ALTER TABLE SQUASH PARTITIONS

Merges split folders into one partition and folds merge-append partitions back into the standard layout, reclaiming dead space even in partitions without splits. Before downgrading, follow the safe downgrade procedure. For non-WAL conversion, follow the merge-append disable procedure to prevent new merge-append writes.

Syntax

ALTER TABLE tableName SQUASH PARTITIONS;

Examples

The SQL keyword SHOW PARTITIONS can be used to display partition split details.

For example, Let's consider the following table x containing split partitions:

SHOW PARTITIONS FROM x;

index	partitionBy	name	minTimestamp	maxTimestamp	numRows	diskSize	diskSizeHuman	readOnly	active	attached	detached	attachable
0	DAY	2023-02-04	2023-02-04T00:00:00.000000Z	2023-02-04T23:59:59.940000Z	1440000	71281136	68.0 MiB	FALSE	FALSE	TRUE	FALSE	FALSE
1	DAY	2023-02-05	2023-02-05T00:00:00.000000Z	2023-02-05T20:59:59.880000Z	1259999	65388544	62.4 MiB	FALSE	FALSE	TRUE	FALSE	FALSE
2	DAY	2023-02-05T205959-880001	2023-02-05T20:59:59.940000Z	2023-02-05T21:59:59.940000Z	60002	83886080	80.0 MiB	FALSE	TRUE	TRUE	FALSE	FALSE

The table is partition by day and there are two partitions for 2023-02-05 as a result of partition split.

To merge the two partitions:

ALTER TABLE x SQUASH PARTITIONS;

SHOW PARTITIONS FROM x;

index	partitionBy	name	minTimestamp	maxTimestamp	numRows	diskSize	diskSizeHuman	readOnly	active	attached	detached	attachable
0	DAY	2023-02-04	2023-02-04T00:00:00.000000Z	2023-02-04T23:59:59.940000Z	1440000	71281136	68.0 MiB	FALSE	FALSE	TRUE	FALSE	FALSE
1	DAY	2023-02-05	2023-02-05T00:00:00.000000Z	2023-02-05T21:59:59.940000Z	1320001	65388544	62.4 MiB	FALSE	TRUE	TRUE	FALSE	FALSE