LEAD and LAG taking hours on a very large table!

Sam_P · Apr 6, 2022 12:12AM

Hi @Solomon Yakobson , I had created the index with the leading column being SEQNUM. Then ran the CTAS and it is taking forever.....over 4 hrs now. I had to manually cancel it, yet again.

I'll go ahead and drop the index and re-create it as follows:-

CREATE INDEX IX_COMPOSITE_COLUMNS ON TB_SOURCE
(
    ULIMORE,
    VISIT_DATE_DT,
    SEQNUM,
    ED_UCC_DT,
    ED_UCC_SEQNUM,
    DAD_ACUTE_DISP_DT,
    DAD_ACUTE_ADMIT_DT,
    DAD_ACUTE_SEQNUM,
    1 -- Since all the above columns are NULLable, we need to add a constant for the Function-Based Index to be created 
) 
TABLESPACE "ANALYTICS_INDEX" 
PARALLEL 8 
NOLOGGING 
COMPUTE STATISTICS
;
/

The EXPLAIN PLAN (it did not switch to WINDOW BUFFER):-

Sam_P · Apr 6, 2022 6:36PM

Hello @alvinder , thanks for sharing your code sample.

The ULIMORE column is a VARCHAR2, so your "bucket" query simply picks up the numeric values and ignores the rest of the string values.

Solomon Yakobson · Apr 6, 2022 7:25PM

Show CTAS statement.

SY.

Sam_P · Apr 6, 2022 8:08PM

@Solomon Yakobson

EXPLAIN PLAN FOR 
CREATE TABLE TB_TARGET
PCTFREE 0 
PARALLEL 8 
NOLOGGING 
AS 
SELECT /*+ PARALLEL(8) */ 
    p.SEQNUM,
    p.ULIMORE,
    p.VISIT_DATE_DT,
 
    LAG(p.ED_UCC_DT      IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_ED_UCC_DT,
    LEAD(p.ED_UCC_DT     IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_ED_UCC_DT,
     
    LAG(p.ED_UCC_SEQNUM    IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_ED_UCC_SEQNUM,
    LEAD(p.ED_UCC_SEQNUM   IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_ED_UCC_SEQNUM,
     
    LAG(p.DAD_ACUTE_DISP_DT  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_DAD_DISP_AC_DT,
    LEAD(p.DAD_ACUTE_ADMIT_DT IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_DAD_DISP_AC_DT,
     
    LAG(p.DAD_ACUTE_SEQNUM  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_DAD_DISP_AC_SEQNUM,
    LEAD(p.DAD_ACUTE_SEQNUM  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_DAD_DISP_AC_SEQNUM

FROM
    TB_SOURCE p
;
/

I even tried matching the columns like they were in the INDEX above but still the EXPLAIN PLAN does not perform a WINDOW BUFFER but rather, it shows WINDOW SORT:-

EXPLAIN PLAN FOR 
CREATE TABLE TB_TARGET
PCTFREE 0 
PARALLEL 8 
NOLOGGING 
AS 
SELECT /*+ PARALLEL(8) */ 
    p.ULIMORE,
    p.VISIT_DATE_DT,
    p.SEQNUM, 

    LAG(p.ED_UCC_DT      IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_ED_UCC_DT,
    LEAD(p.ED_UCC_DT     IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_ED_UCC_DT,
     
    LAG(p.ED_UCC_SEQNUM    IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_ED_UCC_SEQNUM,
    LEAD(p.ED_UCC_SEQNUM   IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_ED_UCC_SEQNUM,
     
    LAG(p.DAD_ACUTE_DISP_DT  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_DAD_DISP_AC_DT,
    LEAD(p.DAD_ACUTE_ADMIT_DT IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_DAD_DISP_AC_DT,
     
    LAG(p.DAD_ACUTE_SEQNUM  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_DAD_DISP_AC_SEQNUM,
    LEAD(p.DAD_ACUTE_SEQNUM  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_DAD_DISP_AC_SEQNUM

FROM
    TB_SOURCE p
;
/

Solomon Yakobson · Apr 6, 2022 11:07PM

Post create TB_SOURCE table.

