ALTER TABLE SQUASH PARTITIONS - Questdb

Merges partition parts back into the physical partition.

This SQL keyword is designed to use for downgrading QuestDB to a version earlier than 7.2, when partition split is introduced. Squashing partition parts makes the database compatible with earlier QuestDB versions.

Syntax

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:

questdb-sql

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