SQL> select count(*) from test_update where description like '%5 description%'; COUNT(*) ----- 100000 Elapsed: 00:00:02.63 SQL> create table test_update_rowids as select rowid rid, description from test_update where description like '%5 description%'; Elapsed: 00:00:54.58 The table test_update_rowids stores the rowids and the new values that has to be updated.
ie 100000 rows … Oracle SQL Tuning Tips and Tricks Tutorial -2. The update_forall_8i.sql script shows how this operation would be … For better understanding take a look at the examples bellow. Note that, the larger the number of rows you will collect, the more performance improvement you will achieve. In this example, the bulk operation is approximately twice the speed of the conventional update. Bulk insert,Delete and Update will give your system a huge performance boost. BULK COLLECT reduces context switches between SQL and PL/SQL engine and allows SQL engine to fetch the records at once. BULK COLLECT: SELECT statements that retrieve multiple rows with a single fetch, improving the speed of data retrieval. This BULK COLLECT can be used in 'SELECT' statement to populate the records in bulk or in fetching the cursor in bulk. You should use Bulk Insert,Delete and Update instead of Single Insert,Delete and Update if you are executing Bulk operation. SQL> @update_forall.sql Normal Updates : 202 Bulk Updates : 104. PL/SQL procedure successfully completed. Oracle PL/SQL provides the functionality of fetching the records in bulk rather than fetching one-by-one. Oracle Bulk Collect is recommended to use for handling large number of rows. If you insert high volume data serial, you should switch this insert operation to the Bulk Insert. FORALL: INSERTs, UPDATEs, and DELETEs that use collections to change multiple rows of data very quickly The Performance Difference Between SQL Row-by-row Updating, Batch Updating, and Bulk Updating Posted on April 19, 2018 April 22, 2018 by lukaseder Something that has been said many times, but needs constant repeating until every developer is aware of the importance of this is the performance difference between row-by-row updating and bulk updating.
bulk collect：1回のフェッチで複数の行を取得するselect文。データ取得が高速化される.
forall：コレクションを使用してデータの複数行をすばやく変更するinsert、update、delete In this article, I will cover the two most important of these features: BULK COLLECT and FORALL. 1.