PG_CONSTRAINT
PG_CONSTRAINT records check, primary key, and unique constraints on tables.
Name |
Type |
Description |
---|---|---|
oid |
oid |
Row identifier (hidden attribute, which must be specified) |
conname |
name |
Constraint name (not necessarily unique) |
connamespace |
oid |
OID of the namespace that contains the constraint |
contype |
"char" |
|
condeferrable |
boolean |
Whether the constraint can be deferrable |
condeferred |
boolean |
Whether the constraint can be deferrable by default |
convalidated |
boolean |
Whether the constraint is valid Currently, it can be set to false only for foreign key and check constraints. |
conrelid |
oid |
Table containing this constraint (0 if it is not a table constraint) |
contypid |
oid |
Domain containing this constraint (0 if it is not a domain constraint) |
conindid |
oid |
ID of the index associated with the constraint |
confrelid |
oid |
Referenced table if this constraint is a foreign key. Otherwise, the value is 0. |
confupdtype |
"char" |
Foreign key update action code
|
confdeltype |
"char" |
Foreign key deletion action code
|
confmatchtype |
"char" |
Foreign key match type
|
conislocal |
boolean |
Whether the local constraint is defined for the relationship |
coninhcount |
integer |
Number of direct inheritance parent tables that this constraint has. When the value is not 0, the constraint cannot be deleted or renamed. |
connoinherit |
boolean |
Whether the constraint can be inherited |
consoft |
boolean |
Whether the column indicates an informational constraint |
conopt |
boolean |
Whether you can use the informational constraint to optimize the execution plan |
conkey |
smallint[] |
Column list of the constrained control if this column is a table constraint |
confkey |
smallint[] |
List of referenced columns if this column is a foreign key. |
conpfeqop |
oid[] |
ID list of the equality operators for PK = FK comparisons if this column is a foreign key. |
conppeqop |
oid[] |
ID list of the equality operators for PK = PK comparisons if this column is a foreign key. |
conffeqop |
oid[] |
ID list of the equality operators for FK = FK comparisons if this column is a foreign key. The value is empty because foreign keys are not supported currently. |
conexclop |
oid[] |
ID list of the per-column exclusion operators if this column is an exclusion constraint |
conbin |
pg_node_tree |
Internal representation of the expression if this column is a check constraint |
consrc |
text |
Human-readable representation of the expression if this column is a check constraint |
conincluding |
smallint[] |
Not for constraint, but will be included in the attribute column of INDEX. |
![](https://support.huaweicloud.com/intl/en-us/centralized-devg-v2-gaussdb/public_sys-resources/notice_3.0-en-us.png)
- consrc is not updated when referenced objects change and does not track new column names. Instead of relying on this column to update, you are advised to use pg_get_constraintdef() to extract the definition of a check constraint.
- pg_class.relchecks must agree with the number of check-constraint entries found in the table for each relationship.
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