Sex cam sudbury ont - Updating multiple rows in oracle

If the statement does exist in memory, Oracle Database can reuse it and skip the task of parsing and optimizing the statement.

It's a bit of a kludge, but we can do this in PL/SQL using a Parallel Enable Table Function. COUNT; END LOOP; CLOSE test_cur; COMMIT; PIPE ROW(cnt); RETURN; END; / Note that it receives its data via a Ref Cursor parameter. FK RUN 1 RUN 2 ----------------------------------- ----- ----- 1. A single bitmap index has added around 10% to the overall runtime of PL/SQL solutions, whereas the set-based (SQL-based) solutions run faster than the B-Tree indexes case (above).

Here's the function: CREATE OR REPLACE FUNCTION test_parallel_update ( test_cur IN SYS_REFCURSOR ) RETURN test_num_arr PARALLEL_ENABLE (PARTITION test_cur BY ANY) PIPELINED IS PRAGMA AUTONOMOUS_TRANSACTION; test_rec TEST%ROWTYPE; TYPE num_tab_t IS TABLE OF NUMBER(38); TYPE vc2_tab_t IS TABLE OF VARCHAR2(4000); pk_tab NUM_TAB_T; fk_tab NUM_TAB_T; fill_tab VC2_TAB_T; cnt INTEGER := 0; BEGIN LOOP FETCH test_cur BULK COLLECT INTO pk_tab, fk_tab, fill_tab LIMIT 1000; EXIT WHEN pk_tab. This is a feature of Oracle's parallel-enabled functions; they will apportion the rows of a single Ref Cursor amongst many parallel slaves, with each slave running over a different subset of the input data set. Parallel PL/SQL 28.2 27.2 6.3 Let's see how a Foreign Key constraint affects things. Although not shown here, this effect is magnified with each additional bitmap index.

), how I might cluster rows together that are subject to updates, and what I might do if I just get too many updates to handle. The fastest way to update every row in the table is to rebuild the table from scratch. Case 2 is common in Data Warehouses and overnight batch jobs.

I worry about how ETL tools apply updates (did you know Data Stage applys updates singly, but batches inserts in arrays? The two most common forms of Bulk Updates are: Case 1 is uninteresting.

I include it here because it allows us to compare the cost of context-switches to the cost of updates.

DECLARE CURSOR c1 IS SELECT * FROM test6; rec_cur c1%rowtype; BEGIN OPEN c1; LOOP FETCH c1 INTO rec_cur; EXIT WHEN c1%notfound; UPDATE test SET fk = rec_, fill = rec_WHERE pk = rec_cur.pk; END LOOP; CLOSE C1; END; / This is the simplest PL/SQL method and very common in hand-coded PL/SQL applications.

Using bind variables also improves query performance in the database, eliminates the need for special handling of literal quotation marks in the input, and protects against SQL injection attacks.

The following code shows a typical contains a client copy of the database data.

DECLARE CURSOR rec_cur IS SELECT * FROM test4; TYPE num_tab_t IS TABLE OF NUMBER(38); TYPE vc2_tab_t IS TABLE OF VARCHAR2(4000); pk_tab NUM_TAB_T; fk_tab NUM_TAB_T; fill_tab VC2_TAB_T; BEGIN OPEN rec_cur; LOOP FETCH rec_cur BULK COLLECT INTO pk_tab, fk_tab, fill_tab LIMIT 1000; EXIT WHEN pk_tab. This is to keep the playing field level when comparing to the other methods, which also perform primary key lookups on the target table. With hundreds of rows represented by each block in the index, the chances of two sessions attempting to lock the same block are quite high.

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