一、摒弃掉的：
1、SHOW [GLOBAL] TEMPORARY TABLES功能取消，只能用TEMPORARY_TABLES 和 GLOBAL_TEMPORARY_TABLES
2、innodb_thread_concurrency_timer_based 参数取消，5.5默认是false；打开的化innodb控制线程并发的方式
将会用无锁的计时器机制。默认使用原始的互斥量机制。
3、innodb_recovery_stats参数废除：记录恢复的详细过程到errorlog里面。
4、慢查询日志和show processlist里面的rows_read列不再显示，因为本身是一个很模糊的值，没有太多有意义。
二、替代：
1、 show engine innodb status 的OLDEST VIEW的输出部分在5.6中调整到了视图xtradb_read_view显示
2、 show engine innodb status 的哈希表使用内存部分调整到XTRADB_INTERNAL_HASH_TABLES显示
3、 INNODB_RSEG表重命名成了 XTRADB_RSEG.
4、 为预读区分配固定大小使用了不同的实现方式：缓存预读区的值只在每一个缓存池初始化的时候预先计算一次，
而不是硬编码成64MB（之前版本的做法）
5、响应时间分布统计功能使用插件形式实现，扩展的原来的统计功能，读写分别作了单独统计，复制线程的慢更新
SQL不会被统计到，SHOW QUERY_RESPONSE_TIME命令废除，直接查询query_response_time表，刷新命令也从原来
的FLUSH QUERY_RESPONSE_TIME改成了变量query_response_time_flush控制
三、相似或者等价的功能点（官方版本加入或者percona自己做了进一步升级）：
1、Crash-Resistant Replication被 MYSQL creash safe replication替代
2、Improved InnoDB I/O Scalability功能补丁做了改进（废除参数：innodb_adaptive_flushing_method、
innodb_checkpoint_age_target、innodb_flush_neighbor_pages、innodb_read_ahead
新增：innodb_log_checksum_algorithm）
3、InnoDB Data Dictionary Size Limit功能在5.6中使用table-definition-cache这个变量来限制数据字典大小
4、Expand Table Import被InnoDB transportable tablespaces功能替代
5、The InnoDB data dictionary INFORMATION_SCHEMA tables have been superseded by the MySQL implementations
6、XtraDB SYS_STATS persistent table and index statistics has been replaced by the MySQL 5.6 implementation
7、Dump/Restore of the Buffer Pool被官方5.6功能替代
8、fast_index_creation (replaced by MySQL 5.6’s ALGORITHM= option).
9、Fast InnoDB Checksum has been deprecated after Percona Server 5.5.28-29.2 because the innodb_checksum_algorithm
variable in MySQL 5.6 makes it redundant.
10、Handle BLOB End of Line feature has been replaced by MySQL 5.6 binary-mode configuration option.
11、Percona Server 5.5 implemented utf8_general50_ci and ucs2_general50_ci collations as a fix for
the upstream bug: #27877. These are now being replaced by MySQL 5.6 utf8_general_mysql500_ci
and ucs2_general_mysql500_ci collations.
12、Percona Server INFORMATION_SCHEMA _STATS tables in 5.5 have been replaced by new tables in MySQL 5.6:
INNODB_SYS_TABLES, INNODB_SYS_INDEXES, INNODB_SYS_COLUMNS,INNODB_SYS_FIELDS, INNODB_SYS_FOREIGN,
INNODB_SYS_FOREIGN_COLS,INNODB_SYS_TABLESTATS (although MySQL 5.6 does not have MYSQL_HANDLES_OPENED,
instead it has REF_COUNT). Following tables haven’t been implemented in MySQL 5.6 but information is
available in other tables: INNODB_SYS_STATS - use MYSQL.INNODB_(INDEX|TABLE)_STATS instead,
INNODB_TABLE_STATS - use INNODB_SYS_TABLESTATS or MYSQL.INNODB_TABLE_STATS instead,
and INNODB_INDEX_STATS - use MYSQL.INNODB_INDEX_STATS instead.
四、从5.5引入：
Feature Ported Version
Thread Pool 5.6.10-60.2
Atomic write support for Fusion-io devices 5.6.11-60.3
Improved InnoDB I/O Scalability 5.6.11-60.3
Improved NUMA support 5.6.11-60.3
Suppress Warning Messages 5.6.11-60.3
Improved MEMORY Storage Engine 5.6.11-60.3
Restricting the number of binlog files 5.6.11-60.3
Too Many Connections Warning 5.6.11-60.3
Error Code Compatibility 5.6.11-60.3
Lock-Free SHOW SLAVE STATUS 5.6.11-60.3
Percona Toolkit UDFs 5.6.11-60.3
Support for Fake Changes 5.6.11-60.3
Kill Idle Transactions 5.6.11-60.3
Enforcing Storage Engine 5.6.11-60.3
Utility user 5.6.11-60.3
Extending the secure-file-priv server option 5.6.11-60.3
Expanded Program Option Modifiers 5.6.11-60.3
XtraDB changed page tracking 5.6.11-60.3
PAM Authentication Plugin 5.6.11-60.3
User Statistics 5.6.11-60.3
Slow Query Log 5.6.11-60.3
Extended Show Engine InnoDB Status 5.6.11-60.3
Count InnoDB Deadlocks 5.6.11-60.3
Log All Client Commands (syslog) 5.6.11-60.3
Show Storage Engines 5.6.11-60.3
Thread Based Profiling 5.6.11-60.3
Fixed Size for the Read Ahead Area 5.6.13-60.5
Improved Buffer Pool Scalability 5.6.13-60.6
Multiple Adaptive Hash Search Partitions 5.6.13-60.6
HandlerSocket 5.6.17-66.0
Response Time Distribution 5.6.21-69.0
五：status和变量差异。。。。