The pg_enum catalog contains entries showing the values and labels for each enum type. The internal representation of a given enum value is actually the OID of its associated row in pg_enum.
Table 47-21. pg_enum Columns
|oid||oid||Row identifier (hidden attribute; must be explicitly selected)|
|enumtypid||oid||pg_type.oid||The OID of the pg_type entry owning this enum value|
|enumsortorder||float4||The sort position of this enum value within its enum type|
|enumlabel||name||The textual label for this enum value|
The OIDs for pg_enum rows follow a special rule: even-numbered OIDs are guaranteed to be ordered in the same way as the sort ordering of their enum type. That is, if two even OIDs belong to the same enum type, the smaller OID must have the smaller enumsortorder value. Odd-numbered OID values need bear no relationship to the sort order. This rule allows the enum comparison routines to avoid catalog lookups in many common cases. The routines that create and alter enum types attempt to assign even OIDs to enum values whenever possible.
When an enum type is created, its members are assigned sort-order positions 1..n. But members added later might be given negative or fractional values of enumsortorder. The only requirement on these values is that they be correctly ordered and unique within each enum type.
Please use this form to add your own comments regarding your experience with particular features of PostgreSQL, clarifications of the documentation, or hints for other users. Please note, this is not a support forum, and your IP address will be logged. If you have a question or need help, please see the faq, try a mailing list, or join us on IRC. Note that submissions containing URLs or other keywords commonly found in 'spam' comments may be silently discarded. Please contact the webmaster if you think this is happening to you in error.
Proceed to the comment form.