SY.

alvinder · Apr 6, 2022 11:24PM

Tested with varchar2 for Ulimore.

I am using ora_hash function to assign a number to a string.

This code works for me. I have created 100 buckets running 15 in parallel. You can go for more data. My sample data is 100000

DROP TABLE TB_SOURCE PURGE;


CREATE TABLE TB_SOURCE(
                           SEQNUM            VARCHAR2(18),
                           ULIMORE           VARCHAR2(15),
                           VISIT_DATE_DT     DATE,
                           ED_UCC_DT         DATE,
                           ED_UCC_SEQNUM     VARCHAR2(18),
                           DAD_ACUTE_DISP_DT DATE,
                           DAD_ACUTE_SEQNUM  VARCHAR2(18)
                           )
 /
--Creating sample data.                           
INSERT INTO tb_source
    SELECT
        ROWNUM
      , 
            dbms_random.string(
                'x'
              , 5
            )
        
      , sysdate - ROWNUM
      , sysdate - ROWNUM
      , ROWNUM
      , sysdate - ROWNUM
      , ROWNUM
      
    FROM
        dual
    CONNECT BY
        level < 100000;         


  truncate table tb_source_final;          


 CREATE TABLE TB_SOURCE_final(
                           SEQNUM            VARCHAR2(18),
                           ULIMORE           VARCHAR2(15),
                           VISIT_DATE_DT     DATE,
                           ED_UCC_DT_prev         DATE,
                            ED_UCC_DT_next         DATE,
                           ED_UCC_SEQNUM_prev     VARCHAR2(18),
                            ED_UCC_SEQNUM_next     VARCHAR2(18),
                           DAD_ACUTE_DISP_DT_prev DATE,
                             DAD_ACUTE_DISP_DT_next DATE,
                           DAD_ACUTE_SEQNUM_prev  VARCHAR2(18),
                             DAD_ACUTE_SEQNUM_next  VARCHAR2(18)
                          )
  /
 
 
 create index tb_source_ix1 on tb_source(
                            ora_hash(ulimore,155000000)           ,
                           VISIT_DATE_DT     ,
                           SEQNUM,
                           ED_UCC_DT         ,
                           ED_UCC_SEQNUM     ,
                           DAD_ACUTE_DISP_DT ,
                           DAD_ACUTE_SEQNUM  
                           ) parallel(degree 8);
Alter index tb_source_ix1 noparallel;

create or replace PROCEDURE insert_parallel_execute AS
    l_chunk_sql VARCHAR2(1000);
    l_sql_stmt  VARCHAR2(32000);
    l_try       NUMBER;
    l_status    NUMBER;
BEGIN
    BEGIN
        dbms_parallel_execute.drop_task('insert_aps');
    EXCEPTION
        WHEN OTHERS THEN
            NULL;
    END;
  -- Create the TASK
    dbms_parallel_execute.create_task('insert_aps');


  -- Chunk the table by MANAGER_ID
    l_chunk_sql := 'WITH t AS (
    SELECT DISTINCT
        ora_hash(ulimore,155000000,0) ulimore
    FROM
        tb_source
), t1 AS (
    SELECT
        ulimore
      , NTILE(100)
          OVER(
            ORDER BY
                ulimore
          ) bucket
    FROM
        t
)
SELECT
   MIN(ulimore)start_id
  , MAX(ulimore) end_id
FROM
    t1
GROUP BY
    bucket ';
    
    dbms_parallel_execute.create_chunks_by_sql(
                                              'insert_aps'
                                            , l_chunk_sql
                                            , false
    );


