Log switch checkpoint

Hello
Assume I have two redologs.
Log1-->current
Log2->inactive
After log switch, it becomes.
log1 -->active
log2-->current
The thing is after log switch; checkpoint must be issued and the log1 should be inactive. Why does it show active?
If I manually issue
"alter system checkpoint"
Log1 becomes inactive immeidately.

Mathias Delgado wrote:
Mr sb;
I have also read some other docs.
Please confirm wheter my understanding is correct.
After alter system switch logfile, checkpoint is initiated, not finished.
However when I issue,
"alter system checkpoint"
Checkpoint is issued immediately and therefore the status is of redolog is changed from active to inactive immediately.No , your understanding is incorrect.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> select * from V$log;
    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIM
         1          1         65   52428800          1 YES INACTIVE
      2254888 25-JUN-09
         2          1         66   52428800          1 YES INACTIVE
      2279864 26-JUN-09
         3          1         67   52428800          1 NO  CURRENT
      2300530 27-JUN-09
SQL> select checkpoint_change# from V$datafile;
CHECKPOINT_CHANGE#
           2300531
           2300531
           2300531
           2300531
           2300531
           2300531
           2300531
           2300531
8 rows selected.
SQL> alter system checkpoint;
System altered.
SQL> select checkpoint_change# from V$datafile;
CHECKPOINT_CHANGE#
           2302787
           2302787
           2302787
           2302787
           2302787
           2302787
           2302787
           2302787
8 rows selected.
SQL> select * from V$log;
    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIM
         1          1         65   52428800          1 YES INACTIVE
      2254888 25-JUN-09
         2          1         66   52428800          1 YES INACTIVE
      2279864 26-JUN-09
         3          1         67   52428800          1 NO  CURRENT
      2300530 27-JUN-09
SQL> alter system checkpoint;
System altered.
SQL> select * from V$log;
    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIM
         1          1         65   52428800          1 YES INACTIVE
      2254888 25-JUN-09
         2          1         66   52428800          1 YES INACTIVE
      2279864 26-JUN-09
         3          1         67   52428800          1 NO  CURRENT
      2300530 27-JUN-09
SQL> select checkpoint_change# from V$datafile;
CHECKPOINT_CHANGE#
           2302798
           2302798
           2302798
           2302798
           2302798
           2302798
           2302798
           2302798
8 rows selected.
SQL> alter system switch logfile;
System altered.
SQL> select checkpoint_change# from V$datafile;
CHECKPOINT_CHANGE#
           2302798
           2302798
           2302798
           2302798
           2302798
           2302798
           2302798
           2302798
8 rows selected.
SQL> select * from V$log;
    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIM
         1          1         68   52428800          1 NO  CURRENT
      2302807 27-JUN-09
         2          1         66   52428800          1 YES INACTIVE
      2279864 26-JUN-09
         3          1         67   52428800          1 YES ACTIVE
      2300530 27-JUN-09
SQL> alter system checkpoint;
System altered.
SQL> select * from V$log;
    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIM
         1          1         68   52428800          1 NO  CURRENT
      2302807 27-JUN-09
         2          1         66   52428800          1 YES INACTIVE
      2279864 26-JUN-09
         3          1         67   52428800          1 YES INACTIVE
      2300530 27-JUN-09
SQL> select checkpoint_change# from V$datafile;
CHECKPOINT_CHANGE#
           2302817
           2302817
           2302817
           2302817
           2302817
           2302817
           2302817
           2302817
8 rows selected.
SQL>What you see here, can you try to interpret it?
Alter checkpoint command merely pushes the writing and gets the checkpointing write complete. Its only the log switch which is going to do a complete checkpoint. Active means that the checkpointing for that group is started. The time perilod for which you see this status would depend on the size of the redo log file and also the contents that are there in it when it was switched. After checkpoining is complete for this group, the file be completely empty and would be marked as inactive.
HTH
Aman....

