轉mysql存儲引擎memory，ndb，innodb之選擇

1

mysql的innodb和cluster的NDB引擎都支持事務，在有共同的特性外，也有不一樣之處：
以mysql cluster NDB 7.3和MySQL 5.6之InnoDB爲例：
ndb7.3基於mysql5.6，包括支持innodb1.1，所以能夠在cluster裏使用innodb表，但這些表不是集羣的。
MySQL Cluster NDB存儲引擎用分佈式, shared-nothing的架構實現，這使其和innodb有很多不一樣之處。好比事務、外鍵、表限制等，具體見下表：

Theseare shown in the following table:

Feature	InnoDB1.1	MySQLClusterNDB 7.3, MySQL Cluster NDB7.4
MySQLServer Version	5.6	5.6
InnoDBVersion	InnoDB5.6.23	InnoDB5.6.23
MySQLCluster Version	N/A	NDB7.3.9
StorageLimits	64TB	3TB (Practicalupper limit based on 48 data nodes with 64GB RAM each; can beincreased with disk-based data and BLOBs)
ForeignKeys	Yes	Priorto MySQL Cluster NDB 7.3: No. (Ignored, as withMyISAM) Availablein MySQL Cluster NDB 7.3.
Transactions	Allstandard types	READCOMMITTED
MVCC	Yes	No
DataCompression	Yes	No (MySQLCluster checkpoint and backup files can be compressed)
LargeRow Support (> 14K)	SupportedforVARBINARY,VARCHAR,BLOB,andTEXTcolumns	SupportedforBLOBandTEXTcolumns only (Usingthese types to store very large amounts of data can lower MySQLCluster performance)
ReplicationSupport	Asynchronousand semisynchronous replication using MySQL Replication	Automaticsynchronous replication within a MySQL Cluster. Asynchronousreplication between MySQL Clusters, using MySQL Replication
Scaleoutfor Read Operations	Yes(MySQL Replication)	Yes(Automatic partitioning in MySQL Cluster; MySQL Replication)
Scaleoutfor Write Operations	Requiresapplication-level partitioning (sharding)	Yes(Automatic partitioning in MySQL Cluster is transparent toapplications)
HighAvailability (HA)	Requiresadditional software	Yes(Designed for 99.999% uptime)
NodeFailure Recovery and Failover	Requiresadditional software	Automatic (Keyelement in MySQL Cluster architecture)
Timefor Node Failure Recovery	30seconds or longer	Typically< 1 second
Real-TimePerformance	No	Yes
In-MemoryTables	No	Yes (Somedata can optionally be stored on disk; both in-memory and diskdata storage are durable)
NoSQLAccess to Storage Engine	Nativememcached interface in development (see the MySQL Dev ZonearticleMySQLCluster 7.2 (DMR2): NoSQL, Key/Value, Memcached)	Yes MultipleAPIs, including Memcached, Node.js/JavaScript, Java, JPA, C++,and HTTP/REST
Concurrentand Parallel Writes	Notsupported	Upto 48 writers, optimized for concurrent writes
ConflictDetection and Resolution (Multiple Replication Masters)	No	Yes
HashIndexes	No	Yes
OnlineAddition of Nodes	Read-onlyreplicas using MySQL Replication	Yes(all node types)
OnlineUpgrades	No	Yes
OnlineSchema Modifications	Yes,as part of MySQL 5.6.	Yes.

 

 

數據驅動型應用負載於innodb和NDB存儲引擎之主要不一樣：

 

Workload	InnoDB	MySQLCluster (NDB)
High-VolumeOLTP Applications	Yes	Yes
DSSApplications (data marts, analytics)	Yes	Limited(Join operations across OLTP datasets not exceeding 3TB in size)
CustomApplications	Yes	Yes
PackagedApplications	Yes	Limited(should be mostly primary key access). MySQLCluster NDB 7.3 supports foreign keys.
In-NetworkTelecoms Applications (HLR, HSS, SDP)	No	Yes
SessionManagement and Caching	Yes	Yes
E-CommerceApplications	Yes	Yes
UserProfile Management, AAA Protocol	Yes	Yes

 

這兩種存儲引擎適合的應用場景

 

Preferredapplication requirements forInnoDB	Preferredapplication requirements forNDB
Foreignkeys Note MySQLCluster NDB 7.3 supports foreign keys. Fulltable scans Verylarge databases, rows, or transactions Transactionsother thanREADCOMMITTED	Writescaling 99.999%uptime Onlineaddition of nodes and online schema operations MultipleSQL and NoSQL APIs (seeMySQLCluster APIs: Overview and Concepts) Real-timeperformance Limiteduse ofBLOBcolumns Foreignkeys are supported, although their use may have an impact onperformance at high throughput

 

 

2

如何選擇memory存儲引擎或mysql cluster：
When to Use MEMORY or MySQL Cluster.
Developers looking to deploy applications that use the MEMORY storage engine for important, highly available, or frequently updated data should consider whether MySQL Cluster is a better choice. A typical use case for the MEMORY engine involves these
characteristics:
• Operations involving transient, non-critical data such as session management or caching. When the MySQL server halts or restarts, the data in MEMORY tables is lost.
• In-memory storage for fast access and low latency. Data volume can fit entirely in memory without causing the operating system to swap out virtual memory pages.
• A read-only or read-mostly data access pattern (limited updates).