  -- Execute the DML in parallel
  --   the WHERE clause contain a condition on manager_id, which is the chunk
  --   column. In this case, grouping rows is by manager_id.
    l_sql_stmt := ' insert into  TB_SOURCE_final
  SELECT 
        p.SEQNUM,
        p.ULIMORE,
       p.VISIT_DATE_DT,
       LAG(p.ED_UCC_DT          IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_ED_UCC_DT,
       LEAD(p.ED_UCC_DT         IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_ED_UCC_DT,
       LAG(p.ED_UCC_SEQNUM      IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_ED_UCC_SEQNUM,
       LEAD(p.ED_UCC_SEQNUM     IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_ED_UCC_SEQNUM,
       LAG(p.DAD_ACUTE_DISP_DT  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_DAD_DISP_AC_DT,
       LEAD(p.DAD_ACUTE_DISP_DT IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_DAD_DISP_AC_DT,
       LAG(p.DAD_ACUTE_SEQNUM   IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS PREV_DAD_DISP_AC_SEQNUM,
       LEAD(p.DAD_ACUTE_SEQNUM  IGNORE NULLS)  OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)     AS NEXT_DAD_DISP_AC_SEQNUM
   FROM
       TB_SOURCE p
       where ora_hash(ulimore,155000000) between  :start_id and :end_id';
             
    dbms_parallel_execute.run_task(
                                  'insert_aps'
                                , l_sql_stmt
                                , dbms_sql.native
                                , parallel_level => 15
    );
END insert_parallel_execute;
/

  select status,count(*) from user_parallel_execute_chunks
  where task_name = 'insert_aps'
  group by status;

Jonathan Lewis · Apr 7, 2022 3:49PM

https://community.oracle.com/tech/developers/discussion/comment/16831444#Comment_16831444

Coming back to this after some time away.

Getting the unique identifying columns from the Data Scientist was a good move, and that's then the right query to generate the extra columns he needs. The plan shows an estimated 10G memory of an "optimal" i.e. in-memory sort, so my estimate of 9GB was in the right ballpark.

If this is taking 4.5 hours running parallel 8 the thing to check is HOW is the time being used. Are your PX slaves using 100% CPU, are they stalled waiting for CPU, is time going on interprocess communication with that hash distribution, are you spending a lot of time on I/O, and is this for tablescans, temp reads and writes, or reading undo. Is it possible that Oracle hasn't noticed a data skew and one process is doing almost all the sorting ... etc,

I've just published a script that will report all the session stats for the PX processes in a parallel query; I'm looking for the one that does the same for events and will publish that shortly. In 4.5 hours you should be able to get some good indications of why the CTAS is taking so long.

Regards

Jonathan Lewis

UPDATE: The script for parallel wait events is now online.

Sam_P · Apr 7, 2022 9:13PM

Thanks @Jonathan Lewis . I had to manually cancel the CTAS after 4.5 hrs as I could not go on...

Thanks for your 2 scripts. If I understand correctly, I should run 3 separate windows (sessions) of Oracle SQLCl (command line) tool -- in one window, I start running the CTAS, followed by running your 2 separate scripts in the rest of the windows.

For this test, I have done the following:-

1. Created a duplicate copy of the source table with only the columns that we need and called it as TB_SOURCE_COPY_TRIMMED.

2. Columns SEQNUM, ULIMORE and VISIT_DATE_DT do not contain any NULL values.

3. Because we know from the Data Scientist that the composite columns (SEQNUM, ULIMORE, VISIT_DATE_DT) uniquely identify a record, I proceeded to create a UNIQUE index and a Primary Key constraint on TB_SOURCE_COPY_TRIMMED table. @Solomon Yakobson, @Jonathan Lewis @alvinder Please see the script attached.

4. Running the EXPLAIN PLAN shows:-

@Jonathan Lewis I'll attach the px_stats.log and px_wait.log files after a few hours pass-by.

01_TB_SOURCE_COPY_TRIMMED.txt

Solomon Yakobson · Apr 7, 2022 9:51PM

Again, compare plans:

SQL> CREATE UNIQUE INDEX UX_COMPOSITE_KEYS
  2  ON TB_SOURCE_COPY_TRIMMED
  3  (
  4          SEQNUM,
  5          ULIMORE,
  6          VISIT_DATE_DT
  7  );


Index created.