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    IPCCHEAD_UK01) */SFCH_SYS_ID,SFCH_DT,DECODE(NVL(SSTN_SRN,SFCH
    TEMPREF_NO),SSTN_SRN, NULL ,SFCH_TEMP_REF_NO) SFCH_TEMP_REF_NO
    ,NVL(SFCH_STUD_SRN,SSTN_SRN) SFCH_STUD_SRN,SFCH_COURSE_CODE,SFCH
    SCHEMECODE,SFCH_EXMP_STUD_YN,SFCH_EXMP_STUD_REASON,DEH_APPLICA
    2,288,204 1 2,288,204.0 4.3 54.31 59.36 3103356680
    DECLARE job BINARY_INTEGER := :job; next_date DATE := :mydate;
    broken BOOLEAN := FALSE; BEGIN BEGIN /*Quest SOO PPCM job */ qu
    est_ppcm_snapshot_pkg.take_snapshot; END; :mydate := next_date;
    IF broken THEN :b := 1; ELSE :b := 0; END IF; END;
    2,253,877 1 2,253,877.0 4.2 52.70 56.21 579012758
    DELETE FROM QUEST_PPCM_SQL_TEXT TXT WHERE INSTANCE_ID >= 0 AND N
    OT EXISTS (SELECT 1 FROM QUEST_PPCM_SQL_SNAPSHOT SNAP WHERE SNAP
    .SNAPSHOT_ID > 0 AND SNAP.INSTANCE_ID= TXT.INSTANCE_ID AND SNAP.
    SQL_ID = TXT.SQL_ID)
    1,656,006 24 69,000.3 3.1 10.00 24.26 4081782417
    SELECT PISH_COURSE_CODE FROM OV_STU_PAYINSLIP_IPCC_DTL WHERE
    PISH_BANK_CODE = :b1 AND PISH_NO BETWEEN :b2 AND :b3 AND PISD_
    CURR_CODE = :b4 AND PISH_REGION_CODE = :b5 ORDER BY 1
    SQL ordered by Gets for DB: ICAI Instance: icai Snaps: 70 -73
    -> End Buffer Gets Threshold: 10000
    -> Note that resources reported for PL/SQL includes the resources used by
    all SQL statements called within the PL/SQL code. As individual SQL
    statements are also reported, it is possible and valid for the summed
    total % to exceed 100
    CPU Elapsd
    Buffer Gets Executions Gets per Exec %Total Time (s) Time (s) Hash Value
    1,567,946 12 130,662.2 2.9 21.99 47.39 1585476974
    SELECT NVL(TO_CHAR(A.DEH_APPLICATION_DT,'DD/MM/RRRR'), NULL ),NV
    L(TO_CHAR(A.DEH_DT,'DD/MM/RRRR'), NULL ) FROM OT_DAK_ENTRY_HEA
    D A,OT_DAK_ENTRY_DETL B,OT_FIRM_NAME_APPR_HEAD C WHERE A.DEH_SY
    S_ID = B.DED_DEH_SYS_ID AND B.DED_DAK_SYS_ID = C.FNAH_DED_SYS_I
    D AND C.FNAH_SYS_ID = (SELECT MAX(B.FNAH_SYS_ID) FROM OT_FIR
    1,216,226 4 304,056.5 2.3 9.90 54.25 937031003
    SELECT TRIM(STUD_SRN)
    Q1_REGNO, TR
    IM(STUD_TEMP_REF_NO)
    Q1_TEMPNO, STUD_TITLE
    1,138,801 178 6,397.8 2.1 18.13 1009.80 1617597
    SELECT SRN,ACTIVITYDESCRIPTION,STATUS,DOCUMENTNO,DOCUMENTDATE FR
    OM OV_ART_TRANS_STATUS WHERE (SRN=:1) order by DOCUMENTDATE
    1,029,221 230 4,474.9 1.9 20.27 20.76 1838125769
    SELECT MRH_DT,MRH_FIRST_NAME,MRH_MIDDLE_NAME,MRH_SUR_NAME,MRH_ST
    ATUS FROM OM_MEM_REG_HEAD WHERE DECODE(:b1,1,MRH_MRN,MRH_MFCH
    TEMPREF_NO) = :b2
    778,949 52 14,979.8 1.5 20.32 21.85 4142254844
    SELECT LTRIM(RTRIM(DECODE(TIT_NAME,'MR.','CA.','MS.','CA.','MRS.
    ','CA.') || ' ' || MRH_FIRST_NAME || ' ' || MRH_MIDDLE_NAME
    || ' ' || MRH_SUR_NAME || ' ' || DECODE(MRH_APPR_UID, NULL ,
    NULL ,DECODE(MRH_MEM_STATUS,2, NULL ,DECODE(MRH_FELLOW_STATUS_YN
    ,'Y','FCA','ACA'))) || DECODE(MRH_RESI_STATUS,'A','
    755,893 517 1,462.1 1.4 90.43 89.07 1033584013
    SELECT DECODE(MFCD_FEE_TYPE,'M08',1,'M05',2,'M06',3,'M09',4,'M10
    ',5,'M11',6,'M12',7,'M07',8,'M13',9,'M14',10,'M15',11,'M04',12,'
    M03',13,'M02',14,'M01',15,'M21',16,'M22',17,'M23',18,'EXCESS',19
    ,20) FEE_SEQ,MFCD_FEE_TYPE FEE_TYPE,SUM(MFCD_AMT) AMOUNT FROM
    OT_MEM_FEE_COL_HEAD,OT_MEM_FEE_COL_DETL WHERE MFCH_SYS_ID = MFC
    751,010 1,090 689.0 1.4 28.61 31.41 1734754400
    SELECT ROWID,PIIPD_ICAI_EXAM_APPEARED,PIIPD_REG_NO,PIIPD_MTH,PII
    PD_YR,PIIPD_ROLL_NO,PIIPD_EXT_EXAM_APPEARED,PIIPD_EXAM_CODE_1,PI
    IPD_SUBJ_CODE_1,PIIPD_GROUP_1,PIIPD_ROLL_NO_1,PIIPD_LAST_PAPER_D
    T_1,PIIPD_EXAM_CODE_2,PIIPD_SUBJ_CODE_2,PIIPD_GROUP_2,PIIPD_ROLL
    SQL ordered by Reads for DB: ICAI Instance: icai Snaps: 70 -73
    -> End Disk Reads Threshold: 1000
