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The biggest penalties are borne when we embed SQL lookups inside PL/SQL functions or when we simply call PL/SQL functions repeatedly from SQL.
Context-switching and excessive I/O can degrade performance of even the most simple queries.
We will begin by creating a simple cache-enabled PL/SQL function.
We will base this on a Steven Feuerstein best-practice example and create a function to encapsulate the business rule for formatting a full customer name, as follows.
We specify (through syntax) that a PL/SQL function is to be cached; or rather, its results are to be cached.
All examples are created in the SH supplied schema.In addition, we have included a call to a COUNTER package.We will use this throughout this article to keep a count of how many times our function is executed. As stated, we are going to keep track of how many times this is executed, so we will initialise a counter as follows.For this reason, this article on the Query Result Cache is recommended background reading.It includes details of many of the shared components, the result cache architecture, how it is allocated and managed, what it contains and how to investigate it. For the investigations in this article, the result_cache_max_size is set to 25M.