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Changes since a version ​

CHANGES: read the rows appended to a table since an earlier version.

Applies to: Embedded ❌, Enterprise ✅

CHANGES reads the rows appended to a table since an earlier version, without rescanning rows that were already there:

sql
SELECT * FROM events CHANGES (INFORMATION => APPEND_ONLY) AT (VERSION => 42)

This returns the rows appended after version 42, up to the table's current version at the time the query runs.

Strictly append-only ​

The clause is named for what it requires, not just what it does: every change to the table between the starting version and the current one must be an append. If any of them inserted with changes other than a pure append -- an update, a delete, a merge -- the query is refused rather than silently returning an incomplete or wrong result. Re-run it with a later starting version that is itself after the non-append write, or read the table in full instead of incrementally.

INFORMATION => APPEND_ONLY is the only supported value: it names what kind of history the clause is willing to read, not a choice among several. AT (VERSION => ...) takes a positive integer; there is no AT (TIMESTAMP => ...) form for this clause, unlike other version qualifiers.

Where the clause can go ​

It attaches to a table in FROM, including inside a subquery, a CTE, a join, a set operation, or EXPLAIN:

sql
WITH recent AS (
  SELECT * FROM events CHANGES (INFORMATION => APPEND_ONLY) AT (VERSION => 42)
)
SELECT count(*) FROM recent

SELECT * FROM events CHANGES (INFORMATION => APPEND_ONLY) AT (VERSION => 10) a
JOIN events CHANGES (INFORMATION => APPEND_ONLY) AT (VERSION => 20) b
  ON a.id = b.id

Each occurrence of a table keeps its own starting version, even when the same table is referenced more than once in one statement.

Unsupported forms ​

CHANGES (INFORMATION => DEFAULT)only APPEND_ONLY is supported
AT (TIMESTAMP => ...)only AT (VERSION => ...) is supported
AT (VERSION => 0)the starting version must be positive
... END (VERSION => ...)not supported; the current version is always the end
CHANGES ... TABLESAMPLE (...)cannot be combined on the same table reference
TableCREATE, ALTER, CLONE and versioning basics.SelectThe rest of the query grammar this clause attaches to.