Best way to change partition key on existing table

Question

Hi,
Using Oracle 11.20.3 on AIX.
We have a table about 800 million rows and 120gb in size.
Want to try copies oif this table to evalaute different partitiong strategies.
What is the quickest way to do this?
Would have liked say datapump table 1 tro disk and datapumo import the data to new table but do the tables need to be of the same format.
Thanks

Answer 1

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Using Oracle 11.20.3 on AIX.
We have a table about 800 million rows and 120gb in size.
Want to try copies oif this table to evalaute different partitiong strategies.
What is the quickest way to do this?
Would have liked say datapump table 1 tro disk and datapumo import the data to new table but do the tables need to be of the same format.
>
First your subject asks a different question that the text you posted: Best way to change partition key on existing table. The answer to that question is YOU CAN'T. All data has to be moved to change the partition key since each partition/subpartition is in its own segment. You either create a new table or use DBMS_REDEFINITION to redefine the table online.
Why do you want to export all data to a file first? That just adds to the time and cost of doing the op.
What problem are you trying to use partitioning to solve? Performance? Data maintenance? For performance the appropriate partitioning key and whether to use subpartitions depends on the types of queries and the query predicates you typically use as well as the columns that may be suitable for partition keys.
For maintenance a common method is to partition on a date by year/month/day so you can more easily load new daily/weekly/monthly data into its own partition or drop old data that no longer needs to be kept online.
You should use a small subset of the data when testing your partitionings strategies.
Can you do the partitioning offline in an outage window? If not then using the DBMS_REDEFINITION is your only option.
Without knowing what you are trying to accomplish only general advice can be given. You even mentioned that you might want to use a different set of columns than the curren table has.
A standard heap table uses ONE segment for its data (ignoring possible LOB segments). A partitioned/subpartitioned table uses ONE segment for each partition/subpartition. This means that ALL data must be moved to partition the table (unless you are only creating one partition).
This means that every partitioning scheme that uses a different partition key requires ALL data to be moved again for that test.
Provide some information about what problem you are trying to solve.
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Is this quicker than datapump?
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Yes - exporting the data simplying moves it all an additional time. Ok to export if you need a backup before you start.
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Found artcle which talks about using merge option on datapump import to convert partitioned table to non-partitioned table.
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How would that apply to you? That isn't what you said you wanted to do.