CODEWITHSUNDEEP
postgresqlliquibase
wabrit
wabrit

Reputation: 265

Liquibase dropDefaultValue on PostgreSQL maps to "SET DEFAULT" not "DROP DEFAULT"

I'm running liquibase against a PostgreSQL 9.6 DB and have a dropDefaultValue change to a NON-NULLABLE column.

- dropDefaultValue:
    columnDataType: VARCHAR(255)
    columnName: bar
    tableName: foo

I expected this to result in a DROP DEFAULT instruction (as suggested in the docs - https://www.liquibase.org/documentation/changes/drop_default_value.html) but instead I see:

ALTER TABLE public.foo ALTER COLUMN  bar SET DEFAULT NULL

With the net effect that the column still has a default value (of NULL) rather than no default at all. Is this to be expected?

Upvotes: 0

Views: 1854

Answers (1)

Laurenz Albe
Laurenz Albe

Reputation: 246393

My experiments show that the pg_attrdef row vanishes if I run

ALTER TABLE ... ALTER ... SET DEFAULT NULL;

But maybe there are ways to enter a NULL row.

However that may be, it is fine, and Liquibase isn't doing anything wrong. NULL is the “default DEFAULT value”.

A column can be defined as NOT NULL and still have a NULL default value — the only consequence is that you can never use the default value for that column.

Upvotes: 2

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