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Use the stream attributes properties tab to specify the characteristics of the the data in a table column.
This setting is not available from the repository browser. It opens from:
- the Stream properties → Attributes table
- other attribute lists.
Stream Attribute Properties
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Basic Settings
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- String for text strings
- Bigstring for text
- Integer for text
- Float for text
- Decimal for text
- Date for text
- Datetime for text
- Graphic for text
- TrueFalse for text
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Length
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This field is available when Type is String. Enter the maximum number of characters allowed in text data. For unlimited text strings, set a Type of Bigstring.
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For example, to specify numbers must have two digits before and after the decimal point, such as 12.34, enter:
Significant Figures 4
Decimal Places 2
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This field is available when Type is Decimal. Enter the maximum number of digits allowed after the decimal point.
This must be less than the number of significant figures.
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The order of the attributes in the stream. Stream attribute expressions are evaluated in this order.
This is important when you need to use the results of a calculation in another attribute:
- either in its expression
- or in a $ variable
In the attribute list, the attribute that calculates the result must come before the attribute that requires the result.
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Advanced
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To improve performance, index an attribute when the stream has a large data set and an output pipe from the stream uses this attribute to:
- filter the stream data
- sort or group the stream data.
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| Note |
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| This option affects the behaviour of filters for PhixFlow instances running on Oracle or MariaDB (MySQL) databases. For PhixFlow instances running on a SQL Server database, filters are always case-independent. |
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Enter an expression to be evaluated for each stream item (data record) in the stream. The expression can
- either use the value of this attribute
- or calculate a different value
Once calculated, the cache key value persists throughout subsequent 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.
This means you can use a "persistent" attribute value in other expressions.
CHECK THIS
Access Permissions
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to do
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If you load data without specifying a type what happens?
Does PhixFlow make a best guess at what the type is and if it's not sure, assumes string??
All stream attributes have a type. The default is String.
What if you want to change a format - e.g set a decimal or date format?
Once the stream has data the attribute type can only be changed if the database allows the change. This is database dependent and you will see an error if your change is not allowed. If the stream has no data then any change in attribute type is possible.
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 50. The minimum length is 1 and the maximum length is 4000.
do we need to tell users about any information-loss if data that is naturally a different type gets loaded as a string?
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Apply a bigstring type to text strings over 4000 characters long. Bigstring is a different data type to string and has some restrictions on filtering, sorting and aggregation.
For PhixFlow instances that use an Oracle database, bigstrings cannot be sorted or aggregated. On Oracle bigstrings may only be filtered with the conditions:
(not) containsis (not) null(not) starts with(not) ends with.
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? If you store a number with decimal places as an integer it will be truncated.
Integer has a precision which is the maximum number of digits. The default is 10. The minimum is 1 and maximum is 38.
Float
Apply a float type to non-integer numbers with an undefined level of precision.
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Apply a decimal type to non-integer numbers with a set level of precision. Decimals have a specific number of:
- significant figures: the total number of digits stored,
- decimal places: the number of digits after the decimal place.
The maximum number of integer digits is therefore the significant figure minus the decimal places. By default, decimals have 10 significant figures and 2 decimal places, and therefore 8 integer digits.
If the number of integer digits present in a decimal field exceeds the specified format, running analysis will fail and PhixFlow will report an error.
If the number of decimal digits present in a decimal field exceeds the specified format, PhixFlow will round to the required precision. For example, if a data record includes the number 12.3456, but the decimal type can have 4 significant figures and 2 decimal places, PhixFlow records 12.35.
| Note |
|---|
Ensure your decimal type has the number of decimal places you need for your data. Once the data is loaded into PhixFlow, you will not be able to recover excess decimal places. |
Date
Apply a date type to representations of a calendar day.
Are there any specific formats to say are recognised/not recognised?
What about word formats e.g. Tuesday the fourteenth of February? Words are not recognised except three letter month abbreviations eg 14 Feb 2019 is accepted.
"yyyyMMdd",
"dd/MM/yy",
"dd MM yy",
"dd-MM-yy",
"MM/dd/yy",
"MM dd yy",
"MM d yy",
"MM-dd-yy"
"dd/MMM/yy",
"dd-MMM-yy",
"dd MMM yy",
"MMM/dd/yy",
"MMM-dd-yy",
"MMM dd yy",
"MMM d yy"
"dd/MM/yyyy",
"dd-MM-yyyy",
"dd MM yyyy",
"MM/dd/yyyy",
"MM-dd-yyyy",
"MM dd yyyy",
"MM d yyyy"
"dd-MMM-yyyy",
"dd/MMM/yyyy",
"dd MMM yyyy",
"MMM/dd/yyyy",
"MMM-dd-yyyy",
"MMM dd yyyy",
"MMM d yyyy"
Datetime
Apply a datetime type to representations of a time, or day and time.
Are there any specific formats to say are recognised/not recognised?
Same formats as for date but with HH:mm:ss on the end.
"yyyyMMdd.HHmmss"
"dd/MM/yy HH:mm:ss",
"dd-MM-yy HH:mm:ss",
"dd MM yy HH:mm:ss",
"MM/dd/yy HH:mm:ss",
"MM-dd-yy HH:mm:ss",
"MM dd yy HH:mm:ss",
"MM d yy HH:mm:ss"
"dd/MMM/yy HH:mm:ss",
"dd-MMM-yy HH:mm:ss",
"dd MMM yy HH:mm:ss",
"MMM/dd/yy HH:mm:ss",
"MMM-dd-yy HH:mm:ss",
"MMM dd yy HH:mm:ss",
"MMM d yy HH:mm:ss"
"dd/MM/yyyy HH:mm:ss",
"dd-MM-yyyy HH:mm:ss",
"dd MM yyyy HH:mm:ss",
"MM/dd/yyyy HH:mm:ss",
"MM-dd-yyyy HH:mm:ss",
"MM dd yyyy HH:mm:ss",
"MM d yyyy HH:mm:ss"
"dd/MMM/yyyy HH:mm:ss",
"dd-MMM-yyyy HH:mm:ss",
"dd MMM yyyy HH:mm:ss",
"MMM/dd/yyyy HH:mm:ss",
"MMM-dd-yyyy HH:mm:ss",
"MMM dd yyyy HH:mm:ss",
"MMM d yyyy HH:mm:ss"
Graphic
Is this still available?
TrueFalse
Apply a TrueFalse type to fields that can have the values true or false.
What happens if the field is empty? Or has something other than True/False?
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