I have a query - whch used to be run in 30 minutes and now hangs on for hours and not finishing. The wait i see is
wait event latch: cache buffers chains.
This is a 11.1.0.7 2 Node RAC environment runing on HP-UX Itanium.
I want to simulate latch : cache buffer chains wait event due to use of nested loop join for lookup tables
This is what a tried :
-- create parent / child tables
SQL>drop table emp1 purge;
drop table dept1 purge;
create table dept1 (dept_id number primary key,
dept_name char(30));
[Code]....
I traced many queries like the one given below (dept_id between 1 and n where n varied from 10 to 1000) but they always result in hash join
1* select d.dept_name, e.id from sys.dept1 d, sys.emp1 e where d.dept_id = e.dept_id and e.dept_id < 1000
Execution Plan
----------------------------------------------------------
Plan hash value: 619452140
----------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 998K| 41M| 680 (2)| 00:00:09 |
|* 1 | HASH JOIN | | 998K| 41M| 680 (2)| 00:00:09 |
|* 2 | TABLE ACCESS FULL| DEPT1 | 999 | 34965 | 4 (0)| 00:00:01 |
|* 3 | TABLE ACCESS FULL| EMP1 | 999K| 8780K| 672 (2)| 00:00:09 |
----------------------------------------------------------------------------
what can I do to get a nested loop join to simulate latch : cache buffer chains?
I have a question about buffer in oracle.
1. Which process makes the clean buffers to free/empty buffers?
2.Who makes the buffer that are clean to empty?
What is the difference between cache fusion and Cache Coherency. Both are same or different functionality.
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TTversion : TimesTen Release 11.2.2.3.0 (64 bit Linux/x86_64) (tt112230:53376) 2012-05-24T09:20:08Z
We are testing a AWT cache group ( with CacheAwtParallelism=4 ).
Application(1 process) to the DML generates to TimesTen(DSN=TEST).
At this point, Are delivered to the 4 parallel DML?
[TEST]
Driver=/home/TimesTen/tt112230/lib/libtten.so
DataStore=/home/TimesTen/DataStore/TEST/test
PermSize=1024
TempSize=512
PLSQL=1
[code].......
i have a application which uses 32 tables for retrieval in this 4 tables are important and have a size more than 100 mb can i move the index of these 4 tables cache memory to improve the applications retrieval performance if i done so ,then that will affect any other applications performance
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note : in general
In Oracle 9i
I know that db_block_size defines the standard/default block size for my datafiles.
I know db_cache_size defines the size of the my default database buffer of the size of my standard/default block size.
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db_16k_cache_size
db_4k_cache_size
db_32k_cache_size
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11.2.0.2.0
OEL.
Design stage of New SAN. I can put a lot of the database, including redo on SSD.
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[URL]
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give a script to find how much my db buffe cache and redo log buffer cache is used and how much is free.
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RAM 4 Gigs
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Statistic Total per Second per Trans
--------------------------------- ------------------ -------------- ------------
free buffer requested 54,694,995 15,226.9 2,523.7
free buffer requested 23,412,674 6,501.7 2,585.9
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Total System Global Area 2148534928 bytes
Fixed Size 731792 bytes
Variable Size 1879048192 bytes
Database Buffers 268435456 bytes
Redo Buffers 319488 bytes
5.top 5 waitevents during db slow performance & high cpu utilization (>80%) issue.
Top 5 Timed Events
~~~~~~~~~~~~~~~~~~ % Total
Event Waits Time (s) Ela Time
-------------------------------------------- ------------ ----------- --------
latch free 1,848,898 153,793 52.00
buffer busy waits 395,280 87,201 29.49
db file scattered read 3,488,648 34,199 11.56
enqueue 4,052 10,897 3.68
CPU time 5,567 1.88
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Top 5 Timed Events
~~~~~~~~~~~~~~~~~~ % Total
Event Waits Time (s) Ela Time
-------------------------------------------- ------------ ----------- --------
CPU time 1,860 45.32
db file scattered read 1,133,669 985 23.99
imm op 776 605 14.73
sbtinfo2 208 139 3.40
sbtbackup 2 123 3.00
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i have created form with table page to enter hotel details there is on 6 check box which are not database column .i have create these check box to keep days details when hotel give service .so i have use
LOV FORP1_MON STATIC2:;1 MONDAYP1_TUE STATIC2:;2 TUESDAYP1_WED STATIC2:;3 WEDNESDAYP1_THR STATIC2:;4 THURSDAYP1_FRI STATIC2:;5 FRIDAYP1_SAT STATIC2:;6 SATURDAYP1_SUN STATIC2:;7 SUNDAY
i have one more column operating days where i have use computaation to keep operating days.
:P1_MON||:P1_TUS||:P1_WED||:P1_THR||:P1_FRI||:P1_SAT||:P1_SUN
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If sga Buffer Cache Size consume full of SGA_target size, if possible that it will cause performance any issue. I am facing CPU 100% consuming while single query execute, Which query generate monthly report data.
I have two question
1)How to fix the CPU 100% consuming
2)How to find total number user hit oracle specific schema.
Oracle 10.2.0.5 Standard
Sga_target : 14G
Sga_max :20G
Pga :3G
Below SGA details
NAME BYTES/1024/1024
-------------------------------- ---------------
Fixed SGA Size 2.01795197
Redo Buffers 13.9804688
Buffer Cache Size 13632
Shared Pool Size 640
Large Pool Size 16
Java Pool Size 16
Streams Pool Size 16
Granule Size 16
Maximum SGA Size 20480
Startup overhead in Shared Pool 208
Free SGA Memory Available 6144