Why do CentOS MySQL repostitories have different configurations for different chipsets?

user1032531 asked:

I installed two new CentOS 6.4 installations; one on an i686 VPS and the other on a physical x86_64 desktop, installed MySQL 5.1.69 on both using yum install mysql-server using CentOS’s repository, and made no other changes. SHOW VARIABLES; are identical on both except for the following. Why are they different? Does one have “better” values than another? If so, why is one better than the other.

+---------------------------+-----------------------+-------------------------+
|                           |         i386          |         x86_64          |
+---------------------------+-----------------------+-------------------------+
| max_binlog_cache_size     | 4294963200            | 18446744073709500000    |
| max_seeks_for_key         | 4294967295            | 18446744073709500000    |
| max_write_lock_count      | 4294967295            | 18446744073709500000    |
| myisam_max_sort_file_size | 2146435072            | 9223372036853720000     |
| myisam_mmap_size          | 4294967295            | 18446744073709500000    |
| plugin_dir                | /usr/lib/mysql/plugin | /usr/lib64/mysql/plugin |
+---------------------------+-----------------------+-------------------------+

My answer:


One architecture is 32-bit and the other is 64-bit. Those values correspond more or less exactly to the maximum unsigned and signed 32-bit and 64-bit vaules.


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