MySQL Cluster offers the same features as the MEMORY engine with higher performance levels, and provides additional features not available with MEMORY:
• Row-level locking and multiple-thread operation for low contention between clients.
• Scalability even with statement mixes that include writes.
• Optional disk-backed operation for data durability.
• Shared-nothing architecture and multiple-host operation with no single point of failure, enabling 99.999% availability.
• Automatic data distribution across nodes; application developers need not craft custom sharding or partitioning solutions.
• Support for variable-length data types (including BLOB and TEXT) not supported by MEMORY.

MEMORY存儲引擎和MySQL Cluster的更多細節對比參見白皮書《Scaling Web Services with MySQL Cluster: An Alternative to the MySQL Memory Storage Engine》

Table 15.4 MEMORYStorage Engine Features

Storagelimits	RAM	Transactions	No	Lockinggranularity	Table
MVCC	No	Geospatialdata type support	No	Geospatialindexing support	No
B-treeindexes	Yes	T-treeindexes	No	Hashindexes	Yes
Full-textsearch indexes	No	Clusteredindexes	No	Datacaches	N/A
Indexcaches	N/A	Compresseddata	No	Encrypteddata[a]	Yes
Clusterdatabase support	No	Replicationsupport[b]	Yes	Foreignkey support	No
Backup/ point-in-time recovery[c]	Yes	Querycache support	Yes	Updatestatistics for data dictionary	Yes
[a]Implemented in the server (via encryption functions), ratherthan in the storage engine. [b]Implemented in the server, rather than in the storage engine. [c]Implemented in the server, rather than in the storage engine.

 

 

3

myisam, memory, ndb, archive, innodb存儲引擎功能彙總：

Table 15.1 StorageEngines Feature Summary

Feature	MyISAM	Memory	InnoDB	Archive	NDB
Storagelimits	256TB	RAM	64TB	None	384EB
Transactions	No	No	Yes	No	Yes
Lockinggranularity	Table	Table	Row	Table	Row
MVCC	No	No	Yes	No	No
Geospatialdata type support	Yes	No	Yes	Yes	Yes
Geospatialindexing support	Yes	No	Yes[a]	No	No
B-treeindexes	Yes	Yes	Yes	No	No
T-treeindexes	No	No	No	No	Yes
Hashindexes	No	Yes	No[b]	No	Yes
Full-textsearch indexes	Yes	No	Yes[c]	No	No
Clusteredindexes	No	No	Yes	No	No
Datacaches	No	N/A	Yes	No	Yes
Indexcaches	Yes	N/A	Yes	No	Yes
Compresseddata	Yes[d]	No	Yes[e]	Yes	No
Encrypteddata[f]	Yes	Yes	Yes	Yes	Yes
Clusterdatabase support	No	No	No	No	Yes
Replicationsupport[g]	Yes	Yes	Yes	Yes	Yes
Foreignkey support	No	No	Yes	No	No
Backup/ point-in-time recovery[h]	Yes	Yes	Yes	Yes	Yes
Querycache support	Yes	Yes	Yes	Yes	Yes
Updatestatistics for data dictionary	Yes	Yes	Yes	Yes	Yes
[a]InnoDB support for geospatial indexing is available in MySQL5.7.5 and higher. [b]InnoDB utilizes hash indexes internally for its AdaptiveHash Index feature. [c]InnoDB support for FULLTEXT indexes is available in MySQL5.6.4 and higher. [d]Compressed MyISAM tables are supported only when using thecompressed row format. Tables using the compressed row formatwith MyISAM are read only. [e]Compressed InnoDB tables require the InnoDB Barracuda fileformat. [f]Implemented in the server (via encryption functions), ratherthan in the storage engine. [g]Implemented in the server, rather than in the storageengine. [h]Implemented in the server, rather than in the storageengine.

 

要選mysql cluster要根據ndb存儲引擎的特徵和應用場景作詳細測試，安裝簡測見個人博文《centos65安裝簡測mysql cluster 7.3.7》http://blog.csdn.net/beiigang/article/details/43485585

 

參考

http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster.html

 

 

 

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