (limited to 'sql/ha_innodb.cc')
| -rw-r--r-- | sql/ha_innodb.cc | 29 |
1 files changed, 25 insertions, 4 deletions
diff --git a/sql/ha_innodb.cc b/sql/ha_innodb.cc index ea8eaf6653e..b7b72426053 100644 --- a/sql/ha_innodb.cc +++ b/sql/ha_innodb.cc @@ -3501,10 +3501,8 @@ ha_innobase::records_in_range( /************************************************************************* Gives an UPPER BOUND to the number of rows in a table. This is used in -filesort.cc and the upper bound must hold. TODO: Since the number of -rows in a table may change after this function is called, we still may -get a 'Sort aborted' error in filesort.cc of MySQL. The ultimate fix is to -improve the algorithm of filesort.cc. */ +filesort.cc and its better if the upper bound hold. +*/ ha_rows ha_innobase::estimate_number_of_rows(void) @@ -3570,6 +3568,29 @@ ha_innobase::scan_time() return((double) (prebuilt->table->stat_clustered_index_size)); } +/* + Calculate the time it takes to read a set of ranges through and index + This enables us to optimise reads for clustered indexes. +*/ + +double ha_innobase::read_time(uint index, uint ranges, ha_rows rows) +{ + ha_rows total_rows; + double time_for_scan; + if (index != table->primary_key) + return handler::read_time(index, ranges, rows); // Not clustered + if (rows <= 2) + return (double) rows; + /* + Assume that the read is proportional to scan time for all rows + one + seek per range. + */ + time_for_scan= scan_time(); + if ((total_rows= estimate_number_of_rows()) < rows) + return time_for_scan; + return (ranges + (double) rows / (double) total_rows * time_for_scan); +} + /************************************************************************* Returns statistics information of the table to the MySQL interpreter, in various fields of the handle object. */ |