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Mintrans and Maxtrans
segments, such as tables have an interested transaction list in their db block. The size of this list can be set with the parameters mintrans and maxtrans.
The interested transaction list is an array that keeps track of (some of) the most recent transactions on a block. The size of this array is specified by the initrans parameter when an object is created. If more entries are needed in the ITL and if there is enough space in the block, the array can grow up to maxtrans.
This can be demonstrated with 3 sessions:
create table t_ (a number) initrans 1 maxtrans 2; insert into t_ values (1); insert into t_ values (2); insert into t_ values (3); commit; update t_ set a = 101 where a = 1;
update t_ set a = 102 where a = 2;
update t_ set a = 103 where a = 3;
This third session hangs until one of the other session commits or rolls back.