What happens to Existing index after table partition and created with local index

Question

Hi guys,
desc part id  number, name  varchar2(100), salary  number
In an existing table  PART  i am  adding 1 more column DATASEQ NUMBER. i am asked to partition the table part based on dataseq.now the table is created with this logic
create table part( id  number, name  varchar2(100), salary  number, DATASEQ  number) partition by list(dataseq) (partition PART_INITIAL  values (1));
Suggestionn required. since  the table is partitioned based on DATASEQ i am asked to add local index on dataseq. i have added local index to dataseq create index idx on part(dataseq) LOCAL; Now my question is  already there is existing index is for the column ID and salary.
1)  IDX for  dataseq is created locally so that it will have partition on each partition on the main table. Please tell me what happens to the existing index on the column ID and salary.. will it again created in local?
Please suggest
S

Answer 1

Hi,
first of all, in reality "partition a table" means create a new table a migrate existing data there (although theoretically you can use dbms_redefinition to partition an existing table -- however, it's just doing the same thing behind the scenes). This means that you also get to decide what to do with the indexes -- which indexes will be local, which will be global (you can also re-evaluate some of existing indexes and decide that they're not really needed).
Second of all, the choice of partitioning key looks odd. Partitioning is a data manageability technique more than anything else, so in order to benefit from it you need to find a good partitioning key. A recently added column named "data_seq" doesn't look like a good candidate. Can you provide more details about this column and why it was chosen as a partitioning key?
I suspect that whoever suggested this partitioning scheme is making a huge mistake. A non-partitioned table is much better in all aspects (including manageability and performance) than wrongly partitioned one.
Best regards,
Nikolay