Chunking Bulk Collections Using the LIMIT Clause (2022)

Chunking Bulk Collections Using the LIMIT Clause (1)


Oracle Tips by Burleson Consulting

The following Tip is from the outstanding book "Oracle PL/SQL Tuning: Expert Secrets for High Performance Programming" by Dr. Tim Hall, Oracle ACE of the year, 2006:

PL/SQL collections are essentially arrays in memory, so massive collections can have a detrimental effect on system performance due to the amount of memory they require. In some situations, it may be necessary to split the data being processed into chunks to make the code more memory-friendly. This “chunking” can be achieved using the LIMIT clause of the BULK COLLECT syntax.

The bulk_collect_limit.sql script uses the LIMIT clause to split the collection into chunks of 10,000; processing each chunk in turn. Notice the use of the explicit cursor for this operation.

bulk_collect_limit.sql

SET SERVEROUTPUT ON
DECLARE
TYPE t_bulk_collect_test_tab IS TABLE OF bulk_collect_test%ROWTYPE;

l_tab t_bulk_collect_test_tab;

CURSOR c_data IS
SELECT *
FROM bulk_collect_test;
BEGIN
OPEN c_data;
LOOP
FETCH c_data
BULK COLLECT INTO l_tab LIMIT 10000;

-- Process contents of collection here.
DBMS_OUTPUT.put_line(l_tab.count || ‘ rows’);
EXIT WHEN c_data%NOTFOUND;
END LOOP
CLOSE c_data;
END;
/

For the purpose of this test, the bulk_collect_limit.sql script simply displays the size of the collection. But in a real situation, the contents of the collection would be processed at this time. The output from this script clearly demonstrates that the query has been split into 10,000 row chunks, with the remainder being processed in the last chunk.

SQL> @bulk_collect_limit.sql
10000 rows
10000 rows
10000 rows
10000 rows
10000 rows
10000 rows
1202 rows

PL/SQL procedure successfully completed.

The bulk_collect_limit_8i.sql script displays the same behavior, but is coded to use individual collections to support previous Oracle versions.

bulk_collect_limit_8i.sql

SET SERVEROUTPUT ON
DECLARE
TYPE t_owner_tab IS TABLE OF bulk_collect_test.owner%TYPE;
TYPE t_object_name_tab IS TABLE OF bulk_collect_test.object_name%TYPE;
TYPE t_object_id_tab IS TABLE OF bulk_collect_test.object_id%TYPE;

l_owner_tab t_owner_tab;
l_object_name_tab t_object_name_tab;
l_object_id_tab t_object_id_tab;

CURSOR c_data IS
SELECT owner,
object_name,
object_id
FROM bulk_collect_test;
BEGIN
OPEN c_data;
LOOP
FETCH c_data
BULK COLLECT INTO l_owner_tab,
l_object_name_tab,
l_object_id_tab
LIMIT 10000;
DBMS_OUTPUT.put_line(l_owner_tab.count || ' rows');
EXIT WHEN c_data%NOTFOUND;
END LOOP;
CLOSE c_data;
END;
/

(Video) Oracle PL SQL : Learn Bulk Collect and FOR ALL | Bulk Collect and LIMIT With Example

Oracle 10g performs implicit array fetches of 100 records in cursor FOR loops, making this limit clause method unnecessary provided an array size of 100 records is suitable for your purposes. The effects of this implicit array processing are displayed by the implicit_array_processing.sql script.

implicit_array_processing.sql

SET SERVEROUTPUT ON
DECLARE
TYPE t_bulk_collect_test_tab IS TABLE OF bulk_collect_test%ROWTYPE;

l_tab t_bulk_collect_test_tab;

CURSOR c_data IS
SELECT *
FROM bulk_collect_test;

l_start NUMBER;
BEGIN
-- Time a regular population.
l_start := DBMS_UTILITY.get_time;

FOR cur_rec IN (SELECT *
FROM bulk_collect_test)
LOOP
NULL;
END LOOP;

DBMS_OUTPUT.put_line('Regular : ' ||
(DBMS_UTILITY.get_time - l_start));

-- Time bulk with LIMIT 10.
l_start := DBMS_UTILITY.get_time;

OPEN c_data;
LOOP
FETCH c_data
BULK COLLECT INTO l_tab LIMIT 10;
EXIT WHEN c_data%NOTFOUND;
END LOOP;
CLOSE c_data;

