CHECKPOINT
.CLUSTER
.)Database serverPGDATA
is commonly used to refer to the data directory.SELECT
. Certain functions can return sets; those are called set-returning functions.COMMIT
and ROLLBACK
. They are invoked via the CALL
command.SELECT
but it can be an INSERT
, UPDATE
, or DELETE
command if the RETURNING
clause is specified.pg_catalog
.CREATE
command. Most objects are specific to one database, and are commonly known as local objects.pg_catalog
. These tables contain data in internal representation and are not typically considered useful for user examination; a number of user-friendlier views, also in schema pg_catalog
, offer more convenient access to some of that information, while additional tables and views exist in schema information_schema
(see Chapter 36) that expose some of the same and additional information as mandated by the SQL standard.pg_default
.3
(values under that are reserved) and the epoch value is incremented by one. In some contexts, the epoch and xid values are considered together as a single 64-bit value.INSERT
, UPDATE
, DELETE
, TRUNCATE
) is applied to a relation. A trigger executes within the same transaction as the statement which invoked it, and if the function fails, then the invoking statement also fails.VACUUM
command, but can also be handled automatically via autovacuum processes.SELECT
statement, but has no storage of its own. Any time a query references a view, the definition of the view is substituted into the query as if the user had typed it as a subquery instead of the name of the view.all-visible
) indicates that all tuples in the page are visible to all transactions. The second one (all-frozen
) indicates that all tuples in the page are marked frozen.WAL