Function Dialog v8
Use the Function
dialog to define a function. If you drop and then recreate a function, the new function is not the same entity as the old; you must drop existing rules, views, triggers, etc. that refer to the old function.
The Function
dialog organizes the development of a function through the following dialog tabs: General
, Definition
, Code
, Options
, Parameters
, and Security
. The SQL
tab displays the SQL code generated by dialog selections.
Use the fields in the General
tab to identify a function:
- Use the
Name
field to add a descriptive name for the function. The name will be displayed in theBrowser
tree control. - Use the drop-down listbox next to
Owner
to select the name of the role that will own the function. - Use the drop-down listbox next to
Schema
to select the schema in which the function will be created. - Store notes about the function in the
Comment
field.
Click the Definition
tab to continue.
Use the fields in the Definition
tab to define the function:
- Use the drop-down listbox next to
Return type
to select the data type returned by the function, if any. - Use the drop-down listbox next to
Language
to select the implementation language. The default issql
. - Use the fields in the
Arguments
to define an argument. Click theAdd
icon (+) to set parameters and values for the argument:- Use the drop-down listbox in the
Data type
field to select a data type. - Use the drop-down listbox in the
Mode
field to select a mode. SelectIN
for an input parameter; selectOUT
for an output parameter; selectINOUT
for both an input and an output parameter; or, selectVARIADIC
to specify a VARIADIC parameter. - Provide a name for the argument in the
Argument Name
field. - Specify a default value for the argument in the
Default Value
field.
- Use the drop-down listbox in the
Click the Add
icon (+) to define another argument; to discard an argument, click the trash icon to the left of the row and confirm deletion in the Delete Row popup.
Click the Code
tab to continue.
- Use the
Code
field to write the code that will execute when the function is called.
Click the Options
tab to continue.
Use the fields in the Options
tab to describe or modify the action of the function:
Use the drop-down listbox next to
Volatility
to select one of the following.VOLATILE
is the default value.VOLATILE
indicates that the function value can change even within a single table scan, so no optimizations can be made.STABLE
indicates that the function cannot modify the database, and that within a single table scan it will consistently return the same result for the same argument values.IMMUTABLE
indicates that the function cannot modify the database and always returns the same result when given the same argument values.
Move the
Returns a Set?
switch to indicate if the function returns a set that includes multiple rows. The default isNo
.Move the
Strict?
switch to indicate if the function always returns NULL whenever any of its arguments are NULL. IfYes
, the function is not executed when there are NULL arguments; instead a NULL result is assumed automatically. The default isNo
.Move the
Security of definer?
switch to specify that the function is to be executed with the privileges of the user that created it. The default isNo
.Move the
Window?
switch to indicate that the function is a window function rather than a plain function. The default isNo
. This is currently only useful for functions written in C. The WINDOW attribute cannot be changed when replacing an existing function definition. For more information about the CREATE FUNCTION command, see the PostgreSQL core documentation available at:http://www.postgresql.org/docs/current/static/functions-window.html
Use the
Estimated cost
field to specify a positive number representing the estimated execution cost for the function, in units of cpu_operator_cost. If the function returns a set, this is the cost per returned row.Use the
Estimated rows
field to specify a positive number giving the estimated number of rows that the query planner should expect the function to return. This is only allowed when the function is declared to return a set. The default assumption is 1000 rows.Move the
Leak proof?
switch to indicate whether the function has side effects. The default isNo
. This option can only be set by the superuser.Use the
Support function
field to specify a planner support function to use for the function.
Click the Parameters
tab to continue.
Use the fields in the Parameters
tab to specify settings that will be applied when the function is invoked. Click the Add
icon (+) to add a Name
/Value
field in the table.
- Use the drop-down listbox in the
Name
column in theParameters
panel to select a parameter. - Use the
Value
field to specify the value that will be associated with the selected variable. This field is context-sensitive.
Click the Security
tab to continue.
Use the Security
tab to assign privileges and define security labels.
Use the Privileges
panel to assign usage privileges for the function to a role.
- Select the name of the role from the drop-down listbox in the
Grantee
field. - Click inside the
Privileges
field. Check the boxes to the left of one or more privileges to grant the selected privilege to the specified user. - The current user, who is the default grantor for granting the privilege, is displayed in the
Grantor
field.
Click the Add
icon (+) to assign additional privileges; to discard a privilege, click the trash icon to the left of the row and confirm deletion in the Delete Row
popup.
Use the Security Labels
panel to define security labels applied to the function. Click the Add
icon (+) to add each security label selection:
- Specify a security label provider in the
Provider
field. The named provider must be loaded and must consent to the proposed labeling operation. - Specify a a security label in the
Security Label
field. The meaning of a given label is at the discretion of the label provider. PostgreSQL places no restrictions on whether or how a label provider must interpret security labels; it merely provides a mechanism for storing them.
Click the Add
icon (+) to assign additional security labels; to discard a security label, click the trash icon to the left of the row and confirm deletion in the Delete Row
popup.
Click the SQL
tab to continue.
Your entries in the Function
dialog generate a generate a SQL command (see an example below). Use the SQL
tab for review; revisit or switch tabs to make any changes to the SQL command.
Example
The following is an example of the sql command generated by selections made in the Function
dialog:
The example demonstrates creating an edbspl
function named emp_comp
. The function adds two columns (p_sal and p_comm), and then uses the result to compute a yearly salary, returning a NUMERIC value.
- Click the
Info
button (i) to access online help.View context-sensitive help in theTabbed browser
, where a new tab displays the PostgreSQL core documentation. - Click the
Save
button to save work. - Click the
Cancel
button to exit without saving work. - Click the
Reset
button to restore configuration parameters.