DBMS_OUTPUT.put_line('LIMIT 10 : ' ||
(DBMS_UTILITY.get_time - l_start));

-- Time bulk with LIMIT 100.
l_start := DBMS_UTILITY.get_time;

OPEN c_data;
LOOP
FETCH c_data
BULK COLLECT INTO l_tab LIMIT 100;
EXIT WHEN c_data%NOTFOUND;
END LOOP;
CLOSE c_data;

DBMS_OUTPUT.put_line('LIMIT 100: ' ||
(DBMS_UTILITY.get_time - l_start));
END;
/

The results of running this script against an Oracle 9i and 10g database are displayed below.

SQL> -- 9i
SQL> @implicit_array_processing.sql
Regular : 36
LIMIT 10 : 12
LIMIT 100: 7

(Video) Oracle PLSQL - BULK Extract, Insert, Update and Delete

PL/SQL procedure successfully completed.

SQL>
SQL> -- 10g
SQL> @implicit_array_processing.sql
Regular : 19
LIMIT 10 : 51
LIMIT 100: 17

PL/SQL procedure successfully completed.

When the script is run against an Oracle 9i database, both bulk operations are faster than the regular for loop. Against an Oracle 10g database, the bulk operation using an array size of 10 rows is actually slower than the cursor for loop, while the operation with an array size of 100 rows is slightly faster. This clearly demonstrates the implicit array processing being done by Oracle 10g.

The next section shows alternative methods of limiting the data returned by bulk collections.

Manually Limiting Bulk Collection Volumes

Although large operations can be processed in chunks, sometimes only a subset of the total number of rows needs to be processed. To process a subset, four possible methods are available:

The bulk_collect_manual_limit.sql script shows how these four options are implemented.

bulk_collect_manual_limit.sql

SET SERVEROUTPUT ON
DECLARE
TYPE t_bulk_collect_test_tab IS TABLE OF bulk_collect_test%ROWTYPE;

l_tab t_bulk_collect_test_tab;

CURSOR c_data IS
SELECT *
FROM bulk_collect_test;
BEGIN
-- Fixed number of rows using LIMIT.
OPEN c_data;
FETCH c_data
BULK COLLECT INTO l_tab LIMIT 100;
CLOSE c_data;

(Video) 30 How to update a large SQL table in batches | How to update a large SQL table in Chunks

DBMS_OUTPUT.put_line('LIMIT (100 rows) : ' || l_tab.count || ' rows');

-- Fixed number of rows using ROWNUM.
SELECT *
BULK COLLECT INTO l_tab
FROM bulk_collect_test
WHERE rownum < 101;

DBMS_OUTPUT.put_line('ROWNUM (100 rows) : ' || l_tab.count || ' rows');

-- Approximate percentage of rows.

SELECT *
BULK COLLECT INTO l_tab
FROM bulk_collect_test SAMPLE (10);
DBMS_OUTPUT.put_line('SAMPLE (~ 10% rows) : ' || l_tab.count || ' rows');

-- Approximate percentage of blocks.

SELECT *
BULK COLLECT INTO l_tab
FROM bulk_collect_test SAMPLE BLOCK (10);

DBMS_OUTPUT.put_line('SAMPLE (~ 10% blocks) : ' || l_tab.count || ' rows');
END;
/

The type of output expected from this script is shown below.

SQL> @bulk_collect_manual_limit.sql
LIMIT (100 rows) : 100 rows
ROWNUM (100 rows) : 100 rows
SAMPLE (~ 10% rows) : 6174 rows
SAMPLE (~ 10% blocks) : 3358 rows

PL/SQL procedure successfully completed.

The SAMPLE options are approximations, so the number of rows may vary. In addition, the SAMPLE BLOCK value could vary greatly, depending on the spread of rows within the blocks returned.

