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:
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and sends data from the input to the output. Pipes allows you to control which attributes and which records from the input are delivered by to the output, although in most cases - with minimal configuration - you will get all columns and the records from the current data set.
The pipe must be enabled to make it active.
For advanced configuration, see Advanced Pipe Configuration.
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A pipe joining a datasource to a data collector has no editable details. All the output data set configuration occurs in the SQL query on the collector. |
Name
The name is used to refer to the pipe in other model elements.
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The name can have no special characters except _, it has to start with a letter and cannot be an Attribute Function name. |
Type
There are 3 options available:
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- Pull: pull pipes are the most common type in PhixFlow - they "pull" data from the input to the output. Pull pipes are shown as solid arrows on models.
- Look-up: look-up pipes are used to enrich data. Typically, you will have one of more pull pipes to supply the base data for an output, and if needed a one or more look-up pipes to enrich the base data with values from additional inputs. Look-up pipes are shown as dashed lines on models.
- Push: data is "pushed" rather than "pulled" into the output stream. Push pipes are most commonly used when sending data from streams to exporters (File Exporters, Database Exporters, HTTP Exporters). Push pipes are shown as dotted lines on
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- models.
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Data To Read
Specify what input data to use. There are 4 options available:
- Latest:
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- supply data from the current run (the latest stream set). This is the mostly commonly used option.
- Previous:
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- Read Future Data
- Only collect from the same run
- Max Stream Sets
- Historied
- From Data Offset
- To Date Offset
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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.
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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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Mandatory
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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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When doing a lookup, there are two common scenarios:
- The pipe does a single lookup onto a stream or database table to get a large number of records in one go (e.g. 1000 records)
- The pipe does many lookups, getting a small number of records for each lookup (e.g. 10 records at a time).
Try to estimate the largest number of records that the lookup pipe reads on a single read from a stream or database collector.
The cache is used when carrying out lookups from streams or database collectors. During a lookup, PhixFlow will retrieve records in sets that match the filter on the pipe, e.g.
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WHERE AddresssLine1 = _out.Address |
For efficiency, the records are cached (stored temporarily in memory) so that if the same set of records need to be looked up again they are readily available without going back to the database.
There is a limit to how many records can be stored in the cache. The Cache Size field allows you to specify this limit. If no value is set, it will default to the system-wide default, specified in the maximum pipe cache size in the System Tuning tab of the System Configuration dialog.
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If a single read brings back a number of records exceeding 90% of the specified cache size, a warning message will be logged to the console. If a single read brings back 100% or more of the cache size, and the enforce cache size limit flag is ticked in the system configuration, then the analysis run will stop completely.
A model administrator can use this information to make an informed decision about the design of the model. |
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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 Look Ups
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During File Export
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During Drill Down
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The following fields are configured through separate tabs on the form:
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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
- Formssupply data from the previous run (the previous stream set). This is used when you are comparing, for example, today's data with yesterday's.
- All: read data from the current run and all previous runs (all stream sets).
- Custom: If you are setting up a transactional model, choose this option so that you can select Only collector from same run. There are other fields revealed by selecting this option (see Advanced Pipe Configuration), but you are recommended not to update these unless directed to by PhixFlow consultants or support.
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If the Only collect from same run flag is ticked, the pipe will only collect data from inputs from the same analysis run that is generating the output data. This is only used when building a transactional model. |
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In some circumstances the input Stream may have Stream Sets that have dates in the future relative to the Stream Set being generated for the output Stream. This may happen, for example, if you have rolled back a number of Stream Sets on the output Stream but have not rolled back the corresponding Stream Sets on the input Stream, and have then requested that the output Stream is brought up to date. Some of the Stream Sets on the input Stream will have dates in the future relative to the some of the Stream Sets you are rebuilding. By default, pipes will ignore any Stream Sets with dates in the future relative to the Stream Set you are generating. This is so that if you are rebuilding an old Stream Set the pipe will retrieve the same data on the rerun as it retrieved when the Stream Set was first built. Similarly, if you are running a Transactional Stream, it is possible that while your analysis run is taking place, other analysis runs which started after yours may have completed before yours. These will have generated additional Stream Sets on the input Stream with a future data relative to the date of the Stream Set you are generating. For Transactional input Streams it is possible to tell the pipe not to ignore these future Stream Sets by ticking the Read Future Data tick box on the Advanced tab. |
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.
