I have a table which has two partitions (by range): first_half and second_half based on a column "INSERT_DAY".
I need to add subpartitions "SUCCESS" and "NONSUCCESS" based on the values of another column "STATUS" (subpartition by list) i.e. I need to transform my range partition to composite (range-list) partition.
I do not wish to drop existing tables or partitions. What is the ALTER query for this?
PS: The database is Oracle 9i
No alter query for adding subpartitions as far as i know.
To get the desired result performe the folowing steps
Create the table in the structure you want using create as select with the partitions and the sub partitions.
switch the names of the two tables.
you can also explore the use of dbms_Redefinition but if you have a luxury of a littel downtime it's not worth it.
Related
We have a primary table that is Range partitioned by date with a 1-month interval. It's also a list sub-partitioned with 4 distinct values. So essentially it is one month partition having 4 sub-partitions.
Database: Oracle 19c
I need advice on how to effectively move the partition/sub-partition data from active schema to historical schema in another database.
Also, there are about 30 tables that are referenced partitioned on the primary table for which the data needs to be moved as well. Overall I'm looking to move about 2500 subpartitions
I'm not sure if an exchange partition would be the right approach in this scenario?
TIA
You could use exchange to get the data rapidly out of your active table, but you would still then to send that table over the wire to the remote history database to load it in.
In which case, using "exchange" probably is just adding more steps to the process for little gain. (There are still potential uses here depending on how you want to handle indexing etc).
But simplest is perhaps just transferring the data over, assuming a common structure between the two tables, ie
insert /*+ APPEND */ into history_table#remote_db
select * from active_table partition ( myparname )
I can't remember if partition naming syntax is supported over a db link, but if not, then the appropriate date predicates will do the same trick, and then just follow up with:
alter table active_table truncate partition myparname;
I need to update the some tables in my application from some other warehouse tables which would be updating weekly or biweekly. I should update my tables based on those. And these are having foreign keys in another tables. So I cannot just truncate the table and reinsert the whole data every time. So I have to take the delta and update accordingly based on few primary key columns which doesn't change. Need some inputs on how to implement this approach.
My approach:
Check the last updated time of those tables, views.
If it is most recent then compare each row based on the primary key in my table and warehouse table.
update each column if it is different.
Do nothing if there is no change in columns.
insert if there is a new record.
My Question:
How do I implement this? Writing a PL/SQL code is it a good and efficient way? as the expected number of records are around 800K.
Please provide any sample code or links.
I would go for Pl/Sql and bulk collect forall method. You can use minus in your cursor in order to reduce data size and calculating difference.
You can check this site for more information about bulk collect, forall and engines: http://www.oracle.com/technetwork/issue-archive/2012/12-sep/o52plsql-1709862.html
There are many parts to your question above and I will answer as best I can:
While it is possible to disable referencing foreign keys, truncate the table, repopulate the table with the updated data then reenable the foreign keys, given your requirements described above I don't believe truncating the table each time to be optimal
Yes, in principle PL/SQL is a good way to achieve what you are wanting to
achieve as this is too complex to deal with in native SQL and PL/SQL is an efficient alternative
Conceptually, the approach I would take is something like as follows:
Initial set up:
create a sequence called activity_seq
Add an "activity_id" column of type number to your source tables with a unique constraint
Add a trigger to the source table/s setting activity_id = activity_seq.nextval for each insert / update of a table row
create some kind of master table to hold the "last processed activity id" value
Then bi/weekly:
retrieve the value of "last processed activity id" from the master
table
select all rows in the source table/s having activity_id value > "last processed activity id" value
iterate through the selected source rows and update the target if a match is found based on whatever your match criterion is, or if
no match is found then insert a new row into the target (I assume
there is no delete as you do not mention it)
on completion, update the master table "last processed activity id" to the greatest value of activity_id for the source rows
processed in step 3 above.
(please note that, depending on your environment and the number of rows processed, the above process may need to be split and repeated over a number of transactions)
I hope this proves helpful
I want to delete around 1 million records from a table which is partitioned and table size is around 10-13 millions , As of now only 2 partition exist in the table containining July month data and august month data, and i want to delete from July month.Can you please let me know if a simple delete from table paritition (0715) is ok to do ? Possibilities of fragmentation ? or any best way out?
Thank you
DELETE is rather costly operation on large partitioned tables (but 10M is not realy large). Typically you try to avoid it and remove the data partition-wise using drop partition.
The simplest schema is rolling window, where you define a range partitioning schema by dropping the oldest partitian after the retention interval.
If you need more controll you may use CTAS and exchange back approach.
Instead of deleting a large part of a partition create a copy of it
create table TMP as
select * from TAB PARTITION (ppp)
where <predicate to filter out records to be ommited for partition ppp>
Create indexes on the TMP table in the same structure as the LOCAL indexes of the partitioned table.
Than exchange the temporary table with the partition
ALTER TABLE TAB
EXCHANGE PARTITION ppp WITH TABLE TMP including indexes
WITHOUT VALIDATION
Note no fragmenatation as a result, in contrary you may use it to reorganize the partition data (e.g. with ORDER BY in CTAS or with COMPRESS etc.)
You can delete truncate the partition from the given table. Delete also you can perform if you want to delete few rows from the partition. Plz share your table structure along with the partition details so that it will be easy for people here to assist you.
I have a partitioned table in greenplum(modeled after psql), which has been partitioned with specific range of values.
Now, i have to insert the data again into the same table. New values for Partitions might overlap with existing ones. I have created alter command with new start and end dates. But, if the overlaps are there, the command fails. So, i need to create partition for each date, in order to avoid whole command failure.
Just wondering, if there is a way in greenplum to create partitions based on the inserted data automatically, just like hive does.
thanks for your help.
Greenplum does not (currently) create additional partitions for data which does not fit into an existing partition.
If you have a default partition on the table it will receive all the records which do not fit into one of the specified partitions. You can then use ALTER TABLE ... SPLIT DEFAULT PARTITION (see the documentation if required) to create the new partitions for any new dates at the end of the load batch.
I have a table Customer_Chronics in Oracle 11g.
The table has three key columns as shown below :
branch_code
customer_id
period
I have partitioned by table by list of branch_code, and now I'm having dilemma. Which is better:
Create unique index indexNumberOne on Customer_Chronics (PERIOD, CUSTOMER_ID);
Create unique index indexNumberTwo on Customer_Chronics (branch_code, PERIOD, CUSTOMER_ID);
The actual data must be unique by period, customer_id. If I put a unique index only on these two columns Oracle will check all partitions on the table when inserting new records?
The only way to enforce uniqueness is with a unique constraint on the columns of interest. So that's your first option. The database will check all values across all partitions it this case. But as it's a unique index that shouldn't take too long no matter how big the table gets (if that's your concern).
Yes, If you put unique index on that two columns only, Oracle will create a global index and will check all partitions. This is one of challenges I face sometime because we prefer local indexs for big tables (small tables should be OK).