The bulk_collect_manual_limit_8i.sql script shows how these four options are implemented in legacy versions of Oracle.

bulk_collect_manual_limit_8i.sql

SET SERVEROUTPUT ON
DECLARE
TYPE t_owner_tab IS TABLE OF bulk_collect_test.owner%TYPE;
TYPE t_object_name_tab IS TABLE OF bulk_collect_test.object_name%TYPE;
TYPE t_object_id_tab IS TABLE OF bulk_collect_test.object_id%TYPE;

l_owner_tab t_owner_tab;
l_object_name_tab t_object_name_tab;
l_object_id_tab t_object_id_tab;

(Video) PL/SQL Collections

CURSOR c_data IS
SELECT owner,
object_name,
object_id
FROM bulk_collect_test;
BEGIN
-- Fixed number of rows using LIMIT.
OPEN c_data;
FETCH c_data
BULK COLLECT INTO l_owner_tab,
l_object_name_tab,
l_object_id_tab
LIMIT 100;
CLOSE c_data;

DBMS_OUTPUT.put_line('LIMIT (100 rows) : ' || l_owner_tab.count || ' rows');

-- Fixed number of rows using ROWNUM.

SELECT owner,
object_name,
object_id
BULK COLLECT INTO l_owner_tab,
l_object_name_tab,
l_object_id_tab
FROM bulk_collect_test
WHERE rownum < 101;

DBMS_OUTPUT.put_line('ROWNUM (100 rows) : ' || l_owner_tab.count || ' rows');

-- Approximate percentage of rows.

SELECT owner,
object_name,
object_id
BULK COLLECT INTO l_owner_tab,
l_object_name_tab,
l_object_id_tab
FROM bulk_collect_test SAMPLE (10);

DBMS_OUTPUT.put_line('SAMPLE (~ 10% rows) : ' || l_owner_tab.count || ' rows');

-- Approximate percentage of blocks.

SELECT owner,
object_name,
object_id
BULK COLLECT INTO l_owner_tab,
l_object_name_tab,
l_object_id_tab
FROM bulk_collect_test SAMPLE BLOCK (10);

DBMS_OUTPUT.put_line('SAMPLE (~ 10% blocks) : ' || l_owner_tab.count || ' rows');
END;
/

The output from the bulk_collect_manual_limit_8i.sql script is similar to the output of the previous script. Notice the variation in the values displayed by the SAMPLE options.

SQL> @bulk_collect_manual_limit_8i.sql
LIMIT (100 rows) : 100 rows
ROWNUM (100 rows) : 100 rows
SAMPLE (~ 10% rows) : 6113 rows
SAMPLE (~ 10% blocks) : 8093 rows

PL/SQL procedure successfully completed.

The following section shows how bulk collections can be used in conjunction with the returning clause of DML statements.

Chunking Bulk Collections Using the LIMIT Clause (2) This is an excerpt from the bestselling book "Oracle PL/SQL Tuning: Expert Secrets for High Performance Programming" by Dr. Tim Hall, Oracle ACE of the year, 2006.

You can buy the book for only $23.95 (30%-off) when you buy directly from the publisher, and you also get instant access to the code depot of PL/SQL tuning scripts:

FAQs

What is use of limit clause in bulk collect? ›

What does LIMIT clause do? LIMIT clause restricts the number of rows fetched using BULK COLLECT with FETCH statement.

How do I set bulk collect limits? ›

To overcome this Oracle has provided 'LIMIT' clause that defines the number of records that needs to be included in the bulk. Syntax: FETCH <cursor_name> BULK COLLECT INTO <bulk_variable> LIMIT <size>; In the above syntax, the cursor fetch statement uses BULK COLLECT statement along with the LIMIT clause.

What is bulk collect and for all limit? ›

BULK COLLECT: These are SELECT statements that retrieve multiple rows with a single fetch, thereby improving the speed of data retrieval. FORALL: These are INSERT, UPDATE, and DELETE operations that use collections to change multiple rows of data very quickly.

Can we use bulk collect in SELECT statement? ›

Here are some things to know about how BULK COLLECT works: It can be used with all three types of collections: associative arrays, nested tables, and VARRAYs. You can fetch into individual collections (one for each expression in the SELECT list) or a single collection of records.

What is the limit clause used for? ›

The LIMIT clause can restrict the result set of the query to some maximum number of rows. If this clause specifies a value smaller than the number of qualifying rows, the query returns only a subset of the rows that satisfy the selection criteria.

How does limit clause work? ›

The SQL LIMIT clause restricts how many rows are returned from a query. The syntax for the LIMIT clause is: SELECT * FROM table LIMIT X;. X represents how many records you want to retrieve. For example, you can use the LIMIT clause to retrieve the top five players on a leaderboard.

