Materialized view takes long to refresh

Question

On Oracle 11g2, I created a materialized view fast refresh on commit CREATE MATERIALIZED VIEW mv_case
PARALLEL BUILD IMMEDIATE REFRESH FAST ON COMMIT ENABLE QUERY REWRITE AS
SELECT p.jperson_id,offense_id,CASE_SENTENCE_DATE,court_ref,CASE_COURT_ORI,
  c.CASE_VERDICT_DATE,CASE_DOCKET,c.CASE_EXPUNGED,c.jcase_id,cc.CYCLEID_ID,
  p.rowid p_rowid,xc.rowid xc_rowid,c.rowid c_rowid,cxo.rowid cxo_rowid,cc.rowid cc_row_id
FROM jperson p,jperson_x_jcase xc,jcase c,jcase_x_offense cxo,jcase_x_cycleid cc
where p.jperson_id = xc.jperson_id(+) and xc.jcase_id = c.jcase_id(+)
  and c.jcase_id = cxo.jcase_id(+) and c.jcase_id=cc.jcase_id;
create index idx_mv_case_pid on mv_case(jperson_id);
ALTER TABLE mv_case ADD (CONSTRAINT PK_MV_CASE PRIMARY KEY(jcase_id,offense_id)) ;
create index idx_mv_case_p_rowid on mv_case(p_rowid);
create index idx_mv_case_xc_rowid on mv_case(xc_rowid);
create index idx_mv_case_c_rowid on mv_case(c_rowid);
create index idx_mv_case_cxo_rowid on mv_case(cxo_rowid);
create index idx_mv_case_cc_rowid on mv_case(cc_row_id); I inserted one single row into one of the master table
insert into jcase_x_offense (offense_id,jcase_id) values ('test_row3','test_row3');
commit; The commit tooks a quite long. I looked into the trace file and the actual insert took 0.01 seconds but one of the internel DML took most of time. I copy the relevant TKPROF output for the internal DML belowINSERT INTO QAPF.MV_CASE SELECT /*+ NO_MERGE(JV$) */
  MAS$4.JPERSON_ID,JV$.OFFENSE_ID,MAS$2.CASE_SENTENCE_DATE,
  MAS$2.COURT_REF,MAS$2.CASE_COURT_ORI,MAS$2.CASE_VERDICT_DATE,
  MAS$2.CASE_DOCKET,MAS$2.CASE_EXPUNGED,MAS$2.JCASE_ID,
  MAS$0.CYCLEID_ID,MAS$4.ROWID,MAS$3.ROWID,MAS$2.ROWID,JV$.RID$,
  MAS$0.ROWID
  FROM ( SELECT MAS$.ROWID RID$  ,  MAS$.*  FROM  QAPF.JCASE_X_OFFENSE MAS$ WHERE ROWID IN
          (SELECT  /*+ HASH_SJ */ CHARTOROWID(MAS$.M_ROW$$) RID$
           FROM QAPF.MLOG$_JCASE_X_OFFENSE MAS$ WHERE MAS$.XID$$ = :1 )) JV$,
  JCASE_X_CYCLEID AS OF SNAPSHOT(:B_SCN)  MAS$0, JCASE AS OF SNAPSHOT(:B_SCN)  MAS$2,
  JPERSON_X_JCASE AS OF SNAPSHOT(:B_SCN)  MAS$3, JPERSON AS OF SNAPSHOT(:B_SCN)  MAS$4
  WHERE (MAS$4.JPERSON_ID=MAS$3.JPERSON_ID(+)
  AND MAS$3.JCASE_ID=MAS$2.JCASE_ID(+)
  AND MAS$2.JCASE_ID=JV$.JCASE_ID(+)
  AND MAS$2.JCASE_ID=MAS$0.JCASE_ID)
  AND NOT EXISTS (
    SELECT 1 FROM QAPF.MV_CASE SNA2$
    WHERE (SNA2$.P_ROWID = MAS$4.ROWID)
    AND (SNA2$.XC_ROWID = MAS$3.ROWID OR MAS$3.ROWID IS NULL )
    AND (SNA2$.C_ROWID = MAS$2.ROWID OR MAS$2.ROWID IS NULL )
    AND (SNA2$.CC_ROW_ID = MAS$0.ROWID OR MAS$0.ROWID IS NULL )
    AND JV$.RID$ IS NULL)
  AND NOT EXISTS (
    SELECT 1  FROM JCASE_X_OFFENSE MAS_INNER$, JCASE AS OF SNAPSHOT(:B_SCN)  MAS_OUTER$
    WHERE MAS$2.ROWID = MAS_OUTER$.ROWID AND JV$.RID$ IS NULL
    AND MAS_OUTER$.JCASE_ID=MAS_INNER$.JCASE_ID)
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1     99.51     364.87     377012   17412972          1           0
Fetch        0      0.00       0.00          0          0          0           0
total        2     99.51     364.87     377012   17412972          1           0
Rows     Row Source Operation
      0  LOAD TABLE CONVENTIONAL  (cr=17412968 pr=377012 pw=120527 time=0 us)
      0   FILTER  (cr=17412968 pr=377012 pw=120527 time=0 us)
3363837    HASH JOIN RIGHT OUTER (cr=264914 pr=280254 pw=120527 time=35845080 us cost=299444 size=1029332286 card=3363831)
      1     VIEW  (cr=112490 pr=180864 pw=119722 time=0 us cost=30743 size=78 card=1)
