changingColumnType

Diagnostic Category: lint/safety/changingColumnType

Since: vnext

Sources: - Inspired from: squawk/changing-column-type

Description

Changing a column type may break existing clients.

Changing a column's data type requires an exclusive lock on the table while the entire table is rewritten. This can take a long time for large tables and will block reads and writes.

Instead of changing the type directly, consider creating a new column with the desired type, migrating the data, and then dropping the old column.

Examples

Invalid

ALTER TABLE "core_recipe" ALTER COLUMN "edits" TYPE text USING "edits"::text;

code-block.sql:1:1 lint/safety/changingColumnType ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Changing a column type requires a table rewrite and blocks reads and writes.

  > 1 │ ALTER TABLE "core_recipe" ALTER COLUMN "edits" TYPE text USING "edits"::text;
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    2 │ 

  i Consider creating a new column with the desired type, migrating data, and then dropping the old column.

How to configure

{
  "linter": {
    "rules": {
      "safety": {
        "changingColumnType": "error"
      }
    }
  }
}