What is the max limit for bulk collect in Oracle? ›

From a syntax point of view, the limit value can't exceed 2147483647 as it's a pls_integer .

Why bulk collect is faster? ›

When you use bulk binds, you move multiple rows of data from one VM to the other with a single context shift, significantly reducing the number of context shifts, making your code faster.

What is difference between bulk collect and bulk bind? ›

Bulk binds can improve the performance when loading collections from a queries. The BULK COLLECT INTO construct binds the output of the query to the collection.

What are the features of bulk collect? ›

Attributes of Bulk Collect

It uses the same attributes as the cursor and it has a % bulk rowcount. This attribute returns the number of rows from the table that means it shows the total number of counts. The word 'n' denotes the collection's value sequence for which the row count is required.

How do I use bulk collect? ›

BULK COLLECT INTO clause (PL/SQL)
  1. The data type of the array-variable element must not be a record type.
  2. There must be an array-variable for each column in the SELECT list.
  3. The data type of each column in the SELECT list must be assignable to the array element data type of the corresponding array-variable .

Is bulk collect faster than cursor? ›

Definitely there is increase in performance with bulk insert because of less number of context switches from PLSQL engine to SQL engine when compared to cursor for loop insert.

Can we use bulk collect without cursor? ›

No, it can't be done in this way. Use FORALL statement instead.

Does bulk collect overwrite? ›

The SQL engine automatically initializes and extends the collections you reference in the BULK COLLECT clause. It starts filling the collections at index 1, inserts elements consecutively (densely), and overwrites the values of any elements that were previously defined. You cannot use the SELECT...

Is it good to use limit keyword with bulk collect Mcq? ›

You can always use LIMIT clause along with the Bulk Collect to limit the number of rows fetched from the database.

What are the 3 rules of limits? ›

The limit of a product is equal to the product of the limits. The limit of a quotient is equal to the quotient of the limits. The limit of a constant function is equal to the constant.

What are two transaction limits examples? ›

A per transaction limit controls the maximum amount of money that can be moved electronically at one time. For example, let's say you have to pay a vendor $1500. If your merchant account has a per withdrawal transaction limit of $1000, you would have split the payment into two parts - $1000 and $500.

How do I get last 10 rows in SQL? ›

SELECT * FROM ( SELECT * FROM yourTableName ORDER BY id DESC LIMIT 10 )Var1 ORDER BY id ASC; Let us now implement the above query. mysql> SELECT * FROM ( -> SELECT * FROM Last10RecordsDemo ORDER BY id DESC LIMIT 10 -> )Var1 -> -> ORDER BY id ASC; The following is the output that displays the last 10 records.

What are two reasons to use a query limit? ›

Question: Why do you use a Query Limit? Select all that apply. Unit Testing Handle Distinct Queries Limit the number of columns Limit Large Data Migrations Which shape sends the data down a path and defines custom error messages reported in the Manage tab?

Does limit speed up query? ›

The answer, in short, is yes. If you limit your result to 1, then even if you are "expecting" one result, the query will be faster because your database wont look through all your records. It will simply stop once it finds a record that matches your query.

What can I use instead of limits in SQL? ›

For Microsoft databases like SQL Server or MSAccess, you can use the SELECT TOP statement to limit your results, which is Microsoft's proprietary equivalent to the SELECT LIMIT statement.

How do you pass more than 1000 values in clause? ›

Your basic options are:
  1. Use a (temporary) table. Load the values into another table first, then use the temp table in your IN condition: ...
  2. Split the list into groups < 1,000. ...
  3. Use a multi-value IN list. ...
  4. Pass the values as one string and split it in SQL.
26 Feb 2021

How can I speed up bulk insert in Oracle? ›

  1. main points to consider for your case is to use Append hint as this will directly append into the table instead of using freelist. ...
  2. Use a bulk insert instead instead of iterating in PL/SQL.
  3. Use sqlloaded to load the data directly into the table if you are getting data from a file feed.
27 Sept 2008

Does Oracle have limit clause? ›

The LIMIT clause is used to specify the maximum number M of results to return to the application. M is computed by an expression that may be a single integer literal, or a single external variable, or any expression which is built from literals and external variables and returns a single non-negative integer.

What are the advantages of bulk binding? ›

By using BULK BIND we can maximize the performance of time spent in the SQL context. The new Bulk Binds feature in PL/SQL 8.1 allows us to operate on multiple rows in a single DML statement.