    CPU Elapsd
    Physical Reads Executions Reads per Exec %Total Time (s) Time (s) Hash Value
    227,513 2 113,756.5 10.1 22.04 79.36 2837394537
    SELECT STUD_SRN,STUD_FIRST_NAME,STUD_MIDDLE_NAME,STUD_MAIDEN_NAM
    E,STUD_SURNAME,STUD_FATHER_NAME,STUD_BIRTH_DT,STUD_COMM_CODE,STU
    D_SEX,STUD_HANDICAPPED_YN,STUD_HANDICAPPED_REASON,STUD_LANG_CODE
    ,STUD_NATIONALITY_CODE,STUD_EMAIL,STUD_PERMNT_ADDR_LINE_1,STUD_P
    ERMNT_ADDR_LINE_2,STUD_PERMNT_ADDR_LINE_3,STUD_PERMNT_ADDR_LINE_
    220,939 12 18,411.6 9.8 21.99 47.39 1585476974
    SELECT NVL(TO_CHAR(A.DEH_APPLICATION_DT,'DD/MM/RRRR'), NULL ),NV
    L(TO_CHAR(A.DEH_DT,'DD/MM/RRRR'), NULL ) FROM OT_DAK_ENTRY_HEA
    D A,OT_DAK_ENTRY_DETL B,OT_FIRM_NAME_APPR_HEAD C WHERE A.DEH_SY
    S_ID = B.DED_DEH_SYS_ID AND B.DED_DAK_SYS_ID = C.FNAH_DED_SYS_I
    D AND C.FNAH_SYS_ID = (SELECT MAX(B.FNAH_SYS_ID) FROM OT_FIR
    198,343 2 99,171.5 8.8 5.82 46.25 1414719916
    UPDATE OM_MEM_REG_HEAD SET MRH_MRN=:b1 WHERE MRH_SYS_ID = :b2
    198,343 2 99,171.5 8.8 5.81 46.10 1414796677
    UPDATE OT_DAK_ACTV_HISTORY SET DAH_REG_NO = :B1 WHERE DAH_REG_NO
    = :B3 AND TRUNC(DAH_ACTV_ED_DT ) <= TRUNC(:B2 ) AND DAH_ACTV_ST
    ATUS = 'C'
    173,892 2 86,946.0 7.7 13.85 16.34 3262067067
    SELECT STUD_SRN,STUD_FIRST_NAME,STUD_MIDDLE_NAME,STUD_MAIDEN_NAM
    E,STUD_SURNAME,STUD_FATHER_NAME,STUD_BIRTH_DT,STUD_COMM_CODE,STU
    D_SEX,STUD_HANDICAPPED_YN,STUD_HANDICAPPED_REASON,STUD_LANG_CODE
    ,STUD_NATIONALITY_CODE,STUD_EMAIL,STUD_PERMNT_ADDR_LINE_1,STUD_P
    ERMNT_ADDR_LINE_2,STUD_PERMNT_ADDR_LINE_3,STUD_PERMNT_ADDR_LINE_
    112,038 9 12,448.7 5.0 9.23 10.14 2058267852
    SELECT ROWID,STUD_DT,STUD_TXN_CODE,STUD_NO,STUD_AMD_NO,STUD_REF_
    FROM,STUD_REF_TXN_CODE,STUD_REF_NO,STUD_TEMP_REF_NO,STUD_SRN,STU
    D_TITLE,STUD_STATUS,STUD_FIRST_NAME,STUD_MIDDLE_NAME,STUD_SURNAM
    E,STUD_MAIDEN_NAME,STUD_NAME_STATUS,STUD_FATHER_NAME,STUD_NATION
    ALITY_CODE,STUD_NATION_PROOF_ENCL_YN,STUD_SEX,STUD_HANDICAPPED_Y
    102,583 1 102,583.0 4.5 4.51 285.99 802587273
    SELECT ROWID,DEH_DT,DEH_TXN_CODE,DEH_NO,DEH_AMD_NO,DEH_REF_FROM,
    DEH_REF_TXN_CODE,DEH_REF_NO,DEH_REF_SYS_ID,DEH_REGION_CODE,DEH_A
    PPLICATION_DT,DEH_DOC_STATUS,DEH_STATUS,DEH_PRINT_STATUS,DEH_CLO
    STATUS,DEHSYS_ID,DEH_COMP_CODE,DEH_ACNT_YR,DEH_AMD_DT,DEH_AMD_
    UID,DEH_AMD_RES_CODE,DEH_REF_FROM_NUM,DEH_CR_UID,DEH_CR_DT,DEH_U
    98,825 3 32,941.7 4.4 6.70 6.66 2078892348
    /*SELECT STUD_SRN
    Q1_RE
    GNO, O_GET_OLD_REG_NO(STUD_SRN, :BP_COURSE) OLD_NO, TIT_NAME||'
    '||STUD_FIRST_NAME||' '||STUD_MIDDLE_NAME||' '||STUD_SURNAME
    Q1_NAME, LTRIM(RTRIM(A.STUD_CORRES_ADDR_LINE_1 ))||DECO
    96,187 2 48,093.5 4.3 10.78 16.53 3301514821
    SELECT MFCD_PAYIN_SLIP_NO MFCD_PAYIN_SLIP_NO
    , DECODE(MFCD_BANK_CODE ,'ICI',1,2) ICI_FIRST
    , DECODE(MFCD_INSTR_TYPE,'S',1,'L
    SQL ordered by Reads for DB: ICAI Instance: icai Snaps: 70 -73
    -> End Disk Reads Threshold: 1000
    CPU Elapsd
    Physical Reads Executions Reads per Exec %Total Time (s) Time (s) Hash Value
    ',2,'O',3,4) TYPE_FIRST , MFCD_PAYIN_SLIP_DT , FM_BANK
    .BANK_NAME , BAD_ADDR1 ADD1
    80,683 4 20,170.8 3.6 9.90 54.25 937031003
    SELECT TRIM(STUD_SRN)
    Q1_REGNO, TR
    IM(STUD_TEMP_REF_NO)
    Q1_TEMPNO, STUD_TITLE
    77,972 8 9,746.5 3.5 8.92 8.84 2241526944
    SELECT ROWID,STUD_DT,STUD_TXN_CODE,STUD_NO,STUD_AMD_NO,STUD_REF_
    FROM,STUD_REF_TXN_CODE,STUD_REF_NO,STUD_TEMP_REF_NO,STUD_SRN,STU
    D_TITLE,STUD_STATUS,STUD_FIRST_NAME,STUD_MIDDLE_NAME,STUD_SURNAM
    E,STUD_MAIDEN_NAME,STUD_NAME_STATUS,STUD_FATHER_NAME,STUD_NATION
    ALITY_CODE,STUD_NATION_PROOF_ENCL_YN,STUD_SEX,STUD_HANDICAPPED_Y
    75,667 3 25,222.3 3.4 3.34 25.09 3345305231
