org.apache.hadoop.hive.ql.cache.results

Class QueryResultsCache

java.lang.Object

org.apache.hadoop.hive.ql.cache.results.QueryResultsCache

public final class QueryResultsCache
extends Object

A class to handle management and lookup of cached Hive query results.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	QueryResultsCache.CacheEntry
static class	QueryResultsCache.CacheEntryStatus
static class	QueryResultsCache.InvalidationEventConsumer
static class	QueryResultsCache.LookupInfo
static class	QueryResultsCache.QueryInfo

Method Summary

Modifier and Type	Method and Description
QueryResultsCache.CacheEntry	addToCache(QueryResultsCache.QueryInfo queryInfo, org.apache.hadoop.hive.common.ValidTxnWriteIdList txnWriteIdList) Add an entry to the cache.
static void	cleanupInstance()
void	clear()
static void	decrementMetric(String name)
static void	decrementMetric(String name, long count)
static QueryResultsCache	getInstance()
long	getSize()
static void	incrementMetric(String name)
static void	incrementMetric(String name, long count)
static void	initialize(HiveConf conf)
QueryResultsCache.CacheEntry	lookup(QueryResultsCache.LookupInfo request) Check if the cache contains an entry for the requested LookupInfo.
void	notifyTableChanged(String dbName, String tableName, long updateTime)
void	removeEntry(QueryResultsCache.CacheEntry entry)
boolean	setEntryValid(QueryResultsCache.CacheEntry cacheEntry, FetchWork fetchWork) Updates a pending cache entry with a FetchWork result from a finished query.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

initialize

public static void initialize(HiveConf conf)
                       throws IOException

Throws:

IOException

getInstance

public static QueryResultsCache getInstance()

lookup

public QueryResultsCache.CacheEntry lookup(QueryResultsCache.LookupInfo request)

Check if the cache contains an entry for the requested LookupInfo.

Parameters:

request -

addReader - Should the reader count be incremented during the lookup. This will ensure the returned entry can be used after the lookup. If true, the caller will be responsible for decrementing the reader count using CacheEntry.releaseReader().

Returns:

The cached result if there is a match in the cache, or null if no match is found.

addToCache

public QueryResultsCache.CacheEntry addToCache(QueryResultsCache.QueryInfo queryInfo,
                                               org.apache.hadoop.hive.common.ValidTxnWriteIdList txnWriteIdList)

Add an entry to the cache. The new entry will be in PENDING state and not usable setEntryValid() is called on the entry.

Parameters:

queryInfo -

Returns:

setEntryValid

public boolean setEntryValid(QueryResultsCache.CacheEntry cacheEntry,
                             FetchWork fetchWork)

Updates a pending cache entry with a FetchWork result from a finished query. If successful the cache entry will be set to valid status and be usable for cached queries. Important: Adding the entry to the cache will increment the reader count for the cache entry. CacheEntry.releaseReader() should be called when the caller is done with the cache entry.

Parameters:

cacheEntry -

fetchWork -

Returns:

clear

public void clear()

getSize

public long getSize()

notifyTableChanged

public void notifyTableChanged(String dbName,
                               String tableName,
                               long updateTime)

removeEntry

public void removeEntry(QueryResultsCache.CacheEntry entry)

cleanupInstance

public static void cleanupInstance()

incrementMetric

public static void incrementMetric(String name,
                                   long count)

decrementMetric

public static void decrementMetric(String name,
                                   long count)

incrementMetric

public static void incrementMetric(String name)

decrementMetric

public static void decrementMetric(String name)