What is the difference between cursor and bulk collect? ›

You always use a cursor if you returning data from the database. Bulk collect is the operation of loading arrays from a cursor in one go, rather than one-by-one.

Which command is used to implement bulk binding? ›

To do bulk binds with INSERT , UPDATE , and DELETE statements, you enclose the SQL statement within a PL/SQL FORALL statement. To do bulk binds with SELECT statements, you include the BULK COLLECT clause in the SELECT statement instead of using INTO .

What is bulk collect in PL SQL with example? ›

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. All the rows are retrieved with only 2 context switches.

How do you trace error handling? ›

Add Back Trace to Error Handler

CREATE OR REPLACE PROCEDURE proc3 IS BEGIN DBMS_OUTPUT. put_line ('calling proc2'); proc2; EXCEPTION WHEN OTHERS THEN DBMS_OUTPUT. put_line ('Error backtrace at top level:'); DBMS_OUTPUT. put_line (DBMS_UTILITY.

What is meant bulk collect in PL SQL? ›

Description. BULK COLLECT INTO array-variable. Identifies one or more variables with an array data type. Each row of the result is assigned to an element in each array in the order of the result set, with the array index assigned in sequence.

What are the collection methods in Oracle? ›

A collection method is a built-in function or procedure that operates on collections and is called using dot notation. You can use the methods EXISTS , COUNT , LIMIT , FIRST , LAST , PRIOR , NEXT , EXTEND , TRIM , and DELETE to manage collections whose size is unknown or varies.

What is difference between for and forall in Oracle? ›

FOR is an actual loop which will go through records one by one and do some processing. FORALL is NOT an actual loop, it's just a notation for a bulk DML operation. It will NOT go through rows one by one. For example, you can do some row processing in a FOR loop, but you won't be able to do it in FORALL.

Why do we use collection in Oracle? ›

Using PL/SQL Collections with SQL Statements. Collections let you manipulate complex datatypes within PL/SQL. Your program can compute subscripts to process specific elements in memory, and use SQL to store the results in database tables.

What is bulk insert in Oracle? ›

A Bulk insert is a process or method provided by a database management system to load multiple rows of data into a database table. Bulk insert may refer to: Transact-SQL BULK INSERT statement. PL/SQL BULK COLLECT and FORALL statements. MySQL LOAD DATA INFILE statement.

How can you trace the PL SQL code? ›

To use Trace, you start the tracing session, run your application, then stop the tracing session. As the program executes, trace data is collected and stored in database tables. For information about the DBMS_TRACE subprograms, see Oracle Database PL/SQL Packages and Types Reference.

What is bulk load in Oracle? ›

The bulk loader, bulkload , is a bulk management tool. It takes input data in LDIF or SQL*Loader format and loads the data directly into Oracle Internet Directory's schema in the metadata repository. It has three main phases: check , generate and load .

How can I speed up bulk insert in SQL? ›

Removing indexes prior to large inserts on a table, including when using SQL Bulk Insert, may be a best practice to increase performance.

What is the difference between cursor and collections? ›

One of the key differences is that cursors work on Sets of data, whereas collections work on structured arrays. Cursors are far more efficient at processing data than doing it through collections.

Can we use cursor in forall? ›

The simplest answer is to not use a cursor. Instead, build the select from xyz into the insert statement. In general, you should avoid opening cursors inside of cursor loops; that's what joins are for.

Can we store Varray in database? ›

You can create a VARRAY type of XMLType or LOB type for procedural purposes, such as in PL/SQL or view queries. However, database storage for varrays of these types is not supported. Thus you cannot create an object table or an object type column of a varray type of XMLType or LOB type.

How do you handle exceptions in bulk? ›

Key components of bulk DML with exception handling: A collection variable to hold the data. The FORALL construct which iterates through values in the collection variable. The SAVE EXCEPTIONS clause which tracks the exceptions being raised during bulk DML.

Is bulk insert a transaction? ›

BulkInsert doesn't create a transaction by default. If you want to save multiple lists, you will need to handle the transaction in your code.

How do you handle too many rows exceptions in PL SQL? ›

Handle an exception by trapping it with a handler or propagating it to the calling environment. For example, if your SELECT statement returns more than one row, TimesTen returns an error (exception) at runtime. As the following example shows, you would see TimesTen error 8507, then the associated ORA error message.

