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1 B4M36DS2, BE4M36DS2: Database Systems 2 h p:// Prac cal Class 7 Cassandra Mar n Svoboda mar n.svoboda@fel.cvut.cz Charles University in Prague, Faculty of Mathema cs and Physics Czech Technical University in Prague, Faculty of Electrical Engineering

2 Data Model Database system structure Instance keyspaces tables rows columns Keyspace Table (column family) Collec on of (similar) rows Table schema must be specified, yet can be modified later on Row Collec on of columns Rows in a table do not need to have the same columns Each row is uniquely iden fied by a primary key Column Name-value pair + addi onal data B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

3 Data Model Column values Empty value Atomic value Na ve data types such as texts, integers, dates, Tuples Tuple of anonymous fields, each of any type (even different) User defined types (UDT) Set of named fields of any type Collec ons Lists, sets, and maps Nested tuples, UDTs, or collec ons are allowed, but currently only in frozen mode (such elements are serialized when stored) B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

4 Query Language CQL = Cassandra Query Language DDL statements creates a new keyspace creates a new table DML statements selects and projects rows from a single table inserts rows into a table updates columns of rows in a table removes rows from a table B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

5 First Steps Connect to our NoSQL server SSH / SFTP and PuTTY / WinSCP :22 Start CQLSH shell Basic useful commands Clear the shell terminal window Terminates the current database connec on B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

6 Keyspace Create your personal keyspace Use your login name as a name of your keyspace List all exis ng keyspaces Switch to your keyspace B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

7 Tables Create a new table for users Columns: integer iden fier, first name, last name View table defini on Insert new users into the table of users 1, Irena, Holubova 2, Mar n, Svoboda Browse exis ng users Find all users Find a specific user with iden fier 1 B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

8 Filtering Try to find a par cular user according to their last name Create a secondary index for last names Try to find a par cular user once again Enable filtering B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

9 Types Create a user-defined type for names of people Fields: first, last Create a new table for contacts Columns id: integer iden fier name: first and last name address: triple of street, city and ZIP code s: set of addresses apps: list of preferred messenger applica ons phones: map of phone numbers (work, home, ) B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

10 Inser on Insert new records into the table of contacts 1 Irena Holubova Malostranske names, Praha, holubova@ksi.mff.cuni.cz WhatsApp, Messenger work Mar n Svoboda svoboda@ksi.mff.cuni.cz, mar n.svoboda@mff.cuni.cz Viber, WhatsApp work , fax B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

11 Update Modify exis ng contact records Replace certain columns of a person with id 1 Replace address: Malostranske names 25, Praha, Replace applica ons: Hangouts Modify certain columns of a person with id 1 Add new address: holubova@ksi.mff.cuni.cz Add new applica ons: Messenger and WhatsApp Add new phone number: home Modify certain columns of a person with id 1 Remove address: irena.holubova@mff.cuni.cz Remove applica ons: Hangouts and Messenger Remove phone number: home B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

12 Dele on Modify columns of exis ng contact records Remove / update certain columns of a person with id 1 Remove address column Remove the first applica on Remove phone number to work B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

13 Aggrega on and Ordering Create a new table for messages Columns sender: integer iden fier of a sender app: name of a messenger applica on used date: date a given message was sent me: me a given message was sent recipient: integer iden fier of a recipient message: message text Primary key involves the following columns sender, app, date, and me Columns sender and app are considered to be par oning B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

14 Aggrega on and Ordering Insert the following rows into the table of messages B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

15 Aggrega on and Ordering Find all messages of a user with id 2 sent using whatsapp Order the rows according to dates and mes, both in descending order Aggregate messages sent by a par cular user with id 2 Return the overall number of sent messages for each combina on of an applica on name and message date B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

16 References CQL Cassandra Query Language h p://cassandra.apache.org/doc/latest/cql/ B4M36DS2, BE4M36DS2: Database Systems 2 Prac cal Class 7: Cassandra

Column-Family Stores: Cassandra

NDBI040: Big Data Management and NoSQL Databases h p://www.ksi.mff.cuni.cz/ svoboda/courses/2016-1-ndbi040/ Lecture 10 Column-Family Stores: Cassandra Mar n Svoboda svoboda@ksi.mff.cuni.cz 13. 12. 2016