Updating large tables Adult free live tv

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In this article I will demonstrate a fast way to update rows in a large table Consider a table called which has more than 5 millions rows.

Suppose you want to update a column with the value 0, if it that column contains negative value.

The large update has to be broken down to small batches, like 10,000, at a time. It is also easy to restart in case of interruption.

WAITFOR DELAY can be included to slow down the batch processing.

You declare a local table to hold the primary key values of the table being updated, then use the OUTPUT clause to capture the primary key values for the rows that are updated. For the WHILE loop to start, the @@ROWCOUNT function must return a value greater than 0.

As callout A in Listing 1 shows, you can trick the WHILE loop into initially executing by including a meaningless SET statement right before the WHILE condition.

I want to test on a level playing field and remove special factors that unfairly favour one method, so there are some rules: TEST (Update Source) - 100K rows TEST (Update target) - 10M rows Name Type Name Type ------------------------------ ------------ ------------------------------ ------------ PK NUMBER PK NUMBER FK NUMBER FK NUMBER FILL VARCHAR2(40) FILL VARCHAR2(40) 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.

The UPDATE portion of the code works in an identical fashion to the Implicit Cursor Loop, so this is not really a separate "UPDATE" method as such.

In one table I'm updating 5 million records (seems to be updating about 744,000 records every 10 mins). The where predicates would prevent this from working correctly.After that, the WHILE condition is dependent on the UPDATE statement’s row count.The WHERE clauses in callout B prevent the same row from being updated twice. Just for testing purpose what I did is, I selected table with 14 records and set a row count of 5.This query is supposed to update records in 5, 5 and 4 but it just updates first 5 records.

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