What is Pragma Autonomous_transaction? ›

The AUTONOMOUS_TRANSACTION pragma changes the way a subprogram works within a transaction. A subprogram marked with this pragma can do SQL operations and commit or roll back those operations, without committing or rolling back the data in the main transaction.

Which is faster in or exists? ›

The EXISTS clause is faster than IN when the subquery results are very large. The IN clause is faster than EXISTS when the subquery results are very small.

Where can a bulk collect clause be used? ›

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.

Where can a bulk collect clause be used Mcq? ›

Where can a BULK COLLECT clause be used?
  • SELECT INTO statement and FETCH statement.
  • RETURNING INTO clause and SELECT INTO statement.
  • FORALL statement and SELECT INTO statement.
  • SELECT INTO statement, RETURNING INTO statement and FETCH statement.
1 Oct 2019

What is collection limit? ›

Collection limitation is exactly what it says. It is limiting the amount of PII collected. Information should only be collected if it is needed and when it is needed. It should be retained only as long as necessary.

What is limit clause SQL? ›

The SQL LIMIT clause constrains the number of rows returned by a SELECT statement. For Microsoft databases like SQL Server or MSAccess, you can use the SELECT TOP statement to limit your results, which is Microsoft's proprietary equivalent to the SELECT LIMIT statement.

What is limit query? ›

The limit keyword is used to limit the number of rows returned in a query result. It can be used in conjunction with the SELECT, UPDATE OR DELETE commands LIMIT keyword syntax.

Why bulk collect is faster in Oracle? ›

When you use bulk binds, you move multiple rows of data from one VM to the other with a single context shift, significantly reducing the number of context shifts, making your code faster. And every time I insert a row, I'm doing the same thing.

How can I speed up my collections? ›

Some companies have sped up collections simply by changing their billing cycle from twice-a-month to once-a-week. Another idea is to invoice early in the month. Many companies do a once-a-month check run and, if your invoice happens to miss their monthly run, you'll have to wait another 30 days to get paid.

What does the collection method limit returns? ›

Function that returns the maximum number of elements that the collection can have. If the collection has no maximum size, then LIMIT returns NULL .

Do collections have a time limit? ›

A collector only has a certain number of years where they can take you to court to force you to pay a debt that you owe. The maximum statute nationwide is 15 years. However, in most states, the period for credit card contracts and loans is limited to 4-6 years.

Does limit make SQL faster? ›

If the sql expect to get more than one result, then it can speed up. The reason is because 'limit' can reduce the resultset size hence the memory and data to transfer is lesser.

Why I Cannot use limit in SQL? ›

"LIMIT" is a keyword specific to MySQL. Unless you have your environment connected to a MySQL database, it won't work. This has nothing to do with OutSystems, as the Platform passes on to the database whatever you write in an SQL query.

How do you use limits in database? ›

The SQL SELECT LIMIT statement is used to retrieve records from one or more tables in a database and limit the number of records returned based on a limit value. TIP: SELECT LIMIT is not supported in all SQL databases. For databases such as SQL Server or MSAccess, use the SELECT TOP statement to limit your results.

What is the difference between LIMIT and offset? ›

The limit option allows you to limit the number of rows returned from a query, while offset allows you to omit a specified number of rows before the beginning of the result set. Using both limit and offset skips both rows as well as limit the rows returned.

How do I LIMIT the number of rows returned in SQL? ›

If you don't need to omit any rows, you can use SQL Server's TOP clause to limit the rows returned. It is placed immediately after SELECT. The TOP keyword is followed by integer indicating the number of rows to return. In our example, we ordered by price and then limited the returned rows to 3.

What is difference between bulk collect and bulk bind in Oracle? ›

To do bulk binds with SELECT statements, you include the BULK COLLECT clause in the SELECT statement instead of using INTO . According to the online documentation, BULK COLLECT is explained as; "The keywords BULK COLLECT tell the SQL engine to bulk-bind output collections before returning them to the PL/SQL engine.

How can I improve my Oracle query performance? ›

How do you improve database performance with Oracle query optimization?
  1. Find high-consuming SQL statements. ...
  2. Collect data used by the optimizer. ...
  3. Figure out where the performance problems lie. ...
  4. Optimize. ...
  5. Keep from backsliding.
28 Jul 2020

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