Multiplier
This causes the pipe to present each candidate set to the output stream in a different way than usual. The multiplier flag is on the Advanced tab of the form.
When processing data, a Stream will usually take one candidate set from each of its input pipes. If the multiplier flag is ticked on one of these, then the stream changes its behaviour to take / instead takes one record from the 'multiplied'/multiplier pipe, and all the records on the other pipes contribute to the pool of candidate sets available to the stream in the usual way. The process then repeats with the next record in the multiplier pipe record set.
Filters, sorting and grouping, aggregating
Filters, sorting and grouping, and aggregating configured through their own 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. |
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Pipe Form Reference
The following fields are configured on the Details tab:
| Field | Description |
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| Name | The name of the pipe. |
| Input | Name of the input stream providing data to the pipe. Non-editable field. |
| Output | Name of the output stream, that is, the stream at the end (the arrow end) of the pipe. |
| Type | Determine whether the pipe is a pull, push or lookup. |
| Data To Read | This field is used to determine which Streamsets to read from the input Stream. |
| 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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Mandatory | 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. | |||||||||||||||||||||||||
| Multiplier | When processing data, a Stream first constructs CandidateSets ready for processing from its (non-Multiplier) input Pipes. For each Multiplier Pipe, the Stream then multiplies each CandidateSet by creating a copy of the original CandidateSet for each row returned from the Multiplier Pipe. Note that each resulting CandidateSet contains the original CandidateSet plus one row from the Multiplier Pipe. | |||||||||||||||||||||||||
| Execution Strategy | The Execution Strategy determines how this pipe should be implemented. See the section on Directed Merge Strategy | |||||||||||||||||||||||||
| Max Workers | The maximum number of concurrent worker tasks. If blank, this defaults to 1. | |||||||||||||||||||||||||
| Worker Size | 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. | |||||||||||||||||||||||||
| Cache Size | The cache is used when carrying out lookups from streams or database collectors. When doing a lookup, there are two common scenarios:
In case 2, the results returned are typically based on a key value, e.g. an account number. This will be used in the filter of the pipe, if you are reading from a stream, or in the query, if you are reading from a database collector. For example, the query in a database collector will include the condition:
For efficiency, the records are cached (stored temporarily in memory) so that if the same set of records need to be looked up again they are readily available without going back to the database. This field allows you to set a limit on the size of the cache. Setting a limit is important because if you do not, the cache can become very large and consume a lot of memory, which can lead to a slow down in both your tasks and those of other users of PhixFlow. To set the cache size, try to estimate the largest number of records that the lookup pipe will return on a single read. If you do not set a limit, it will default to the system-wide default, specified in the Maximum Pipe Cache Size in the System Tuning tab of the System Configuration.
