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dsbulk

https://docs.datastax.com/en/dsbulk/doc/ datastax/dsbulk (8)
Languages:Java
Templates:Cassandra
License:Apache 2.0

DataStax Bulk Loader Overview

The DataStax Bulk Loader tool (DSBulk) is a unified tool for loading into and unloading from Cassandra-compatible storage engines, such as OSS Apache Cassandra®, DataStax Astra and DataStax Enterprise (DSE).

Out of the box, DSBulk provides the ability to:

  1. Load (import) large amounts of data into the database efficiently and reliably;
  2. Unload (export) large amounts of data from the database efficiently and reliably;
  3. Count elements in a database table: how many rows in total, how many rows per replica and per token range, and how many rows in the top N largest partitions.

Currently, CSV and Json formats are supported for both loading and unloading data.

Documentation

The most up-to-date documentation is available online.

We also recommend reading the series of blog posts made by Brian Hess; they target a somewhat older version of DSBulk, but most of the contents are still valid and very useful:

  1. DataStax Bulk Loader Pt. 1 — Introduction and Loading
  2. DataStax Bulk Loader Pt. 2 — More Loading
  3. DataStax Bulk Loader Pt. 3 — Common Settings
  4. DataStax Bulk Loader Pt. 4 — Unloading
  5. DataStax Bulk Loader Pt. 5 — Counting
  6. DataStax Bulk Loader: Examples for Loading From Other Locations

Developers and contributors: please read our Contribution Guidelines.

Basic Usage

Launch the tool with the appropriate script in the bin directory of your distribution. The help text of the tool provides summaries of all supported settings.

The dsbulk command takes a subcommand argument followed by options:

# Load data
dsbulk load <options>

# Unload data
dsbulk unload <options>

# Count rows
dsbulk count <options>

Long options

Any DSBulk or Java Driver setting can be entered on the command line as a long-option argument of the following general form:

--full.path.of.setting "some-value"

DSBulk settings always start with dsbulk; for convenience, this prefix can be omitted in a long option argument, so the following two options are equivalent and both map to DSBulk's dsbulk.batch.mode setting:

--dsbulk.batch.mode PARTITION_KEY
--batch.mode PARTITION_KEY

Java Driver settings always start with datastax-java-driver; for convenience, this prefix can be shortened to driver in a long option argument, so the following two options are equivalent and both map to the driver's datastax-java-driver.basic.cloud.secure-connect-bundle setting:

--datastax-java-driver.basic.cloud.secure-connect-bundle /path/to/bundle
--driver.basic.cloud.secure-connect-bundle /path/to/bundle

Most settings have default values, or values that can be inferred from the input data. However, sometimes the default value is not suitable for you, in which case you will have to specify the desired value either in the application configuration file (see below), or on the command line.

For example, the default value for connector.csv.url is to read from standard input or write to standard output; if that does not work for you, you need to override this value and specify the source path/url of the csv data to load (or path/url where to send unloaded data).

See the Settings page or DSBulk's template configuration file for details.

Short options (Shortcuts)

For convenience, many options (prefaced with --), have shortcut variants (prefaced with -). For example, --dsbulk.schema.keyspace has an equivalent short option -k.

Connector-specific options also have shortcut variants, but they are only available when the appropriate connector is chosen. This allows multiple connectors to overlap shortcut options. For example, the JSON connector has a --connector.json.url setting with a -url shortcut. This overlaps with the -url shortcut option for the CSV connector, that actually maps to --connector.csv.url. But in a given invocation of dsbulk, only the appropriate shortcut will be active.

Run the tool with --help and specify the connector to see its short options:

dsbulk -c csv --help

Configuration Files vs Command Line Options

All DSBulk options can be passed as command line arguments, or in a configuration file.

Using one or more configuration files is sometimes easier than passing all configuration options via the command line.

By default, the configuration files are located under DSBulk's conf directory; the main configuration file is named application.conf. This location can be modified via the -f switch. See examples below.

