Ronald Bradford
MySQL Expert

MySQL Expert Ronald Bradford shares valuable input in MySQL Performance Tuning, MySQL Scalability and general MySQL Help from his two decades of working with MySQL, Oracle, Ingres and development technologies.

Archive for the ‘memcached’ Category

NoSQL options

Tuesday, October 6th, 2009

The NoSQL event in New York had a number of presentations on non relational technologies including of Hadoop, MongoDB and CouchDB.

Coming historically from a relational background of 20 years with Ingres, Oracle and MySQL I have been moving my focus towards non relational data store. The most obvious and well used today is memcached, a non persistent distributed key/value pair store. There are a number of persistent key/value stores in the marketplace, Tokyo Cabinet, Project Voldemort and Redis to name a few.

My list of data store products helps to identify the complex name space of varying products that now exist. A trend is towards schema less solutions, the ability to better manage dynamically typed/formatted information and the Agile Methodology release approach is simply non achievable in a statically type relational database table/column structure. The impact of constant ALTER TABLE commands in a MySQL database makes your production system unusable.

In a highly distribute online and increasing offline operation, fault tolerance and data synchronization and eventual consistency are required features in complex topologies such as multi-master.

I advise and promote a technology agnostic solution when possible. With the use of an API this is actually achievable, however in order to use a variety of backend data store products, one must consider the design patterns for optimal management. Two factors to support a highly distributed data set are no joins and minimal transactional semantics. The Facebook API is a great example, where there are no joins for their MySQL Relational backend. The movement back to a logical and non-normalized schema, or move towards a totally schemaless solution do require great though in the architectural concepts of your application.

Ultimately feature requirements will dictate the relative strengths and weaknesses of products. Full text search is a good example. CouchDB provides native support via Lucene. Another feature I like of couchDB is its append only data mode. This makes durability easy, and auto-recovery after crash a non issue, another feature a transactional relational database can not achieve.

With a 2 day no:sql(east) conference this month, there is definitely greater interest in this space.

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Posted in 10gen, Cloud Computing, Databases, Ingres, MySQL, Open Source, Oracle, Professional, Uncategorized, memcached | 7 Comments »

multi-threaded memcached

Thursday, June 11th, 2009

I discovered while compiling Wafflegrid today that by default, the Ubuntu binaries for memcached are not-multithreaded.

Following the installation of memcached from apt-get and libmemcached I ran memslap for:

$ memslap -s localhost
    Threads connecting to servers 1
    Took 1.633 seconds to load data

$ memstat -s localhost
Listing 1 Server

Server: localhost (11211)
     pid: 23868
     uptime: 54
     time: 1244575816
     version: 1.2.2
     pointer_size: 32
     rusage_user: 0.90000
     rusage_system: 0.120000
     curr_items: 10000
     total_items: 10000
     bytes: 5430000
     curr_connections: 1
     total_connections: 3
     connection_structures: 2
     cmd_get: 0
     cmd_set: 10000
     get_hits: 0
     get_misses: 0
     evictions: 0
     bytes_read: 5430000
     bytes_written: 5430000
     limit_maxbytes: 0
     threads: 1

By installed the Latest RC 1.4.0 we see.

memslap -s localhost
    Threads connecting to servers 1
    Took 0.866 seconds to load data

memstat -s localhost

Listing 1 Server

Server: localhost (11211)
     pid: 8651
     uptime: 375
     time: 1244577237
     version: 1.4.0-rc1
     pointer_size: 32
     rusage_user: 0.110000
     rusage_system: 0.130000
     curr_items: 10000
     total_items: 10000
     bytes: 5510000
     curr_connections: 5
     total_connections: 8
     connection_structures: 6
     cmd_get: 0
     cmd_set: 10000
     get_hits: 0
     get_misses: 0
     evictions: 0
     bytes_read: 5510000
     bytes_written: 5510000
     limit_maxbytes: 0
     threads: 5

Thanks Matt for pointing that one out.

Posted in Databases, General, Linux, MySQL, Open Source, Professional, Ubuntu, Wafflegrid, memcached | 4 Comments »