Oracle Block change Tracking

Oracle Block change Tracking
============================
============================

Oracle Block change Tracking improves the incremental Backup performance and
is used to record changed blocks in each datafile in a change tracking file.
If change Tracking is enabled, RMAN uses block change tracking file to identify
changed blocks for incremental backups and avoids full datafile scans during the backup.Block change tracking feature introduce in Oracle 10g R1. By default,
the Block change tracking file is created as Oracle managed file in
DB_CREATE_FILE_DEST.By default, Oracle will not record block change information.
You can Enable or disable the change tracking when the database is open or mounted.

Enable and Disable Block Change Tracking:
===============================================

SQL>ALTER DATABASE ENABLE BLOCK CHANGE TRACKING;

Run the below command to create change tracking file in a specified location.
===========================================================================

SQL> ALTER DATABASE ENABLE BLOCK CHANGE TRACKING
USING FILE 'D:\oradata\orcl\block_change_track.ora' REUSE;

Run the below command to disable block change tracking
=======================================================

SQL> ALTER DATABASE DISABLE BLOCK CHANGE TRACKING;

Run the below Query to monitor the status of block change tracking
==================================================================

SQL> SELECT FILE,STATUS,BYTES FROM V$BLOCK_CHANGE_TRACKING;

SQLPLUS COMMAND DESCRIPTION

SQLPLUS - COMMAND

========================================
GET A LIST OF SET COMMAND
---------------------------
SQLPLUS> HELP SET
========================================
Syntax:
SET option value

SHO[W] option

========================================
APPI[NFO]{ON|OFF|text}
Application info for performance monitor (see DBMS_APPLICATION_INFO)

ARRAY[SIZE] {15|n}
Fetch size (1 to 5000) the number of rows that will be retrieved in one go.

AUTO[COMMIT] {OFF|ON|IMM[EDIATE]|n}
Autocommit commits after each SQL command or PL/SQL block

AUTOP[RINT] {OFF|ON}
Automatic PRINTing of bind variables.(see PRINT)

AUTORECOVERY [ON|OFF]
Configure the RECOVER command to automatically apply
archived redo log files during recovery - without any user confirmation.

AUTOT[RACE] {OFF|ON|TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]]
Display a trace report for SELECT, INSERT, UPDATE or DELETE statements
EXPLAIN shows the query execution path by performing an EXPLAIN PLAN.
STATISTICS displays SQL statement statistics.
Using ON or TRACEONLY with no explicit options defaults to EXPLAIN STATISTICS

BLO[CKTERMINATOR] {.|c|OFF|ON}
Set the non-alphanumeric character used to end PL/SQL blocks to c

CMDS[EP] {;|c|OFF|ON}
Change or enable command separator - default is a semicolon (;)

COLSEP { |text}
The text to be printed between SELECTed columns normally a space.

COM[PATIBILITY] {V5|V6|V7|V8|NATIVE}
Version of oracle - see also init.ora COMPATIBILITY=
You can set this back by up to 2 major versions e.g. Ora 9 supports 8 and 7

CON[CAT] {.|c|OFF|ON}
termination character for substitution variable reference
default is a period.

COPYC[OMMIT] {0|n}
The COPY command will fetch n batches of data between commits.
(n= 0 to 5000) the size of each fetch=ARRAYSIZE.
If COPYCOMMIT = 0, COPY will commit just once - at the end.

COPYTYPECHECK {OFF|ON}
Suppres the comparison of datatypes while inserting or appending to DB2

DEF[INE] {&|c|OFF|ON}
c = the char used to prefix substitution variables.
ON or OFF controls whether to replace substitution variables with their values.
(this overrides SET SCAN)

DESCRIBE [DEPTH {1|n|ALL}][LINENUM {ON|OFF}][INDENT {ON|OFF}]
Sets the depth of the level to which you can recursively describe an object
(1 to 50) see the DESCRIBE command

ECHO {OFF|ON}
Display commands as they are executed

EMB[EDDED] {OFF|ON}
OFF = report printing will start at the top of a new page.
ON = report printing may begin anywhere on a page.

ESC[APE] {\|c|OFF|ON}
Defines the escape character. OFF undefines. ON enables.

FEED[BACK] {6|n|OFF|ON}
Display the number of records returned (when rows >= n )
OFF (or n=0) will turn the display off
ON will set n=1

FLAGGER {OFF|ENTRY|INTERMED[IATE]|FULL}
Checks to make sure that SQL statements conform to the ANSI/ISO SQL92 standard.
non-standard constructs are flagged as errors and displayed
See also ALTER SESSION SET FLAGGER.