    SELECT DISTINCT SFCH_STUD_SRN FROM OT_STUDENT_FEE_COL_HEAD A,O
    T_STUDENT_FEE_COL_DETL B WHERE B.SFCD_SFCH_SYS_ID = A.SFCH_SYS_
    ID AND B.SFCD_INSTR_BANK_CODE = :b1 AND B.SFCD_INSTR_NO = :b2
    72,658 52 1,397.3 3.2 20.32 21.85 4142254844
    SELECT LTRIM(RTRIM(DECODE(TIT_NAME,'MR.','CA.','MS.','CA.','MRS.
    ','CA.') || ' ' || MRH_FIRST_NAME || ' ' || MRH_MIDDLE_NAME
    || ' ' || MRH_SUR_NAME || ' ' || DECODE(MRH_APPR_UID, NULL ,
    NULL ,DECODE(MRH_MEM_STATUS,2, NULL ,DECODE(MRH_FELLOW_STATUS_YN
    ,'Y','FCA','ACA'))) || DECODE(MRH_RESI_STATUS,'A','
    48,619 3 16,206.3 2.2 4.19 4.11 496772197
    SELECT ROWID,STUD_DT,STUD_TXN_CODE,STUD_NO,STUD_AMD_NO,STUD_REF_
    FROM,STUD_REF_TXN_CODE,STUD_REF_NO,STUD_TEMP_REF_NO,STUD_SRN,STU
    D_TITLE,STUD_STATUS,STUD_FIRST_NAME,STUD_MIDDLE_NAME,STUD_SURNAM
    E,STUD_MAIDEN_NAME,STUD_NAME_STATUS,STUD_FATHER_NAME,STUD_NATION
    ALITY_CODE,STUD_NATION_PROOF_ENCL_YN,STUD_SEX,STUD_HANDICAPPED_Y
    48,063 230 209.0 2.1 20.27 20.76 1838125769
    SELECT MRH_DT,MRH_FIRST_NAME,MRH_MIDDLE_NAME,MRH_SUR_NAME,MRH_ST
    ATUS FROM OM_MEM_REG_HEAD WHERE DECODE(:b1,1,MRH_MRN,MRH_MFCH
    SQL ordered by Executions for DB: ICAI Instance: icai Snaps: 70 -73
    -> End Executions Threshold: 100
    CPU per Elap per
    Executions Rows Processed Rows per Exec Exec (s) Exec (s) Hash Value
    38,614 38,614 1.0 0.00 0.00 1741347688
    SELECT SYSDATE FROM SYS.DUAL
    12,490 12,488 1.0 0.00 0.00 2614155871
    SELECT DECODE(:b1,'L',DECODE(:b2,'ENG',STATUS_NAME,STATUS_BL_NAM
    E),DECODE(:b2,'ENG',STATUS_SHORT_NAME,STATUS_BL_SHORT_NAME)) STA
    TUS_DESC,STATUS_FRZ_FLAG_NUM FROM OM_STATUS WHERE STATUS_CODE
    = :b4
    8,629 8,628 1.0 0.00 0.00 1644340447
    SELECT DECODE(:b1,'L',DECODE(:b2,'ENG',FEE_TYPE_NAME,FEE_TYPE_BL
    NAME),DECODE(:b2,'ENG',FEETYPE_SHORT_NAME,FEE_TYPE_BL_SHORT_NA
    ME)) FEE_NAME,FEE_TYPE_FRZ_FLAG_NUM FROM OM_FEE_TYPE WHERE FE
    E_TYPE_CODE = :b4
    7,275 7,272 1.0 0.00 0.34 3716207873
    update seq$ set increment$=:2,minvalue=:3,maxvalue=:4,cycle#=:5,
    order$=:6,cache=:7,highwater=:8,audit$=:9,flags=:10 where obj#=:
    1
    6,293 6,283 1.0 0.00 0.00 2804237544
    SELECT DECODE(:b1,'L',DECODE(:b2,'ENG',CITY_NAME,CITY_BL_NAME),D
    ECODE(:b2,'ENG',CITY_SHORT_NAME,CITY_BL_SHORT_NAME)) CITY_NAME,C
    ITY_TALUK_CODE,CITY_DIST_CODE,CITY_STATE_CODE,CITY_REGION_CODE,C
    ITY_FRZ_FLAG_NUM FROM OM_CITY WHERE CITY_CODE = :b4
    6,221 6,221 1.0 0.00 0.00 484036617
    SELECT DAH_SYS_ID.NEXTVAL FROM DUAL
    6,221 6,221 1.0 0.00 0.00 2945494810
    SELECT COUNT(DAH_SYS_ID) FROM OT_DAK_ACTV_HISTORY WHERE DAH_ACTV
    TYPE = :B2 AND DAHTXN_SYS_ID = :B1
    5,979 5,979 1.0 0.00 0.00 35936114
    SELECT STUD_DOC_STATUS FROM OM_STUDENT_HEAD WHERE STUD_SYS_ID
    = :b1
    4,637 4,637 1.0 0.00 0.00 1237293873
    SELECT DECODE(:b1,'L',DECODE(:b2,'ENG',COU_NAME,COU_BL_NAME),DEC
    ODE(:b2,'ENG',COU_SHORT_NAME,COU_BL_SHORT_NAME)) COU_NAME,COU_FR
    Z_FLAG_NUM FROM OM_COUNTRY WHERE COU_CODE = :b4
    4,404 1,276 0.3 0.00 0.00 1829426463
    SELECT NVL(TAU_FROM_VALUE,0), NVL(TAU_TO_VALUE,0) FROM IM_TXN_AU
    TH_USER WHERE TAU_TA_TYPE = :B3 AND TAU_TXN_CODE = :B2 AND TAU_A
    UTH_UID = :B1
    4,220 4,220 1.0 0.00 0.00 1006906503
    UPDATE OT_DAK_ACTV_HISTORY SET DAH_ACTV_ED_DT = :B3 , DAH_ACTV_S
    TATUS = 'C' WHERE DAH_ACTV_TYPE = :B2 AND DAH_TXN_SYS_ID = :B1
    3,874 66 0.0 0.00 0.00 4284733339
    SELECT TIT_NAME ||' '|| AR_FIRST_NAME||' '||AR_MIDDLE_NAME||' '|
    |AR_SUR_NAME FROM OT_ARTICLE_REGISTRATION, OM_TITLE WHERE TRIM(A
    SQL ordered by Executions for DB: ICAI Instance: icai Snaps: 70 -73
    -> End Executions Threshold: 100                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            

