Tuesday, November 23, 2010

DataStage Functions

Posted by Venkat ♥ Duvvuri 8:45 AM, under | No comments

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In its simplest form, IBM InfoSphere DataStage performs data transformation and movement from source systems to target systems in batch and in real time. The data sources might include indexed files, sequential files, relational databases, archives, external data sources, enterprise applications, and message queues.

DataStage manages data that arrives and data that is received on a periodic or scheduled basis. It enables companies to solve large-scale business problems with high-performance processing of massive data volumes. By leveraging the parallel processing capabilities of multiprocessor hardware platforms, DataStage can scale to satisfy the demands of ever-growing data volumes, stringent real-time requirements, and ever-shrinking batch windows.

Leveraging the combined suite of IBM Information Server, DataStage can simplify the development of authoritative master data by showing where and how information is stored across source systems. DataStage can also consolidate disparate data into a single, reliable record, cleanses and standardizes information, removes duplicates, and links records together across systems. This master record can be loaded into operational data stores, data warehouses, or master data applications such as IBM MDM using IBM InfoSphere DataStage.
IBM InfoSphere DataStage delivers four core capabilities:

* Connectivity to a wide range of mainframe, legacy, and enterprise applications, databases, file formats, and external information sources.

* Prebuilt library of more than 300 functions including data validation rules and very complex transformations.

* Maximum throughput using a parallel, high-performance processing architecture.

* Enterprise-class capabilities for development, deployment, maintenance, and high-availability. It leverages metadata for analysis and maintenance. It also operates in batch, real time, or as a Web service.

IBM InfoSphere DataStage enables an integral part of the information integration process.

Functions used in IBM InfoSphere DataStage and QualityStage


The functions that are valid in IBM® InfoSphere® DataStage® and QualityStage are also valid in IBM Information Server
FastTrack, The following is a list of functions that are generally used when defining a column derivation in a Transformer stage.
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Date and time functions


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The following table lists the functions that are available in the Date and Time category (Square brackets indicate an argument is optional):
Name Description Arguments Output
DateFromDaysSince Returns a date by adding an integer to a baseline date number (int32) [baseline date] date
DateFromJulianDay Returns a date from the given julian date juliandate (uint32) date
DaysSinceFromDate Returns the number of days from source date to the given date source_date

given_date

days since (int32)
HoursFromTime Returns the hour portion of a time time hours (int8)
JulianDayFromDate Returns julian day from the given date date julian date (int32)
MicroSecondsFromTime Returns the microsecond portion from a time time microseconds (int32)
MinutesFromTime Returns the minute portion from a time time minutes (int8)
MonthDayFromDate Returns the day of the month given the date date day (int8)
MonthFromDate Returns the month number given the date date month number (int8)
NextWeekdayFromDate Returns the date of the specified day of the week soonest after the source date source date

day of week (string)

date
PreviousWeekdayFromDate Returns the date of the specified day of the week most recent before the source date source date

day of week (string)

date
SecondsFromTime Returns the second portion from a time time seconds (dfloat)
SecondsSinceFromTimestamp Returns the number of seconds between two timestamps timestamp base timestamp seconds (dfloat)
TimeDate Returns the system time and date as a formatted string - system time and date (string)
TimeFromMidnightSeconds Returns the time given the number of seconds since midnight seconds (dfloat) time
TimestampFromDateTime Returns a timestamp form the given date and time date time timestamp
TimestampFromSecondsSince Returns the timestamp from the number of seconds from the base timestamp seconds (dfloat)

[base timestamp]

timestamp
TimestampFromTimet Returns a timestamp from the given unix time_t value timet (int32) timestamp
TimetFromTimestamp Returns a unix time_t value from the given timestamp timestamp timet (int32)
WeekdayFromDate Returns the day number of the week from the given date. Origin day optionally specifies the day regarded as the first in the week and is Sunday by default date [origin day] day (int8)
YeardayFromDate Returns the day number in the year from the given date date day (int16)
YearFromDate Returns the year from the given date date year (int16)
YearweekFromDate Returns the week number in the year from the given date date week (int16)
Date, Time, and Timestamp functions that specify dates, times, or timestamps in the argument use strings with specific formats: For a date, the format is %yyyy-%mm-%dd For a time, the format is %hh:%nn:%ss, or, if extended to include microseconds, %hh:%nn:%ss.x where x gives the number of decimal places seconds is given to. For a timestamp the format is %yyyy-%mm-%dd %hh:%nn:%ss, or, if extended to include microseconds, %yyyy-%mm-%dd %hh:%nn:%ss.x where x gives the number of decimal places seconds is given to. This applies to the arguments date, baseline date, given date, time, timestamp, and base timestamp. Functions that have days of week in the argument take a string specifying the day of the week, this applies to day of week and origin day.
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Logical Functions


