Consistency

Functions
kv_error_t	kv_create_simple_consistency (kv_consistency_enum type, kv_consistency_t **consistencyp)
	Creates a consistency guarantee used for read operations. More...
kv_error_t	kv_create_time_consistency (kv_timeout_t time_lag, kv_timeout_t timeout_ms, kv_consistency_t **consistencyp)
	Creates a consistency policy which describes the amount of time the replica is allowed to lag the master. More...
kv_error_t	kv_create_version_consistency (const kv_version_t *version, kv_timeout_t timeout_ms, kv_consistency_t **consistencyp)
	Creates a consistency policy which ensures that the environment on a replica node is at least as current as denoted by the specified version. More...
kv_consistency_enum	kv_get_consistency_type (const kv_consistency_t *consistency)
	Identifies the consistency policy type used by the provided policy. More...
void	kv_release_consistency (kv_consistency_t **consistencyp)
	Releases the resource used by consistency structure. More...

Detailed Description

Consistency policies are used with read operations to describe how likely it is that the data on your replicas will be identical to, or consistent with, the data on your master server. The most stringent consistency policy requires that the read operation be performed on the master server. In general, the stricter your consistency policy, the slower your store's read throughput.

Function Documentation

kv_error_t kv_create_simple_consistency	(	kv_consistency_enum	type,
		kv_consistency_t **	consistencyp
	)

Creates a consistency guarantee used for read operations.

Parameters

[in]	type	The type of consistency, see kv_consistency_enum.
[out]	consistencyp	The output consistency, it should be released using kv_release_consistency().

Returns

KV_SUCCESS on success, and an error code (a negative number) on failure.

kv_error_t kv_create_time_consistency	(	kv_timeout_t	time_lag,
		kv_timeout_t	timeout_ms,
		kv_consistency_t **	consistencyp
	)

Creates a consistency policy which describes the amount of time the replica is allowed to lag the master.

Parameters

[in]	time_lag	The time_lag parameter specifies the time interval, in milliseconds, by which the replica may be out of date with respect to the master when a transaction is initiated on the replica.
[in]	timeout_ms	The timeout_ms parameter describes how long a replica may wait for the desired consistency to be achieved before giving up.
[out]	consistencyp	The output consistency, it should be released using kv_release_consistency().

Returns

KV_SUCCESS on success, and an error code (a negative number) on failure.

kv_error_t kv_create_version_consistency	(	const kv_version_t *	version,
		kv_timeout_t	timeout_ms,
		kv_consistency_t **	consistencyp
	)

Creates a consistency policy which ensures that the environment on a replica node is at least as current as denoted by the specified version.

Parameters

[in]	version	The version parameter identifies the version that must be seen at the replica in order to consider it current. It is obtained from the result using kv_result_get_version() or kv_result_get_prev_row_version().
[in]	timeout_ms	The timeout_ms parameter describes how long a replica may wait for the desired consistency to be achieved before giving up.
[out]	consistencyp	The output consistency, it should be released using kv_release_consistency().

Returns

KV_SUCCESS on success, and an error code (a negative number) on failure.

kv_consistency_enum kv_get_consistency_type

(

const kv_consistency_t *

consistency

)

Identifies the consistency policy type used by the provided policy.

Parameters

[in]

consistency

Returns

the consistency policy type.

void kv_release_consistency

(

kv_consistency_t **

consistencyp

)

Releases the resource used by consistency structure.

Parameters

[in]

consistencyp

The consistency structure to release.