Package com.google.cloud.spanner.watcher

Enum TimebasedShardProvider.Interval

java.lang.Object

java.lang.Enum<TimebasedShardProvider.Interval>

com.google.cloud.spanner.watcher.TimebasedShardProvider.Interval

All Implemented Interfaces:

Serializable, Comparable<TimebasedShardProvider.Interval>

Enclosing class:

TimebasedShardProvider

public static enum TimebasedShardProvider.Interval
extends Enum<TimebasedShardProvider.Interval>

Enum Constant Summary

Enum Constants

Enum Constant	Description
DAY	Creates a shard for each unique date.
DAY_OF_MONTH	Creates a cyclic shard for each day of month (1-31).
DAY_OF_WEEK	Creates a cyclic shard for each weekday (1-7).
DAY_OF_YEAR	Creates a cyclic shard for each day of year (1-366).
HOUR_OF_DAY	Creates a cyclic shard for each hour of a day (0-23).
MINUTE_OF_HOUR	MINUTE_OF_HOUR is mainly intended for testing purposes.
MONTH	Creates a shard for each month and year.
WEEK	Creates a shard for each week and year.
WEEK_OF_YEAR	Creates a cyclic shard for each week of year (1-53).
YEAR	Creates a shard for each year.

Method Summary

Modifier and Type	Method	Description
TimebasedShardProvider.TimebasedShardId	getCurrentShardId(com.google.cloud.spanner.ReadContext readContext)	Fetches the current shard id from the database.
String	getShardIdExpression()	Returns the SQL expression that calculates the current shard id.
boolean	isCyclic()	Returns true if this interval is cyclic, i.e.
static TimebasedShardProvider.Interval	valueOf(String name)	Returns the enum constant of this type with the specified name.
static TimebasedShardProvider.Interval[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

DAY

public static final TimebasedShardProvider.Interval DAY

Creates a shard for each unique date.

WEEK

public static final TimebasedShardProvider.Interval WEEK

Creates a shard for each week and year.

MONTH

public static final TimebasedShardProvider.Interval MONTH

Creates a shard for each month and year.

YEAR

public static final TimebasedShardProvider.Interval YEAR

Creates a shard for each year.

MINUTE_OF_HOUR

public static final TimebasedShardProvider.Interval MINUTE_OF_HOUR

MINUTE_OF_HOUR is mainly intended for testing purposes. Creates a cyclic shard for each minute of an hour (0-59). Using MINUTE_OF_HOUR means that the shard value will change very frequently, and transactions that run longer than 1 minute will potentially receive the wrong shard value.

HOUR_OF_DAY

public static final TimebasedShardProvider.Interval HOUR_OF_DAY

Creates a cyclic shard for each hour of a day (0-23).

DAY_OF_WEEK

public static final TimebasedShardProvider.Interval DAY_OF_WEEK

Creates a cyclic shard for each weekday (1-7).

DAY_OF_MONTH

public static final TimebasedShardProvider.Interval DAY_OF_MONTH

Creates a cyclic shard for each day of month (1-31).

WEEK_OF_YEAR

public static final TimebasedShardProvider.Interval WEEK_OF_YEAR

Creates a cyclic shard for each week of year (1-53).

DAY_OF_YEAR

public static final TimebasedShardProvider.Interval DAY_OF_YEAR

Creates a cyclic shard for each day of year (1-366).

Method Detail

values

public static TimebasedShardProvider.Interval[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (TimebasedShardProvider.Interval c : TimebasedShardProvider.Interval.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static TimebasedShardProvider.Interval valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

getCurrentShardId

public TimebasedShardProvider.TimebasedShardId getCurrentShardId(com.google.cloud.spanner.ReadContext readContext)

Fetches the current shard id from the database. It is the responsibility of all clients that write data to tables that are being watched that the correct shard id is written to the table. Failure to do so will cause the change to be missed by Spanner Change Watchers. The shard id will remain constant during the complete interval that has been chosen. It is therefore possible for clients to cache the current shard id value, as long as the client renews the shard id once the interval has passed. The shard is calculated in UTC, which means that for example a shard id based on DAY will change at the moment that the current system time in UTC changes 23:59 to 00:00.

getShardIdExpression

public String getShardIdExpression()

Returns the SQL expression that calculates the current shard id. This expression can be included in DML statements to automatically set the current shard id. See Samples#watchTableWithTimebasedShardProviderExample(String, String, String, String) for an example on how to use this.

isCyclic

public boolean isCyclic()

Returns true if this interval is cyclic, i.e. the same shard id will be generated at later moment again. DAY_OF_WEEK, DAY_OF_MONTH and DAY_OF_YEAR are examples of cyclic intervals.