Binlog event checksum

Introduction

The my.cnf option rpl_event_checksums enables the use of binlog event checksums. Note that both slaves and masters must used this patch when this is enabled. It is disabled by default.

Details

From tests I ran in the past, the use of checksums reduced performance by 10%. For tests that I run today it reduces performance by 3% to 7% at high levels of concurrency. The checksum is computed with crc32. The use of adler32 from zlib in place of crc32 does not change performance. These are results from sysbench readwrite on a 16-core server for 1 to 64 concurrent users:

Checksum	1 user	2 users	4 users	8 users	16 users	32 users	64 users
none	170	379	702	1113	1227	1191	1103
crc32	171	371	688	1064	1205	1153	1067