1.1.1

Related Topics
CREATE DISKSTORE on page 480
CREATE TABLE on page 491
Persist Table Data to a Disk Store on page 86
Evicting table data from memoryUse eviction to remove table data from memory, or to persist the overflow data in a disk store.
Creating a Disk Store or Using the Default
You can create a disk store for persistence and/or overflow or use the default disk store. Data from multiple
tables can be stored in the same disk store.
Default Disk Stores
Tables that do not name a disk store but specify persistence or overflow in their CREATE TABLE statement are
automatically assigned to the default disk store, SQLF-DEFAULT-DISKSTORE. Also, gateway,
AsyncEventListener, and DBSynchronizer queues always use the default disk store. The default diskstore is
saved to the SQLFire data store's working directory, unless you change the value of the sys-disk-dir boot
property to specify another location.
Note: SQLFire locator and data store members also create disk store files in order to persist the data
dictionary for the tables and indexes created the SQLFire distributed system. These persistence files are
stored in the datadictionary subdirectory of each locator and data store that joins the distributed
system. The data dictionary is always persisted, regardless of whether you configure data persistence or
overflow for individual tables. Table data is not persisted by default; if you shut down al SQLFire members,
the tables are empty on the next startup.
Never move or modify the datadictionary subdirectory or the associated disk store files in
datadictionary. If the data dictionary of a SQLFire locator or data store member is unavailable, it
can prevent other members from starting if the "offline" member potentially holds a more recent copy of
the data dictionary. In this case, members will display a ConflictingPersistentDataException when
attempting to start.
Create a Disk Store
You create a named disk store in the data dictionary using the CREATE DISKSTORE DDL statement. You
then assign the disk store to an individual table by specifying the disk store in the table's CREATE TABLE DDL
statement. You can store data from multiple tables and queues in the same named disk store.
Persist Table Data to a Disk Store
You configure the persistence settings for a partitioned or replicated table when you create the table with the
CREATE TABLE DDL statement. SQLFire automatically recovers data from disk for persistent tables when
you restart SQLFire members.
Procedure
1. Ensure that the data dictionary is persisted in your SQLFire cluster. SQLFire persists the data dictionary by
default for all data stores, but you can explicitly enable or disable data dictionary persistence using the
persist-dd boot property.
Note: All SQLFire data stores in the same cluster must use a consistent persist-dd value. Accessors
cannot persist data, and you cannot set persist-dd to true for an accessor.
vFabric SQLFire User's Guide86
Managing Your Data in vFabric SQLFire