SQL> ALTER TABLE     TB_SOURCE_COPY_TRIMMED
  2  ADD CONSTRAINT  PK_COMPOSITE_KEYS
  3  PRIMARY KEY     (SEQNUM, ULIMORE, VISIT_DATE_DT)
  4  USING INDEX     UX_COMPOSITE_KEYS
  5  ;


Table altered.


SQL> set sqlbla on
SQL> EXPLAIN PLAN FOR
  2  CREATE TABLE TB_TARGET_WITH_LEAD_LAG
  3  PARALLEL 8
  4  NOLOGGING
  5  AS
  6  SELECT /*+ PARALLEL(8) */
  7          p.SEQNUM,
  8          p.ULIMORE,
  9          p.VISIT_DATE_DT,
 10
 11          LAG(p.ED_UCC_DT           IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_ED_UCC_DT,
 12          LEAD(p.ED_UCC_DT          IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_ED_UCC_DT,
 13
 14          LAG(p.ED_UCC_SEQNUM       IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_ED_UCC_SEQNUM,
 15          LEAD(p.ED_UCC_SEQNUM      IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_ED_UCC_SEQNUM,
 16
 17          LAG(p.DAD_ACUTE_DISP_DT   IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_DAD_DISP_AC_DT,
 18          LEAD(p.DAD_ACUTE_ADMIT_DT IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_DAD_DISP_AC_DT,
 19
 20          LAG(p.DAD_ACUTE_SEQNUM    IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_DAD_DISP_AC_SEQNUM,
 21          LEAD(p.DAD_ACUTE_SEQNUM   IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_DAD_DISP_AC_SEQNUM
 22
 23  FROM
 24          TB_SOURCE_COPY_TRIMMED p
 25  ;


Explained.


SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);


PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1332415219


-------------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                          | Name                    | Rows  | Bytes | Cost (%CPU)| Time     |    TQ  |IN-OUT| PQ Distrib |
-------------------------------------------------------------------------------------------------------------------------------------------
|   0 | CREATE TABLE STATEMENT             |                         |     1 |    78 |     3  (34)| 00:00:01 |        |      |            |
|   1 |  PX COORDINATOR                    |                         |       |       |            |          |        |      |            |
|   2 |   PX SEND QC (RANDOM)              | :TQ10001                |     1 |    78 |     3  (34)| 00:00:01 |  Q1,01 | P->S | QC (RAND)  |
|   3 |    LOAD AS SELECT (HYBRID TSM/HWMB)| TB_TARGET_WITH_LEAD_LAG |       |       |            |          |  Q1,01 | PCWP |            |
|   4 |     OPTIMIZER STATISTICS GATHERING |                         |     1 |    78 |     3  (34)| 00:00:01 |  Q1,01 | PCWP |            |
|   5 |      WINDOW SORT                   |                         |     1 |    78 |     3  (34)| 00:00:01 |  Q1,01 | PCWP |            |
|   6 |       PX RECEIVE                   |                         |     1 |    78 |     2   (0)| 00:00:01 |  Q1,01 | PCWP |            |
|   7 |        PX SEND HASH                | :TQ10000                |     1 |    78 |     2   (0)| 00:00:01 |  Q1,00 | P->P | HASH       |
|   8 |         PX BLOCK ITERATOR          |                         |     1 |    78 |     2   (0)| 00:00:01 |  Q1,00 | PCWC |            |
|   9 |          TABLE ACCESS FULL         | TB_SOURCE_COPY_TRIMMED  |     1 |    78 |     2   (0)| 00:00:01 |  Q1,00 | PCWP |            |
-------------------------------------------------------------------------------------------------------------------------------------------


Note
-----
   - dynamic statistics used: dynamic sampling (level=2)
   - Degree of Parallelism is 8 because of hint


21 rows selected.


SQL> CREATE UNIQUE INDEX UX2_COMPOSITE_KEYS
  2  ON TB_SOURCE_COPY_TRIMMED
  3  (
  4          ULIMORE,
  5          VISIT_DATE_DT,
  6          SEQNUM,
  7          ED_UCC_DT,
  8          ED_UCC_SEQNUM,
  9          DAD_ACUTE_DISP_DT,
 10          DAD_ACUTE_ADMIT_DT,
 11          DAD_ACUTE_SEQNUM
 12  );


Index created.