DSBulk ships with a default, empty application.conf file that users can customize to their needs; it also has a template configuration file that can serve as a starting point for further customization.

Configuration files are also required to be compliant with the HOCON syntax. This syntax is very flexible and allows sections to be grouped together in blocks, e.g.:

dsbulk {
  connector {
    name = "csv"
    csv {
      url = "C:\\Users\\My Folder"
      delimiter = "\t"
    }
  }
}

The above is equivalent to the following snippet using dotted notation instead of blocks:

dsbulk.connector.name = "csv"
dsbulk.connector.csv.url = "C:\\Users\\My Folder"
dsbulk.connector.csv.delimiter = "\t"

You can split your configuration in more than one file using file inclusions; see the HOCON documentation for details. The default configuration file includes another file called driver.conf, also located in the conf directory. This file should be used to configure the Java Driver for DSBulk. This file is empty as well; users can customize it to their needs. A driver template configuration file can serve as a starting point for further customization.

Important caveats:

  1. In configuration files, it is not possible to omit the prefix dsbulk. For example, to select the connector to use in a configuration file, use dsbulk.connector.name = csv, as in the example above; on the command line, however, you can use --dsbulk.connector.name csv or --connector.name csv to achieve the same effect, as stated above.
  2. In configuration files, it is not possible to abbreviate the prefix datastax-java-driver to driver. For example, to select the consistency level to use in a configuration file, use datastax-java-driver.basic.request.consistency = QUORUM in a configuration file; on the command line, however, you can use both --datastax-java-driver.basic.request.consistency = QUORUM or --driver.basic.request.consistency = QUORUM to achieve the same effect.
  3. Options specified through the command line override options specified in configuration files. See examples for details.

Escaping and Quoting Command Line Arguments

Regardless of whether they are supplied via the command line or in a configuration file, all option values are expected to be in valid HOCON syntax: control characters, the backslash character, and the double-quote character all need to be properly escaped.

For example, \t is the escape sequence that corresponds to the tab character:

dsbulk load -delim '\t'

In general, string values containing special characters (such as a colon or a whitespace) also need to be properly quoted with double-quotes, as required by the HOCON syntax:

dsbulk load -h '"host.com:9042"'

File paths on Windows systems usually contain backslashes; \\ is the escape sequence for the backslash character, and since Windows paths also contain special characters, the whole path needs to be double-quoted:

dsbulk load -url '"C:\\Users\\My Folder"'

However, when the expected type of an option is a string, it is possible to omit the surrounding double-quotes, for convenience:

dsbulk load -url 'C:\\Users\\My Folder'

Similarly, when an argument is a list, it is possible to omit the surrounding square brackets; making the following two lines equivalent:

dsbulk load --codec.nullStrings 'NIL, NULL'
dsbulk load --codec.nullStrings '[NIL, NULL]'

The same applies for arguments of type map: it is possible to omit the surrounding curly braces, making the following two lines equivalent:

dsbulk load --connector.json.deserializationFeatures '{ USE_BIG_DECIMAL_FOR_FLOATS : true }'
dsbulk load --connector.json.deserializationFeatures 'USE_BIG_DECIMAL_FOR_FLOATS : true'

This syntactic sugar is only available for command line arguments of type string, list or map; all other option types, as well as all options specified in a configuration file must be fully compliant with HOCON syntax, and it is the user's responsibility to ensure that such options are properly escaped and quoted.

Also, note that this syntactic sugar is not capable of quoting single elements inside a list or a map; all elements in a list or a map must be individually quoted if they contain special characters. For example, to specify a list with 2 contact points containing port numbers, it is necessary to quote each contact point individually, however the surrounding brackets, as explained above, can be omitted for brevity:

dsbulk load -h '"host1.com:9042","host2.com:9042"'

