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Manual Locking and User-Defined Locks- Locking and Latching
So far, we have looked mostly at locks that Oracle places for us transparently. When we update a table, Oracle places a TM lock on…
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With Bind Variables- Locking and Latching
Now I’d like to look at the same situation as presented in the previous section, but this time using a program that uses significantly less…
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Setting Up for the Test- Locking and Latching
In order to test, we’ll need a schema (set of tables) to work with. We’ll be testing with multiple users and want to measure the…
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Performance/Scalability Comparison- Locking and Latching
Table 6-1 summarizes the CPU usage by each implementation, as well as the latching results as we increase the number of users beyond two. As…
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Without Bind Variables- Locking and Latching
In the first instance, our PL/SQL code will not use bind variables, but rather will use string concatenation to insert data: To automate this, the…
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Measuring the Cost of Latching a Shared Resource- Locking and Latching
As an example, we’ll study the cost of latching the shared pool. We’ll compare a well- written program (one that uses bind variables) and a…
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Latches- Locking and Latching
Latches are lightweight serialization devices used to coordinate multiuser access to shared data structures, objects, and files. Latches are locks designed to be held for…
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DDL Locks- Locking and Latching-1
DDL locks are automatically placed against objects during a DDL operation to protect them from changes by other sessions. For example, if I perform the…
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TX (Transaction) Locks- Locking and Latching-4
This output shows that we were able to lock 37 rows but ran out of transaction slots for the 38th row. For this given block,…
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TM (DML Enqueue) Locks- Locking and Latching
TM locks are used to ensure that the structure of a table is not altered while you are modifying its contents. For example, if you…