1.1

a table that has dependent tables (for example, child rows with foreign keys). If a DELETE statement
is called for a parent table row that was locally destroyed through eviction, the DELETE succeeds
in SQLFire. However, the DELETE operation can later fail in the backend database when
DBSynchronizer asynchronously sends the DELETE command, if dependent rows still exist.
If eviction with the DESTROY action is required for dependent tables, consider using a trigger or
writer implementation to listen for DELETE events on the parent table. The trigger or writer should
fail the DELETE operation if child rows are found to exist in the backend database.
• Overflow the row data to disk.
Note: When you configure an overflow table, only the evicted rows are written to disk. If you restart
or shut down a member that hosts the overflow table, the table data that was in memory is lost unless
you explicitly configure persistence (or you configure one or more replicas with a partitioned table).
See Using Disk Stores to Persist Data on page 77.
3. If you want to overflow data to disk (or persist the entire table to disk), configure a named disk store to use
for the overflow data. If you do not specify a disk store when creating an overflow table, SQLFire stores the
overflow data in the default disk store.
4. Create the table with the required eviction configuration.
For example, to evict using LRU entry count and overflow evicted rows to a disk store:
CREATE TABLE Orders(OrderId INT NOT NULL,ItemId INT )
EVICTION BY LRUCOUNT 2 EVICTACTION OVERFLOW 'OverflowDiskStore'
ASYNCHRONOUS
If you do not specify a disk store, SQLFire overflows table data to the default disk store.
To create an overflow table and persist the entire table, so that the entire table is available through peer
restarts:
CREATE TABLE Orders(OrderId INT NOT NULL,ItemId INT )
EVICTION BY LRUCOUNT 2 EVICTACTION OVERFLOW PERSISTENT
'OverflowDiskStore' ASYNCHRONOUS
The table uses the same named disk store for both overflow and persistence.
To create a table that simply removes evicted data from memory without persisting the evicted data, use the
DESTROY eviction action. For example:
CREATE TABLE Orders(OrderId INT NOT NULL,ItemId INT )
EVICTION BY LRUMEMSIZE 1000 EVICTACTION DESTROY
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Evicting Table Data from SQLFire