Load Examples

  • Load table table1 in keyspace ks1 from CSV data read from stdin. Use a cluster with a localhost contact point. Field names in the data match column names in the table. Field names are obtained from a header row in the data; by default the tool presumes a header exists in each file being loaded:

    dsbulk load -k ks1 -t table1

  • Load table table1 in keyspace ks1 from a gzipped CSV file by unzipping it to stdout and piping to stdin of the tool:

    gzcat table1.csv.gz | dsbulk load -k ks1 -t table1

  • Load the file export.csv to table table1 in keyspace ks1 using the short form option for url and the tab character as a field delimiter:

    dsbulk load -k ks1 -t table1 -url export.csv -delim '\t'

  • Specify a few hosts (initial contact points) that belong to the desired cluster and load from a local file, without headers. Map field indices of the input to table columns:

    dsbulk load -url ~/export.csv -k ks1 -t table1 -h '10.200.1.3,10.200.1.4' -header false -m '0=col1,1=col3'

  • Specify port 9876 for the cluster hosts and load from an external source url:

    dsbulk load -url https://192.168.1.100/data/export.csv -k ks1 -t table1 -h '10.200.1.3,10.200.1.4' -port 9876

  • Load all csv files from a directory. The files do not have header rows. Map field indices of the input to table columns:

    dsbulk load -url ~/export-dir -k ks1 -t table1 -m '0=col1,1=col3' -header false

  • Load a file containing three fields per row. The file has no header row. Map all fields to table columns in field order. Note that field indices need not be provided.

    dsbulk load -url ~/export-dir -k ks1 -t table1 -m 'col1, col2, col3' -header false

  • With default port for cluster hosts, keyspace, table, and mapping set in conf/application.conf:

    dsbulk load -url https://192.168.1.100/data/export.csv -h '10.200.1.3,10.200.1.4'

  • With default port for cluster hosts, keyspace, table, and mapping set in dsbulk_load.conf:

    dsbulk load -f dsbulk_load.conf -url https://192.168.1.100/data/export.csv -h '10.200.1.3,10.200.1.4'

  • Load table table1 in keyspace ks1 from a CSV file, where double-quote characters in fields are escaped with a double-quote; for example, "f1","value with ""quotes"" and more" is a line in the CSV file:

    dsbulk load -url ~/export.csv -k ks1 -t table1 -escape '\"'

Unload Examples

Unloading is simply the inverse of loading and due to the symmetry, many settings are used in both load and unload.

  • Unload data to stdout from the ks1.table1 table in a cluster with a localhost contact point. Column names in the table map to field names in the data. Field names must be emitted in a header row in the output:

    dsbulk unload -k ks1 -t table1

  • Unload data to stdout from the ks1.table1 and gzip the result:

    dsbulk unload -k ks1 -t table1 | gzip > table1.gz

  • Unload data to a local directory (which may not yet exist):

    dsbulk unload -url ~/data-export -k ks1 -t table1

Count Examples

When counting rows in a table, no connector is required, and schema.mapping should not be present.

  • Count the total rows in the ks1.table1 table in a cluster with a localhost contact point.

    dsbulk count -k ks1 -t table1

  • Count the total number of rows per token range in the ks1.table1 table in a cluster with a localhost contact point.

    dsbulk count -k ks1 -t table1 -stats ranges

  • Count the total number of rows per host in the ks1.table1 table in a cluster with a localhost contact point.

    dsbulk count -k ks1 -t table1 -stats hosts

  • Count the total number of rows for the biggest 100 partitions in the ks1.table1 table in a cluster with a localhost contact point (by default, DSBulk returns the number of rows for the 10 biggest partitions in the table).

    dsbulk count -k ks1 -t table1 -stats partitions -partitions 100

  • Count the total number of rows, the total number of rows per token range, the total number of rows per hosts in the ks1.table1, and the total number of rows for the biggest 10 partitions table in a cluster with a localhost contact point.

    dsbulk count -k ks1 -t table1 -stats global,ranges,hosts,partitions

Command-line Help

Available settings along with defaults are documented here, they are also documented in DSBulk's template configuration file and in the driver template configuration file. This information is also available on the command-line via the help subcommand.

  • Get help for common options and a list of sections from which more help is available:

    dsbulk help

  • Get help for all connector.csv options:

    dsbulk help connector.csv

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