Streams are a key model component. They represent a structured store of data within PhixFlow receiving data from one or more components, processing it then storing it.
Stream Properties
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The tab toolbar has the following additional buttons:
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| Field | Description |
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| Name | The name of the stream. |
| Enabled | Whether or not the stream is enabled to run. |
| Static Data | If ticked, this stream can be used to hold static data. This is usually reference, or "look up" data used as part of a stream calculation. In technical terms, setting this means that the stream will only update itself when the user requests an analysis run on the stream directly, either ad-hoc through the user interface, or via a task plan. When this stream is part of a larger analysis run, unlike all other types of stream the stream will not attempt to update itself. |
| Period | This is the period of the stream. This can be either a regular period, or variable. There are four possible settings:
When the period is first set to Transactional the UID stream attribute will be created if it does not already exist. |
| Stream Type | The type of function used to generate this stream. Possible stream types are:
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| Supersede Items on Pipe | You can select a "loop" pipe - that is, a pipe linking the stream back into itself - in this field. If you do, new records will be compared to existing records, using the selected loop pipe, and if a repeated record is found, the old one will be marked as 'superseded'. |
| Audit Manual Changes | Only applies when period is Transactional. If ticked, updates and deletes initiated by stream actions (not those carried out by analysis runs) will automatically mark the existing record as superceded and create a new stream set. The new versions of the updated records will be placed in the new stream set. Inserts will simply create a new stream set, and add the inserted record into that stream set. When Audit Manual Changes is first set, the attributes
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| Field | Description | ||
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| Indexed | Tick this option if this field should be indexed in the underlying database. An indexed field should be used to increase performance on very large streams in the following situations:-
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| Filter conditions are case-independent by default | If ticked, new filter conditions on this field are case-insensitive by default. The filter window → Ignore Case check box inherits this setting; see Filters on Data Views. For case-insensitive filters, there is no difference if the attribute is also indexed.
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| Key | For in-memory streams, whether this field will be used as a key value. See How To: Summarise unsorted data with In Memory Streams. | ||
| Cache Key | If a cache key is set, the value of this attribute persists throughout the stream calculation, rather than being created from scratch for each stream item as normal. This allows you to keep track of the calculation as it progresses. The cache key is an expression that is evaluated for each stream item, and of course it can use the existing value of the attribute, in other words, to value it had in the previous stream item processed in the stream calculation. This allows expressions to use the "persistent" attribute value on subsequent stream items. The expression provided in the Cache Key is evaluated for each stream item so that this "persistent" attribute can refer to multiple value keyed on the "Cache Key". |
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Which fields can have "null"?
String
Apply a string type to sequences of characters (i.e., letters, numerals, symbols and punctuation marks). By default string attribute types have a fixed length of how long?
do we need to tell users about any information-loss if data that is naturally a different type gets loaded as a string?
Anchor Bigstring Bigstring
Bigstring
| Bigstring | |
| Bigstring |
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The maximum bigstring size can be configured in System Configuration → System Tuning → Maximum Bigstring Size.
Integer
Apply an integer type to whole numbers (not a fractions or decimals) that can be positive, negative, or zero.
What happens if you attempt to load a float or decimal number into an integer attribute?
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