  • Log file switch (checkpoint incomplete)

    hello,
    Lately, I have a lot of update/delete work on my OLTP production database. Generally this database is heavy loaded with much inserts especially at the daytime so I do my work at nights :) However, this work cause some contention. I have run AWR raport and I see "log file switch (checkpoint incomplete)" on a second place in wait events. I have a six redo log groups, each file 400MB, redo log buffer 12MB, mttr 0, checkpoint interval 0 and checkpoint timeout 1800 so checkpoints are usually "made by" log switches. Normally I have 2-5 switches per hour, but when I am doing my work it's abut 15-20 switches/hour. Can I speed it up by resizing redo files or by adding more groups ? I don't have test environment to test it so I am wondering if somone has experiense with that?
    thanks
    10gr2, linux

    Hi Helter,
    i have expirienced the same problem only with smaller log files and 3 groups, the solution you suggested helped me solve the issue, eversince i don't have any "checkpoint incomplete" error masaages in the alert log file.
    i have enlarged each group to be 100 mb (initially was 50 mb) and added 2 more groups.
    hope this solution will help you too.
    dBarak

  • Nor more Checkpoints at every log-switch in 10.2 ?

    Hi,
    i working with Oracle about 12 years but i havn´t seen this before:
    REM There is no work/application in the database now:
    select group#,status from v$log;
    GROUP# STATUS
    1 CURRENT
    2 ACTIVE
    4 ACTIVE
    5 ACTIVE
    6 ACTIVE
    First as i know only one or two (for a short time) shiould be active.
    OK wait 90 seconds:
    SQL> /
    GROUP# STATUS
    1 CURRENT
    2 ACTIVE
    4 ACTIVE
    5 ACTIVE
    6 ACTIVE
    Try a log switch:
    alter system switch logfile;
    SQL> select group#,status from v$log;
    GROUP# STATUS
    1 ACTIVE
    2 CURRENT
    4 ACTIVE
    5 ACTIVE
    6 ACTIVE
    How can i now drop one of the redo-logs ?
    => Solution:
    alter system checkpoint;
    select group#,status from v$log;
    GROUP# STATUS
    1 INACTIVE
    2 CURRENT
    4 INACTIVE
    5 INACTIVE
    6 INACTIVE
    Does anybody know what Oracle changed here ?
    Thanks in advance
    Marco

    hi,
    welcome to Oracle10g:
    show paramater FAST_START_MTTR_TARGET
    if it is '0', then auto-checking-pointing is DISABLED, this happens to be the default on Oracle XE (under review)
    By default, Oracle 10g supports automatic checkpoint tuning by making the best effort to write out SGA buffer cache dirty buffers w/o impacting the throughput of runtime physical I/O, thus achieving reasonable crash recovery time.
    Setting the FAST_START_MTTR_TARGET parameter to a non-zero value or not setting this parameter enables automatic checkpoint tuning. The STATISTICS_LEVEL must be TYPICAL OR ALL. After a period of time, see V$MTTR_TARGET_ADVICE for various value for this parameter.

  • Checkpoint and log switch

    I would like to know if when a redo log is filled, the new redo log can be written in parallel with the chekpoint.
    Or simply, what's the sequence for log switching:
    1 - redo log is filled -> checkpoint -> new log writes. or
    2 - redo log is filled -> checkpoint/new log writes (in parallel)
    Best Regards,
    Rogerio C. Schreiner
    null

    I'm tempted to say 'don't worry about it', because L_C_T has been deprecated since 9i: instead use FAST_START_MTTR_TARGET to control the rate of checkpointing.
    But that aside, L_C_T essentially says: "if a block was dirtied (changed) by a transaction whose redo was generated more that X seconds ago -where X is the number of seconds LCT is set to- then that block will be flushed to disk the next time DBWR wakes up on the '3 second rule'"
    L_C_INTERVAL means something similar: "If a block was dirtied by a transaction whose redo can be found in the redo log more than Y redo blocks away from the current checkpoint marker, where Y is the setting for LCI, flush it next time DBWR wakes up"
    A checkpoint does not always result in a log switch, but a log switch always results in a checkpoint.
    You can't really answer your third question, because the LCT parameter doesn't mean "Every 1800 seconds, flush everything to disk" (as it used to in version 8.0). But if a block was dirtied more than 1800 seconds ago, it will be a candidate for flushing to disk next time DBWR wakes up. But that doesn't tell us when a log switch will occur: that will only happen when the redo log fills up and we have to switch to the next log to keep going. I can't tell anything about the size of your logs or the rate at which they will fill up from the parameters you list.
    A parameter does exist which will force a log switch every so often. It's called ARCHIVE_LAG_TARGET, and it's set to a number of seconds. If that was set to 1800, I could say with confidence that you'd log switch every half hour. But that's not what you had in your question, of course!
    You might care to read this slightly more technical description of the parameters:
    http://www.jlcomp.demon.co.uk/faq/log_checkpoint.html
    (though I think Jonathan's timelines are wrong, because the change to the effect of the parameters came in with 8i).
    Message was edited by:
    howardjr

