Package com.hazelcast.mapstore

Class GenericMapStore<K,V>

java.lang.Object
com.hazelcast.mapstore.GenericMapLoader<K,V>
com.hazelcast.mapstore.GenericMapStore<K,V>
Type Parameters:
K - type of the key
V - type of the value
All Implemented Interfaces:
MapLoader<K,V>, MapLoaderLifecycleSupport, MapStore<K,V>
public class GenericMapStore<K,V> extends GenericMapLoader<K,V> implements MapStore<K,V>, MapLoaderLifecycleSupport
GenericMapStore is an implementation of MapStore built on top of Hazelcast SQL engine.

It works with any SQL connector supporting SELECT, INSERT, UPDATE and DELETE statements.

Usage:

First define data connection, e.g. for JDBC use JdbcDataConnection: 

Config config = new Config();
 config.addDataConnectionConfig(
   new DataConnectionConnection("mysql-ref")
     .setType("Jdbc")
     .setProperty("jdbcUrl", dbConnectionUrl)
 );

Then create a Map with MapStore using the GenericMapStore implementation: 

MapConfig mapConfig = new MapConfig(mapName);
 MapStoreConfig mapStoreConfig = new MapStoreConfig();
 mapStoreConfig.setClassName(GenericMapStore.class.getName());
 mapStoreConfig.setProperty(GenericMapStore.DATA_CONNECTION_REF_PROPERTY, "mysql-name");
 mapConfig.setMapStoreConfig(mapStoreConfig);
 instance().getConfig().addMapConfig(mapConfig);

The GenericMapStore creates a SQL mapping with name "__map-store." + mapName. This mapping is removed when the map is destroyed.

Note : When GenericMapStore uses GenericRecord as value, even if the GenericRecord contains the primary key as a field, the primary key is still received from IMap method call

  • Constructor Details

    • GenericMapStore

      public GenericMapStore()

  • Method Details

    • store

      public void store(K key, V value)
      Description copied from interface: MapStore
      Stores the key-value pair in the external store.

      Invocation semantics depend on configuration:

      • Write-through (writeDelaySeconds == 0): this method is invoked synchronously as part of the IMap.put() call. If this method throws an exception, the map operation fails.
      • Write-behind (writeDelaySeconds > 0): this method may be invoked asynchronously on a background thread, potentially long after the original map operation has completed.

      Under normal circumstances Hazelcast provides at-least-once delivery semantics for calls to this method. Implementations must therefore be idempotent and tolerate retries, reordering, and duplicate invocations.

      Specified by:
      store in interface MapStore<K,V>
      Parameters:
      key - key of the entry to store
      value - value of the entry to store

    • storeAll

      public void storeAll(Map<K,V> map)
      Description copied from interface: MapStore
      Stores multiple entries in the external store.

      This method is primarily used with write-behind enabled (writeDelaySeconds > 0) when batching is applicable. Hazelcast may still invoke MapStore.store(Object, Object) instead of this method depending on runtime conditions (for example, batch size, write coalescing, or number of distinct keys in the current write window). Implementations must not rely on this method being invoked for every flush.

      Error handling and retries:

      • If this method throws an exception, Hazelcast treats the batch as failed and starts retry handling.
      • If the provided map has not been modified (no entries removed to signal partial success), Hazelcast retries storeAll(map) up to three times, waiting about 1 second between attempts.
      • After the final batch attempt fails, Hazelcast falls back to calling MapStore.store(Object, Object) for the remaining entries, one by one.
      • If the implementation removes entries from map as they are stored (before throwing), Hazelcast treats removed entries as successful and does not retry them; only the entries still present in map are retried and/or passed to the per-entry fallback.

      This allows implementations to signal partial success explicitly. Entries left in the map after an exception will be retried individually; removed entries will not be passed to subsequent calls.

      Hazelcast does not provide transactional guarantees across entries. Batch boundaries do not imply atomicity.

      Specified by:
      storeAll in interface MapStore<K,V>
      Parameters:
      map - map of entries to store

    • delete

      public void delete(K key)
      Description copied from interface: MapStore
      Deletes the entry with the given key from the external store.

      Invocation semantics depend on configuration:

      • Write-through: invoked synchronously as part of IMap.remove().
      • Write-behind: invoked asynchronously on a background thread.

      Hazelcast provides at-least-once delivery semantics. Implementations must tolerate retries and duplicate invocations. Deleting a non-existent entry should be treated as a successful no-op.

      Specified by:
      delete in interface MapStore<K,V>
      Parameters:
      key - the key to delete from the store

    • deleteAll

      public void deleteAll(Collection<K> keys)
      Description copied from interface: MapStore
      Deletes multiple entries from the external store.

      This method is primarily used with write-behind enabled (writeDelaySeconds > 0) when batching is applicable. Hazelcast may still invoke MapStore.delete(Object) instead of this method depending on configuration and runtime conditions. Implementations must not rely on this method being invoked for every flush.

      Error handling and retries:

      • If this method throws an exception, Hazelcast initiates retry handling.
      • On retry, Hazelcast invokes MapStore.delete(Object) one-by-one for the remaining keys.
      • If the implementation removes successfully deleted keys from the provided keys collection before throwing, those keys are treated as successful and are not retried.

      This allows implementations to signal partial success explicitly. Keys left in the keys collection after an exception will be retried individually; removed keys will not be passed to subsequent calls.

      Batch deletion does not imply atomicity or ordering guarantees.

      Specified by:
      deleteAll in interface MapStore<K,V>
      Parameters:
      keys - the keys of the entries to delete