Search results “Alter index oracle nologging”
How to Detect Soft Corruption in Oracle 12c Database
Detection of Soft Corruption in 12c: To use the scripts below replace : , ",# and $ by proper bracket Lets Create a tablespace and small table. SQL: create tablespace DEMO1 datafile '/u02/tstdb1/TSTDB1/datafile/demo01.dbf' size 50M SQL: create table objects tablespace DEMO1 as select * from dba_objects; SQL: alter table objects add constraint pk_obj primary key #object_id$; SQL: create index idx_obj_name on objects#object_name$ tablespace demo1; Backup tablespace. RMAN: backup tablespace DEMO1; We need to put the DB in archivelog first Rebuild index with NOLOGGING option to simulate soft corruption later. RMAN: alter index idx_obj_name rebuild nologging; Confirm that we have datafiles that require backup because they have been affected with NOLOGGING operation. RMAN: report unrecoverable; Simulate corruption. RMAN: alter database datafile 5 offline; RMAN: restore datafile 5; RMAN: recover datafile 5; RMAN: alter database datafile 5 online; Query table with corrupted index and notice error. SQL: select count#*$ from objects where object_name like 'A%'; Let’s perform validation of datafile to check block corruption. RMAN: backup validate check logical datafile 5; Notice that we have 457 blocks marked corrupt but v$database_block_corruption view is empty. SQL: select count#*$ from v$database_block_corruption; Let’s query v$nonlogged_block view. set lines 200 set pages 999 select file#, block#, blocks,object#,reason from v$nonlogged_block; Will RMAN detect that we have corrupted blocks? RMAN: backup datafile 5; RMAN backup won’t fail due to NOLOGGING corrupt blocks and our backup will contain soft corrupted blocks. Let’s Identify corrupt segments using v$nonlogged_block view. set lines 2000 set pages 9999 col owner for a20 col partition_name for a10 col segment_name for a20 SELECT e.owner, e.segment_type, e.segment_name, e.partition_name, c.file# , greatest#e.block_id, c.block#$ corr_start_block# , least#e.block_id+e.blocks-1, c.block#+c.blocks-1$ corr_end_block# , least#e.block_id+e.blocks-1, c.block#+c.blocks-1$ - greatest#e.block_id, c.block#$ + 1 blocks_corrupted FROM dba_extents e, V$NONLOGGED_BLOCK c WHERE e.file_id = c.file# AND e.block_id "= c.block# + c.blocks - 1 AND e.block_id + e.blocks - 1 := c.block# UNION SELECT s.owner, s.segment_type, s.segment_name, s.partition_name, c.file# , header_block corr_start_block# , header_block corr_end_block# , 1 blocks_corrupted FROM dba_segments s, V$NONLOGGED_BLOCK c WHERE s.header_file = c.file# AND s.header_block between c.block# and c.block# + c.blocks - 1 UNION SELECT null owner, null segment_type, null segment_name, null partition_name, c.file# , greatest#f.block_id, c.block#$ corr_start_block# , least#f.block_id+f.blocks-1, c.block#+c.blocks-1$ corr_end_block# , least#f.block_id+f.blocks-1, c.block#+c.blocks-1$ - greatest#f.block_id, c.block#$ + 1 blocks_corrupted FROM dba_free_space f, V$NONLOGGED_BLOCK c WHERE f.file_id = c.file# AND f.block_id "= c.block# + c.blocks - 1 AND f.block_id + f.blocks - 1 := c.block# order by file#, corr_start_block# / This is the best outcome to get if you notice corruption errors. All errors are related to index corruption so we could fix this problem rebuilding index. alter index idx_obj_name rebuild; Simply issuing "alter index rebuild" command won't work. We should mark index unusable to drop segment before rebuilding it or just rebuild index with online option. It is better choice to mark index unusable because you don't need additional space then, but I will simply rebuild index with online option and see what will happen. SQL: alter index idx_obj_name rebuild online; Index altered. SQL: select count#*$ from objects where object_name like 'A%'; No errors... but, let's validate datafile for corruption. RMAN: backup validate check logical datafile 5; Notice "Marked Corrupt" column. Hm... 457 like before. Don't worry, this is not new corruption. These are FREE blocks which will be reused and Oracle will automatically re-format those blocks. Query the v$nonlogged_block view again as given above. We could force re-formatting creating dummy table and inserting data to dummy table. Check Doc ID 336133.1. create table s # n number, c varchar2#4000$ $ nologging tablespace DEMO1; SQL: BEGIN FOR i IN 1..1000000 LOOP INSERT /*+ APPEND */ INTO sys.s select i, lpad#'REFORMAT',3092, 'R'$ from dual; commit ; END LOOP; END; / SQL: drop table sys.s purge; Notice that we don't have corrupted blocks any more. RMAN: backup validate check logical datafile 5;
Views: 160 OracleDBA
Why Use Parallel Processing?
