#Alter table add column postgres update#
#Alter table add column postgres plus#

For information on the permissible expression for default value expr, refer to the Default Values section. If a default value is not specified, then any old default value that exists and which is appropriate to the new data type will be used. For example, in data types, BOOL cannot be converted to TIMESTAMP, and for the content of a column, if you have CHAR (3) with the content '123', then it can be converted to DECIMAL, however, if the content is 'ABC', it cannot be converted.Ī default value must be convertible to the data type. The data type and the content specified in the columns must be convertible.

If the optional clause IF EXISTS is specified, then the statement does not throw an exception if the column does not exist.If the column that is dropped is a part of the partitioning key (see ALTER TABLE (Distribution/Partitioning) for more information), then the partitioning keys are dropped and the new rows of the table will not be partitioned any more.

If the column that is dropped is a part of the distribution key (see ALTER TABLE (Distribution/Partitioning) for more information), then the distribution keys are dropped and the new rows of the table will be distributed randomly across the cluster nodes.

When you specify this option, the foreign key reference to the column is deleted even when the referencing table does not belong to the current user.

If a column that you need to delete has foreign key references, then specify the option CASCADE CONSTRAINTS.

For information about constraints, refer to the ALTER TABLE (Constraints) section.

If the clause IF NOT EXISTS is specified, then statement does not throw an error message if the column already exists.

For more information, refer to the Identity Columns section.

For identity columns, a monotonically increasing number is generated if the table already possesses rows.

For information on the permissible expressions for default value expr, refer to Default Values section.

If the default value expression is not appropriate for the specified data type, an error message is displayed, and the statement is not executed.

If the table already contains rows, the content of the inserted column will be set to the default value if it has been specified.

For example, a value of -1 implies that all values in the column are distinct, while a value of -0.5 implies that each value appears twice on the average. When set to a negative value, which must be greater than or equal to -1, ANALYZE will assume that the number of distinct nonnull values in the column is linear in the size of the table the exact count is to be computed by multiplying the estimated table size by the absolute value of the given number.

When set to a positive value, ANALYZE will assume that the column contains exactly the specified number of distinct nonnull values.

#Alter table add column postgres plus#

n_distinct affects the statistics for the table itself, while n_distinct_inherited affects the statistics gathered for the table plus its inheritance children. Currently, the only defined per-attribute options are n_distinct and n_distinct_inherited, which override the number-of-distinct-values estimates made by subsequent ANALYZE operations. This form sets or resets per-attribute options.

#Alter table add column postgres update#

SET STATISTICS acquires a SHARE UPDATE EXCLUSIVE lock. For more information on the use of statistics by the PostgreSQL query planner, refer to Section 14.2. The target can be set in the range 0 to 10000 alternatively, set it to -1 to revert to using the system default statistics target ( default_statistics_target). This form sets the per-column statistics-gathering target for subsequent ANALYZE operations. sequence_option is an option supported by ALTER SEQUENCE such as INCREMENT BY.

These forms alter the sequence that underlies an existing identity column. If DROP IDENTITY IF EXISTS is specified and the column is not an identity column, no error is thrown. Like SET DEFAULT, these forms only affect the behavior of subsequent INSERT and UPDATE commands they do not cause rows already in the table to change. These forms change whether a column is an identity column or change the generation attribute of an existing identity column. RENAME CONSTRAINT constraint_name TO new_constraint_nameĪLTER TABLE ALL IN TABLESPACE name ]ĪTTACH PARTITION partition_name AS IDENTITY