FLU[SH] {OFF|ON}
Buffer display output (OS)
(no longer used in Oracle 9)

HEA[DING] {OFF|ON}
print column headings

HEADS[EP] {||c|OFF|ON}
Define the heading separator character (used to divide a column heading onto > one line.)
OFF will actually print the heading separator char
see also: COLUMN command

INSTANCE [instance_path|LOCAL]
Change the default instance for your session, this command may only be issued when
not already connected and requires Net8

LIN[ESIZE] {150|n}
Width of a line (before wrapping to the next line)
Earlier versions default to 80, Oracle 9 is 150

LOBOF[FSET] {n|1}
Starting position from which CLOB and NCLOB data is retrieved and displayed

LOGSOURCE [pathname]
Change the location from which archive logs are retrieved during recovery
normally taken from LOG_ARCHIVE_DEST

LONG {80|n}
Set the maximum width (in chars) for displaying and copying LONG values.

LONGC[HUNKSIZE] {80|n}
Set the fetch size (in chars) for retrieving LONG values.

MARK[UP] HTML [ON|OFF]
[HEAD text] [BODY text] [TABLE text]
[ENTMAP {ON|OFF}][SPOOL {ON|OFF}]
[PRE[FORMAT] {ON|OFF}]
Output HTML text, which is the output used by iSQL*Plus.

NEWP[AGE] {1|n}
The number of blank lines between the top of each page and the top title.
0 = a formfeed between pages.

NULL text
Replace a null value with 'text'
The NULL clause of the COLUMN command will override this for a given column.

NUMF[ORMAT] format
The default number format.
see COLUMN FORMAT.

NUM[WIDTH] {10|n}
The default width for displaying numbers.

PAGES[IZE] {14|n}
The height of the page - number of lines.
0 will suppress all headings, page breaks, titles

PAU[SE] {OFF|ON|text}
press [Return] after each page
enclose 'text' in single quotes

RECSEP {WR[APPED]|EA[CH]|OFF}
Print a single line of the RECSEPCHAR between each record.
WRAPPED = print only for wrapped lines
EACH=print for every row

RECSEPCHAR {_|c}
Define the RECSEPCHAR character, default= ' '

SCAN {OFF|ON}
OFF = disable substitution variables and parameters

SERVEROUT[PUT] {OFF|ON} [SIZE n] [FOR[MAT] {WRA[PPED]|WOR[D_WRAPPED]|TRU[NCATED]}]
whether to display the output of stored procedures (or PL/SQL blocks)
i.e., DBMS_OUTPUT.PUT_LINE

SIZE = buffer size (2000-1,000,000) bytes

SHOW[MODE] {OFF|ON}
Display old and new settings of a system variable

SPA[CE] {1|n}
The number of spaces between columns in output (1-10)

SQLBL[ANKLINES] {ON|OFF}
Allow blank lines within an SQL command. reverts to OFF after the curent command/block.

SQLC[ASE] {MIX[ED]|LO[WER]|UP[PER]}
Convert the case of SQL commands and PL/SQL blocks
(but not the SQL buffer itself)

SQLPLUSCOMPAT[IBILITY] {x.y[.z]}
Set the behavior or output format of VARIABLE to that of the
release or version specified by x.y[.z].

SQLCO[NTINUE] {> |text}
Continuation prompt (used when a command is continued on an additional line using a hyphen -)

SQLN[UMBER] {OFF|ON}
Set the prompt for the second and subsequent lines of a command or PL/SQL block.
ON = set the SQL prompt = the line number.
OFF = set the SQL prompt = SQLPROMPT.

SQLPRE[FIX] {#|c}
set a non-alphanumeric prefix char for immediately executing one line of SQL (#)

SQLP[ROMPT] {SQL>|text}
Set the command prompt.

SQLT[ERMINATOR] {;|c|OFF|ON}|
Set the char used to end and execute SQL commands to c.
OFF disables the command terminator - use an empty line instead.
ON resets the terminator to the default semicolon (;).

SUF[FIX] {SQL|text}
Default file extension for SQL scripts

TAB {OFF|ON}
Format white space in terminal output.
OFF = use spaces to format white space.
ON = use the TAB char.
Note this does not apply to spooled output files.
The default is system-dependent. Enter SHOW TAB to see the default value.

TERM[OUT] {OFF|ON}
OFF suppresses the display of output from a command file
ON displays the output.
TERMOUT OFF does not affect the output from commands entered interactively.