      1      HASH JOIN SEMI (cr=112490 pr=180864 pw=119722 time=0 us cost=72627 size=208 card=1)
11354346       TABLE ACCESS FULL JCASE_X_OFFENSE (cr=112488 pr=112447 pw=0 time=4814838 us cost=30703 size=749386770 card=11354345)
      1       TABLE ACCESS BY INDEX ROWID MLOG$_JCASE_X_OFFENSE (cr=2 pr=0 pw=0 time=0 us cost=1 size=142 card=1)
      1        INDEX RANGE SCAN IDX_MLOG$_XID_JCASE_X_OFFENSE (cr=1 pr=0 pw=0 time=0 us cost=1 size=0 card=1)(object id 98375)
3363837     HASH JOIN  (cr=152424 pr=99390 pw=805 time=29973970 us cost=268690 size=766953468 card=3363831)
2994042      INDEX FAST FULL SCAN JPERSON_I0 (cr=18134 pr=0 pw=0 time=772990 us cost=17450 size=134731845 card=2994041)(object id 83738)
3363837      HASH JOIN  (cr=134290 pr=99390 pw=805 time=25292580 us cost=212128 size=615581073 card=3363831)
3363837       HASH JOIN  (cr=69008 pr=34127 pw=805 time=4750330 us cost=101637 size=393568929 card=3363837)
3363837        TABLE ACCESS FULL JCASE_X_CYCLEID (cr=33337 pr=33322 pw=0 time=2942460 us cost=33569 size=222013242 card=3363837)
6586646        TABLE ACCESS FULL JCASE (cr=35671 pr=0 pw=0 time=1584102 us cost=35988 size=335918895 card=6586645)
6586635       TABLE ACCESS FULL JPERSON_X_JCASE (cr=65282 pr=65263 pw=0 time=5446686 us cost=65632 size=434717844 card=6586634)
3363837    FILTER  (cr=17148054 pr=96758 pw=0 time=0 us)
3363837     MAT_VIEW ACCESS BY INDEX ROWID MV_CASE (cr=17148054 pr=96758 pw=0 time=0 us cost=7 size=40 card=1)
32464070      INDEX RANGE SCAN IDX_MV_CASE_P_ROWID (cr=4489770 pr=15250 pw=0 time=19576798 us cost=3 size=0 card=7)(object id 98467)
      0    FILTER  (cr=0 pr=0 pw=0 time=0 us)
      0     NESTED LOOPS  (cr=0 pr=0 pw=0 time=0 us cost=4 size=78 card=1)
      0      TABLE ACCESS BY USER ROWID JCASE (cr=0 pr=0 pw=0 time=0 us cost=1 size=45 card=1)
      0      INDEX RANGE SCAN JCASE_X_OFFENSE_I0 (cr=0 pr=0 pw=0 time=0 us cost=3 size=33 card=1)(object id 83623)Questions:
1) what are the objects like JCASE AS OF SNAPSHOT(:B_SCN) ? Can I index them? I tried access it but got error
select * from JCASE AS OF SNAPSHOT(:B_SCN) ;
ORA-08187: snapshot expression not allowed here
08187. 00000 - "snapshot expression not allowed here"
*Cause:    A snapshot expression using AS OF was specified when not allowed.
*Action:   Do not use the AS OF clause
2) In the inline view following the firs FROM, it used ROWID in where clause. I tried create an index on ROWID, and error
create index idx_jcase_offense_rid on JCASE_X_OFFENSE(rowid)
ERROR at line 1:
ORA-00904: : invalid identifier
Note: I checked that I have indexes all fields in all where clauses in the DML except rowid.
Thanks for help.

Answer 1

sybrand_b wrote:
1 Apparently Oracle is using Flashback technology when no materialized view logs have been set up
As your MV is a complex MV it is not a candidate for FAST REFRESH ON COMMIT.
I haven't looked closely at how 11.2 has changed the "fast refresh on commit" - but I would have expected it to raise an Oracle error when the OP tried to create the materialized view with that option if it were not possible.
I think your first comment is probably the more important one - if the user sets up suitable materialized view logs on all the tables in the outer join then it's possible that the fast refresh could work properly.
This is pure speculation, of course, based on the absence of an error message.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
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