Die durchschnittliche Verarbeitungszeit zwischen allen Zeitstempeldatensätzen in Oracle SQL muss ermittelt werden

Das Ausführen von Zeitintervallen und insbesondere das Erstellen von Aggregationen (Summen, Durchschnitte) über viele Intervalle oder Intervallgruppen hinweg ist in Oracle nicht einfach. Die AVG-Funktion funktioniert nicht mit Zeitstempelintervallen, sie erwartet Zahlen. Wir müssen also unser eigenes Aggregationsobjekt und unsere eigene Funktion erstellen, die dies tun wird.

Zunächst die Objektspezifikation :

CREATE OR REPLACE TYPE AvgInterval 
AS OBJECT (
runningSum INTERVAL DAY(9) TO SECOND(9),
runningCnt number,

STATIC FUNCTION ODCIAggregateInitialize
  ( actx IN OUT AvgInterval
  ) RETURN NUMBER,

MEMBER FUNCTION ODCIAggregateIterate
  ( self  IN OUT AvgInterval,
    val   IN       DSINTERVAL_UNCONSTRAINED
  ) RETURN NUMBER,

MEMBER FUNCTION ODCIAggregateTerminate
  ( self             IN   AvgInterval,
    returnValue  OUT DSINTERVAL_UNCONSTRAINED,
    flags           IN   NUMBER
  ) RETURN NUMBER,

MEMBER FUNCTION ODCIAggregateMerge
  (self  IN OUT AvgInterval,
   ctx2 IN      AvgInterval
  ) RETURN NUMBER
);

Und der Objektkörper :

CREATE OR REPLACE TYPE BODY AvgInterval AS
STATIC FUNCTION ODCIAggregateInitialize
  ( actx IN OUT AvgInterval
  ) RETURN NUMBER IS 
  BEGIN
    IF actx IS NULL THEN
      actx := AvgInterval (INTERVAL '0 0:0:0.0' DAY TO SECOND, 0);
    ELSE
      actx.runningSum := INTERVAL '0 0:0:0.0' DAY TO SECOND;
      actx.runningCnt := 0;
    END IF;
    RETURN ODCIConst.Success;
  END;

MEMBER FUNCTION ODCIAggregateIterate
  ( self  IN OUT AvgInterval,
    val   IN     DSINTERVAL_UNCONSTRAINED
  ) RETURN NUMBER IS
  BEGIN
    self.runningSum := self.runningSum + val;
    self.runningCnt := self.runningCnt + 1;
    RETURN ODCIConst.Success;
  END;

MEMBER FUNCTION ODCIAggregateTerminate
  ( self        IN  AvgInterval,
    ReturnValue OUT DSINTERVAL_UNCONSTRAINED,
    flags       IN  NUMBER
  ) RETURN NUMBER IS
  BEGIN
    if (runningCnt <> 0) then
        returnValue := (self.runningSum/runningCnt);
    else
        returnValue := self.runningSum;
    end if;
    RETURN ODCIConst.Success;
  END;

MEMBER FUNCTION ODCIAggregateMerge
  (self IN OUT AvgInterval,
   ctx2 IN     AvgInterval
  ) RETURN NUMBER IS
  BEGIN
    self.runningSum := self.runningSum + ctx2.runningSum;
    self.runningCnt := self.runningCnt + ctx2.runningCnt;
    RETURN ODCIConst.Success;
  END;

END;

Zu guter Letzt die Funktion das das obige Objekt verwendet :

CREATE OR REPLACE FUNCTION avg_interval( x DSINTERVAL_UNCONSTRAINED) 
RETURN DSINTERVAL_UNCONSTRAINED  PARALLEL_ENABLE
AGGREGATE USING AvgInterval;

Jetzt können wir es benutzen so :

with x as (
    select systimestamp - 1/24 as created_date, systimestamp as modified_date from dual
    union
    select systimestamp - 2/24 as created_date, systimestamp as modified_date from dual
    union
    select systimestamp - 3/24 as created_date, systimestamp as modified_date from dual
)
select avg_interval(modified_date - created_date)
from x;

Ausgabe:

+00 02:00:00.562669

Wir können auch über Gruppen aggregieren damit :

with x as (
    select 'FL' as state, to_dsinterval('0 00:56:30') as duration from dual
    union
    select 'FL' as state, to_dsinterval('0 02:08:40') as duration from dual
    union
    select 'GA' as state, to_dsinterval('0 01:01:00') as duration from dual
)
select state, avg_interval(duration)
from x
group by state;

Ausgabe:

FL  +00 01:32:35.000000
GA  +00 01:01:00.000000