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Striim Platform 4.1.0 documentation

Delta Lake Writer properties

When creating a Delta Lake Writer target in TQL, you must specify values for the Connection URL, Hostname, Personal Access Token, and Tables properties. If not specified, the other properties will use their default values.

property

type

default value

notes

CDDL Action

String

Process

See Handling schema evolution.

Connection Retry Policy

String

initialRetryDelay=10s, retryDelayMultiplier=2, maxRetryDelay=1m, maxAttempts=5, totalTimeout=10m

Do not change unless instructed to by Striim support.

Connection URL

String

the JDBC URL from the JDBC/ODBC tab of the Databricks cluster's Advanced options (see Get connection details for a cluster)

External Stage Type

enum

DBFSROOT

With the default value (not recommended), events are staged to DBFS storage at the path specified in Stage Location.

If running Databricks on AWS, set to S3 and set the S3 properties as detailed below.

If running Azure Databricks, set to ADLSGen2 and set the ADLS properties as detailed below.

Hostname

String

the Server Hostname from the JDBC/ODBC tab of the Databricks cluster's Advanced options (see Get connection details for a cluster)

Ignorable Exception Code

String

Set to TABLE_NOT_FOUND to prevent the application from crashing when Striim tries to write to a table that does not exist in the target. See Handling "table not found" errors for more information.

Mode

enum

AppendOnly

With the default value AppendOnly:

  • Updates and deletes from DatabaseReader, IncrementalBatchReader, and SQL CDC sources are handled as inserts in the target.

  • Primary key updates result in two records in the target, one with the previous value and one with the new value. If the Tables setting has a ColumnMap that includes @METADATA(OperationName), the operation name for the first event will be DELETE and for the second INSERT.

Set to Merge to handle updates and deletes as updates and deletes instead. In Merge mode:

  • Since Delta Lake does not have primary keys, you may include the keycolumns option in the Tables property to specify a column in the target table that will contain a unique identifier for each row: for example, Tables:'SCOTT.EMP,mydatabase.employee keycolumns(emp_num)'.

  • You may use wildcards for the source table provided all the tables have the key columns. For example, Tables:'DEMO.%,mydatabase.% KeyColumns(...)'.

  • If you do not specify keycolumns , Striim will use the source table's keycolumns as a unique identifier. If the source table has no keycolumns, Striim will concatenate all column values and use that as a unique identifier.

Optimized Merge

Boolean

false

In Flow Designer, this property will be displayed only when Mode is Merge.

Set to True only when Mode is MERGE and the target's input stream is the output of an HP NonStop reader, MySQL Reader, or Oracle Reader source and the source events will include partial records. For example, with Oracle Reader, when supplemental logging has not been enabled for all columns, partial records are sent for updates. When the source events will always include full records, leave this set to false.

Parallel Threads

Integer

Not supported when Mode is Merge.

See Creating multiple writer instances.

Personal Access Token

encrypted password

Used to authenticate with the Databricks cluster (see Generate a personal access token). The user associated with the token must have read and write access to DBFS (see Important information about DBFS permissions). If table access control has been enabled, the user must also have MODIFY and READ_METADATA (see Data object privileges - Data governance model).

Stage Location

String

/

When the External Stage Type is DBFSROOT, the path to the staging area in DBFS, for example, /StriimStage/.

Tables

String

The name(s) of the table(s) to write to. The table(s) must exist in the database.

Specify target table names in uppercase as <database>.<table>.

When the target's input stream is a user-defined event, specify a single table.

The only special character allowed in target table names is underscore (_).

When the input stream of the writer is the output of a DatabaseReader, IncrementalBatchReader, or SQL CDC source it can write to multiple tables. In this case, specify the names of both the source and target tables. You may use the % wildcard for the table names, but not for the schema or database. If the reader uses three-part names, you must use them here as well. SQL Server source table names must be specified in three parts when the source is Database Reader or Incremental Batch Reader (database.schema.%,database.%), but in two parts when the source is MS SQL Reader or MS Jet (schema.%,database.%). Examples:

source.emp,target_database.emp
source_schema.%,target_database.%
source_database.source_schema.%,target_database.%

MySQL and Oracle names are case-sensitive, SQL Server names are not. Specify names as <schema name>.<table name> for MySQL and Oracle and as <database name>.<schema name>.<table name> for SQL Server.

See Mapping columns for additional options.

Upload Policy

String

eventcount:10000, interval:60s

The upload policy may include eventcount and/or interval (see Setting output names and rollover / upload policies for syntax). Buffered data is written to the storage account every time any of the specified values is exceeded. With the default value, data will be written every 60 seconds or sooner if the buffer contains 10,000 events. When the app is undeployed, all data remaining in the buffer is written to the storage account.

Azure Data Lake Storage (ADLS) Gen2 properties for Delta Lake Writer

property

type

default value

notes

Azure Account Access Key

encrypted password

the account access key from Storage accounts > <account name> > Access keys

Azure Account Name

String

the name of the Azure storage account for the blob container

Azure Container Name

String

the blob container name from Storage accounts > <account name> > Containers

If it does not exist, it will be created.

S3 properties for Delta Lake Writer

property

type

default value

notes

S3 Access Key

String

an AWS access key ID (created on the AWS Security Credentials page) for a user with read and write permissions on the bucket

If the Striim host has default credentials stored in the .aws directory, you may leave this blank.

S3 Bucket Name

String

Specify the S3 bucket to be used for staging. If it does not exist, it will be created.

S3 Region

String

the AWS region of the bucket

S3 Secret Access Key

encrypted password

the secret access key for the access key

If the Striim host has default credentials stored in the .aws directory, you may leave this blank.