Changing initrans on a Partitioned Index

Hi all,

We were having high ITL waits and high number of deadlocks (due to the hanging transactions waiting on the ITL on the data block) on a table and index and part of the fix was to increase the INITRANS on the table and on the index.

INITRANS is a physical attribute that determines the initial number of concurrent transaction entries allocated within each data block for a given table/index/cluster. Every transaction that updates a block has to acquire an Interested Transaction List (ITL) slot, in order to store the transaction id, rollback information and ultimately lock the necessary row/index entry within the block.

For an existing object it needs to be rebuild as INITRANS is a physical attribute on the Oracle datablock. So if you change on a table and you want it to take effect for the current data you need to move the table or one partition for example.

If you are doing this type of change on a partitioned index you need to change the index default attribute as well rebuild the index partition or the entire index.

But one thing caught my eye while working on this as after setting the new INITRANS default attribute and rebuilt the index online it did not changed the INITRANS values.

See below the execution on a test system

More“Changing initrans on a Partitioned Index”

ORA-01450 on Index Rebuild

Hello all,
So, I got this:

SQL> ALTER INDEX MATHEUS.INDEX_1 REBUILD online TABLESPACE NEW_TBS;
ALTER INDEX MATHEUS.INDEX_1 REBUILD online TABLESPACE NEW_TBS
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-01450: maximum key length (3215) exceeded

So, is this a bug? Yes it is.

From MOS ALTER INDEX REBUILD ONLINE Fails with ORA-01450 (Doc ID 236329.1):
“This is caused by issue Bug:2525767. The online rebuild of the index creates a journal table and index. This internal journal IOT table contains more columns in its index. Their total length is greater than number reported in ORA-01450 error message. This is a feature of online rebuild.
Maximum key length is calculated with respect to the database block size. It means that current value of the initialization parameter db_block_size is not large enough so that the internal journal IOT can be created without errors.”

Wanna know more, there is a great article on how this works exactly, by Alex Gorbachev: ORA-01450 During Online Index Rebuild

The solution?
It simply cannot be done online as explained, so doing it offline is the solution:

SQL> ALTER INDEX MATHEUS.INDEX_1 REBUILD TABLESPACE NEW_TBS;

Index altered.

Hope it helps, cheers!