Overview

A pipe is a connector that links two elements in a PhixFlow model 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 run.

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Filters are made up of a set of clauses; each clause in turn contains a number of conditions. These conditions must be satisfied for data to be passed through the pipe.

Tip
When the pipe Type is Lookup, the filter controls which data will be cached in memory.

Field

Description

Cache Size

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	pipeCacheSize
	pipeCacheSize

Available when Type is Lookup.

For lookup pipes, PhixFlow uses the pipe cache when it looks-up data from streams or database collectors. 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.

Enter a number to set a limit on the data cache size available for the pipe. You need to estimate the largest number of records that the lookup pipe will return on a single read. Check whether PhixFlow is looking up:

many records
The pipe does a single lookup onto a stream or database table to get a large number of records in one go, for example 10,000 records.
few records may times
The pipe does many lookups, getting a small number of records for each lookup, for example, 10 records at a time. In this case, PhixFlow is usually using a key value, such as an account number, to get the data. The key value is:
- for a stream - the attribute used to filter the pipe
- for a database collector - a condition in the database query. For example:

Code Block
WHERE AccountNumber = _out.AccountNum

If you do not set a limit for the cache, PhixFlow uses the system default set in System Configuration → System Tuning → Maximum Pipe Cache Size.

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title	Warnings and Errors

In the log for an analysis run, which is available in the system console, PhixFlow reports warnings when a single read returns:

over 90% of the specified cache size
100% or more of the cache size.

PhixFlow reports an error and stops the analysis run when:

a single read returns 100% or more of the cache size
and the System Configuration → Enforce Cache Size limit flag is ticked.

Code Block

title	Error Message: Cache Size Limit Exceeded

The Pipe "stream_name.lookup_pipe_name" cache is 100% full (the cache size is 10).

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title	More cache details

Every time the lookup pipe is referenced, PhixFlow calculates the values of all of the variable elements of the query or pipe filter, and checks if it already has a set of data in the cache retrieved using this set of variable values. If so the data is immediately returned from the cache. Otherwise, a new set of data is read from the stream of collector. If adding the new records to the cache would cause it to exceed the maximum cache size, previously cached results are removed to make enough room for the new results.

Pipe View

Use this option to look up data from attributes that are present in a stream view on the input stream.

Select a stream view from the list. If the input stream has no views, the list will be empty.

Note
Sorting or filtering of records must be set directly on the pipe. It is not inherited from the pipe view.

Use the pipe view to limit the attributes that the pipe reads when : a stream has lots of attributes containing many data

records but

records but you only need data from a few attributes.

Only the data for the attributes in the stream view are sent to the output stream.

Pipe views are very useful:

during lookups a pipe loads and caches all of the attributes from the stream. This can use a lot of memory, especially when there are many records.
during file export all data records from all attributes are exported.

To set up a pipe view:

Create a new view on the source stream. In the view, only add the attributes you need.
In the pipe Pipe View option, select the pipe view.
Run analysis. PhixFlow only looks-up or exports data from the attributes specified on the view.

Expand

title	Using pipe views with file exporters

If a File Exporter is configured to export to Excel or to HTML:

and it has an Excel template, PhixFlow uses this template and does not use any template specified in the pipe view.
but it does not have an Excel template, PhixFlow will use the Excel template specified in the pipe view (if there is one)
and the pipe view is a chart view, PhixFlow will export a PNG picture of the chart.

Include History Records

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to filter out superseded records.

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to include superseded records.

Condition

Select one of the options

Where ALL...
Where ANY...

To add more conditions, hover your mouse pointer over this field to display the button and add another condition to your filter.

Clause

Select an option from the list. PhixFlow adds more fields where you can:

select how the filter matches (for example, equals, contains, is null)
enter a string that the filter uses to match the data. The string can be an expression or a literal string.

Filter Icons

Hover your mouse pointer over conditions or clauses to display:

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_add
_add
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another condition or clause to the filter
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_delete
_delete
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the selected clause or condition from the filter.
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_filter_literal
_filter_literal
nopanel true
indicates the value entered is a literal value. Click this icon to treat the value as an expression.
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_filter_expression
_filter_expression
nopanel true
indicates the value entered is an expression. Click this icon to treat the value to a literal string.
Note: ["123", "234", "345"] looks like a literal value but it can be evaluated as an expression.
Open the expression in a larger editor.

