Oracle – Extract SDO_GEOMETRY Line Vertices into Nested Table

I know a bit about Oracle performance and pretty much nothing about custom data types, but I'll try to give you a plan to improve performance.

1) Verify that you cannot get an explain plan.

It's possible to get explain plans even if you don't have sophisicated database software. What happens if you execute set autotrace on explain?

You could also try DBMS_XPLAN. First save off the plan by wrapping your query with a few extra key words:

explain plan for (SELECT... your query goes here); 

Then execute this:

SELECT PLAN_TABLE_OUTPUT FROM TABLE(DBMS_XPLAN.DISPLAY());

It's possible that neither of those will work and you truly cannot get an explain plan. I just wanted to verify that because with an explain plan it'll be much easier for the community to help you.

2) Consider requirements.

You said that 20 seconds isn't good enough. Have you or someone else defined exactly what is good enough? Is there any room for negotiation? Does your query need to be exactly one SELECT query? Could you populate a global temporary table in one step and select the results you wanted in the next? Could you create a stored procedure that returns a result set and call that?

3) Establish a lower bound for the time required to complete the query.

I suggest running a simple query that "cheats" to figure out what a well-optimized query would look like. For example, how long does this query that gets only the first vertices take?

SELECT
    ROWNUM
    ,ROAD_ID
    ,VERTEX_INDEX
    ,SDE.ST_X(ST_POINT) AS X
    ,SDE.ST_Y(ST_POINT) AS Y
FROM
(
    SELECT  
          ROWNUM
          ,a.ROAD_ID
          ,1 VERTEX_INDEX
          ,SDE.ST_PointN(a.SHAPE, 1) AS ST_POINT
    FROM  ENG.ROAD a
)
ORDER BY ROAD_ID, VERTEX_INDEX;

I suspect that will give you 4000 rows. If you multiply that query's response time by 17.5/4 that could give you a good lower bound for the total execution time.

If your lower bound for the total execution time is longer than what you established in step 2 then you either need to get creative with your data model by calculating results ahead of time and storing them in tables or you need to renegotiate the required response time.

4) Benchmark to figure out which functions are contributing the most to your execution time.

You were on the right track with Update #1 but you need to try to control for the amount of work being done. For example, is it possible to write a group of relatively simple queries that execute each function exactly 10000 times? How do the response times compare?

5) Go to work.

Depending on the requirements established in step 2 and what you found in step 4 try any trick that you can think of to reduce the query runtime. Are you able to pre-compute results and save off them? If the problem relates to the number of times the functions are executed then the undocumented materialize hint may be helpful. That forces Oracle to create a hidden temp table behind the scenes to store the results. I do not know if it is compatible with the special data types that you are using.

For example, maybe something like this performs better? Apologies if it does not compile but I have no way to test.

WITH ROAD_CTE (ROAD_ID, VERTEX_INDEX, SHAPE) AS
(
    SELECT /*+ materalize */
      a.ROAD_ID
    , b.NUMBERS VERTEX_INDEX
    , a.SHAPE
    FROM ENG.ROAD a
    CROSS JOIN ENG.NUMBERS b
    WHERE b.NUMBERS <= SDE.ST_NUMPOINTS(a.SHAPE)
)
, CTE_WITH_ST_POINT (ROAD_ID, VERTEX_INDEX, ST_POINT) AS
(
    SELECT /*+ materalize */
      rcte.ROAD_ID
    , rcte.VERTEX_INDEX
    , SDE.ST_PointN(rcte.SHAPE, rcte.VERTEX_INDEX) ST_POINT
    FROM ROAD_CTE rcte
)
SELECT 
      ROAD_ID
    , VERTEX_INDEX
    , SDE.ST_X(ST_POINT) AS X
    , SDE.ST_Y(ST_POINT) AS Y
FROM CTE_WITH_ST_POINT
ORDER BY ROAD_ID, VERTEX_INDEX;

If you're still stuck after all of this I suspect that it'll at least give you additional information that you can edit into the question. Good luck!

