Replace Database Parameters

This article explains how to change custom parameter values in an Exasol database.

Exasol databases are configured using parameters that are written as key-value pairs in the format "-parameter":"value". Parameters that are not explicitly defined will fall back on default values hard-coded in the application. The default values should be adequate for most use cases, but can be changed by adding custom parameter values in the configuration if needed.

This article explains how to update existing custom parameter values.

Invalid parameters will prevent the database from starting. To avoid unnecessary downtime, create a support case to get guidance from Support before you add or change database parameters.

Prerequisites

  • The database must be stopped. For more information, see Stop a Database.

  • The custom parameters that are to be replaced must exist in the database.

Procedure

The following examples use ConfD through the command-line tool confd_client, which is available on all database nodes. You can also access ConfD through XML-RPC in your own Python programs. For more information, see ConfD.

  1. Connect to the cluster operating system (COS) using c4 connect -i PLAY_ID -s cos.

    Example:
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    ./c4 connect -i c3275f84 -s cos

    For more information about how to use c4 connect, see How to use c4.

  2. To find the database name when you are connected to COS, use the ConfD job db_list.

    Example:
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    confd_client db_list
    - MY_DATABASE

  3. To find currently defined custom parameters, use the ConfD job db_info. Any custom parameters will be listed in the params: section.

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    confd_client db_info db_name: MY_DATABASE | grep params
     params: -forceProtocolEncryption=1 -soft_replicationborder_in_numrows=1000000

  4. If the database is running, stop it now using the ConfD job db_stop. For example:

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    confd_client db_stop db_name: MY_DATABASE

  5. To replace parameters, use the ConfD job db_configure with the attribute params: followed by the parameters to be replaced. For example:

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    confd_client db_configure db_name: MY_DATABASE params: '[-forceProtocolEncryption=0, -soft_replicationborder_in_numrows=2000000]'

  6. To verify that the configuration has been updated, use the ConfD job db_info. Any custom parameters will be listed in the params: section.

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    confd_client db_info db_name: MY_DATABASE | grep params
     params: -forceProtocolEncryption=0 -soft_replicationborder_in_numrows=2000000

  7. Start the database using the ConfD job db_start. For example:

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    confd_client db_start db_name: MY_DATABASE