INSERT causing lots of buffer gets

Question

select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
CORE    11.2.0.2.0      Production
TNS for Linux: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - ProductionSQL
desc tab
Name                                            Null?    Type
DEF_ID                                   NOT NULL VARCHAR2(64)
INST_ID                                     NOT NULL VARCHAR2(64)
BUSINESS_KEY                             NOT NULL VARCHAR2(64)
BUSINESS_DATA                                     CLOB
TIME                                 NOT NULL TIMESTAMP(6)
REQUEST_CXT                                     NOT NULL VARCHAR2(4000)
IS_PROCESSED                                    NOT NULL NUMBER(3)
ON_STATUS                                                  TIMESTAMP(6)
RVN                                             NOT NULL NUMBER(10)
HV                                                 NUMBER(10)
ID                                          NOT NULL VARCHAR2(128)
STATE                                                CHAR(1)
insert into tab(def_id, inst_id, business_key,
businessdata, time, is_processed, next_retry_time, on_status, req_cxt, hv,
id, op_type, rvn ) values
(:1, :2, :3, :4, :5, :6, :7, :8, :9, :10, :11, 'I', 0)
BUSINESS_DATA IS A clob datatype
table got two indexes
1.idx1(pk) on (inst_id,def_id,rvn)
2.idx2 on (id,state,op_type)
High buffer gets in past
select a.sql_id,TO_DATE(TO_CHAR(b.BEGIN_INTERVAL_TIME,'DD-MON-YY HH24:MI'),'DD-MON-YY HH24:MI') as sdate,a.PLAN_HASH_VALUE,a.EXECUTIONS_DELTA EXE_D,
case (executions_delta) when 0 then 0 else ceil(a.ROWS_PROCESSED_DELTA/a.EXECUTIONS_DELTA) end as RD,
case (executions_delta) when 0 then 0 else ceil(a.ELAPSED_TIME_DELTA/a.EXECUTIONS_DELTA) end as  ELA_D_MCR_SEC,
case (executions_delta) when 0 then 0 else ceil(a.BUFFER_GETS_DELTA/a.EXECUTIONS_DELTA) end as  BG_D,
case (executions_delta) when 0 then 0 else ceil(a.IOWAIT_DELTA/a.EXECUTIONS_DELTA) end as W_IO_D_MCR_SEC
from dba_hist_sqlstat a ,dba_hist_snapshot b where a.snap_id=b.snap_id and a.sql_id = 'ayzxbxqvp5dk3' and a.PARSING_SCHEMA_NAME='SAL_WORKFLOW'
and BEGIN_INTERVAL_TIME>=TO_DATE('27-MAR-2013 21:00', 'dd-mon-yyyy hh24:mi') AND END_INTERVAL_TIME<=TO_DATE('27-MAR-2013 23:00', 'dd-mon-yyyy hh24:mi')
order by 1,2;
SQL_ID           SDATE                PLAN_HASH_VALUE        EXE_D           RD   ELA_D_MCR_SEC         BG_D   W_IO_D_MCR_SEC
ayzxbxqvp5dk3    27.Mar.13/21:00:00                 0         2406            1           15876         1396             7052
ayzxbxqvp5dk3    27.Mar.13/21:10:00                 0         2502            1           16401         1420             7001
ayzxbxqvp5dk3    27.Mar.13/21:20:00                 0         3552            1           17444         1203             7183
ayzxbxqvp5dk3    27.Mar.13/21:30:00                 0         2825            1           17860         1474             6310
ayzxbxqvp5dk3    27.Mar.13/22:00:00                 0         1942            1           16250         1629             6510
ayzxbxqvp5dk3    27.Mar.13/22:10:00                 0         2114            1           16276         1795             6170
ayzxbxqvp5dk3    27.Mar.13/22:20:00                 0         2031            1           16769         1746             6604
ayzxbxqvp5dk3    27.Mar.13/22:40:00                 0         2233            1           16435         1838             6348
8 rows selected.
select a.sql_id,TO_DATE(TO_CHAR(b.BEGIN_INTERVAL_TIME,'DD-MON-YY HH24:MI'),'DD-MON-YY HH24:MI') as sdate,a.PLAN_HASH_VALUE,a.EXECUTIONS_DELTA EXE_D,
