Forms: Pipe
A pipe is a connector that links two elements in a PhixFlow model. A pipe joining a datasource to a data collector has no editable details.
Form: Pipe Details
The following fields are configured on the Details tab:
Field | Description |
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Name | The name of the pipe. The name is automatically generated when the pipe is first created to be 'in' (or the equivalent word in the user's selected language). If the name 'in' has already been used then a number will be added to the name to make it unique, e.g. in2 |
Input | The name of the pipe. In particular, this name will be used in any attribute expressions defined for the stream, when referring to attributes of the input stream. Please note Pipes cannot have the same name as any of the PhixFlow Attribute Functions, otherwise Expressions, using them will not function correctly |
Output | Name of the output stream, that is, the stream at the end (the arrow end) of the pipe. This cannot be edited through the dialogue; if you wish to update this, you will need to go back into the model view, delete the existing pipe and create a new pipe between the two streams as needed. |
Type | There are 3 options available:
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DataToRead | This field is used to determine which Streamsets to read from the input Stream. There are 4 options available:
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Static | Normally when a Pipe requests data from a non-static input Stream then that Stream will first attempt to bring itself up to date, generating new Streamsets as necessary, before supplying the data requests. However, if this field is ticked, the input Stream will not attempt to do this. |
Enabled | If this flag is not ticked then it is an indication to PhixFlow that the Stream is not ready to be used during any analysis runs and should be therefore be ignored. |
The following fields are configured on the Advanced tab:
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If ticked, when multiple Streams are being merged then there must be an input record from this Pipe for an output record to be generated by the output Stream.
If this is a push pipe with positive offsets and this flag is ticked then the notification to create another stream set will only be pushed along the pipe if the last stream set created contains at least one record.
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The Execution Strategy determines how this pipe should be implemented.
Where this pipe is a push or pull pipe into a Merge Stream, the Default Execution Strategy is to select all stream items from the input Stream sorted by the Group By attributes, then to read items from all input pipes simultaneously, constructing candidate sets from items with matching key values.
Where the Directed Execution Strategy is applied to a pipe (the pipe must not be mandatory), the other pipes with the Default Strategy operate as above, each being sorted then merged to generate a sequence of candidate sets; the Directed pipe then runs worker tasks to select the additional items by matching key value. These selects are batched up so that each worker reads items for many key values in a single select (see Worker Size), and many workers are run in parallel (see Max Workers).
In general, the Directed strategy should only be used where
- the number of items in the source Stream is so large that the sorting phase of the Default strategy takes too long, or
- only a small subset of the items are needed (the majority being discarded because they have key values that don't match the key values read on one of the other mandatory pipes).
Changing the Execution Strategy will make the Merge faster or slower depending on the input data and the details of the input and output Streams, but will not change the business logic of the Merge (i.e. which input items are grouped into candidate sets).
If the input to the pipe is a Collector, the list of key values is made available as _keyList. This will typically be used with an in clause in the Collector query. For example:
select * from customer where account_num in ({_keyList}) order by account_num
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The maximum number of concurrent worker tasks.
If blank, this defaults to 1.
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The number of key values to read for a single worker task (which runs a single select statement).
If blank, this defaults to 1000. This is the maximum value that can be used when reading from an Oracle database.
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The offset applied to the start of the collection period, relative to the period in the output stream that requires populating.
The units are the period of the output stream, that is, if the output stream has a daily period, then setting from date offset = -1.0 means that the start of the collection period will be 1 day earlier than the start of the period in the output stream that is being calculated.
If this is a push pipe then a positive offset can be input. This will tell the stream to run again and generate another stream set.
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The offset applied to the end of the collection period, relative to the period in the output stream that requires populating.
The units are the period of the output stream, that is, if the output stream has a daily period, then setting to date offset = -1.0 means that the end of the collection period will be 1 day earlier than the end of the period in the output stream that is being calculated.
If this is a push pipe then a positive offset can be input. This will tell the stream to run again and generate another stream set.
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- Only collect from the same run
- Max Stream Sets (this may also be set to zero)
- Historied
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During Drill Down
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During Look Ups
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During File Export
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The following fields are configured through separate tabs on the form:
Field | Description |
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Filter | Allows the user to set up a filter on the pipe. |
Sort/Group | See the Order By Attribute form. |
Aggregate Attributes | See the Aggregate Attribute form. |
Form Icons
The form provides the standard form icons.
The form also provides the following icons on the Filter tab:
Adds a clause to the filter. | |
Deletes the selected clause or condition from the filter. | |
Adds a condition to a clause of the filter. |
The form also provides the following icons on both the Sort/Group and Aggregate Attributes tabs:
Shows the list of attributes that can be added as sort/group or aggregate attributes. | |
Deletes the selected object from the list. | |
Adds an object to the list. |
See Also
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