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

MDEV-21580: Allow packed sort keys in sort buffer

Browse Source 
This task deals with packing the sort key inside the sort buffer, which  would
lead to efficient usage of the memory allocated for the sort buffer.

The changes brought by this feature are
  1) Sort buffers would have sort keys of variable length
  2) The format for sort keys inside the sort buffer would look like
     |<sort_length><null_byte><key_part1><null_byte><key_part2>.......|
      sort_length is the extra bytes that are required to store the variable
      length of a sort key.
  3) When packing of sort key is done we store the ORIGINAL VALUES inside
     the sort buffer and not the STRXFRM form (mem-comparable sort keys).
  4) Special comparison function packed_keys_comparison() is introduced
     to compare 2 sort keys.

This patch also contains contributions from Sergei Petrunia.
This commit is contained in:
Varun Gupta
2020-03-10 04:56:38 +05:30
parent 561b5ce364
commit b753ac066b
23 changed files with 2075 additions and 299 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
sql/sql_select.cc
View File

@ -24060,7 +24060,7 @@ static int remove_dup_with_hash_index(THD *thd, TABLE *table,
field_length=field_lengths;
for (ptr= first_field ; *ptr ; ptr++)
{
(*ptr)->make_sort_key(key_pos, *field_length);
(*ptr)->make_sort_key_part(key_pos, *field_length);
key_pos+= (*ptr)->maybe_null() + *field_length++;
}
/* Check if it exists before */