TI[ME] {OFF|ON}
Display the time at the command prompt.

TIMI[NG] {OFF|ON}
ON = display timing statistics for each SQL command or PL/SQL block run.
OFF = suppress timing statistics

TRIM[OUT] {OFF|ON}
Display trailing blanks at the end of each line.
ON = remove blanks, improving performance
OFF = display blanks.
This does not affect spooled output.
SQL*Plus ignores TRIMOUT ON unless you set TAB ON.

TRIMS[POOL] {ON|OFF}
Allows trailing blanks at the end of each spooled line.
This does not affect terminal output.

UND[ERLINE] {-|c|ON|OFF}
Set the char used to underline column headings to c.

VER[IFY] {OFF|ON}
ON = list the text of a command before and after replacing substitution variables with values.
OFF = dont display the command.

WRA[P] {OFF|ON}
Controls whether to truncate or wrap the display of long lines.
OFF = truncate
ON = wrap to the next line
The COLUMN command (WRAPPED and TRUNCATED clause) can override this for specific columns.

How to keep Source code creation History

How to keep Source code creation History
==========================================

CREATE TABLE halim.SOURCE_HIST
(
CHANGE_DATE DATE NULL,
NAME VARCHAR2(30 BYTE) NULL,
TYPE VARCHAR2(12 BYTE) NULL,
LINE NUMBER NULL,
TEXT VARCHAR2(4000 BYTE) NULL
)


CREATE OR REPLACE TRIGGER change_hist
AFTER CREATE ON halim.SCHEMA
DECLARE
BEGIN
IF ora_dict_obj_type IN
('PROCEDURE', 'FUNCTION', 'PACKAGE', 'PACKAGE BODY', 'TYPE')
THEN
INSERT INTO source_hist
SELECT SYSDATE, user_source.*
FROM user_source
WHERE TYPE = ora_dict_obj_type AND NAME = ora_dict_obj_name;
END IF;
EXCEPTION
WHEN OTHERS
THEN
raise_application_error (-20000, SQLERRM);
END;
/


SELECT DISTINCT change_date, NAME, TYPE
FROM source_hist
ORDER BY change_date DESC

who are waiting for same record?

who are waiting for same record?
====================================
Solutions:
=========
1.

SELECT * FROM V$SESSION
WHERE trim(row_wait_obj#||row_wait_file#||row_wait_block#||row_wait_row#) =
(SELECT trim(row_wait_obj#||row_wait_file#||row_wait_block#||row_wait_row#)
FROM (
-------------------------------------------
select sid,d.object_name,
row_wait_obj#, row_wait_file#, row_wait_block#, row_wait_row#,
dbms_rowid.rowid_create ( 1, ROW_WAIT_OBJ#, ROW_WAIT_FILE#, ROW_WAIT_BLOCK#, ROW_WAIT_ROW# ) rowidd
from v$session s, dba_objects d
where
s.ROW_WAIT_OBJ# = d.OBJECT_ID
and owner='STLBAS'
and OBJECT_TYPE='TABLE'
and sid=:SID
-------------------------------------------
))


select * from test ---object_name
where rowid='AAARJHAAGAACd13AAA'


2. Any rows returned are direct evidence of the problem
=======================================================

SELECT DECODE(request,0,'Holder: ','Waiter: ')||sid sess,
id1, id2, lmode, request, type
FROM V$LOCK
WHERE (id1, id2, type) IN
(SELECT id1, id2, type FROM V$LOCK WHERE request>0)
ORDER BY id1, request


3. can also give interesting information about session waiting for lock.
=======================================================================

$ORACLE_HOME/rdbms/admin/utllockt.sql



4. Script to find locks in the database
=======================================

select
(select username || ' - ' || osuser from v$session where sid=a.sid) blocker,
a.sid || ', ' ||
(select serial# from v$session where sid=a.sid) sid_serial,
' is blocking ',
(select username || ' - ' || osuser from v$session where sid=b.sid) blockee,
b.sid || ', ' ||
(select serial# from v$session where sid=b.sid) sid_serial
from v$lock a, v$lock b
where a.block = 1
and b.request > 0
and a.id1 = b.id1
and a.id2 = b.id2;

efficiant way to check the table is empty

----very efficiant way to check the table is empty
--or
-----checking the first rows value
=====================================================
---empno is primary_key column
--or
---empno is index column

select /*+ FIRST_ROWS */ empno from emp where rownum = 1;