How to choose the partition in oracle tables?

Question

Dear all,
i m in need to create the partitions on prod.db tables since i m not aware of creating partitions?i just go through some theroy concepts and understood the range and list partitions (i.e)Range is normally used for values less than like jan,feb,march or values less than 50,000 values less than 1,00,000 like that each partition is having separate tablespaces to increase the performance. and for list is used to denoting the directions like west,east,north,south like that.
Now what i want to know is ?
1.)when will i can go ahead with partitions?
2.)before creating partitions is it advise to create index or not needed?
3.)if i started to create partition what is the leading column have to create partition and which partition has to choose?
pls let me know and pardon me if i did any mistakes.
thanks in advance..

Answer 1

I had to research on same topic. One of my teammates suggested few points that might help you also.
Advantages of partitioning:
1) Partitioning enables data management operations such data loads, index creation and rebuilding, and backup/recovery at the partition level, rather than on the entire table. This results in significantly reduced times for these operations.
2) Partitioning improves query performance. In some cases, the results of a query can be achieved by accessing a subset of partitions, rather than the entire table. Parallel queries/DML and Partition-wise Joins are also got benefited much.
3) Partitioning increases the availability of mission-critical databases if critical tables and indexes are divided into partitions to reduce the maintenance windows, recovery times, and impact of failures. (Each partition can have separate physical attributes such as pctfree, pctused, and tablespaces.)
Partitioning can be implemented without requiring any modifications to your applications. For example, you could convert a nonpartitioned table to a partitioned table without needing to modify any of the SELECT statements or DML statements which access that table. You do not need to rewrite your application code to take advantage of partitioning.
Disadvantages of partitioning:-
1) Advantages of partition nullified when you use bind variables.
Additional administration tasks to manage partitions viz. If situation arises for rebuilding of index then rebuilding should to be done for each individual partition.
2) Need more space to implement partitioning objects.
3) More time for some tasks, such as create non-partitioning indexes, collection of “global" statistics (dbms_stat’s granularity parameter to be set to GLOBAL. if sub partition are used then we have to set it to ALL).
4) Partition would implies a modification (of explain plan) for ALL the queries against the partitioned tables. So, if some queries use the choosing partition key and may greatly improve, some other queries not use the partition key and are dramatically bad impact by the partitioning.
5) To get the full advantage of partitioning (partition pruning, partition-wise joins, and so on), you must use the Cost Based Optimizer (CBO). If you use the RBO, and a table in the query is partitioned, Oracle kicks in the CBO while optimizing it. But because the statistics are not present, the CBO makes up the statistics, and this could lead to severely expensive optimization plans and extremely poor performance.
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Abou