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Warning: This documentation is for a pre-release version of pgAdmin 4
Use the Exclusion constraint dialog to define or modify the behavior of an
exclusion constraint. An exclusion constraint guarantees that if any two rows
are compared on the specified column or expression (using the specified
operator), at least one of the operator comparisons will return false or null.
The Exclusion constraint dialog organizes the development of an exclusion
constraint through the following dialog tabs: General, Definition, and
Columns. The SQL tab displays the SQL code generated by dialog selections.
Use the fields in the General tab to identify the exclusion constraint:
Click the Definition tab to continue.
Use the fields in the Definition tab to define the exclusion constraint:
Use the drop-down listbox next to Tablespace to select the tablespace in
which the index associated with the exclude constraint will reside.
Use the drop-down listbox next to Access method to specify the type of
index that will be used when implementing the exclusion constraint:
Select gist to specify a GiST index.
Select spgist to specify a space-partitioned GiST index.
Select btree to specify a B-tree index.
Select hash to specify a hash index.
Use the Fill Factor field to specify a fill factor for the table and
associated index. The fill factor is a percentage between 10 and 100. 100
(complete packing) is the default.
Move the Deferrable? switch to the Yes position to specify that the
timing of the constraint is deferrable, and can be postponed until the end of
the statement. The default is No.
If enabled, move the Deferred? switch to the Yes position to specify the
timing of the constraint is deferred to the end of the statement. The default
Use the Constraint field to provide a condition that a row must satisfy to
be included in the table.
Click the Columns tab to continue.
Use the fields in the Columns tab to to specify the column(s) to which the
constraint applies. Use the drop-down listbox next to Column to select a
column and click the Add icon (+) to provide details of the action on the
Use Include columns field to specify columns for INCLUDE clause of the
constraint. This option is available in Postgres 11 and later.
Click the SQL tab to continue.
Your entries in the Exclusion Constraint dialog 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.
The following is an example of the sql command generated by user selections in
the Exclusion Constraint dialog:
The example shown demonstrates creating an exclusion constraint named
exclude_department that restricts additions to the dept table to those
additions that are not equal to the value of the deptno column. The
constraint uses a btree index.