How to crate a dynamic size array, collection

Question

Hi,
Can someone point me to some tutorial on how to create a dynamic size array. Actually I have multiple cursors and on different tables and want to loop through each cursor and get some values from each cursor and put it in an array. But don't know how to create or initialize an array as I don't know the size. Is there any other way.
Here is what I am doing I have 6 cursors on different tables, I loop through each cursor and get some specific data that I need to place at one place after looping through all the cursors which then finally needs to be inserted in one table. But before the insert I need to validate each data so want to have all the data in some array or some other place for temporary storage from it's easier to do the validate and insert rather than while looping through the cursors as there may be duplicates which I am trying to remove.
As this procedure will be called multiple times so wanted to save the cursor data in temporary array before inserting in the final table. Looking for some faster and efficient way.
Any help is appreciated.
Thanks

Answer 1

guest0012 wrote:
All the 6 cursors are independent and no relation i.e. can have a join and have one sql as no relationship in tables.If there is no relation, then what are your code doing combining unrelated rows into the same GTT/array?
Now using GTT when I do an insert how do I make sure the same data doesnot already exists. i.e. GTT will only have one column. Then create a unique index or primary key for the GTT and use that to enforce uniqueness.
So everytime I iterate over a cursor I have to insert into GTT and then finally again have to iterate over GTT and then do an insert in the final table which maybe a performance issue Which is why using SQL will be faster and more scalable - and if PL/SQL code/logic can be used to glue these "no relationship" tables together, why can't that not be done in SQL?
that's why i was wondering if can use any kind of array or collection as it will be a collection of numbersAnd that will reside in expensive PGA memory. Which means a limit on the size of the collection/array you can safely create without impacting server performance, or even cause a server crash by exhausting all virtual memory and causing swap space to trash.
and finally will just iterate ovr array and use FOR ALL for insert but don't know what will be the size of the array as I only know after looping the cursors the total number of records to be stored. So wondering if how to do it through collection/array is there a way to intialize the array and keep populating it with the data with defining the size before hand.You cannot append the bulk collect of one cursor into the collection used for bulk collecting another cursor.
Collections are automatically sized to the number of rows fetched. If you want to manually size collection, the Extend() method needs to be used, where the method's argument specifies the number of cells/locations to add to the collection.
From what you describe about the issue you have - collections are not the correct choice. If you are going to put the different tables's data into the same collection, then you can also combine those tables's data using a single SQL projection (via a UNION for example).
And doing the data crunching side in SQL is always superior in scalability and performance, than doing it in PL/SQL.