SqlPersistenceStorageEngine (Firebase Android Client Library 2.3.1 API)

java.lang.Object
- com.firebase.client.android.SqlPersistenceStorageEngine

All Implemented Interfaces:

com.firebase.client.core.persistence.PersistenceStorageEngine
```
public class SqlPersistenceStorageEngine
extends Object
implements com.firebase.client.core.persistence.PersistenceStorageEngine
```
This class is an Android/SQL-backed implementation of PersistenceStorageEngine. The implementation uses 3 tables for persistence: - writes: A list of all currently outstanding (visible) writes. A row represents a single write containing a unique-across-restarts write id, the path string, the type which can be 'o' for an overwrite or 'm' for a merge, and the serialized node wrapped. Part number is NULL for normal writes. Large writes (>256K) are split into multiple rows with increasing part number. - serverCache: Cached nodes from the server. A row represents a node at a path. To allow for fast writes, a row added later can overwrite a part of a previous row at a higher path. When loading the cache, all rows at a path and deeper need to be combined to get the latest cached node. To ensure this representation is unambiguous, updates for a given path need to delete any node at the same or any deeper path. There is a size threshold after which children-nodes are split up and each child is saved individually (and can be split up again). This is so deeper reads don't need to read massive amounts of data and single rows don't have excessive amount of data in them. - trackedQueries: Queries tracked in our cache. Each row has a unique-across-restarts id, the path/query and metadata about the query (whether we have complete data, when it was last used, and whether it's currently active). These tracked queries are used to determine what serverCache data exists, whether it's complete, and what serverCache data can be pruned. - trackedKeys: Keys in tracked queries. For each query in trackedQueries that is filtered (i.e. not a loadsAllData() query), we'll track which keys are in the query. This allows us to re-load only the keys of interest when restoring the query, as well as prune data for keys that aren't tracked by any query. As mentioned earlier, for "fast writes", serverCache may end up with overlapping rows. As an example, you might have the following rows: /foo/: {"bar": 1, "baz": 2, "qux": 3} /foo/bar/: 4 /foo/qux/: null /foo/quu/: 5 => yields {"bar": 4, "baz": 2, "quu": 5} at /foo Large serverCache leaf nodes might be split into multiple parts to avoid the limitation of ~1MB per row for the SQL cursor. Consecutive leaf node parts will be saved as .part-XXXX without a trailing slash at the end. /leaf/node/path/.part-0000 /leaf/node/path/.part-0001 ... To ensure prefix queries work on paths, each path must start and end with a '/'. Schema: - writes table + id: unique id across restarts + path: path for this write as string + node: serialized node/merge-map as JSON (utf-8) bytes + part: The part number for multi-part/split writes starting with 0, NULL if not split + type: 'o' for overwrite and 'm' for merge - serverCache + path: path for this node as string + value: serialized node as JSON (utf-8) bytes - trackedQueries + id: unique id across restarts + path: Path of query. + query: A serialization of the query parameters. + lastUse: When this query was last used (e.g. there was an active listener). + complete: Whether serverCache contains complete data for the query. + active: Whether we have an active listener for the query. - trackedKeys + id: id of the trackedQuery for which this is a tracked key. + key: The tracked key belonging to the trackedQuery identified by id.

Constructor Summary

Constructors
Constructor and Description
`SqlPersistenceStorageEngine(android.content.Context context, com.firebase.client.core.Context firebaseContext, String cacheId)`

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`beginTransaction()`
`void`	`deleteTrackedQuery(long trackedQueryId)`
`void`	`endTransaction()`
`List<com.firebase.client.core.persistence.TrackedQuery>`	`loadTrackedQueries()`
`Set<com.firebase.client.snapshot.ChildKey>`	`loadTrackedQueryKeys(long trackedQueryId)`
`Set<com.firebase.client.snapshot.ChildKey>`	`loadTrackedQueryKeys(Set<Long> trackedQueryIds)`
`List<com.firebase.client.core.UserWriteRecord>`	`loadUserWrites()`
`void`	`mergeIntoServerCache(com.firebase.client.core.Path path, com.firebase.client.core.CompoundWrite children)`
`void`	`mergeIntoServerCache(com.firebase.client.core.Path path, com.firebase.client.snapshot.Node node)`
`void`	`overwriteServerCache(com.firebase.client.core.Path path, com.firebase.client.snapshot.Node node)`
`void`	`pruneCache(com.firebase.client.core.Path root, com.firebase.client.core.persistence.PruneForest pruneForest)`
`void`	`purgeCache()`
`void`	`removeAllUserWrites()`
`void`	`removeUserWrite(long writeId)`
`void`	`resetPreviouslyActiveTrackedQueries(long lastUse)`
`void`	`saveTrackedQuery(com.firebase.client.core.persistence.TrackedQuery trackedQuery)`
`void`	`saveTrackedQueryKeys(long trackedQueryId, Set<com.firebase.client.snapshot.ChildKey> keys)`
`void`	`saveUserMerge(com.firebase.client.core.Path path, com.firebase.client.core.CompoundWrite children, long writeId)`
`void`	`saveUserOverwrite(com.firebase.client.core.Path path, com.firebase.client.snapshot.Node node, long writeId)`
`com.firebase.client.snapshot.Node`	`serverCache(com.firebase.client.core.Path path)`
`long`	`serverCacheEstimatedSizeInBytes()`
`void`	`setTransactionSuccessful()`
`void`	`updateTrackedQueryKeys(long trackedQueryId, Set<com.firebase.client.snapshot.ChildKey> added, Set<com.firebase.client.snapshot.ChildKey> removed)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - SqlPersistenceStorageEngine
```
public SqlPersistenceStorageEngine(android.content.Context context,
                           com.firebase.client.core.Context firebaseContext,
                           String cacheId)
```
- Method Detail
  - saveUserOverwrite
```
public void saveUserOverwrite(com.firebase.client.core.Path path,
                     com.firebase.client.snapshot.Node node,
                     long writeId)
```
    Specified by:
    
