ok, i have the stat now :

SQL> execute procedure UPDATE_SEARCH_FAST('EZAEQS');
Current memory = 427063120
Delta memory = 17084
Max memory = 427095572
Elapsed time= 0.02 sec
Buffers = 50000
Reads = 0
Writes 0
Fetches = 2975

SQL> commit;
Current memory = 427023280
Delta memory = -39840
Max memory = 427097404
Elapsed time= 0.07 sec
Buffers = 50000
Reads = 2
Writes 150
Fetches = 2


SQL> execute procedure UPDATE_SEARCH_FAST('UqSAZAE');
Current memory = 427061216
Delta memory = 1578108
Max memory = 427086236
Elapsed time= 0.11 sec
Buffers = 50000
Reads = 1019
Writes 0
Fetches = 12683

SQL> commit;
Current memory = 427020348
Delta memory = -40868
Max memory = 427095500
Elapsed time= 0.62 sec
Buffers = 50000
Reads = 2
Writes 264
Fetches = 2


the procedure UPDATE_SEARCH_FAST simply do some DELETE and INSERT in one table. the same amout of insert/delete will be done in every call. the params is simply use in one colums that is part of multiple "multi column index"

i put 50 000 as a page buffer for testing, but set 512 or 1024 not change anything (below it's can slow down the exec time)

thanks by advance
stephane