MULTISET EXCEPT

The element types of the nested tables must be comparable.

Comparison Conditions

Two objects of nonscalar type are comparable if they are of the same named type and there is a one-to-one correspondence between their elements. In addition, nested tables of user-defined object types, even if their elements are comparable, must have MAP methods defined on them to be used in equality or IN conditions.

The problem is, the above can not be done with a record type. record types have only fields, and can not have member functions. Furthermore:

Record Comparisons

Records cannot be tested natively for nullity, equality, or inequality.

These BOOLEAN expressions are illegal:

• My_Record IS NULL
• My_Record_1 = My_Record_2
• My_Record_1 > My_Record_2

This fails:

create or replace package p1 as
  type typ_Rec is record(id customers.customer_id%type, name customers.cust_first_name%type);                 
  type typ_NT is table of typ_Rec;
  function f1 (tab typ_NT) return typ_NT;
end;
/

Package created.

create or replace package body p1 as
  function f1 (tab typ_NT) return typ_NT as
    tab1 typ_NT := typ_NT();
  begin
    return tab multiset except tab1;
  end;
end;
/

Warning: Package Body created with compilation errors.

SQL> show errors
Errors for PACKAGE BODY P1:

LINE/COL ERROR
-------- -----------------------------------------------------------------
5/5      PL/SQL: Statement ignored
5/12     PLS-00306: wrong number or types of arguments in call to
         'MULTISET_EXCEPT_ALL'

UNION works, because you did not specify ALL or DISTINCT, and in this case, UNION ALL is the default. UNION ALL does not need to perform comparison. But if you try UNION DISTINCT (which removes duplicates), that will also fail:

create or replace package body p1 as
  function f1 (tab typ_NT) return typ_NT as
    tab1 typ_NT := typ_NT();
  begin
    return tab multiset union distinct tab1;
  end;
end;
/

Warning: Package Body created with compilation errors.

SQL> show errors
Errors for PACKAGE BODY P1:

LINE/COL ERROR
-------- -----------------------------------------------------------------
5/5      PL/SQL: Statement ignored
5/12     PLS-00306: wrong number or types of arguments in call to
         'MULTISET_UNION_DISTINCT'

You need an object type for this.

create or replace type typ_Obj as object
(
  id number(6),
  name varchar2(20)
);
/

Type created.

create or replace package p1 as
  type typ_NT is table of typ_Obj;
  function f1 (tab typ_NT) return typ_NT;
end;
/

Package created.

create or replace package body p1 as
  function f1 (tab typ_NT) return typ_NT as
    tab1 typ_NT := typ_NT();
  begin
    return tab multiset except tab1;
  end;
end;
/

Warning: Package Body created with compilation errors.

SQL> show errors
Errors for PACKAGE BODY P1:

LINE/COL ERROR
-------- -----------------------------------------------------------------
5/5      PL/SQL: Statement ignored
5/12     PLS-00306: wrong number or types of arguments in call to
         'MULTISET_EXCEPT_ALL'

Notice how it still failed, because I did not define the MAP function, I did not tell the database how it can compare two user-defined objects. Now try again, this time with defining MAP (and here I assume objects have unique identifiers and two objects equal if their identifiers equal):

create or replace type typ_Obj as object
(
  id number(6),
  name varchar2(20),
  MAP MEMBER FUNCTION get_idno RETURN NUMBER
);
/

Type created.

CREATE or replace TYPE BODY typ_Obj AS
  MAP MEMBER FUNCTION get_idno RETURN NUMBER IS
  BEGIN
    RETURN id;
  END;
END;
/

Type body created.

create or replace package body p1 as
  function f1 (tab typ_NT) return typ_NT as
    tab1 typ_NT := typ_NT();
  begin
    return tab multiset except tab1;
  end;
end;
/

Package body created.

And finally it worked, no warning.