General Information of a Space

The general information of a space contains the following: Data in Memory, Persistence, Replication, Timeouts, Query, Locks, Field Definition, and Key Definition.

Data in Memory

The Data in Memory header contains the following information:
  • Distribution Policy: The type of distributed policy. Select one of the following types of policies:
    • DISTRIBUTED: Storage of entries is distributed amongst the seeder members of the space. The entries are distributed uniformly according to the values of the primary key fields.
    • NON-DISTRIBUTED: Storage of entries is assigned to a single seeder member of the Space.
  • Min Seeder Count: The minimum seeder count. The default is 1 that means at least one seeder member must be assigned for storing the entries.
  • Time to live: The Time to Live (TTL) is specified in milliseconds. It represents the lifetime of each entry created in the space. If TTL is set in the space definition, each entry is automatically deleted from the space when it expires. The default is -1 which means the entries never expire by default.
  • Capacity: Every seeder member can specify the maximum number of entries to be stored per seeder member. On reaching the capacity, further insertion of an entry into the space by a Put operation results in an exception. If Eviction policy is set, the member evicts another stored entry based on the Eviction Policy set.
  • Eviction Policy: The following are the two types of Eviction policies:
    • None: This is the default. If the capacity of a seeder exceeds, the seeder throws an exception on the space operation.
    • LRU: On reaching the maximum capacity, the seeder evicts entries using the 'Least Recently Used' algorithm to make room for new entries being inserted in the space.

Persistence

The Persistence header contains the following information:
  • Type: The types of persistence. It is either SHARED_NOTHING or SHARED_ALL.
  • Persist Policy: Specifies the type of persistence policy. It is either asynchronous or synchronous. The default is asynchronous.
  • Sync Interval: The synchronization interval. This is available only for SHARED_NOTHING persistence policy. The file synchronization interval for the SHARED_NOTHING persistence file reside on each seeder member.

Replication

The Replication header contains the following information:
  • Rep Count: The number of replicas to be maintained. The default is 0 to indicate that no replicas are maintained except for the original copy.

Timeouts

The Timeouts header contains the following information:
  • Space Wait: The interval in milliseconds. Specifies the amount of time space operations wait until a space becomes READY. For example, a space is not READY when there is no seeder or there are insufficient number of seeders as specified by the minimum number of seeder count.
  • Read Timeout: The interval in milliseconds for a Read operation to timeout. The default is 60000 ms.
  • Write Timeout: The interval in milliseconds for a Write operation to timeout. The default is 60000 ms.

Query

The Query header contains the following information:
  • Query Limit: The maximum number of entries to return on executing a query using the space browser. The default is 10000.
  • Query Timeout: The interval in milliseconds for a query to timeout. The default is 60000 ms.

Locks

The Locks header contains the following information:
  • Time to live: The time in milliseconds until a lock is automatically cleared. The default of -1 is used to indicate that a lock never expires.
  • Wait timeout: Time in milliseconds to wait for the lock to be cleared if the entry is currently locked. The default is -1 to indicate that the lock operation waits forever to acquire the lock.
  • Lock Scope: The scope of a lock. By default, it is the THREAD scope. It can be either of the following:
    • THREAD: Only the processing thread can unlock the key that was previously locked.
    • PROCESS: Any processing thread in the process can unlock the key that was previously locked.

Field Definition

The Field Definition lists all the fields defined for the space.

Key Definition

The Key Definition lists all the fields defined for the space. The Index type can be a HASH or a TREE.
General Information of a Space
Space General Info