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The following table lists the functions available in the Logical category (square brackets indicate an argument is optional):
Name Description Arguments Output
Not Returns the complement of the logical value of an expression expression Complement (int8)
BitAnd Returns the bitwise AND of the two integer arguments number 1 (uint64) number 2 (uint64) number (uint64)
BitOr Returns the bitwise OR of the two integer arguments number 1 (uint64) number 2 (uint64) number (uint64)
BitXOr Returns the bitwise Exclusive OR of the two integer arguments number 1 (uint64) number 2 (uint64) number (uint64)
BitExpand Returns a string containing the binary representation in "1"s and "0"s of the given integer number (uint64) string
BitCompress Returns the integer made from the string argument, which contains a binary representation of "1"s and "0"s. number (string) number (uint64)
SetBit Returns an integer with specific bits set to a specific state, where

origfield is the input value to perform the action on,

bitlist is a string containing a list of comma separated bit numbers to set the state of, and bitstate is either 1 or 0, indicating which state to set those bits.

origfield (uint64) bitlist (string)

bitstate (uint8)

number (uint64)
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Mathematical Functions


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The following table lists the functions available in the Mathematical category (square brackets indicate an argument is optional):
Name Description Arguments Output
Abs Absolute value of any numeric expression number (int32) result (dfloat)
Acos Calculates the trigonometric arc-cosine of an expression number (dfloat) result (dfloat)
Asin Calculates the trigonometric arc-sine of an expression number (dfloat) result (dfloat)
Atan Calculates the trigonometric arc-tangent of an expression number (dfloat) result (dfloat)
Ceil Calculates the smallest dfloat value greater than or equal to the given decimal value number (decimal) result (dfloat)
Cos Calculates the trigonometric cosine of an expression number (dfloat) result (dfloat)
Cosh Calculates the hyperbolic cosine of an expression number (dfloat) result (dfloat)
Div Outputs the whole part of the real division of two real numbers (dividend, divisor) dividend (dfloat) divisor (dfloat) result (dfloat)
Exp Calculates the result of base 'e' raised to the power designated by the value of the expression number (dfloat) result (dfloat)
Fabs Calculates the absolute value of the given value number (dfloat) result (dfloat)
Floor Calculates the largest dfloat value less than or equal to the given decimal value number (decimal) result (dfloat)
Ldexp Calculates a number from an exponent and mantissa mantissa (dfloat)

exponent (int32)

result (dfloat)
Llabs Returns the absolute value of the given integer number (uint64) result (int64)
Ln Calculates the natural logarithm of an expression in base 'e' number (dfloat) result (dfloat)
Log10 Returns the log to the base 10 of the given value number (dfloat) result (dfloat)
Max Returns the greater of the two argument values number 1 (int32) number 2(int32) result (int32)
Min Returns the lower of the two argument values number 1 (int32) number 2 (int32) result (int32)
Mod Calculates the modulo (the remainder) of two expressions (dividend, divisor) dividend (int32) divisor (int32) result (int32)
Neg Negate a number number (dfloat) result (dfloat)
Pwr Calculates the value of an expression when raised to a specified power (expression, power) expression (dfloat) power (dfloat) result (dfloat)
Rand Return a psuedo random integer between 0 and 232-1 - result (uint32)
Random Returns a random number between 0 232-1 - result (uint32)
Sin Calculates the trigonometric sine of an angle number (dfloat) result (dfloat)
Sinh Calculates the hyperbolic sine of an expression number (dfloat) result (dfloat)
Sqrt Calculates the square root of a number number (dfloat) result (dfloat)
Tan Calculates the trigonometric tangent of an angle number (dfloat) result (dfloat)
Tanh Calculates the hyperbolic tangent of an expression number (dfloat) result (dfloat)

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Null handling functions


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The following table lists the functions available in the Null Handling category (square brackets indicate an argument is optional):
Name Description Arguments Output
IsNotNull Returns true when an expression does not evaluate to the null value any true/false (int8)
IsNull Returns true when an expression evaluates to the null value any true/false (int8)
MakeNull Change an in-band null to out of band null any (column)

string (string)

