Cassandra table and keyspace configuration tool.

Cassandra's DDL covers what is traditionally considered schema, but also information that is more configuration in nature. For example, consider keyspace creation:

CREATE KEYSPACE "globaldomain_T_mathoid__ng_mml" WITH replication = {'class': 'NetworkTopologyStrategy', 'codfw': '3', 'eqiad': '3'}  AND durable_writes = true;
-- \___________________________________________/      \________________________________________________________________________________________________________/
--                    |                                                                                   |
--                  schema                                                                          configuration

A keyspace in Cassandra is a namespace to associate tables with (similar to a database in MySQL terminology). Here, globaldomain_T_mathoid__ng_mml is the keyspace, and everything that follows the WITH is configuration pertaining to associated tables (replication, or whether or not to make use of the commitlog).

It is similar with tables:

-- Schema ~~~~~~~~~~~~~~~
CREATE TABLE "globaldomain_T_mathoid__ng_mml".data (
    "_domain" text,
    key text,
    headers text,
    tid timeuuid,
    value text,
    PRIMARY KEY (("_domain", key))
-- Configuration ~~~~~~~~
) WITH bloom_filter_fp_chance = 0.01
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND comment = ''
    AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'}
    AND compression = {'chunk_length_in_kb': '32', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND crc_check_chance = 1.0
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 86400
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.0
    AND speculative_retry = '99PERCENTILE';

Likewise, the DDL describes both schema, and table-specific configuration. In the example above, "globaldomain_T_mathoid__ng_mml".data is the table name, followed within the parenthesis by the names and types of the attributes. This is schema, as it models the data to be stored there. Everything that follows the WITH however, is configuration.

This is an important distinction (schema v configuration), because schema is determined by the application; No change in schema makes sense without a corresponding change to the application. Configuration however is site-specific, and operational in nature; Parameters can be unique to a use-case, and updated frequently outside of any change to the application. Schema is determined by application developers, configuration by users/operators.

Unfortunately, it is colloquial to refer to the entire DDL for a keyspace and/or table as schema. However, every effort is made throughput this ticket to use the term schema to mean only that which determines the data model, and configuration to refer to the corresponding operational settings.

table-properties allows the user to create the YAML representation (via -d switch) of existing keyspaces and tables. When saved the configuration can be changed and then used as input for table-properties to generate the ALTER statements.

keyspaces:
- durable_writes: true
  name: globaldomain_T_mathoid__ng_mml
  replication:
    class: SimpleStrategy
    replication_factor: 1
  tables:
  - bloom_filter_fp_chance: 0.01
    caching:
      keys: ALL
      rows_per_partition: NONE
    cdc: null
    comment: ''
    compaction:
      class: SizeTieredCompactionStrategy
      max_threshold: 32
      min_threshold: 4
    compression:
      chunk_length_in_kb: 32
      class: LZ4Compressor
    crc_check_chance: 1.0
    dclocal_read_repair_chance: 0.1
    default_time_to_live: 0
    extensions: {}
    flags:
    - compound
    gc_grace_seconds: 86400
    id: 1de04a10-a409-11e9-94f8-6dbc19352e3a
    max_index_interval: 2048
    memtable_flush_period_in_ms: 0
    min_index_interval: 128
    name: data
    read_repair_chance: 0.0
    speculative_retry: 99PERCENTILE

Python 3.4 or higher is required. Either clone the repo or download a zipped (release) version.

Install the dependencies with

pip install -r requirements.txt

From the command prompt, execute below to get help on available options

table-properties -h

To write the current configuration as formatted YAML to stdout

table-properties -d

Once you have an existing configuration, you can make changes to that YAML file and use it as an input file.

table-properties <filename>

This generates ALTER statements if any differences between the configurations were detected. Use

table-properties <filename> | cqlsh

to update Cassandra's configuration.

If the server connection is different from the default values, in addition to the CLI switches, an existing cqlshrc file can be used to provide those settings.

table-properties -r <cqlshrc filename>

  -h, --help                              show this help message and exit
  -i <ip>, --ip <ip>                      Host IP address or name. Default: localhost
  -C <filename>, --clientcert <filename>  Client cert file name.
  -d, --dump                              Dump current configuration to STDOUT
  -k <filename>, --clientkey <filename>   Client key file name.
  -l <filename>, --log <filename>         Log file name. If none is provied, STDERR is used.
  -p <port #>, --port <port #>            Port number. Default: 9042
  -P, --password                          Prompt for password.
  -q, --quiet                             When the flag is set exit with 0 only if the configuration matches the YAML file. Exit with code 1 otherwise.
  -r <filename>, --rcfile <filename>      cqlrc file name. Default: ~/.cassandra/cqlshrc
  -s, --ssl                               Use SSL/TLS encryption for client server communication.
  -u <user name>, --username <user name>  User name for plain text authentication.
  -v, --version                           Display version number and exit