redis.write

Write to a Redis Enterprise database

Write to a Redis Enterprise database

Properties

Name Type Description Required
connection string Name of Redis connection specified in config.yaml.
Defaults to connection named target.		 no
data_type
 string Type of Redis target data structure.
Enum: hash(default), json, set, sorted_set, stream, string.
Takes precedence over system property target_data_type.		 no
nest object Nest (embed) object within a different key.
If nesting is specified, the following parameters are ignored: key, args and on_update.		 no
key object Definition of the target Redis key.
 yes
∟ expression string Expression used to calculate the target key. yes
∟ language string Language used to define the expression.
Enum: jmespath, sql.		 yes
args object Arguments for modifying the target key.
Specific to the data type.		 no
mapping array Array of fields (or field: alias pairs) to be written to a Redis key.
Supported for hashes, json documents and streams only.		 no
on_update string Target key update strategy
Enum: merge, replace (default).		 no
expire integer TTL in seconds for the modified key to expire.
If not specified (or expire: 0), the target key will never expire.		 no

Notes:

  • Job parameters always override system properties. In particular, data_type will override target_data_type and on_update will override json_update_strategy properties respectively.
  • Mapping for JSON documents supports nested paths (e.g. path.to.field) which results in creating a nested element in Redis key. When a dot is used in a field name, it must be escaped with a backslash (e.g. path\.to\.field). Nested paths are not supported for hashes and streams.
  • For strings Write-behind will automatically assume on_update: replace regardless of what was declared in the job file. Appends and increments are not currently supported.
  • For streams Write-behind will ignore on_update property since they are append only.

Notes:

  • Job parameters always override system properties. In particular, data_type will override target_data_type and on_update will override json_update_strategy properties respectively.
  • Mapping for JSON documents supports nested paths (e.g. path.to.field) which results in creating a nested element in Redis key. When a dot is used in a field name, it must be escaped with a backslash (e.g. path\.to\.field). Nested paths are not supported for hashes and streams.

Example

source:
  server_name: chinook
  schema: public
  table: invoice
output:
  # this block will use the default connection: target - since no explicit connection is specified,
  # the data will be written in a JSON format as the data_type: json is specified for the block
  - uses: redis.write
    with:
      data_type: json
      key:
        expression: concat(['invoice_id:', InvoiceId])
        language: jmespath
      mapping: # only the fields listed below will be written to a JSON document
        - InvoiceId: id # this will create an element with a different name
        - InvoiceDate: date
        - BillingAddress: address.primary.street # this will create a nested element in the JSON document
        - BillingCity: "address.primary.city name" # this will create a nested element with a space in the name
        - BillingState: address.primary.state
        - BillingPostalCode: "address.primary.zip\\.code" # this will create a nested element with a dot in the name
        - Total # this will create an element with the same name as the original field
      on_update: merge
  # this block will use the explicitly specified connection: target1 - it must be defined in config.yaml
  # the data will be written to the corresponding Redis set, based on a value of the key expression
  - uses: redis.write
    with:
      connection: target
      data_type: set
      key:
        expression: concat(['invoices:', BillingCountry])
        language: jmespath
      args:
        member: InvoiceId
  # this block will use the explicitly specified connection: target1 - it must be defined in config.yaml
  # the data will be written to the Redis sorted set named invoices:sorted as specified in the key expression
  - uses: redis.write
    with:
      connection: target1
      data_type: sorted_set
      key:
        expression: "`invoices:sorted`"
        language: jmespath
      args:
        score: Total
        member: InvoiceId
  # this block will use the specified connection: target2 - this, again, has to be defined in config.yaml
  # the data will be written to a Redis stream named invoice:events as specified in the key expression
  - uses: redis.write
    with:
      connection: target2
      data_type: stream
      key:
        expression: "`invoice:events`"
        language: jmespath
      mapping: # only the fields listed below will be written to a stream message, with two of them renamed as message_id and country
        - InvoiceId: message_id
        - BillingCountry: country
        - Total
  # this block will use the default connection: target - since no explicit connection is specified,
  # the data will be written to a Redis string as the data_type: string is specified for the block
  - uses: redis.write
    with:
      data_type: string
      key:
        expression: concat(['Invoice:', InvoiceId])
        language: jmespath
      args:
        value: Total # only the Total field will be written to a string
      expire: 100 # the key will expire in 100 seconds

args: object

Arguments for modifying the target key

Properties

Name Type Description Required
score string Field name used as a score for sorted sets.
Valid for sorted sets only.		 yes
member string Field name used as a member for sets and sorted sets.
Valid for sets and sorted sets only.		 yes
value string Field name used as a value for strings.
Valid for strings only.		 yes

nest: object

Nest (embed) object within a different key

Properties

Name Type Description Required
parent object Parent object definition. yes
∟ server_name string Server name. no
∟ schema string Schema name. no
∟ table string Parent table. yes
parent_key string Field name used to identify the parent key (usually FK). yes
child_key string Optional field name used to identify the parent key value (if different from parent_key) in the child record. If not specified, then the field name defined in parent_key is used to lookup the value. no
nesting_key string Field name used to create the nesting key (usually PK). yes
path string Path, where the nested object should reside in a parent document.
Must start with the root (e.g. $.<children-elements-here>)		 yes
structure string Data structure used to represent the object in a parent document (map is the only supported value). no

Notes:

  • When nest object is defined, Write-behind will automatically assume data_type: json and on_update: merge regardless of what was declared in the job file.
  • Nesting job cannot be used together with any of the these properties: key, args. The key is automatically calculated based on the following template: <parent_table>:<parent_key>:<parent_key.value | child_key.value>.
  • When expire is specified, it will be applied to the parent key. Therefore all nested objects will expire together with the parent key.

Example

source:
  server_name: chinook
  schema: public
  table: InvoiceLine
output:
  - uses: redis.write
    with:
      nest:
        parent:
          # server_name: chinook
          # schema: public
          table: Invoice
        nesting_key: InvoiceLineId
        parent_key: InvoiceId
        # child_key: ParentInvoiceId
        path: $.InvoiceLineItems
        # structure: map

Note: In the example above child_key is not needed, because the FK in the child table InvoiceLine is defined using the same field name InvoiceId as in the parent table Invoice. If instead a FK was defined differently (e.g. InvoiceLine.ParentInvoivceId = Invoice.InvoiceId), then child_key parameter would be required to describe this relationship in the child job.

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