-
NullToEmpty Returns an empty string if input column is null, otherwise returns the input column value input column input column value or empty string
NullToZero Returns zero if input column is null, otherwise returns the input column value input column input column value or zero
NullToValue Returns specified value if input column is null, otherwise returns the input column value input column, value input column value or value
SetNull Assign a null value to the target column - -
Hint: true = 1 false = 0
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Number functions


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The following table lists the functions available in the Number category (square brackets indicate an argument is optional):
Name Description Arguments Output
MantissaFromDecimal Returns the mantissa from the given decimal number (decimal) result (dfloat)
MantissaFromDFloat Returns the mantissa from the given dfloat number (dfloat) result (dfloat)
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Raw functions


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The following table lists the functions available in the Raw category (square brackets indicate an argument is optional):
Name Description Arguments Output
RawLength Returns the length of a raw string input string (raw) Result (int32)
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String functions


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The following table lists the functions available in the String category (square brackets indicate an argument is optional):
Name Description Arguments Output
AlNum Return whether the given string consists of alphanumeric characters string (string) true/false (int8)
Alpha Returns 1 if string is purely alphabetic string (string) result (int8)
CompactWhiteSpace Return the string after reducing all consective whitespace to a single space string (string) result (string)
Compare Compares two strings for sorting string1 (string)

string2 (string)

[justification (L or R)]

result (int8)
ComparNoCase Case insensitive comparison of two strings string1 (string) string2 (string) result (int8)
ComparNum Compare the first n characters of the two strings string1 (string) string2 (string)

length (int16)

result (int8)
CompareNumNoCase Caseless comparison of the first n characters of the two strings string1 (string) string2 (string)

length (int16)

result (int8)
Convert Converts specified characters in a string to designated replacement characters fromlist (string)

tolist (string)

expression (string)

result (string)
Count Count number of times a substring occurs in a string string (string)

substring (string)

result (int32)
Dcount Count number of delimited fields in a string string (string)

delimiter (string)

result (int32)
DownCase Change all uppercase letters in a string to lowercase string (string) result (string)
DQuote Enclose a string in double quotation marks string (string) result (string)
Field Return 1 or more delimited substrings string (string) delimiter (string)

occurrence (int32) [number (int32)]

result (string)
Index Find starting character position of substring string (string) substring (string) occurrence (int32) result (int32)
Left Leftmost n characters of string string (string)

number (int32)

result (string)
Len Length of string in characters string (string) result (int32)
Num Return 1 if string can be converted to a number string (string) result (int8)
PadString Return the string padded with the optional pad character and optional length string (string)

padlength (int32)

result (string)
Right Rightmost n characters of string string (string)

number (int32)

result (string)
Soundex Returns a string which identifies a set of words that are (roughly) phonetically alike based on the standard, open algorithm for SOUNDEX evaluation string (string) result (string)
Space Return a string of N space characters length (int32) result (string)
Squote Enclose a string in single quotation marks string (string) result (string)
Str Repeat a string string (string)

repeats (int32)

result (string)
StripWhiteSpace Return the string after stripping all whitespace from it string (string) result (string)
Trim Remove all leading and trailing spaces and tabs plus reduce internal occurrences to one string (string) [stripchar (string)] [options (string)] result (string)
TrimB Remove all trailing spaces and tabs string (string) result (string)
TrimF Remove all leading spaces and tabs string (string) result (string)
Trim Leading Trailing Returns a string with leading and trailing whitespace removed string (string) result (string)
Upcase Change all lowercase letters in a string to uppercase string (string) result (string)
Hint: true = 1 false = 0
Possible options for the Trim function are:
* L Removes leading occurrences of character.
* T Removes trailing occurrences of character.
* B Removes leading and trailing occurrences of character.
* R Removes leading and trailing occurrences of character, and reduces multiple occurrences to a single occurrence.
* A Removes all occurrences of character.
* F Removes leading spaces and tabs.
* E Removes trailing spaces and tabs.
* D Removes leading and trailing spaces and tabs, and reduces multiple spaces and tabs to single ones.
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Vector function


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The following function can be used within expressions to access an element in a vector column. The vector index starts at 0.
Name Description Arguments Output
ElementAt Accesses an element of a vector input column index (int) element of vector
This can be used as part of, or the whole of an expression. For example, an expression to add 1 to the third element of an vector input column 'InLink.col1' would be: ElementAt(InLink.col1, 2) + 1
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Type Conversion Functions


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The following table lists the functions available in the Type Conversion category (square brackets indicate an argument is optional):
Name Description Arguments Output
DateToString Return the string representation of the given date date

