Attempting to rewrite a very lengthy query - plsql

Question

I am currently trying to improve on a query that is being used to build a view. The query is in PL/SQL, in an Oracle database. There are 3 different types of reports (100,200, and 300) that are generated at each building. We track the consecutive years that each report is generated, and based on the combination of (1) the type(s) of report(s) generated for a given year and (2) the consecutive years each report has been generated, we arrive at a Result type for that building.
Here is a description of the criteria for the Result types:
Result 600 - If all 3 report types have been generated in the current year, where:
Level 1: all reports were generated in 1 consecutive year (this is the first year)
Level 2: at least 1 report type has been generated for 2 consecutive years (none have 3 consecutive years)
Level 3: at least one report type has been generated for 3 consecutive years
Result 100 - Only report type 100 has been generated in the current year, where:
Level 1 - 1 consecutive year
Level 2 - 2 consecutive years
Level 3 - 3 consecutive years
Result 200 - Only report type 200 has been generated in the current year, where:
Level 1 - 1 consecutive year
Level 2 - 2 consecutive years
Level 3 - 3 consecutive years
Result 300 - Only report type 300 has been generated in the current year, where:
Level 1 - 1 consecutive year
Level 2 - 2 consecutive years
Level 3 - 3 consecutive years
Result 400 - Only reports 100 and 200 have been generated, where:
Level 1: both reports were generated in 1 consecutive year (this is the first year)
Level 2: at least 1 report type has been generated for 2 consecutive years (neither have 3 consecutive years)
Level 3: at least one report type has been generated for 3 consecutive years
Result 500 - Only reports 100 and 300 have been generated, where:
Level 1: both reports were generated in 1 consecutive year (this is the first year)
Level 2: at least 1 report type has been generated for 2 consecutive years (neither have 3 consecutive years)
Level 3: at least one report type has been generated for 3 consecutive years
Result 700 - Only reports 200 and 300 have been generated, where:
Level 1: both reports were generated in 1 consecutive year (this is the first year)
Level 2: at least 1 report type has been generated for 2 consecutive years (neither have 3 consecutive years)
Level 3: at least one report type has been generated for 3 consecutive years
Still with me? Sweet. So here is the current code that is used to generate this view, which is simply a display of the result:
CREATE OR REPLACE FORCE VIEW REPORTS.REPORT_RESULT_VIEW
(
BUILDING,
BUILDING_NAME,
GROUP,
YEAR,
TYPE,
SUBTYPE,
CONSEC,
RESULT
)
AS
WITH cte1
AS (SELECT 1 ID_100,
1 ID_200,
1 ID_300,
'600 Level 1' RESULT
FROM DUAL
UNION ALL
SELECT 2 ID_100,
2 ID_200,
2 ID_300,
'600 Level 2' RESULT
FROM DUAL
UNION ALL
SELECT 3 ID_100,
3 ID_200,
3 ID_300,
'600 Level 3' RESULT
FROM DUAL
UNION ALL
SELECT 1 ID_100,
1 ID_200,
2 ID_300,
'600 Level 2' RESULT
FROM DUAL),
(note - there are 63 total combinations that are listed in the actual code... I only entered the first few to give you an idea of how it is set up)
cte2
AS ( SELECT MAX (ID_100) ID_100_CONSEC,
MAX (ID_200) ID_200_CONSEC,
MAX (ID_300) ID_300_CONSEC,
YEAR,
BUILDING
FROM (SELECT CONSEC ID_100,
NULL ID_200,
NULL ID_300,
YEAR,
TYPE || SUBTYPE TYPE,
BUILDING
FROM REPORT_MASTER_VIEW
WHERE TYPE || SUBTYPE = '100'
UNION
SELECT NULL ID_100,
CONSEC ID_200,
NULL ID_300,
YEAR,
TYPE || SUBTYPE TYPE,
BUILDING
FROM REPORT_MASTER_VIEW
WHERE TYPE || SUBTYPE = '200'
UNION
SELECT NULL ID_100,
NULL ID_200,
CONSEC ID_300,
YEAR,
TYPE || SUBTYPE TYPE,
BUILDING
FROM REPORT_MASTER_VIEW
WHERE TYPE || SUBTYPE = '300')
GROUP BY YEAR, BUILDING),
cte3
AS (SELECT c2.*, c1.RESULT
FROM cte2 c2
JOIN
cte1 c1
ON NVL (c2.ID_100_CONSEC, 0) = c1.ID_100
AND NVL (c2.ID_200_CONSEC, 0) = c1.ID_200
AND NVL (c2.ID_300_CONSEC, 0) = c1.ID_300)
SELECT t1."BUILDING",
t1."BUILDING_NAME",
t1."GROUP",
t1."YEAR",
t1."TYPE",
t1."SUBTYPE",
t1."CONSEC",
t2.RESULT
FROM REPORT_MASTER_VIEW t1
JOIN
cte3 t2
ON t1.BUILDING = t2.BUILDING AND t1.YEAR = t2.YEAR
WHERE T1.TYPE IN ('100', '200' '300')
ORDER BY t1.BUILDING;
Now, because for every report combination, it has to run through all the possible combinations, this view takes about 24 seconds to build. In the app that it is referenced in, it takes nearly a minute to load the page. For this reason, I am trying to figure out ways to make the query more efficient. At first, I was thinking of using nested CASE statements, but I wasn't really sure how that would work. Any suggestions on how to better approach this is greatly appreciated.

