Hangcheck Timer Not Needed for 11gR2 RAC

Hangcheck Timer FAQ (Doc ID 232355.1)

Do I need the hangcheck-timer with 11gR2 ?

Answer

-----------

The hangcheck-timer is not needed with 11gR2. This is documented in 'Oracle® Grid Infrastructure Installation Guide 11g Release 2 (11.2) for Linux' section 'Improved Input/Output Fencing Processes'.

Oracle 11gR2 Whatsnew Doc

Improved Input/Output Fencing Processes

Oracle Clusterware 11g release 2 (11.2) replaces the oprocd and Hangcheck processes with the cluster synchronization service daemon Agent and Monitor to provide more accurate recognition of hangs and to avoid false termination.

Identifying Corruption

IDENTIFYING CORRUPTION


Find Corrupt Segments
set linesize 140
col owner format a10
col segment_type format a10
col segment_name format a30
col partition_name format a15
col file# format 999
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
       , null description
    FROM dba_extents e, v$database_block_corruption c
   WHERE e.file_id = c.file#
     AND e.block_id <= c.block# + c.blocks - 1
     AND e.block_id + e.blocks - 1 >= c.block#
  UNION
  SELECT s.owner, s.segment_type, s.segment_name, s.partition_name, c.file#
       , header_block corr_start_block#
       , header_block corr_end_block#
       , 1 blocks_corrupted
       , 'Segment Header' description
    FROM dba_segments s, v$database_block_corruption 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
       , 'Free Block' description
    FROM dba_free_space f, v$database_block_corruption 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#
/

Generate Tablespace DDL

GENERATE TABLESPACE DDL

select dbms_metadata.get_ddl('TABLESPACE',tablespace_name) from dba_tablespaces;

or

select 'select dbms_metadata.get_ddl(''TABLESPACE'','''||tablespace_name||''') from dual;' from dba_tablespaces;

RMAN Backup File Order

RMAN BACKUP FILE ORDER

Question:
Assuming a single channel and filesperset=1, what order does RMAN choose to backup datafiles?

Answer:
The order of files is random. The File Names are read from V$DATAFILE view and due to performance bug, the ORDER BY FILE# clause is removed, hence the query can return file# in random order.

Reset Oracle Sequence in-place

HOW TO RESET A SEQUENCE IN-PLACE

  This avoids drop/create, and re-plumbing grants and synonyms.

  1. Set the "increment by" value to -nextval-1
  2. Increment the sequence
  3. Set the "increment by" value back to 1

SQL> select myschema.mysequence.nextval from dual;

   NEXTVAL

----------

1887203408

SQL> alter sequence myschema.mysequence increment by -1887203407;

Sequence altered.

SQL> select myschema.mysequence.nextval from dual;

   NEXTVAL

----------

         1

SQL> alter sequence myschema.mysequence increment by 1;

Sequence altered.

SQL> select myschema.mysequence.nextval from dual;

   NEXTVAL

----------

         2

SQL> alter system flush shared_pool;

System altered.

Oracle Database 12c Multitenant Architecture Overview

Oracle Database 12c Architecture Overview