Cache Extraction Filter

A cache extraction filter allows you to further filter the data retrieved by a pipe. These are not commonly used, but are sometimes helpful when either:

Optimising performance on a lookup pipe when for a set of records, the record you require from the lookup depends on non-key data, e.g. the date
When getting data from a pull pipe when the filter requires that you compare one value in each record with another; this is not possible within a standard filter.

For case 1, when using a lookup pipe, data retrieved is stored in a cache. See cache size for details. The cache extraction filter allows you, as you are processing a set of output records, to use different cached entries from the lookup for each of the records are you are processing. This is very fast compared to looking up from the source (i.e. going back to an external DB table or even another PhixFlow stream) for each output record.

E.g. you want to look up the credit rating for a customer for a set of transactions - in the output, each transaction is represented by a single output record. You create an indexed lookup pipe using CustNo as the key for the index. This means that for each new CustNo you encounter in the data, all the credit rating entries for that CustNo would be retrieved by the pipe and placed into the cache. The credit rating for each customer is fully historied, so you get a number of entries for each CustNo. To get the relevant lookup entry for each output report (each transaction), you need to compare the transaction date of the output record to the dates of credit rating entries in the cache. So to extract the relevant record, you include a cache extraction filter in the form:

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StartDate >= _out.TransDate && (EndDate <= _out.TransDate \|\| EndDate == _NULL)

Cache extraction filters are entered free hand.

The attribute names referenced must exist in a stream. This means that the each attribute must be one of:

an attribute in a source stream, if you are reading from a stream
if you are reading from an external database table, one of the fields returned by the database collector AND an attribute in the output stream. This means to use an attribute with the source as a database collector, there must be an attribute of matching name in the output stream
an attribute in the destination stream, in which case you will refer to it using the format _out.AttributeName

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Country Is in ["England","France","Germany"] fx

Sort/Group

For lookup pipes this section is called Order/Index.

Use this section to group and sort data as it comes through the pipe. This section has:

a toolbar with standard buttons
a grid that lists the attributes that you want to sort or use to group
below the grid are the following options:

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Note

You cannot aggregate data from attributes if the pipe's input is from:

If you need to aggregate data from a database collector, you can use an SQL query.

This section has:

a toolbar with standard buttons
a grid that lists the attributes that you want to aggregate.

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Field

Description

Data Expected

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means the pipe may receive no data from its input during an analysis run.

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means PhixFlow reports an error if the pipe receives no data from the input datasource, collector or stream during an analysis run.

Allow Incomplete Stream Sets

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to complete a stream set before passing the data to the output stream. During the analysis run, PhixFlow pulls data into the input stream until the stream set is complete. If it cannot complete the stream set, PhixFlow reports an error message.

PhixFlow cannot complete a stream set if:

either the input stream is set to be
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_static
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or all of the pipes reading from the stream are static.

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PhixFlow ignores incomplete stream sets in a static input stream and does not report an error.

Tip
You must tick this check box on all the pipes that will read from a static (or effectively static) input stream in the analysis run. PhixFlow will report an error if there is any pipe trying to complete the stream set during the analysis run.

Pipes that are not used in the analysis run do not try to complete a stream set, so will not report an error. (Unused pipes can occur if they lead to streams on branches of the model that are not being run.)

Buffer Size

Enter a number for 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.

Max Records To Read

Enter a number for 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. For example:

a pipe can be connected to a File Collector that reads multiple files simultaneously
the pipe strategy is Directed with multiple workers.

Strategy

Select an option to specify how this pipe should be implemented. See the section on Directed Merge Strategy

Default: this is the way pipes usually works
Directed: when reading from a large data set; see Using Directed Pipes to Read from Large Data Sets

Max Workers

This field is available when Strategy is Directed

Enter the maximum number of concurrent worker tasks. When no value is specified, this defaults to 1.

Worker Size

This field is available when Strategy is Directed

Enter the number of key values to read for a single worker task, which runs a single select statement.

When no value is specified, this defaults to 1000. This is the maximum value that can be used when reading from an Oracle database.

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Version	Old Version 76	New Version 77
Changes made by	Fiona Sargeant	Fiona Sargeant
Saved on	Dec 10, 2019	Dec 10, 2019

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