The database writer can write uncommitted info also to datafiles as a result of following activities. When uncommitted data belonging to a tablespace is flushed to disk as a result of Tablespace offline Tablespace read only Tablespace begin backup Manual checkpoint Whenever checkpoint is initiated manually, all the dirty blocks containing committed/uncommitted data in buffer cache are flushed to disk . Flush buffer cache If buffer cache containing dirty blocks is flushed, dirty blocks containing uncommitted data are written to datafiles. Before a logfile gets overwritten A redo log cannot be overwritten until changes recorded in it are written to disk by DBWR. Hence, before a redo log containing uncommitted data is overwritten, uncommitted changes recorded in it are written to datafiles by DBWR.
you mean we able to start or use the oracle db with these 2 tablespace ? answer is no .. default ts are 5 .. also without those 5 ts we can use the db in oracle.... if you are able to do anything just share here with snaps or reference's will see that
@@RACSINFOTECH I apologies not 2 but 3 tablespace are ONLY must, see below. DB version is 12c. SQL> conn / as sysdba Connected to an idle instance. SQL> startup nomount ORACLE instance started. Total System Global Area 452984832 bytes Fixed Size 8621616 bytes Variable Size 369099216 bytes Database Buffers 67108864 bytes Redo Buffers 8155136 bytes SQL> create database testdb; Database created. SQL> select * from v$tablespace; TS# NAME INC BIG FLA ENC CON_ID ---------- ------------------------------ --- --- --- --- ---------- 0 SYSTEM YES NO YES 0 1 SYSAUX YES NO YES 0 2 SYS_UNDOTS YES NO YES 0 SQL> select status from v$Instance; STATUS ------------ OPEN SQL> create table emp (eno number); Table created. SQL> insert into emp values(100); 1 row created. SQL> commit; Commit complete. SQL> select * from emp; ENO ---------- 100
Could you please upload 2-3 years experience dba interview questions.
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thanks for this is very use full as fresher
dbwr will write not ONLY commit transaction but also uncommitted transaction to datafiles. Please verify this?
The database writer can write uncommitted info also to datafiles as a result of following activities.
When uncommitted data belonging to a tablespace is flushed to disk as a result of
Tablespace offline
Tablespace read only
Tablespace begin backup
Manual checkpoint
Whenever checkpoint is initiated manually, all the dirty blocks containing committed/uncommitted data in buffer cache are flushed to disk .
Flush buffer cache
If buffer cache containing dirty blocks is flushed, dirty blocks containing uncommitted data are written to datafiles.
Before a logfile gets overwritten
A redo log cannot be overwritten until changes recorded in it are written to disk by DBWR. Hence, before a redo log
containing uncommitted data is overwritten, uncommitted changes recorded in it are written to datafiles by DBWR.
SYSTEM, SYSAUX are only MANDATORY tablespaces not five. can any database run with just these 2 tablespaces or not check?
you mean we able to start or use the oracle db with these 2 tablespace ? answer is no .. default ts are 5 .. also without those 5 ts we can use the db in oracle.... if you are able to do anything just share here with snaps or reference's will see that
@@RACSINFOTECH
I apologies not 2 but 3 tablespace are ONLY must, see below. DB version is 12c.
SQL> conn / as sysdba
Connected to an idle instance.
SQL> startup nomount
ORACLE instance started.
Total System Global Area 452984832 bytes
Fixed Size 8621616 bytes
Variable Size 369099216 bytes
Database Buffers 67108864 bytes
Redo Buffers 8155136 bytes
SQL> create database testdb;
Database created.
SQL> select * from v$tablespace;
TS# NAME INC BIG FLA ENC CON_ID
---------- ------------------------------ --- --- --- --- ----------
0 SYSTEM YES NO YES 0
1 SYSAUX YES NO YES 0
2 SYS_UNDOTS YES NO YES 0
SQL> select status from v$Instance;
STATUS
------------
OPEN
SQL> create table emp (eno number);
Table created.
SQL> insert into emp values(100);
1 row created.
SQL> commit;
Commit complete.
SQL> select * from emp;
ENO
----------
100
Could you please upload interview for 6-7yr experience
No