  • Checkpoint _change# &&log switch

    Hey
    When I issue alter system switch logfile a checkpoint must be issued and therefore checkpoint change # of the datafiles should be incremented.
    However sometimes checkpoint change # of the datafiles doesnt change after the log switch....
    Why?
    ie:
    SQL> select substr(name,1,50) fname,checkpoint_change#,last_change#,status
    from v$datafile;
    FNAME
    CHECKPOINT_CHANGE# LAST_CHANGE# STATUS
    C:\ORACLEXE\ORADATA\XE\SYSTEM.DBF
    219513 SYSTEM
    C:\ORACLEXE\ORADATA\XE\UNDO.DBF
    219513 ONLINE
    C:\ORACLEXE\ORADATA\XE\SYSAUX.DBF
    219513 ONLINE
    FNAME
    CHECKPOINT_CHANGE# LAST_CHANGE# STATUS
    C:\ORACLEXE\ORADATA\XE\USERS.DBF
    219399 219399 OFFLINE
    SQL> alter system switch logfile;
    System altered.
    select substr(name,1,50) fname,checkpoint_change#,last_change#,status
    from v$datafile;
    FNAME
    CHECKPOINT_CHANGE# LAST_CHANGE# STATUS
    C:\ORACLEXE\ORADATA\XE\SYSTEM.DBF
    219513 SYSTEM
    C:\ORACLEXE\ORADATA\XE\UNDO.DBF
    219513 ONLINE
    C:\ORACLEXE\ORADATA\XE\SYSAUX.DBF
    219513 ONLINE
    FNAME
    CHECKPOINT_CHANGE# LAST_CHANGE# STATUS
    C:\ORACLEXE\ORADATA\XE\USERS.DBF
    219399 219399 OFFLINE

    ALTER SYSTEM SWITCH LOGFILE may take some time to complete its job. if you wait a couple of seconds after each statement to switch log, it looks OK:
    SQL> select * from v$version;
    BANNER
    Oracle Database 10g Express Edition Release 10.2.0.1.0 - Product
    PL/SQL Release 10.2.0.1.0 - Production
    CORE    10.2.0.1.0      Production
    TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
    NLSRTL Version 10.2.0.1.0 - Production
    SQL> select log_mode from v$database;
    LOG_MODE
    NOARCHIVELOG
    SQL> select file#, checkpoint_change# from v$datafile;
         FILE# CHECKPOINT_CHANGE#
             1             758989
             2             758989
             3             758989
             4             758989
             5             758989
    SQL>
    SQL> alter system switch logfile;
    Système modifié.
    SQL> host pause
    Appuyez sur une touche pour continuer...
    SQL> select file#, checkpoint_change# from v$datafile;
         FILE# CHECKPOINT_CHANGE#
             1             758994
             2             758994
             3             758994
             4             758994
             5             758994
    SQL> alter system switch logfile;
    Système modifié.
    SQL> host pause
    Appuyez sur une touche pour continuer...
    SQL> select file#, checkpoint_change# from v$datafile;
         FILE# CHECKPOINT_CHANGE#
             1             758996
             2             758996
             3             758996
             4             758996
             5             758996
    SQL> alter system switch logfile;
    Système modifié.
    SQL> host pause
    Appuyez sur une touche pour continuer...
    SQL> select file#, checkpoint_change# from v$datafile;
         FILE# CHECKPOINT_CHANGE#
             1             758998
             2             758998
             3             758998
             4             758998
             5             758998
    SQL>
    SQL>

  • Cannot allocate new log, sequence Checkpoint not complete

    Hi,
    Im having very frequent log switches and Im getting error as
    " cannot allocate new log, sequence Checkpoint not complete"
    I was having 3 redo log groups with 50 MB each. After I found this error in the alert log; I increased teh number of redo log groups to 6 with 50MB each. Still the issue is not getting resolved.
    Please suggest what will be the best solution for this.
    Following is a snippet from alertlog.
    ==================================================
    Sun Apr 19 09:14:08 2009
    Thread 1 advanced to log sequence 5811
    Current log# 2 seq# 5811 mem# 0: /u01/app/oracle/oradata/mview/redo02.log
    Thread 1 cannot allocate new log, sequence 5812
    Checkpoint not complete
    Current log# 2 seq# 5811 mem# 0: /u01/app/oracle/oradata/mview/redo02.log
    Sun Apr 19 09:14:18 2009
    Thread 1 advanced to log sequence 5812
    Current log# 3 seq# 5812 mem# 0: /u01/app/oracle/oradata/mview/redo03.log
    Thread 1 cannot allocate new log, sequence 5813
    Checkpoint not complete
    Current log# 3 seq# 5812 mem# 0: /u01/app/oracle/oradata/mview/redo03.log
    Thread 1 advanced to log sequence 5813
    Current log# 1 seq# 5813 mem# 0: /u01/app/oracle/oradata/mview/redo01.log
    Thread 1 cannot allocate new log, sequence 5814
    Checkpoint not complete
    Current log# 1 seq# 5813 mem# 0: /u01/app/oracle/oradata/mview/redo01.log
    Sun Apr 19 09:14:32 2009
    Thread 1 advanced to log sequence 5814
    Current log# 2 seq# 5814 mem# 0: /u01/app/oracle/oradata/mview/redo02.log
    Thread 1 cannot allocate new log, sequence 5815
    Checkpoint not complete
    Current log# 2 seq# 5814 mem# 0: /u01/app/oracle/oradata/mview/redo02.log
    Thread 1 advanced to log sequence 5815
    Current log# 3 seq# 5815 mem# 0: /u01/app/oracle/oradata/mview/redo03.log
    Thread 1 cannot allocate new log, sequence 5816
    Checkpoint not complete
    Current log# 3 seq# 5815 mem# 0: /u01/app/oracle/oradata/mview/redo03.log
    Sun Apr 19 09:14:44 2009
    =========================================================
    Regards
    Pratheej

