Can we use bulk collect in select statement?
This BULK COLLECT can be used in ‘SELECT’ statement to populate the records in bulk or in fetching the cursor in bulk. Since the BULK COLLECT fetches the record in BULK, the INTO clause should always contain a collection type variable.
When should I use bulk collect?
Use the BULK COLLECT clause to fetch multiple rows into one or more collections with a single context switch. Use the FORALL statement when you need to execute the same DML statement repeatedly for different bind variable values.
What is limit in bulk collect?
LIMIT clause restricts the number of rows fetched using BULK COLLECT with FETCH statement.
Is it good to use limit keyword with bulk collect?
As the number of rows in the table grows, more memory will be consumed. So the general recommendation for production code, working with tables that may grow greatly in size, is to avoid SELECT BULK COLLECT INTO (an implicit query) and instead use the FETCH BULK COLLECT with a LIMIT clause.
How Bulk collect improves performance?
BULK COLLECT improves performance of queries that retrieve more than one row. Use the LIMIT clause to avoid excessive PGA memory consumption. Leave it to the optimizer to speed up “read only” cursor FOR loops. Convert loops that contain inserts, updates, deletes or merges to FORALL statements.
How can you handle multiple rows without using loops in PL SQL?
Handle Multiple Rows Without Loops
- Adding delimiters to a file which has no delimiter.
- Data from 1 column to be separated in multiple columns.
- Handling null in outer join.
- Datastage – flat file concat header.
- Single row converted into multiple rows using transformer stage.
What is bulk collection in Oracle PL SQL?
A bulk collect is a method of fetching data where the PL/SQL engine tells the SQL engine to collect many rows at once and place them in a collection. The SQL engine retrieves all the rows and loads them into the collection and switches back to the PL/SQL engine. The data can now be processed as needed in memory.
When should a close statement be used in PL SQL?
After all rows have been retrieved from the result set that is associated with a cursor, the cursor must be closed. The result set cannot be referenced after the cursor has been closed. However, the cursor can be reopened and the rows of the new result set can be fetched.