ALTER TABLE SET TYPE

Converts a non-WAL table to WAL, or a WAL table to non-WAL.

info

Upgrading QuestDB?

Apply table conversions separately from the version upgrade.

If upgrading, match the following sequence:

  1. Convert/ALTER tables
  2. Restart
  3. Upgrade
  4. Restart

Syntax​

Flow chart showing the syntax of the ALTER TABLE keyword

Flow chart showing the syntax of ALTER TABLE with SET TYPE keyword

Description​

The command schedules the conversion of the specified table to WAL or non-WAL type. The actual conversion takes place on the next restart of the server.

If the command issued more than once before the restart, the last command overrides all previous ones.

If the target type of the conversion is the same as the current type of the table, the conversion request is ignored.

Examples​

To convert a non-WAL table to WAL:

ALTER TABLE weather SET TYPE WAL;
-- now restart instance

To convert a WAL table to non-WAL:

ALTER TABLE weather SET TYPE BYPASS WAL;
-- now restart instance