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There are cooldown and remote_cooldown in current implementation. Cooldown is used to migration partition from HDD to SSD while remote_cooldown is used to migration partition from local storage to S3.

Cooldown

storage_cooldown_time

Users can specify storage_cooldown_time for a table by either create table statement or alter table statement.

CREATE TABLE example_db.table_name
(
    k1 BIGINT,
    k2 LARGEINT,
    v1 VARCHAR(2048) REPLACE,
    v2 SMALLINT SUM DEFAULT "10"
)
UNIQUE KEY(k1, k2)
DISTRIBUTED BY HASH (k1, k2) BUCKETS 32
PROPERTIES(
    "storage_medium" = "SSD",
    "storage_cooldown_time" = "2015-06-04 00:00:00"
);

ALTER TABBLE example_db.table_name SET ("storage_cooldown_time" = "2015-06-04 00:00:00")

Uses Users can also specify storage_cooldown_time for a partition via modify partition statement.

ALTER TABLE example_db.table_name MODIFY PARTITION ("storage_cooldown_time" = "2015-06-04 00:00:00")

storage_cooldown_seconds

Storage_cooldown_time works on absolute time, sometimes users want to set a ttl time range on a partition or time. So storage_cooldown_seconds and dynamic_partition.hot_partition_num come. storage_cooldown_seconds is a config in fe.conf, it is strange that it does not implemented as an attribute of a table or a partition.

Users can specify storage_cooldown_seconds in fe.conf, when the config is set, a partition in ssd is cooldown to hdd {storage_cooldown_seconds} seconds after the partition is created.

Decision

Action

Result

Scheduling

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