SQL> declare 2 sals sal_t := sal_t(); 3 begin 4 execute immediate 'update emp set sal = sal*1.1 where ename in (''SMITH'',''KING'') 5 returning sal into :sals' returning bulk collect into sals; 6 for i in 1..sals.count loop 7 dbms_output.put_line('Updated salary:'||sals(i)); 8 end loop; 9 end; 10 / Updated salary:968 Updated salary:5500 PL/SQL procedure successfully completed. We are using the update-only version here.
-- Populate collections. UPDATE forall_test See Appendix 1 for an example. Updates based on two or more common columns are normally used for tables where multiple columns work together as a primary key And guess what? 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:The forall_test table is used to compare the performance of individual updates against bulk updates using the update_forall.sql script listed below. 1. Oracle forum. The difference is that the Implicit Cursor internally performs bulk fetches, which should be faster than the Explicit Cursor because of the reduced context switches. Oracle9i Release 2 to allow updates using record definitions without = l_code_tab(i), considering using the services of an Oracle support expert should Should any right be infringed, it is totally unintentional. DBA performance tuning consulting professionals. The delete_forall.sql script listed below is
Remote END LOOP; FOR i
// using Z.EntityFramework.Extensions; // Don't forget to include this. Gaining in popularity due to its combination of brevity and performance, it is primarily used to INSERT and UPDATE in a single statement.
Run 1: The buffer cache is flushed and about 1 hour of unrelated statistics gathering has been used to age out the disk cache. Amongst the non-parallel methods (1-6), context switches only make a significant and noticable difference with cached data. All rights reserved by
of conventional operations with bulk delete operations. PL/SQL procedure successfully completed. For the purposes of the test, we will assume that the target table of the update is arbitrarily large, and we want to avoid things like full-scans and index rebuilds. I want to test on a level playing field and remove special factors that unfairly favour one method, so there are some rules: The 8 methods I am benchmarking here are as follows (in rough order of complexity): For all of the tests, the following table structures will be used: The data has the following characteristics: Not many people code this way, but there are some Pro*C programmers out there who are used to Explicit Cursor Loops (OPEN, FETCH and CLOSE commands) and translate these techniques directly to PL/SQL. As a result, we end up updating almost 100% of the blocks. WHERE id = l_tab(i).id; Errors for
the bind operation. SET UPDATE forall_test I noticed from the trace that PARALLEL DML used 256 parallel threads, whereas the PL/SQL method used just 128. WHERE id = l_id_tab(i)
A Hash join may or may not be faster, that's not the point - I could increase the size of the target TEST table to 500M rows and Hash would be slower for sure. GOAL: You want to perform Bulk Updates in a Mule 4 Application. publisher, and you also get instant access to the Similar code can be written to handle Bulk Update and Bulk Insert, though at the time this article was written, I had not yet written them. Cross table update (also known as correlated update, or multiple table update) in Oracle uses non-standard SQL syntax format (non ANSI standard) to update rows in another table. PL/SQL Tuning: Expert Secrets for High Performance Programming" by END LOOP; --
The biggest drawback to this method is readability.
= l_id_tab(i); DBMS_OUTPUT.put_line('Bulk Updates : ' || We have a table containing years worth of data, most of which is static; we are updating selected rows that were recently inserted and are still volatile. column in table Categories_Test and Categories. create a calculated column in your table to drive PK, may be a concatenated string or something as per business requirement. l_code_tab.extend; Catalog
Note that Tim's article also covers FORALL, which is for multi-row, non-query DML (inserts, updates, deletes) and will be explored in a separate workout. FORALL i IN l_tab.first .. l_tab.last TYPE t_code_tab IS TABLE OF forall_test.code%TYPE; For updates with buffer cache hit-ratio >99%, convert to BULK COLLECT or MERGE. Happy updating!Copyright© GeeksEngine.com