Configuring Time to Live (TTL)
This section contains recipes for configuration of table's TTL with YDB SDK.
Enabling TTL for an existing table
In the example below, the items of the mytable table will be deleted an hour after the time set in the created_at column:
session.AlterTable(
"mytable",
TAlterTableSettings()
.BeginAlterTtlSettings()
.Set("created_at", TDuration::Hours(1))
.EndAlterTtlSettings()
);
err := session.AlterTable(ctx, "mytable",
options.WithSetTimeToLiveSettings(
options.NewTTLSettings().ColumnDateType("created_at").ExpireAfter(time.Hour),
),
)
session.alter_table('mytable', set_ttl_settings=ydb.TtlSettings().with_date_type_column('created_at', 3600))
The example below shows how to use the modified_at column with a numeric type (Uint32) as a TTL column. The column value is interpreted as the number of seconds since the Unix epoch:
session.AlterTable(
"mytable",
TAlterTableSettings()
.BeginAlterTtlSettings()
.Set("modified_at", TTtlSettings::EUnit::Seconds, TDuration::Hours(1))
.EndAlterTtlSettings()
);
err := session.AlterTable(ctx, "mytable",
options.WithSetTimeToLiveSettings(
options.NewTTLSettings().ColumnSeconds("modified_at").ExpireAfter(time.Hour),
),
)
session.alter_table('mytable', set_ttl_settings=ydb.TtlSettings().with_value_since_unix_epoch('modified_at', UNIT_SECONDS, 3600))
Enabling data eviction to S3-compatible external storage
Warning
Supported only for column-oriented tables. Support for row-oriented tables is currently under development.
To enable data eviction, an external data source object that describes a connection to the external storage is needed. Refer to YQL recipe for examples of creating an external data source.
In the following example, rows of the table mytable will be moved to the bucket described in the external data source /Root/s3_cold_data one hour after the time recorded in the column created_at and will be deleted after 24 hours:
session.AlterTable(
"mytable",
TAlterTableSettings()
.BeginAlterTtlSettings()
.Set("created_at", {
TTtlTierSettings(TDuration::Hours(1), TTtlEvictToExternalStorageAction("/Root/s3_cold_data")),
TTtlTierSettings(TDuration::Hours(24), TTtlDeleteAction("/Root/s3_cold_data"))
})
.EndAlterTtlSettings()
);
Enabling TTL for a newly created table
For a newly created table, you can pass TTL settings along with the table description:
session.CreateTable(
"mytable",
TTableBuilder()
.AddNullableColumn("id", EPrimitiveType::Uint64)
.AddNullableColumn("expire_at", EPrimitiveType::Timestamp)
.SetPrimaryKeyColumn("id")
.SetTtlSettings("expire_at")
.Build()
);
err := session.CreateTable(ctx, "mytable",
options.WithColumn("id", types.Optional(types.TypeUint64)),
options.WithColumn("expire_at", types.Optional(types.TypeTimestamp)),
options.WithTimeToLiveSettings(
options.NewTTLSettings().ColumnDateType("expire_at"),
),
)
session.create_table(
'mytable',
ydb.TableDescription()
.with_column(ydb.Column('id', ydb.OptionalType(ydb.DataType.Uint64)))
.with_column(ydb.Column('expire_at', ydb.OptionalType(ydb.DataType.Timestamp)))
.with_primary_key('id')
.with_ttl(ydb.TtlSettings().with_date_type_column('expire_at'))
)
Disabling TTL
session.AlterTable(
"mytable",
TAlterTableSettings()
.BeginAlterTtlSettings()
.Drop()
.EndAlterTtlSettings()
);
err := session.AlterTable(ctx, "mytable",
options.WithDropTimeToLive(),
)
session.alter_table('mytable', drop_ttl_settings=True)
Getting TTL settings
The current TTL settings can be obtained from the table description:
auto desc = session.DescribeTable("mytable").GetValueSync().GetTableDescription();
auto ttl = desc.GetTtlSettings();
desc, err := session.DescribeTable(ctx, "mytable")
if err != nil {
// process error
}
ttl := desc.TimeToLiveSettings
desc = session.describe_table('mytable')
ttl = desc.ttl_settings