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| Buffer Size | The buffer size used to perform the stream calculation. If a large amount of data is being processed, then setting a large buffer size will give better performance. | |||||||||||||||||||||||||
| Allow Incomplete Stream Sets | Normally, when a pipe tries to read from an input stream that contains an incomplete stream set, PhixFlow will attempt to complete the stream set before passing data down the pipe. However if the stream is static (i.e. the stream has its 'static' flag ticked) or is effectively static (i.e. all of the pipes reading from it in this analysis run are static) then, instead of completing the stream set, an error message is produced indicating that you cannot read from this stream because it contains an incomplete stream set. If you do not want this error message to be produced when reading from static (or effectively static) streams, but would instead prefer PhixFlow to ignore the incomplete stream sets, then you must tick this box on all pipes that will read from the input stream in this analysis run. If there are multiple pipes that read from the input stream during this analysis run and even one of the pipes does not have this box ticked then you will not be allowed to read from the stream and the error message will be produced. Pipes which are not used in the current analysis run (for example where they lead to streams on branches of the model which are not run by the current task plan) have no effect on whether or not the error message is produced. | |||||||||||||||||||||||||
| Data Expected | This field is available when the Pipe Type is Push or Pull. This flag allows the user to specify that the pipe is expecting to receive data. If ticked but no data is received this is treated as an error. | |||||||||||||||||||||||||
| Only collect from same run | Every time the analysis engine runs all of the Streamsets that are created by all of the Streams affected by that analysis run are given the same Run ID. If this flag is ticked then the pipe will only collect Streamsets from the input Stream that have the same Run ID as the Streamset currently being created by the outpu Stream. | |||||||||||||||||||||||||
| Max Stream Sets | In almost all cases this specifies the number of stream sets to be retrieved from the input stream. However, if this is a push pipe with positive offsets this value indicates the maximum number of streamsets that can be created i.e. the maximum number of cycles this pipe can initiate. | |||||||||||||||||||||||||
| Historied | If ticked, the pipe will collect data from the input stream by period. So if the from and to date offsets are both 0.0, and the output stream requires stream generation for the period 17/10/07 - 18/10/07, data will be collected from the input stream for the period 17/10/07 - 18/10/07. If not ticked, all data will be collected from the input stream, regardless of period. In this case, the offsets are still used to determine whether the required data periods in the input stream exist before the stream calculation can be carried out. | |||||||||||||||||||||||||
| From Date Offset | The offset applied to the start of the collection period, relative to the period in the output stream that requires populating. | |||||||||||||||||||||||||
| To Date Offset | The offset applied to the end of the collection period, relative to the period in the output stream that requires populating. | |||||||||||||||||||||||||
| Read Future Data | If you are running a Transactional Stream then it is possible that while your analysis run is taking place, other analysis runs which started after yours may have managed to complete before yours thereby generating additional Streamsets on the input Stream. These additional Streamsets will then have a future data relative to the date of the Streamset you are generating. By default PhixFlow will ignore input Streamsets that have a date in the future relative to the Streamset being generated.
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| Pipe View | The pipe view is used to limit which fields are retrieved down the pipe and in what order, and in some circumstances how each field is to be formatted. You can select from any of the views that have been configured on the source stream. Please note that any sorting or filtering of records will have to be applied directly on the pipe, and will not be inherited from the pipe view. The pipe view is used in three contexts. During Look UpsPipe views can also be used on lookup pipes to limit the fields that are returned by the lookup request. This is most useful in the scenario where the you want to read and cache data on a lookup pipe from a stream that has lots of attributes but where only a small number of attributes are actually required. You can simply create a new view on the source stream listing only the attributes needed, then specify it as the pipe view on the lookup pipe. Only those attributes specified on the view will then be loaded.Without a pipe view, the pipe will load and cache all of the attributes from the stream which may consume a significant amount of free memory if there are a large number of records. During File ExportWhen sending data to a file exporter only those fields specified on the pipe view will be exported. If no pipe view is supplied then all fields will be exported. During Drill DownWhen drilling down from an alarm or stream item the pipe view is only used to determine which attributes from the source stream should be shown in the drill down display and in what order. | |||||||||||||||||||||||||
| Pipe Exporter | An exporter can be selected from the set of Database Exporters configured for the input stream. This exporter can then be used from the Drill Down View. This feature is useful when PhixFlow is used to 'recommend' a set of updates. By configuring an alarm to be generated when a set of recommendations is made, the user can drill down through the alarm to see the list of recommendations and then hit the exporter icon to apply them. Any filters applied on the pipe will be applied when the data is pushed to the pipe exporter, so it is possible that not all of the data in the grid will be exported - some records may be rejected by the filter. | |||||||||||||||||||||||||
| Max Records To Read | The maximum number of records that should be read down this pipe. The pipe may read more than this number of records if it is configured to carry out multiple reads simultaneously e.g. if it is connected to a File Collector which has been configured to read multiple files simultaneously or if this pipe strategy is "Directed" with multiple workers. |
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