oracle - When does a deterministic function use the previous calculated value? -


Consider a deterministic function such as: 

  create or function SCHEMA.GET_NAME (Ss_id nvarchar2) Returns nvarchar2 DATRMist is TMPVR Discussion 2 (500); Select the name from the log into tmpvar from logistics. Organizations_item where id = ss_id; Return tmpvar; END ss_name;

Using Todd I called SCHEMA.GET_NAME (1) and gives it A . I changed the value again from a to the b table and returned SCHEMA.GET_NAME (1) to B .

This is a good result but I am afraid that the price is not being updated, which is said:

When in the Oracle Database One of the contexts faces a deterministic function, compared to reexecuting the function, if you later change the words of the function, you manually reconstruct all the function-based indexes and physical views manually. Do not be.

In the case of GET_NAME (1) an old cached value ( a instead of B )?

If you select from a table, then not the result of your function Deterministic A. It is that always will produce the same output by looking at the same initial conditions.

It is possible to change information in a table, so to quote from a function that chooses from a table is not deterministic:

returns the results of the function Can use any kind of package variable that does not otherwise specify this section to define a function that accesses the database in any way. The results of doing so are not captured if the data Function again chooses not to refine.

In other words, Oracle does not guarantee that the results of the function will be accurate (they are just). If your table is stable and is unlikely to change anytime, then it should be fine, but it is not something I would ever like to trust. To answer your question, let's say that Oracle will return anything other than the cached value within the same transaction / session.

If you need to sharpen it then there are two ways first of all, check that you have an index on id !

  1. Just join this table if your function is only this then there is no need for the existence of the function.

  2. Usage (Not necessarily possible but worth trying). Select 

      from (your_table

    ), get_name (: id), create a memory hash in the results of the oracle function, such as Result cache If you are executing the same function multiple times, the oracle will kill the cache instead of the function.


-

Comments

Post a Comment

Popular posts from this blog

Member with no value in F# -

After I am trying to convert F # to the following C # code: [StructLayout (LayoutKind.Sequential, charset = CharSet.Ansi)] Private class DOCINFOA {[MarshalAs (UnmanagedType.LPStr)] public string nomeDocumento; [Marshall (UnmanagedType.LPStr)] Public string arquivoSaida; [Marshall (UnmanagedType.LPStr)] Public String Tipodo; } I am doing the following: Named place printer module RawPrinterHelper = [& LT; StructLayout (LayoutKind.Sequential, charset = CharSet.Ansi) & gt;] Type DOCINFOA = [& LT; MarshalAs (UnmanagedType.LPStr) & gt;] Member this.nomeDocumento [& LT; MarshalAs (UnmanagedType.LPStr) & gt;] Member this.arquivoSaida [& LT; MarshalAs (UnmanagedType.LPStr) & gt;] Member This Tipoda [/ code> But I get: One type of definition is necessary for one or more members . Can I vacate these members? you val code> member : [& lt; StructLayout (LayoutKind.Sequential, charset = CharSet.Ansi) & gt;] Type DOCINFOA = [...
Read more

java - Joda Time Interval Not returning what I expect -

मेरे पास निम्न प्रोग्राम है import java.util। *; Import java.text। *; आयात करें org.joda.time। *; सार्वजनिक श्रेणी के स्कोप कंट्रोल {सार्वजनिक स्थिर अंतराल मिलनसार () {दिनांक समय currDate = नया दिनांक समय (2008, 4, 4, 15, 30, 0, 0); दिनांक समय epochDate = नया दिनांकटाइम (2000, 1, 1, 12, 0, 0, 0); अंतराल अंतराल = नया अंतराल (युरोप डेट, करोडेट); वापसी अंतराल; } सार्वजनिक स्थिर शून्य मुख्य (स्ट्रिंग [] आर्ग्स) {डबल दिनबात = मिलते समय ()। ToDurationMillis () / 1000/60/60/24; StdOut.println (daysBtween); }} मुझे आउटपुट मिल रहा है: 3016.0 लेकिन जो मैं देख रहा हूं वह है: 3016.1458333333 मैं क्या कर रहा हूँ ? toDurationMillis एक लंबा लौटा देता है, और प्रत्येक प्रभाग को int के रूप में घोषित किया जाता है। जावा इस प्रकार इनट्स को लॉन्ग में परिवर्तित कर देगा और डिवीजन को लंबे समय तक लौटाना होगा। परिणाम को अंत में दोहरे रूप में परिवर्तित करना। डबल्स का उपयोग करके अभिव्यक्ति करने के लिए जावा को बताने के लिए, अभिव्यक्ति के किसी भी घटक को दोहरे रूप में घोषित करें। उदाहरण के लिए: ...
Read more

c# - Showing a SelectedItem's Property -

So I have enabled a rightclick option for my DataGrid. I want to display the only chosen property but it is not behaving like what I would like it to display my name and additional. Public category Paymentinfo {public int PaymentNo {get; Set; } Public string date {get; Set; } Public Double Pay {get; Set; } Public Double Principle {get; Set; } Public Double Interest {get; Set; } Public Double Balance {Received; Set; }} Private Zero MenuItem_OnClick (Object Sender, RoutedEventArgs e) {MessageBox.Show (AmortGrid.SelectedItem.ToString ()); } I'm trying to apply it without using a View Module! If I place a breakpoint where the messagebox and the recipient place it on selected ITEM, then this property will display the payment. A date-payment-principle-interest-balance is the only value that needs payment. Was hoping that it would be something like this MessageBox.Show (AmortGrid.SelectedItem.PaymentNo.ToString ()); When you call ToString () So you get the class typ...
Read more