[format (string)]

result (string)
DecimalToDecimal Returns the given decimal in decimal representation with specified precision and scale decimal (decimal) [rtype (string)] [packedflag (int8)] result (decimal)
DecimalToDFloat Returns the given decimal in dfloat representation number (decimal) ["fix_zero"] result (dfloat)
DecimalToString Return the string representation of the given decimal number (decimal) ["fix_zero"] result (string)
DfloatToDecimal Returns the given dfloat in decimal representation number (dfloat) [rtype (string)] result (decimal)
DfloatToStringNoExp Returns the given dfloat in its string representation with no exponent, using the specified scale number (dfloat) scale (string) result (string)
IsValid Return whether the given string is valid for the given type. Valid types are "date", "decimal", "dfloat", "sfloat", "int8", "uint8", "int16", "uint16", "int32", "uint32", "int64", "uint64", "raw", "string", "time", "timestamp". "ustring" type (string) format (string) result (int8)
StringToDate Returns a date from the given string in the given format date (string)

format (string)

date
StringToDecimal Returns the given string in decimal representation string (string) [rtype (string)] result (decimal)
StringToRaw Returns a string in raw representation string (string) result (raw)
StringToTime Returns a time representation of the given string string (string) [format (string)] time
StringToTimestamp Returns a timestamp representation of the given string string (string) [format (string)] timestamp
TimestampToDate Returns a date from the given timestamp timestamp date
TimestampToString Return the string representation of the given timestamp timestamp [format (string)] result (string)
TimestampToTime Returns the time from a given timestamp timestamp time
TimeToString Return the string representation of the given time time [format (string)] result (string)
StringToUstring Returns a ustring from the given string, optionally using the specified map (otherwise uses project default) string (string) [,mapname (string)] result (ustring)
UstringToString Returns a string from the given ustring, optionally using the specified map (otherwise uses project default) string(ustring)

[,mapname (string)]

result (string)
Rtype: The rtype argument is a string, and should contain one of the following:
* ceil: Round the source field toward positive infinity. E.g, 1.4 -> 2, -1.6 -> -1.
* floor: Round the source field toward negative infinity. E.g, 1.6 -> 1, -1.4 -> -2.
* round_inf: Round or truncate the source field toward the nearest representable value, breaking ties by rounding positive values toward positive infinity and negative values toward negative infinity. E.g, 1.4 -> 1, 1.5 -> 2, -1.4 -> -1, -1.5 -> -2.
* trunc_zero. Discard any fractional digits to the right of the rightmost fractional digit supported in the destination, regardless of sign. For example, if the destination is an integer, all fractional digits are truncated. If the destination is another decimal with a smaller scale, round or truncate to the scale size of the destination decimal. E.g, 1.6 -> 1, -1.6 -> -1.
The default is trunc_zero.
Format string: Date, Time, and Timestamp functions that take a format string (e.g., timetostring(time, stringformat)) need to have the date format specified. The format strings are described in Date and time formats. Where your dates, times, or timestamps convert to or from ustrings, InfoSphere DataStage will pick this up automatically. In these cases the separators in your format string (for example, `:' or `-') can themselves be Unicode characters.
fix_zero: By default decimal numbers comprising all zeros are treated as invalid. If the string fix_zero is specified as a second argument, then all zero decimal values are regarded as valid.
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Type "casting" functions


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There is a special class of type conversion function to help you when performing mathematical calculations using numeric fields. For example, if you have a calculation using an output column of type float derived from an input column of type integer in a Parallel Transformer stage the result will be derived as an integer regardless of its float type. If you want a non-integral result for a calculation using integral operands, you can use the following functions (which act in a similar way as casting in C) to cast the integer operands into non-integral operands:
Name Description Arguments Output
AsDouble Treat the given number as a double number (number) number (double)
AsFloat Treat the given number as a float number (number) number (float)
AsInteger Treat the given number as an integer number (number) number (int)
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Utility functions


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The following table lists the functions available in the Utility category (square brackets indicate an argument is optional):
Name Description Arguments Output
GetEnvironment Returns the value of the given environment variable environment variable (string) result (string)
NextSKChain Returns the value of the surrogate key column for the next record in the chain, or value for the newest record value (number) result (int64)
NextSurrogateKey Returns the value of the next surrogate key None result (int64)
PrevSKChain Returns the value of the surrogate key column for the previous record in the chain, or value for the first record value (number) result (int64)


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