    Anand... wrote:
    Hi Sir,
    Although i too had suggested increasing the redo logfile size, but after going through [http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:69012348056] i was little confused as Tom has mentioned
    Another way is to make the log files smaller, hence increasing the frequency with which we checkpoint ---- Can you explain why so.
    I was a little surprised when I read that posting - but noticed it was dated May 2000 - when databases were still quite small and less busy. (And Tom suggested 25MB as being "modest" rather than "tiny" - which is probably what many people would call 25MB these days). And May 2000 probably means 8.0 or 8.1 - and the whole log buffer, redo generation, checkpointing technology has changed a lot since then.
    Basically, if you hit "checkpoint not complete", you need more online log space so that it's possible during the busiest times to keep generating redo log information while the checkpoint queues are being cleared far enough to allow older log files to be recycled.
    You can do this by adding more log files, or by increasing the sizes of the log files you use. Tom's point, I think, was that if you chose the option to add more files and kept them small (or even made them smaller) then the volume of dirty data blocks that you could create while filling a log file would be small, so the database writer wouldn't have to do much work to make each log file available for re-use. (I'm not sure I'd agree with the approach, though - even for 8i - because it could easily lead to an increase in the volume of datablocks written, even if it did bypass the checkpoint issue).
    Regards
    Jonathan Lewis
    http://jonathanlewis.wordpress.com
    http://www.jlcomp.demon.co.uk
    "For every expert there is an equal and opposite expert."
    Arthur C. Clarke

  • Forcing log switch every minute.

    Hi,
    I want to force a log switch every one minute how can i do it?
    What should be the value of fast_start_mttr_target?
    Does a checkpoint force a log switch?
    Do i need to only reduce the size of redo log to a small size?
    How can i make sure that a log switch will happen after a particular time period for ex. 1Minute,2 minute.
    I want to force a log switch every minute because i want to send the archive redo log to standby database so that not more than 1 minute changes in database are lost. I am using 10g R2 on windows 2003 server.
    I am unable to find a solution. Any help?

    Hi,
    I want to force a log switch every one minute how
    can i do it? yes with archive_lag_target parameter
    http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm#sthref934
    What should be the value of fast_start_mttr_target?incremental or normal checkpoint "fast instance recovery/downtime concerned" introduced from oracle 8, this feature is enabled with the initialization parameter FAST_START_MTTR_TARGET in 9i.
    fast_start_mttr_target to database writer tries to keep the number of dirty blocks in the buffer cache low enough to guarantee rapid recovery in the event of a crash. It frequently updates the file headers to reflect the fact that there are not dirty buffers older than a particular SCN.
    http://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/rcmtunin004.htm#sthref1110
    Does a checkpoint force a log switch? log switch force to checkpoint ,checkpoint never force to log switch.
    Do i need to only reduce the size of redo log to a
    small size?depends yours SLA how far you can risk the data ,but it will effect yours database performance ,recommended to set the size of log which should imply the log swtich after filling to 20 mins,its a trade off risk vs perofrmance.
    How can i make sure that a log switch will happen
    after a particular time period for ex. 1Minute,2
    minute.
    want to force a log switch every minute because i
    want to send the archive redo log to standby database
    so that not more than 1 minute changes in database
    are lost. I am using 10g R2 on windows 2003 server.
    am unable to find a solution. Any help?
    http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm#sthref934Khurram

  • Log switch must occur every 15 to 30 minutes: good practice or myth?

    I often heard that it is recommended to size redo log files in a way that Oracle performs a log switch every 15 to 30 minutes.
    I would like to know if it is true or if it is a myth ?
    I would like to know the best way for sizing redo log files ?
    What happen exactly in the database when a log switch occurs ?
    Please help me to clarify these concepts.

    So we can say that a log switch induces a full checkpoint. That's correct ?Well, no :-) . Indeed with a log switch the checkpoint event is generated requesting DBWR to flush the buffers from the checkpoint-queue to the data files but this is not a full checkpoint and it would not update the datafile and control file headers. The Full Checkpoint happens with the alter system checkpoint ( as shown) , database being shutdown properly.
    Please see the below code which shows the same,
    Connected to:
    Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production
    With the Partitioning, OLAP, Data Mining and Real Application Testing options
    SQL> select checkpoint_change# from V$datafile;
    CHECKPOINT_CHANGE#
               3507400
               3507400
               3507400
               3507400
               3507400
               3507400
               3507400
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    SQL> select * from V$log;
        GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
    FIRST_CHANGE# FIRST_TIM
             1          1         91   52428800          1 NO  CURRENT
          3507399 13-APR-10
             2          1         89   52428800          1 NO  INACTIVE
          3486253 13-APR-10
             3          1         90   52428800          1 NO  INACTIVE
          3486256 13-APR-10
    SQL> alter system switch logfile;
    System altered.
    SQL> select * from V$log;
        GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
    FIRST_CHANGE# FIRST_TIM
             1          1         91   52428800          1 NO  ACTIVE
          3507399 13-APR-10
             2          1         92   52428800          1 NO  CURRENT
          3507906 13-APR-10
             3          1         90   52428800          1 NO  INACTIVE
          3486256 13-APR-10
    SQL> select checkpoint_change# from V$datafile;
    CHECKPOINT_CHANGE#
               3507400
               3507400
               3507400
               3507400
               3507400
               3507400
               3507400
    7 rows selected.
    SQL> select checkpoint_change# from V$datafile;
    CHECKPOINT_CHANGE#
               3507400
               3507400
               3507400
               3507400
               3507400
               3507400
               3507400
    7 rows selected.
    SQL> alter system checkpoint;
    System altered.
    SQL> select checkpoint_change# from V$datafile;
    CHECKPOINT_CHANGE#
               3507936
               3507936
               3507936
               3507936
               3507936
               3507936
               3507936
    7 rows selected.
    SQL>HTH
    Aman....

