CQLSh: the CQL shell¶

pytz¶

By default, cqlsh displays all timestamps with a UTC timezone. To support display of timestamps with another timezone, the pytz library must be installed. See the timezone option in cqlshrc for specifying a timezone to use.

cython¶

The performance of cqlsh’s COPY operations can be improved by installing cython. This will compile the python modules that are central to the performance of COPY.

CONSISTENCY¶

Usage: CONSISTENCY <consistency level>

Sets the consistency level for operations to follow. Valid arguments include:

- ANY
- ONE
- TWO
- THREE
- QUORUM
- ALL
- LOCAL_QUORUM
- LOCAL_ONE
- SERIAL
- LOCAL_SERIAL

SERIAL CONSISTENCY¶

Usage: SERIAL CONSISTENCY <consistency level>

Sets the serial consistency level for operations to follow. Valid arguments include:

• SERIAL

• LOCAL_SERIAL

The serial consistency level is only used by conditional updates (INSERT, UPDATE, and DELETE with an IF condition). For those, the serial consistency level defines the consistency level of the serial phase (or “paxos” phase) while the normal consistency level defines the consistency for the “learn” phase, i.e. what type of reads will be guaranteed to see the update right away. For example, if a conditional write has a consistency level of QUORUM (and is successful), then a QUORUM read is guaranteed to see that write. However, if the regular consistency level of that write is ANY, then only a read with a consistency level of SERIAL is guaranteed to see it (even a read with consistency ALL is not guaranteed to be enough).

SHOW VERSION¶

This command is useful if you want to check which Cassandra version is compatible with your ScyllaDB version. Note that the two standards are not 100% identical and this command is simply a comparison tool.

If you want to display your current ScyllaDB version, refer to Check your current version of Scylla.

The display shows:

• The cqlsh tool version that you’re using

• The Apache Cassandra version that your version of ScyllaDB is most compatible with

• The CQL protocol standard that your version of ScyllaDB is most compatible with

• The native protocol standard that your version of ScyllaDB is most compatible with

Example:

cqlsh> SHOW VERSION

Returns:

[cqlsh 5.0.1 | Cassandra 3.0.8 | CQL spec 3.3.1 | Native protocol v4]

SHOW HOST¶

Prints the IP address and port of the ScyllaDB node that cqlsh is connected to in addition to the cluster name.

Example:

cqlsh> SHOW HOST

Returns:

Connected to Prod_Cluster at 192.0.0.1:9042.

SHOW SESSION¶

Pretty prints a specific tracing session.

Usage: SHOW SESSION <session id>

Example usage:

cqlsh> SHOW SESSION 95ac6470-327e-11e6-beca-dfb660d92ad8

Returns:

Tracing session: 95ac6470-327e-11e6-beca-dfb660d92ad8

 activity                                                  | timestamp                  | source    | source_elapsed | client
-----------------------------------------------------------+----------------------------+-----------+----------------+-----------
                                        Execute CQL3 query | 2016-06-14 17:23:13.979000 | 127.0.0.1 |              0 | 127.0.0.1
 Parsing SELECT * FROM system.local; [SharedPool-Worker-1] | 2016-06-14 17:23:13.982000 | 127.0.0.1 |           3843 | 127.0.0.1
...

SOURCE¶

Reads the contents of a file and executes each line as a CQL statement or special cqlsh command.

Usage: SOURCE <string filename>

Example usage:

cqlsh> SOURCE '/home/thobbs/commands.cql'

CAPTURE¶

Begins capturing command output and appending it to a specified file. Output will not be shown at the console while it is captured.

Usage:

CAPTURE '<file>';
CAPTURE OFF;
CAPTURE;

That is, the path to the file to be appended to must be given inside a string literal. The path is interpreted relative to the current working directory. The tilde shorthand notation ('~/mydir') is supported for referring to $HOME.

Only query result output is captured. Errors and output from cqlsh-only commands will still be shown in the cqlsh session.