Answer 1

WITH cte2 AS
(
SELECT MAX(CASE WHEN TYPE || SUBTYPE = '100' THEN CONSEC END) AS ID_100_CONSEC
, MAX(CASE WHEN TYPE || SUBTYPE = '200' THEN CONSEC END) AS ID_200_CONSEC
, MAX(CASE WHEN TYPE || SUBTYPE = '300' THEN CONSEC END) AS ID_300_CONSEC
, YEAR
, BUILDING
FROM REPORT_MASTER_VIEW
WHERE TYPE || SUBTYPE IN ('100', '200', '300')
GROUP BY
YEAR
, BUILDING
)
,cte3 AS
(
SELECT ID_100_CONSEC
, ID_200_CONSEC
, ID_300_CONSEC
, YEAR
, BUILDING
, CASE
WHEN c2.ID_100_CONSEC = 1 THEN '600 Level 1'
WHEN c2.ID_100_CONSEC = 2 THEN '600 Level 2'
WHEN c2.ID_100_CONSEC = 3 THEN '600 Level 3'
WHEN c2.ID_200_CONSEC = 1 THEN '600 Level 1'
WHEN c2.ID_200_CONSEC = 2 THEN '600 Level 2'
WHEN c2.ID_200_CONSEC = 3 THEN '600 Level 3'
WHEN c2.ID_300_CONSEC = 1 THEN '600 Level 1'
WHEN c2.ID_300_CONSEC = 2 THEN '600 Level 2'
WHEN c2.ID_300_CONSEC = 3 THEN '600 Level 3'
END AS RESULT
FROM cte2
WHERE c2.ID_100_CONSEC IN (1, 2, 3)
OR c2.ID_200_CONSEC IN (1, 2, 3)
OR c2.ID_300_CONSEC IN (1, 2, 3)
)
SELECT t1."BUILDING",
t1."BUILDING_NAME",
t1."GROUP",
t1."YEAR",
t1."TYPE",
t1."SUBTYPE",
t1."CONSEC",
t2.RESULT
FROM REPORT_MASTER_VIEW t1
WHERE T1.TYPE IN ('100', '200', '300')
AND EXISTS
(
SELECT 1
FROM cte3 t2
WHERE t1.BUILDING = t2.BUILDING
AND t1.YEAR = t2.YEAR
)
ORDER BY
t1.BUILDING;
Should be pretty close. I think you will need to polish it a little.