This document discusses interfacing with the Cassandra database using Python. It introduces Cassandra as a column-based key-value store and describes how to create keyspaces and column families using the Cassandra CLI. It then explains how to interface with Cassandra from Python using the pycassa package, including connecting to Cassandra, performing insert, read, delete, batch, and slice operations on column families.

1. 4: Interfacing with Cassandra
Zubair Nabi
zubair.nabi@itu.edu.pk
April 20, 2013
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2. Introduction1
Project website: http://cassandra.apache.org/
1
Disclaimer: Based on the wonderful talk given by Jeremiah Jordan at PyCon 2012
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3. Introduction1
Project website: http://cassandra.apache.org/
Column based key value store (multi-level dictionary)
1
Disclaimer: Based on the wonderful talk given by Jeremiah Jordan at PyCon 2012
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4. Introduction1
Project website: http://cassandra.apache.org/
Column based key value store (multi-level dictionary)
Consists of keyspaces and column families
1
Disclaimer: Based on the wonderful talk given by Jeremiah Jordan at PyCon 2012
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5. Introduction1
Project website: http://cassandra.apache.org/
Column based key value store (multi-level dictionary)
Consists of keyspaces and column families
Keyspace: Namespace for column families (typically one per
application)
1
Disclaimer: Based on the wonderful talk given by Jeremiah Jordan at PyCon 2012
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6. Introduction1
Project website: http://cassandra.apache.org/
Column based key value store (multi-level dictionary)
Consists of keyspaces and column families
Keyspace: Namespace for column families (typically one per
application)
Column family: Contains multiple columns, each of which has a name,
value, and timestamp, and which are referenced by row keys
1
Disclaimer: Based on the wonderful talk given by Jeremiah Jordan at PyCon 2012
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9. Starting up
Running it: sudo cassandra -f
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10. Starting up
Running it: sudo cassandra -f
Running the CLI: cassandra-cli
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11. Creating a keyspace
Connecting to the store: connect localhost/9160;
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12. Creating a keyspace
Connecting to the store: connect localhost/9160;
Creating a keyspace: create keyspace ApplicationData
with placement_strategy =
’org.apache.cassandra.locator.SimpleStrategy’
and strategy_options =
[{replication_factor:1}];
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13. Creating a column family
Referencing a keyspace: use ApplicationData;
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14. Creating a column family
Referencing a keyspace: use ApplicationData;
Creating a column family: create column family UserInfo
and comparator = ’AsciiType’;
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15. Interfacing with Cassandra in Python
Package: pycassa
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16. Interfacing with Cassandra in Python
Package: pycassa
Webpage: https://github.com/pycassa/pycassa
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17. Pycassa Basics
1 import pycassa
2 from pycassa.pool import ConnectionPool
3 from pycassa.columnfamily import ColumnFamily
4
5 pool = ConnectionPool(’ApplicationData’,
6 [’localhost:9160’])
7 col_fam = ColumnFamily(pool, ’UserInfo’)
8 col_fam.insert(’John’, {’email’: ’john@gmail.com’})
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18. Read
1 readData = col_fam.get(’John’,
2 columns=[’email’])
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19. Delete
1 col_fam.remove(’John’,
2 columns=[’email’])
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20. Batch
1 col_fam.batch_insert(
2 {’John’: {’email’: ’john@gmail.com’,
3 ’state’: ’IL’,
4 ’gender’: ’M’},
5 ’Jane’: {’email’: ’jane@python.org’,
6 ’state’: ’CA’
7 ’gender’: ’M’}})
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21. Batch Stream
1 b = col_fam.batch(queue_size=10)
2
3 b.insert(’John’,
4 {’email’: ’john@gmail.com’,
5 ’state’: ’IL’,
6 ’gender’: ’M’})
7
8 b.insert(’Jane’,
9 {’email’: ’jane@python.org’,
10 ’state’: ’CA’})
11
12 b.remove(’John’, [’gender’])
13 b.remove(’Jane’)
14 b.send()
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22. Batch Read
1 readData = col_fam.multiget([’John’, ’Jane’, ’Bill’])
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23. Column Slice
1 d = col_fam.get(’Jane’,
2 column_start=’email’,
3 column_finish=’state’)
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24. Reference(s)
Apache Cassandra and Python:
https://pycon-2012-notes.readthedocs.org/en/
latest/apache_cassandra_and_python.html
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