Setting up for database maintenance

To perform the database maintenance operations, you need a writeable shallow copy of a database . A writable shallow copy of a kdb database only loads the metadata of your database files to make them visible on the file system and loads the actual file content as they are accessed. To optimise time and memory utilization, it is recommended not to load file content initially, as not all files may be necessary for a database maintenance operation. For instance, in the case of renaming a table, no files are read or updated directly.

To create a writeable shallow copy of database, you can create dataviews with read write property set as true and enable on-demand caching in the configuration. A dataview performs minimal loading of files on the file system as needed by a database maintenance operation when on-demand caching is enabled. Reading an existing database file for the first time is slower as compared to accessing the files that have been previously read or newly written. This is because files are loaded onto the file system as they are accessed in case of on-demand caching.

Creating writeable dataviews by using console

Before you proceed, complete the following prerequisites:

• Create a kdb environment. For more information, see Creating a kdb environment.

• Create a kdb database. For more information, see Creating a kdb database.

• Create a new changeset. For more information, see Creating a new changeset.

• Create a kdb volume. Make sure this volume is not used by any other resource. For more information, see Creating a Managed kdb volume.

To create a writeable dataview

1. Sign in to the AWS Management Console and open the Amazon FinSpace console at https://console.aws.amazon.com/finspace.

2. In the left pane, under Managed kdb Insights, choose Kdb environments.

3. From the kdb environments table, choose the name of the environment.

4. On the environment details page, choose the Databases tab.

5. From the list of databases, choose a database name.

6. On database details page, choose the Dataviews tab.

7. Choose Create dataview.

8. On the Create dataview page, enter a unique name for the dataview.

9. (Optional) Enter a description for your dataview.

10. Choose the availability zone that you want to associate with the dataview. Currently, you can only choose single availability zone.

11. Under Changeset update settings, do the following.

    1. Choose Static mode of update.

       Note

       The Read Write option is only available for Static update mode as you cannot perform automatic updates on a writeable dataview.

    2. Select the Changeset ID for the changeset you created to indicate which version of data you want.

    3. Choose Read Write as True to make this dataview as writeable. You cannot change this later.

12. Add Segment configuration.

    Note

    • The Segment configuration is required if Read Write is True.

    • You can only add one segment for a writeable dataview.

    • The Database path is disabled and defaults to \* when Read Write is True as you cannot have partial writeable dataviews on cache.

    1. Choose a volume for caching. Use an exclusive volume for writable dataviews, it should not be in use by any other dataviews.

    2. For On demand caching, choose True to enable on demand caching on the selected database path when a particular file or a column of a database is accessed. When you enable on demand caching, files will only be copied to the dataview when they are accessed by code for reading or writing. When you disable on demand caching, everything is cached. The default value is False.

13. Choose Create dataview. The database details page opens and the table under Dataviews lists the newly created database along with its status.

Creating writeable dataviews by using FinSpace API operations

Before you proceed, complete the following prerequisites:

• Create a kdb environment by using the CreateKxEnvironment API operation.

• Create a kdb database by using the CreateKxDatabase API operation.

• Create a new changeset by using the CreateKxChangeset API operation.

• Create a kdb volume by using the CreateKxVolume API operation. Make sure this volume is unique for this dataview and is not used by any other resource.

To create a dataview with writable shallow copy of a database, create a dataview with the volume that has writable segments by using the CreateKxDataview API operation. You can make dataview as writeable by setting the readWrite parameter as true. You can only use this parameter for a static update mode. The onDemand parameter allows you to enable or disable on-demand caching on the selected dbPaths.

Sample CreateKxDataview API request

{
    "autoUpdate": false,
    "availabilityZoneId": "use1-az1",
    "clientToken": "65117136-4421-4371-0f1a-ce012823126",
    "changesetId": "latest_changesetId",
    "readWrite": true,
    "segmentConfigurations": [{
            "volumeName": "test_vol",
            "dbPaths": [
                "/*"
            ],
            "onDemand": true
        }

    ],
    "azMode": "SINGLE",
    "dataviewName": "test_dv"
}

Following are some of the considerations for the above request.

• The autoUpdate must be false for if readWrite is true on the dataviews.

• You need exclusive volume for creating a writable dataview. The volume mentioned in the segmentConfiguration should not be used by any other dataview.

• The dbPath must be set as "/*" for writable dataview.

• Only a single segmentConfiguration is allowed when readWrite is true. The dbPaths on the segment should be set as "\*" .

• A dataview with readWrite set as true is not allowed to be updated.

• You cannot update the readWrite property later.

• A dataview can only have a single segment if onDemand is true on a segment.