To stop capturing output and show it in the cqlsh session again, use CAPTURE OFF.

To inspect the current capture configuration, use CAPTURE with no arguments.

HELP¶

Gives information about cqlsh commands. To see available topics, enter HELP without any arguments. To see help on a topic, use HELP <topic>. Also, see the --browser argument for controlling what browser is used to display help.

TRACING¶

Enables or disables tracing for queries. When tracing is enabled, once a query completes, a trace of the events during the query will be printed.

Usage:

TRACING ON
TRACING OFF

PAGING¶

Enables paging, disables paging, or sets the page size for read queries. When paging is enabled, only one page of data will be fetched at a time, and a prompt will appear to fetch the next page. Generally, it’s a good idea to leave paging enabled in an interactive session to avoid fetching and printing large amounts of data at once.

Usage:

PAGING ON
PAGING OFF
PAGING <page size in rows>

EXPAND¶

Enables or disables vertical printing of rows. Enabling EXPAND is useful when many columns are fetched, or the contents of a single column are large.

Usage:

EXPAND ON
EXPAND OFF

LOGIN¶

Authenticate as a specified ScyllaDB user for the current session.

Usage:

LOGIN <username> [<password>]

EXIT¶

Ends the current session and terminates the cqlsh process.

Usage:

EXIT
QUIT

CLEAR¶

Clears the console.

Usage:

CLEAR
CLS

DESCRIBE¶

Prints a description (typically a series of DDL statements) of a schema element or the cluster. This is useful for dumping all or portions of the schema.

DESCRIBE CLUSTER
DESCRIBE SCHEMA
DESCRIBE KEYSPACES
DESCRIBE KEYSPACE <keyspace name>
DESCRIBE TABLES
DESCRIBE TABLE <table name>
DESCRIBE MATERIALIZED VIEW <view name>
DESCRIBE TYPES
DESCRIBE TYPE <type name>
DESCRIBE FUNCTIONS
DESCRIBE FUNCTION <function name>
DESCRIBE AGGREGATES
DESCRIBE AGGREGATE <aggregate function name>

In any of the commands, DESC may be used in place of DESCRIBE.

You may also omit what you want to describe and just simply use DESCRIBE <name>. This will look for the object

in a specific order: keyspace, table, view, index, user-defined type, user-defined function, user-defined aggregate.

The DESCRIBE CLUSTER command prints the cluster name and partitioner:

cqlsh> DESCRIBE CLUSTER

Cluster: Test Cluster
Partitioner: Murmur3Partitioner

The DESCRIBE SCHEMA command prints the DDL statements needed to recreate the entire schema. The higher tiers of the statement can also include information that can be used to restore authentication/authorization and service levels. This is especially useful for cloning a cluster or restoring its state from a backup.

See a dedicated article to learn more.

COPY TO¶

Copies data from a table to a CSV file.

COPY <table name> [(<column>, ...)] TO <file name> WITH <copy option> [AND <copy option> ...]

If no columns are specified, all columns from the table will be copied to the CSV file. A subset of columns to copy may be specified by adding a comma-separated list of column names surrounded by parenthesis after the table name.

The <file name> should be a string literal (with single quotes) representing a path to the destination file. The file name can also contain the special value STDOUT (without single quotes) print the CSV to STDOUT.

See Shared COPY Options for options that apply to both COPY TO and COPY FROM.

COPY FROM¶

Copies data from a CSV file to table.

COPY <table name> [(<column>, ...)] FROM <file name> WITH <copy option> [AND <copy option> ...]

If no columns are specified, all columns from the CSV file will be copied to the table. A subset of columns to copy may be specified by adding a comma-separated list of column names surrounded by parenthesis after the table name.

The <file name> should be a string literal (with single quotes) representing a path to the source file. The file name can also contain the special value``STDIN`` (without single quotes) to read the CSV data from STDIN.

See Shared COPY Options for options that apply to both COPY TO and COPY FROM.