Cassandra’s data model cheat sheet

May 2, 2010 Chaker 8 comments

Cassandra is a structured store. It has a rich data model that goes beyond a simple key-value model. This is a good thing as some of the complexity can be pushed to Cassandra, leading to simpler and more efficient applications. There is problem though: the guys who designed Cassandra have given complex names to the (rather simple) data model elements. This post tries to explain(again): “WTF is a SuperColumn“?

Data model elements

You can also download a PDF version.

Column

A name value pair (contains also a time-stamp, not represented here for the sake of clarity).

Column

Super Column

A sorted associative array of columns.

Super Column

Super Column

Column Family

A container for columns sorted by their names. Column Families are referenced and sorted by row keys.

Column Family

Column Family

Super Column Family

A container for super columns sorted by their names. Like Column Families, Super Column Families are referenced and sorted by row keys.

Super Column Family

Super Column Family

Keyspace

Top level element of a schema. Container for column families.

Examples

These examples are extracted from the model of a simple twitter clone discussed here. I picked the statuses column family and the user relationships super column family.

Statuses Column Family

Statuses Column Family

User Relationships Super Column Family

User Relationships Super Column Family

The Cassandra’s data model cheat sheet by Chaker Nakhli, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.

NoSql Cassandra, NoSql

Comments

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Written by Tweets that mention Cassandra’s data model cheat sheet « Chaker Nakhli’s Blog — Topsy.com about 4 months ago.

[...] This post was mentioned on Twitter by alexandre gerlic, Chaker Nakhli. Chaker Nakhli said: Just posted a #cheatsheet for #cassandra 's data model http://bit.ly/c5EXUE #pdf #nosql [...]
Written by Cassandra meets Hector(Sharp) – Chaker Nakhli's Blog about 4 months ago.

[...] The column path object indicates where a column is located in a family or super family. Standard1 is the family name. The second argument is null since the column we want to acess is not embedded into a super column. The last argument is the column name. If you are confused about Cassandra’s data model, you can have a look at this post. [...]
Written by kalpesh about 2 months ago.

Thanks man, the graphical examples asserted what model I had in mind for column families and supercolumns.
Written by Why Cassandra « DivConq about 2 months ago.

[...] these diagrams might help with the terminology – thanks to Chaker Nakhli for that helpful [...]
Written by Pedro Newsletter 14.07.2010 « Pragmatic Programmer Issues – pietrowski.info about 2 months ago.

[...] Cassandra model cheat sheet. [...]
Written by Uncle Mantis about 1 month ago.

What program did you use to make the graphics? I tried PowerPoint to no luck. I am looking for a program that does this but for Cassandra http://wb.mysql.com/
Written by mallikarjun about 2 weeks ago.

Hi,

I have a requirement of using Cassandra in my application. In my application there is one table with lot of data and most of my application uses that table. Due to lot of data,performance of the application is decreasing when i use that table is in Oracle.

So, I have decided to use the Cassandra database for that one table and all other tables in oracle. Lot of business logic is dependent on that table.

No my question is, Can I use the Cassandra for a table which has lot of business logic.

I am unable to implement lot of where clauses for Cassandra database.

Is there any supporting tool to use Cassandra in an efficient way?

Please let me know…
i am in urgency..

Thanks in advance

By Mallik
Written by Chaker about 2 weeks ago.

Hi Mallik,

A big central table with a lot of data and a lot of heterogeneous queries sounds like a bad idea. Before considering migrating to Cassandra you should probably try to do some optimization. I’m really not a db guru but if I were you I’d try to: look at the query plans and see if I can optimize them – see if denormalizng the schema can help – tune data partitioning – add/drop indexes – create views – etc.

If you have transactional data Cassandra is probably not for you. Cassandra is *eventually* consistent and does NOT provide the ACID properties that you are used to have with your Oracle db.

Hope this helps
–Chaker

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