  • Archive log switch

    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:00 o1_mf_1_90491_4341nt0b_.arc
    -rw-r-----   1 oracle     oinstall   13420544 May 20 02:01 o1_mf_1_90492_4341oov9_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:02 o1_mf_1_90493_4341q45y_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:02 o1_mf_1_90494_4341qytf_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:03 o1_mf_1_90495_4341s2w8_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:03 o1_mf_1_90496_4341szog_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:04 o1_mf_1_90497_4341v16m_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:05 o1_mf_1_90498_4341wsbl_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:05 o1_mf_1_90499_4341y0ps_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:06 o1_mf_1_90500_4341yyj1_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:06 o1_mf_1_90501_4342044h_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:07 o1_mf_1_90502_434217j9_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 02:10 o1_mf_1_90503_43426g1z_.arc
    -rw-r-----   1 oracle     oinstall   13424640 May 20 05:01 o1_mf_1_90504_434d70c6_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:22 o1_mf_1_90505_434fhm1b_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:23 o1_mf_1_90506_434fjrgr_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:24 o1_mf_1_90507_434fkxkf_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:24 o1_mf_1_90508_434flzfp_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:25 o1_mf_1_90509_434fnngh_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:26 o1_mf_1_90510_434fp67w_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:27 o1_mf_1_90511_434fqwks_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:28 o1_mf_1_90512_434fslyn_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:29 o1_mf_1_90513_434fvr3c_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:30 o1_mf_1_90514_434fxrsq_.arc
    -rw-r-----   1 oracle     oinstall   13427712 May 20 05:31 o1_mf_1_90515_434fzr8h_.arc
    -rw-r-----   1 oracle     oinstall   13438976 May 20 10:00 o1_mf_1_90516_434xrhf9_.arcmine is 10.2.0.1 database...my log switch is happening intermittently....log file size is 20 MB
    log_checkpoint_interval              integer     0
    log_checkpoint_timeout               integer     1800
    log_checkpoints_to_alert             boolean     FALSEHow can I set to happen log file switch at every 30 Minutes...

    These are two different issues.
    1. There are frequent log switches so the log file size could [should] be increased.
    2. However, there are, at times, gaps of 3 hours and 5 hours between two
    log switches. I presume that Deepa wants to ensure that a log switch occurs
    "at least every 30minutes". It may occur more frequently than that (twice a
    minutes) but the maximum gap between two log switches is desired as 30minutes.
    That is what ARCHIVE_LAG_TARGET does.
    It is not necessary that only in Standby databases would a DBA want a
    maximum duration between log switches. You might be using this in a database
    (as we have in Deepa's case !) where there are long "idle" stretches of time
    with very little activity as well. Say, you have a background job periodically
    backing up archivelogs using OS based methods (not RMAN) -- to tape
    or to an NFS mount point or an offsite storage facility. ARCHIVE_LAG_TARGET
    will help you ensure that the maximum data loss is 30minutes (even if there
    was only 1 transaction of 1 row in those 30minutes) because that is what
    your SLA might specify. This would be part of your media recovery / DR
    requirements.
    log_checkpoint_timeout is not to do with archiveloging but with checkpoints.
    that is a complete different requirement -- that is for instance recovery not
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  • Database log switch and WLS connection pool relation

    Hi,
    We have been facing WLS JDBC connection pool disable and suspension issue very frequently in our environment and as a work around have implemented multi-datasource configuration (fail over method).
    But we need to know the root cause for the same and want to fix the issue too.
    We have tried many options like increasing no. of processes and transaction on Database, fine tune the weblogic datasource but still we could not isolate the issue.
    Recently we have been advised to minimize the log switch on database front and increase the redo log size. Not sure if this will help in isolating the issue or not.
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    We are using WLS 10.3.3.0
    -Rohit

    turn on jdbc logging. The server log should be showing the troubles WLS is having
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  • Is there a way to identify manual log switches?

    Hi!
    A while ago I upgraded a 10g database to 11.2.0.2 64 Bit Windows.
    During the Upgrade we realized that redo logs were configured really small (~10MB) what resulted in a lot of log switches (a few hundred per day). So we adjusted redo log size to 100MB and set archive_lag_target to 1800.
    The amount of log switches went down a little but less far than we expected it. After further analysing the situation we recognized that Oracle is switching logs far before reaching the 100MB log size (and also far before reaching 1800s). All the archived logs have a size of about 15MB. I know that 11g invented something like "preemptive log switching" that switches logs round about 20% before reaching the maximum value (if I remember it correctly..). But switching already at 15% of the maximum size seems strange to me...
    I couldn't find any helpful stuff on Google or Metalink about that topic but today I had a different idea: what if it's the application software that's doing manual log switches?
    (I have no idea why it should do that but I can remember that the application user does require the sysdba privilege - don't ask me why, I didn't write it, I won't defend it...)
    So I checked the alert log but unfortunately I had to realize that there is no difference between an automatic switch and a manual one (only alter system archive log... does get an extra line).
    So my questions are:
    1) Does anybody know a way of distinguishing between an automatic log switch and a manual one? Is there a table or another logfile where this information is recorded?
    2) Has anybody experienced a similar situation where Oracle is switching the logs way before reaching the maximum size?
    Best regards,
    Marcus

    lebigmac wrote:
    1) Does anybody know a way of distinguishing between an automatic log switch and a manual one? Is there a table or another logfile where this information is recorded?
    Off the top of my head - I think the only way to do a manual log switch is to issue "alter system switch log file", and I think that any "alter system" command is written to the alter log in you version of Oracle. (I really ought to check both statements before posting this, but I've been up since 2:30 am).
    2) Has anybody experienced a similar situation where Oracle is switching the logs way before reaching the maximum size?
    It's very common with recent versions of Oracle when private redo threads come into play; but your example seems a little exaggerated. The log file switch has to start when there is enough space left in the log file for all the public and all (or maybe it's the previously used - i'll have to check my book) private redo threads. You could check x$kcrfstrand to see what this sizes look like: http://jonathanlewis.wordpress.com/?s=private+thread
    Regards
    Jonathan Lewis

  • Block size in tt for writing data to transaction log and checkpoint files

    Hello,
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    Although in theory logging can write 2 KB blocks in almost all circumstances it will write 4 KB or larger so yes a filesystem with a 4 KB block size is fine for both checkpointing and logging.
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