Tag: partition

Database, Errors and Bugs, SQL | PLSQL

Changing initrans on a Partitioned Index

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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”

Database, SQL | PLSQL

Rebuild all indexes of a Partioned Table

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Another quick post!

Regarding you frequently need to collect all indexes of a partioned table (local and global indexes), this is a quick script that make the task a little bit easier:

begin
-- local indexes
for i in (select p.index_owner owner, p.index_name, p.partition_name
from dba_indexes i, dba_ind_partitions p
where i.owner='&OWNER'
and   i.table_name='&TABLE'
and   i.partitioned='YES'
and   i.visibility='VISIBLE' -- Rebuild only of the visible indexes, to get real effect :)
and   p.index_name=i.index_name
and   p.index_owner=i.owner
order by 1,2) loop
execute immediate 'alter index '||i.owner||'.'||i.index_name||' rebuild  partition '||i.partition_name||' online parallel 12'; -- parallel 12 solve most of the problems
execute immediate 'alter index '||i.owner||'.'||i.index_name||' parallel 1'; -- If you don't use parallel indexes in your database, or the default parallel of the index, or what you want...
end loop;
-- global indexes
for i in (select i.owner owner, i.index_name
from dba_indexes i
where i.owner='&OWNER'
and   i.table_name='&TABLE'
and   i.partitioned='NO'
and   i.visibility='VISIBLE' -- same comment
order by 1,2) loop
execute immediate 'alter index '||i.owner||'.'||i.index_name||' rebuild online parallel 12'; -- same
execute immediate 'alter index '||i.owner||'.'||i.index_name||' parallel 1'; -- same :)
end loop;
end;
/

I hope this script make your life easier. Hugs!

Matheus.