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API Docs - v4.2.2

Reorder

akslack (Stream Processor)

This stream processor extension performs reordering of an event stream which is out of order.
It implements the AQ-K-Slack based out-of-order handling algorithm which is originally described in
'http://dl.acm.org/citation.cfm?doid=2675743.2771828'.

Syntax

reorder:akslack(<LONG> timestamp, <INT|FLOAT|LONG|DOUBLE> correlation.field, <LONG> batch.size, <LONG> timer.timeout, <LONG> max.k, <BOOL> discard.flag, <DOUBLE> error.threshold, <DOUBLE> confidence.level)

QUERY PARAMETERS

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
timestamp	The attribute used for ordering the events.		LONG	No	No
correlation.field	This corresponds to the data field of which the accuracy directly gets affected, by the adaptive operation of the Alpha K-Slack extension. This field is used to calculate the runtime window coverage threshold which is an upper limit set for the unsuccessfully handled late arrivals.		INT FLOAT LONG DOUBLE	No	No
batch.size	The parameter 'batch.size' denotes the number of events that should be considered in the calculation of an alpha value. It should be a value which should be greater than or equal to fifteen.	10,000	LONG	Yes	No
timer.timeout	This corresponds to a fixed time out value in milliseconds, which is set at the beginning of the process. Once the time out value expires, the extension drains out all the events that are buffered within the reorder extension. The time out has been implemented internally using a timer. The events buffered within the extension are released each time the timer ticks.	-1 (timeout is infinite)	LONG	Yes	No
max.k	This is the maximum threshold value for 'K' parameter in the Alpha K-Slack algorithm.	9,223,372,036,854,775,807 (The maximum Long value)	LONG	Yes	No
discard.flag	This indicates whether the out-of-order events which appear after the expiration of the Alpha K-slack window should be discarded or not. When this value is set to 'true', the events are discarded.	false	BOOL	Yes	No
error.threshold	The error threshold to be applied in Alpha K-Slack algorithm. This parameter must be defined simultaneously with 'confidenceLevel'.	0.03 (3%)	DOUBLE	Yes	No
confidence.level	The confidence level to be applied in Alpha K-Slack algorithm. This parameter must be defined simultaneously with 'errorThreshold'.	0.95 (95%)	DOUBLE	Yes	No

Extra Return Attributes

Name	Description	Possible Types
beta0	The timestamp based on which the reordering is performed.	LONG
beta1	An upper limit value assigned for the unsuccessfully handled late arrivals.	DOUBLE
beta2	The number of events that should be considered in the calculation of an alpha value.	LONG
beta3	The fixed time-out value in milliseconds assigned for flushing all the events buffered inside the extension.	LONG
beta4	The maximum threshold value assigned for 'K' parameter.	LONG
beta5	The flag set to indicate whether the out-of-order events which arrive after buffer eviction are to be discarded or not.	BOOL
beta6	The error threshold value set for Alpha K-Slack algorithm.	DOUBLE
beta7	The confidence level set for the Alpha K-Slack algorithm.	DOUBLE

Examples EXAMPLE 1

define stream InputStream (eventtt long,data double);
@info(name = 'query1')
from InputStream#reorder:akslack(eventtt, data, 20)
select eventtt, data
insert into OutputStream;

This query performs reordering based on the 'eventtt' attribute values. In this example, 20 represents the batch size.

kslack (Stream Processor)

This stream processor extension performs reordering of an out-of-order event stream.
It implements the K-Slack based out-of-order handling algorithm which is originally described in
'https://www2.informatik.uni-erlangen.de/publication/download/IPDPS2013.pdf'.)

Syntax

reorder:kslack(<LONG> timestamp, <LONG> timer.timeout, <LONG> max.k, <BOOL> discard.flag)

QUERY PARAMETERS

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
timestamp	This is the attribute used for ordering the events.		LONG	No	No
timer.timeout	This corresponds to a fixed time-out value in milliseconds, which is set at the beginning of the process. Once the time-out value expires, the extension drains out all the events that are buffered within the reorder extension. The time-out has been implemented internally using a timer. The events buffered within the extension are released each time the timer ticks.	-1 (timeout is infinite)	LONG	Yes	No
max.k	The maximum threshold value for 'K' parameter in the K-Slack algorithm.	9,223,372,036,854,775,807 (The maximum Long value)	LONG	Yes	No
discard.flag	This indicates whether the out-of-order events which appear after the expiration of the K-slack window should be discarded or not. When this value is set to 'true', the events would get discarded.	false	BOOL	Yes	No

Examples EXAMPLE 1

define stream InputStream (eventtt long, price long, volume long);
@info(name = 'query1')
from InputStream#reorder:kslack(eventtt, 1000)
select eventtt, price, volume
insert into OutputStream;

This query performs reordering based on the 'eventtt' attribute values. In this example, the timeout value is set to 1000 milliseconds