database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

Optimize performance of my_bitmap

Browse Source 
MDEV-33502 Slowdown when running nested statement with many partitions

This change was triggered to help some MariaDB users with close to
10000 bits in their bitmaps.

- Change underlaying storage to be 64 bit instead of 32bit.
  - This reduses number of loops to scan bitmaps.
  - This can cause some bitmaps to be 4 byte large.
- Ensure that all not used top-bits are always 0 (simplifes code as
  the last 64 bit storage is not a special case anymore).
- Use my_find_first_bit() to find the first set bit which is much faster
  than scanning trough things byte by byte and then bit by bit.

Other things:
- Added a bool to remember if my_bitmap_init() did allocate the bitmap
  array. my_bitmap_free() will only free arrays it did allocate.
  This allowed me to remove setting 'bitmap=0' before calling
  my_bitmap_free() for cases where the bitmap's where allocated externally.
- my_bitmap_init() sets bitmap to 0 in case of failure.
- Added 'universal' asserts to most bitmap functions.
- Change all remaining calls to bitmap_init() to my_bitmap_init().
  - To finish the change from 2014.
- Changed all usage of uint32 in my_bitmap.h to my_bitmap_map.
- Updated bitmap_copy() to handle bitmaps of different size.
- Removed const from bitmap_exists_intersection() as this caused casts
  on all usage.
- Removed not used function bitmap_set_above().
- Renamed create_last_word_mask() to create_last_bit_mask() (to match
  name changes in my_bitmap.cc)
- Extended bitmap-t with test for more bitmap functions.
This commit is contained in:
Monty
2024-02-18 17:30:01 +02:00
parent d4e1731fbc
commit b5d65fc105
18 changed files with 452 additions and 397 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
sql/sql_insert.cc
View File

@ -1419,7 +1419,7 @@ static bool check_view_insertability(THD * thd, TABLE_LIST *view)
*trans_end= trans_start + num;
Field_translator *trans;
uint used_fields_buff_size= bitmap_buffer_size(table->s->fields);
uint32 *used_fields_buff= (uint32*)thd->alloc(used_fields_buff_size);
my_bitmap_map *used_fields_buff= (my_bitmap_map*)thd->alloc(used_fields_buff_size);
MY_BITMAP used_fields;
enum_column_usage saved_column_usage= thd->column_usage;
DBUG_ENTER("check_key_in_view");
@ -2828,6 +2828,8 @@ TABLE *Delayed_insert::get_local_table(THD* client_thd)
copy->def_read_set.bitmap= (my_bitmap_map*) bitmap;
copy->def_write_set.bitmap= ((my_bitmap_map*)
(bitmap + share->column_bitmap_size));
create_last_bit_mask(&copy->def_read_set);
create_last_bit_mask(&copy->def_write_set);
bitmaps_used= 2;
if (share->default_fields || share->default_expressions)
{