SQL> EXPLAIN PLAN FOR
  2  CREATE TABLE TB_TARGET_WITH_LEAD_LAG
  3  PARALLEL 8
  4  NOLOGGING
  5  AS
  6  SELECT /*+ PARALLEL(8) */
  7          p.SEQNUM,
  8          p.ULIMORE,
  9          p.VISIT_DATE_DT,
 10
 11          LAG(p.ED_UCC_DT           IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_ED_UCC_DT,
 12          LEAD(p.ED_UCC_DT          IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_ED_UCC_DT,
 13
 14          LAG(p.ED_UCC_SEQNUM       IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_ED_UCC_SEQNUM,
 15          LEAD(p.ED_UCC_SEQNUM      IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_ED_UCC_SEQNUM,
 16
 17          LAG(p.DAD_ACUTE_DISP_DT   IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_DAD_DISP_AC_DT,
 18          LEAD(p.DAD_ACUTE_ADMIT_DT IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_DAD_DISP_AC_DT,
 19
 20          LAG(p.DAD_ACUTE_SEQNUM    IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS PREV_DAD_DISP_AC_SEQNUM,
 21          LEAD(p.DAD_ACUTE_SEQNUM   IGNORE NULLS)   OVER (PARTITION BY p.ULIMORE ORDER BY p.VISIT_DATE_DT)         AS NEXT_DAD_DISP_AC_SEQNUM
 22
 23  FROM
 24          TB_SOURCE_COPY_TRIMMED p
 25  ;


Explained.


SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);


PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1877319916


-------------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                          | Name                    | Rows  | Bytes | Cost (%CPU)| Time     |    TQ  |IN-OUT| PQ Distrib |
-------------------------------------------------------------------------------------------------------------------------------------------
|   0 | CREATE TABLE STATEMENT             |                         |     1 |    78 |     2   (0)| 00:00:01 |        |      |            |
|   1 |  PX COORDINATOR                    |                         |       |       |            |          |        |      |            |
|   2 |   PX SEND QC (RANDOM)              | :TQ10001                |     1 |    78 |     1   (0)| 00:00:01 |  Q1,01 | P->S | QC (RAND)  |
|   3 |    LOAD AS SELECT (HYBRID TSM/HWMB)| TB_TARGET_WITH_LEAD_LAG |       |       |            |          |  Q1,01 | PCWP |            |
|   4 |     OPTIMIZER STATISTICS GATHERING |                         |     1 |    78 |     1   (0)| 00:00:01 |  Q1,01 | PCWP |            |
|   5 |      PX RECEIVE                    |                         |     1 |    78 |     1   (0)| 00:00:01 |  Q1,01 | PCWP |            |
|   6 |       PX SEND ROUND-ROBIN          | :TQ10000                |     1 |    78 |     1   (0)| 00:00:01 |  Q1,00 | S->P | RND-ROBIN  |
|   7 |        PX SELECTOR                 |                         |       |       |            |          |  Q1,00 | SCWC |            |
|   8 |         WINDOW BUFFER              |                         |     1 |    78 |     1   (0)| 00:00:01 |  Q1,00 | SCWC |            |
|   9 |          INDEX FULL SCAN           | UX2_COMPOSITE_KEYS      |     1 |    78 |     1   (0)| 00:00:01 |  Q1,00 | SCWP |            |
-------------------------------------------------------------------------------------------------------------------------------------------


Note
-----
   - dynamic statistics used: dynamic sampling (level=2)
   - Degree of Parallelism is 8 because of hint


21 rows selected.


SQL>

SY.

Sam_P · Apr 7, 2022 10:06PM

@Jonathan Lewis . Attached below are the log files.

px_stats.log

px_waits.log

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LEAD and LAG taking hours on a very large table!

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LEAD and LAG taking hours on a very large table!

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