Catalogs (cont)
Side-note: PostgreSQL tuples contain
- owner-specified attributes (from
create table)
- system-defined attributes
oid |
|
unique identifying number for tuple (optional)
|
tableoid |
|
which table this tuple belongs to
|
xmin/xmax |
|
which transaction created/deleted tuple (for MVCC)
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OIDs are used as primary keys in many of the catalog tables.
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