    saveUserOverwrite in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - saveUserMerge
```
public void saveUserMerge(com.firebase.client.core.Path path,
                 com.firebase.client.core.CompoundWrite children,
                 long writeId)
```
    Specified by:
    
    saveUserMerge in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - removeUserWrite
```
public void removeUserWrite(long writeId)
```
    Specified by:
    
    removeUserWrite in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - loadUserWrites
```
public List<com.firebase.client.core.UserWriteRecord> loadUserWrites()
```
    Specified by:
    
    loadUserWrites in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - serverCache
```
public com.firebase.client.snapshot.Node serverCache(com.firebase.client.core.Path path)
```
    Specified by:
    
    serverCache in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - overwriteServerCache
```
public void overwriteServerCache(com.firebase.client.core.Path path,
                        com.firebase.client.snapshot.Node node)
```
    Specified by:
    
    overwriteServerCache in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - mergeIntoServerCache
```
public void mergeIntoServerCache(com.firebase.client.core.Path path,
                        com.firebase.client.snapshot.Node node)
```
    Specified by:
    
    mergeIntoServerCache in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - mergeIntoServerCache
```
public void mergeIntoServerCache(com.firebase.client.core.Path path,
                        com.firebase.client.core.CompoundWrite children)
```
    Specified by:
    
    mergeIntoServerCache in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - serverCacheEstimatedSizeInBytes
```
public long serverCacheEstimatedSizeInBytes()
```
    Specified by:
    
    serverCacheEstimatedSizeInBytes in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - saveTrackedQuery
```
public void saveTrackedQuery(com.firebase.client.core.persistence.TrackedQuery trackedQuery)
```
    Specified by:
    
    saveTrackedQuery in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - deleteTrackedQuery
```
public void deleteTrackedQuery(long trackedQueryId)
```
    Specified by:
    
    deleteTrackedQuery in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - loadTrackedQueries
```
public List<com.firebase.client.core.persistence.TrackedQuery> loadTrackedQueries()
```
    Specified by:
    
    loadTrackedQueries in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - resetPreviouslyActiveTrackedQueries
```
public void resetPreviouslyActiveTrackedQueries(long lastUse)
```
    Specified by:
    
    resetPreviouslyActiveTrackedQueries in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - saveTrackedQueryKeys
```
public void saveTrackedQueryKeys(long trackedQueryId,
                        Set<com.firebase.client.snapshot.ChildKey> keys)
```
    Specified by:
    
    saveTrackedQueryKeys in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - updateTrackedQueryKeys
```
public void updateTrackedQueryKeys(long trackedQueryId,
                          Set<com.firebase.client.snapshot.ChildKey> added,
                          Set<com.firebase.client.snapshot.ChildKey> removed)
```
    Specified by:
    
    updateTrackedQueryKeys in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - loadTrackedQueryKeys
```
public Set<com.firebase.client.snapshot.ChildKey> loadTrackedQueryKeys(long trackedQueryId)
```
    Specified by:
    
    loadTrackedQueryKeys in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - loadTrackedQueryKeys
```
public Set<com.firebase.client.snapshot.ChildKey> loadTrackedQueryKeys(Set<Long> trackedQueryIds)
```
    Specified by:
    
    loadTrackedQueryKeys in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - pruneCache
```
public void pruneCache(com.firebase.client.core.Path root,
              com.firebase.client.core.persistence.PruneForest pruneForest)
```
    Specified by:
    
    pruneCache in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - removeAllUserWrites
```
public void removeAllUserWrites()
```
    Specified by:
    
    removeAllUserWrites in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - purgeCache
```
public void purgeCache()
```
  - beginTransaction
```
public void beginTransaction()
```
    Specified by:
    
    beginTransaction in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - endTransaction
```
public void endTransaction()
```
    Specified by:
    
    endTransaction in interface com.firebase.client.core.persistence.PersistenceStorageEngine
  - setTransactionSuccessful
```
public void setTransactionSuccessful()
```
    Specified by:
    
    setTransactionSuccessful in interface com.firebase.client.core.persistence.PersistenceStorageEngine

Class SqlPersistenceStorageEngine

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

SqlPersistenceStorageEngine

Method Detail

saveUserOverwrite

saveUserMerge

removeUserWrite

loadUserWrites

serverCache

overwriteServerCache

mergeIntoServerCache

mergeIntoServerCache

serverCacheEstimatedSizeInBytes

saveTrackedQuery

deleteTrackedQuery

loadTrackedQueries

resetPreviouslyActiveTrackedQueries

saveTrackedQueryKeys

updateTrackedQueryKeys

loadTrackedQueryKeys

loadTrackedQueryKeys

pruneCache

removeAllUserWrites

purgeCache

beginTransaction

endTransaction

setTransactionSuccessful