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Bug#40634 table scan temporary table is 4x slower due to mmap instead instead of caching

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mmap is slower that caching indeed.
    Here the problem is that mmap is used even if --myisam-use-mmap=OFF

    solved by checking the flag in ha_myisam::extra() as it is called in
    init_read_record()

per-file comments:
  storage/myisam/ha_myisam.cc
Bug#40634 table scan temporary table is 4x slower due to mmap instead instead of caching 
    do nothing for HA_EXTRA_MMAP if no opt_myisam_use_mmap
This commit is contained in:
Alexey Botchkov 2008-11-20 19:16:20 +04:00
parent c3dc1d6dfb
commit fc570243cf
1 changed files with 2 additions and 0 deletions
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2
storage/myisam/ha_myisam.cc
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@ -1789,6 +1789,8 @@ int ha_myisam::extra(enum ha_extra_function operation)
{
if ((specialflag & SPECIAL_SAFE_MODE) && operation == HA_EXTRA_KEYREAD)
return 0;
if (operation == HA_EXTRA_MMAP && !opt_myisam_use_mmap)
return 0;
return mi_extra(file, operation, 0);
}