This video compares the use of parallel and serial processing for the same SQL query. Copyright © 2012 Oracle and/or its affiliates. Oracle® is a registered trademark of Oracle and/or its affiliates. All rights reserved. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the "Materials"). The Materials are provided "as is" without any warranty of any kind, either express or implied, including without limitation warranties of merchantability, fitness for a particular purpose, and non-infringement.
Oracle Core,  Лекция 4
Ссылка на файл с презентацией: https://docs.google.com/presentation/d/1hqsC6hEGybAbEEPko56razF7eLBJQEZ3L-ECWtp7rbM/edit?usp=sharing (презентация может быть с анимацией) Ссылка на краткий конспект лекции:https://docs.google.com/document/d/1UFayi0YIXxLrRuj4-JZj-jooyvpoa4rKLOryBloTtag/edit?usp=sharing 1. Create table: permanent tables, temporary tables (on commit delete/preserve rows) 2. Physical properties таблицы: tablespace, logging, pctfree, pctused, initrans 3. Pctfree и pctused 4. Initrans и maxtrans 5.Storage clause: initial, next, minextents, maxextents, pctincrease, freelists, freelist groups, optimal, buffer_pool (keep,recycle), flash_cache (keep, none), encrypt 6. Table properties: column_properties, cache, result_cache, enable_disable_clause, flashback_archive_clause 7. Alter table: column_clause, constraint_clause, alter_table_partitioning, move_table_clause, enable_disable_clause, rename to, shrink space 8. High water mark. Low high water mark 9. Create index: table index clause, index_expr, index_properties, unusable 10. Reverse indexes 11. Function based indexes 12. Alter index: сжатие (shrink space), параллелизм, физические атрибуты (pctfree, pctused, initrans), logging/nologging, rebuild, enable/disable, unusable, visible/invisible, rename to 13. Индекс по внешнему ключу 14. Причины неиспользования индексов 15. Оператор truncate 16. Неявный commit при выполнении ddl 17. Словари данных Oracle Database, БД Oracle, вебинар Oracle, презентация Oracle, урок Oracle, лекция Oracle, обучение Oracle
Read-Only Tables in Oracle
Here's a quick video showing how to create Read-Only tables in Oracle. For more information see: https://oracle-base.com/articles/11g/read-only-tables-11gr1 Website: https://oracle-base.com Blog: https://oracle-base.com/blog Twitter: https://twitter.com/oraclebase Cameo by David Peake Blog: http://dpeake.blogspot.com/ Twitter: https://twitter.com/orcl_dpeake Cameo appearances are for fun, not an endorsement of the content of this video.
Views: 860 ORACLE-BASE.com
RENAME OR MOVE A DATAFILE (when there is space issue in os level file movement is required) ========================== 1)TABLESPACE SHOULD BE OFFLINE(when we move or rename a datafile users should not access) 2)FROM OS LEVEL DATAFILE COPY TO NEW LOCATION 3)SQL LEVEL RENAME THE DATAFILE TO NEW LOCATION 4)MAKE THE TABLESPACE ONLINE alter tablespace king offline; os level rename king01.dbf TO GOODKING01.dbf os level move the file to new location(KING02.DBF) alter tablespace king rename datafile 'E:\DATABASE\DATABASE\ORADATA\ORCL\KING01.DBF' to 'E:\DATABASE\DATABASE\ORADATA\ORCL\GOODKING01.DBF'; alter tablespace king rename datafile 'E:\DATABASE\DATABASE\ORADATA\ORCL\KING02.DBF' TO 'D:\ORADATA\KING02.DBF'; alter tablespace king online; HOW TO CHECK DATAFILES INFO IN PARTICULAR TABLESPACE ===================================================== COL FILE_NAME FOR A50 COL TABLESPACE_NAME FOR A20 select tablespace_name,file_name from dba_data_files where tablespace_name like '&tablespace_name';
Views: 778 Praveen Biyyapu
How to create and managed tablespace in oracle
How to create and managed tablespace in oracle step by setp
Views: 129 database exert

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