case (executions_delta) when 0 then 0 else ceil(a.ROWS_PROCESSED_DELTA/a.EXECUTIONS_DELTA) end as RD,
case (executions_delta) when 0 then 0 else ceil(a.ELAPSED_TIME_DELTA/a.EXECUTIONS_DELTA) end as  ELA_D_MCR_SEC,
case (executions_delta) when 0 then 0 else ceil(a.BUFFER_GETS_DELTA/a.EXECUTIONS_DELTA) end as  BG_D,
case (executions_delta) when 0 then 0 else ceil(a.IOWAIT_DELTA/a.EXECUTIONS_DELTA) end as W_IO_D_MCR_SEC
from dba_hist_sqlstat a ,dba_hist_snapshot b where a.snap_id=b.snap_id and a.sql_id = 'ayzxbxqvp5dk3' and a.PARSING_SCHEMA_NAME='SAL_WORKFLOW'
and BEGIN_INTERVAL_TIME>=TO_DATE('26-MAR-2013 21:00', 'dd-mon-yyyy hh24:mi') AND END_INTERVAL_TIME<=TO_DATE('26-MAR-2013 23:00', 'dd-mon-yyyy hh24:mi')
order by 1,2;
SQL_ID           SDATE                PLAN_HASH_VALUE        EXE_D           RD   ELA_D_MCR_SEC         BG_D   W_IO_D_MCR_SEC
ayzxbxqvp5dk3    26.Mar.13/21:00:00                 0         2948            1           11052           21            10543
ayzxbxqvp5dk3    26.Mar.13/21:30:00                 0         2042            1           12381           23            11857
ayzxbxqvp5dk3    26.Mar.13/21:40:00                 0         2329            1           12089           23            11586
ayzxbxqvp5dk3    26.Mar.13/21:50:00                 0         2421            1           12209           23            11684
ayzxbxqvp5dk3    26.Mar.13/22:00:00                 0         2360            1           10889           22            10398
ayzxbxqvp5dk3    26.Mar.13/22:10:00                 0         2081            1           11059           22            10562
ayzxbxqvp5dk3    26.Mar.13/22:20:00                 0         2384            1           11464           22            10894
ayzxbxqvp5dk3    26.Mar.13/22:40:00                 0         2196            1           11514           22            11021
8 rows selected.Table is a non partitioned table without any trigger.
select OWNER,TABLE_NAME,SEGMENT_NAME,COLUMN_NAME,INDEX_NAME,CHUNK,ENCRYPT,COMPRESSION,SECUREFILE from dba_lobs where TABLE_NAME='&TABLE_NAME';
OWNER             TABLE_NAME                       SEGMENT_NAME                     COLUMN_NAME            INDEX_NAME                       CHUNK   ENCR   COMPRE   SEC
CLASS       TAB                       SYS_LOB0000119958C00004$$        BUSINESS_DATA   SYS_IL0000119958C00004$$          8192   NONE   NONE     NO
COLUMN_NAME            NUM_DISTINCT    NUM_NULLS   LAST_ANALYZED          SAMPLE_SIZE   AVG_COL_LEN   HISTOGRAM                 DENSITY
BUSINESS_DATA               0            0   16.Apr.13/09:28:06        14584877            87   NONE                  .0000000000Can anyone help me troubleshoot such high spike in buffer_gets ?

Answer 1

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Can anyone help me troubleshoot such high spike in buffer_gets ?
>
You haven't posted anything indicating a 'high spike in buffer_gets'.
All you posted are two sets of data with one set having higher values. Nothing indicates that the values are wrong or larger than they should be.
When a new row is inserted it goes into a block. Oracle has to 'get' that block before it can put the row into it. The more rows you INSERT the more blocks that will likely be needed and the more 'gets' that will likely occur.
You need to post something to support your assertion that there has been a 'spike' and also need to post some reason why that would be an issue even if there has been a spike.