org.postgresql.core.v3.adaptivefetch

Class AdaptiveFetchCache

java.lang.Object

org.postgresql.core.v3.adaptivefetch.AdaptiveFetchCache

public class AdaptiveFetchCache
extends java.lang.Object

The main purpose of this class is to handle adaptive fetching process. Adaptive fetching is used to compute fetch size to fully use size defined by maxResultBuffer. Computing is made by dividing maxResultBuffer size by max row result size noticed so far. Each query have separate adaptive fetch size computed, but same queries have it shared. If adaptive fetch is turned on, first fetch is going to be made with defaultRowFetchSize, next fetching of resultSet will be made with computed adaptive fetch size. If adaptive fetch is turned on during fetching, then first fetching made by ResultSet will be made with defaultRowFetchSize, next will use computed adaptive fetch size. Property adaptiveFetch need properties defaultRowFetchSize and maxResultBuffer to work.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	adaptiveFetch
private java.util.Map<java.lang.String,AdaptiveFetchCacheEntry>	adaptiveFetchInfoMap
private int	maximumAdaptiveFetchSize
private long	maximumResultBufferSize
private int	minimumAdaptiveFetchSize

Constructor Summary

Constructors

Constructor and Description
AdaptiveFetchCache(long maximumResultBufferSize, java.util.Properties info)

Method Summary

Modifier and Type	Method and Description
void	addNewQuery(boolean adaptiveFetch, Query query) Add query to being cached and computing adaptive fetch size.
private int	adjustFetchSize(int actualSize) Set maximum and minimum constraints on given value.
private int	adjustMaximumFetchSize(int actualSize) Set maximum constraint on given value.
private int	adjustMinimumFetchSize(int actualSize) Set minimum constraint on given value.
boolean	getAdaptiveFetch() Get state of adaptive fetch.
int	getFetchSizeForQuery(boolean adaptiveFetch, Query query) Get adaptive fetch size for given query.
void	removeQuery(boolean adaptiveFetch, Query query) Remove query information from caching.
void	setAdaptiveFetch(boolean adaptiveFetch) Set state of adaptive fetch.
void	updateQueryFetchSize(boolean adaptiveFetch, Query query, int maximumRowSizeBytes) Update adaptive fetch size for given query.

Methods inherited from class java.lang.Object

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

Field Detail

adaptiveFetchInfoMap

private final java.util.Map<java.lang.String,AdaptiveFetchCacheEntry> adaptiveFetchInfoMap

adaptiveFetch

private boolean adaptiveFetch

minimumAdaptiveFetchSize

private int minimumAdaptiveFetchSize

maximumAdaptiveFetchSize

private int maximumAdaptiveFetchSize

maximumResultBufferSize

private long maximumResultBufferSize

Constructor Detail

AdaptiveFetchCache

public AdaptiveFetchCache(long maximumResultBufferSize,
                          java.util.Properties info)
                   throws java.sql.SQLException

Throws:

java.sql.SQLException

Method Detail

addNewQuery

public void addNewQuery(boolean adaptiveFetch,
                        Query query)

Add query to being cached and computing adaptive fetch size.

Parameters:

adaptiveFetch - state of adaptive fetch, which should be used during adding query

query - query to be cached

updateQueryFetchSize

public void updateQueryFetchSize(boolean adaptiveFetch,
                                 Query query,
                                 int maximumRowSizeBytes)

Update adaptive fetch size for given query.

Parameters:

adaptiveFetch - state of adaptive fetch, which should be used during updating fetch size for query

query - query to be updated

maximumRowSizeBytes - max row size used during updating information about adaptive fetch size for given query

getFetchSizeForQuery

public int getFetchSizeForQuery(boolean adaptiveFetch,
                                Query query)

Get adaptive fetch size for given query.

Parameters:

adaptiveFetch - state of adaptive fetch, which should be used during getting fetch size for query

query - query to which we want get adaptive fetch size

Returns:

adaptive fetch size for query or -1 if size doesn't exist/adaptive fetch state is false

removeQuery

public void removeQuery(boolean adaptiveFetch,
                        Query query)

Remove query information from caching.

Parameters:

adaptiveFetch - state of adaptive fetch, which should be used during removing fetch size for query

query - query to be removed from caching

adjustFetchSize

private int adjustFetchSize(int actualSize)

Set maximum and minimum constraints on given value.

Parameters:

actualSize - value which should be the computed fetch size

Returns:

value which meet the constraints

adjustMinimumFetchSize

private int adjustMinimumFetchSize(int actualSize)

Set minimum constraint on given value.

Parameters:

actualSize - value which should be the computed fetch size

Returns:

value which meet the minimum constraint

adjustMaximumFetchSize

private int adjustMaximumFetchSize(int actualSize)

Set maximum constraint on given value.

Parameters:

actualSize - value which should be the computed fetch size

Returns:

value which meet the maximum constraint

getAdaptiveFetch

public boolean getAdaptiveFetch()

Get state of adaptive fetch.

Returns:

state of adaptive fetch

setAdaptiveFetch

public void setAdaptiveFetch(boolean adaptiveFetch)

Set state of adaptive fetch.

Parameters:

adaptiveFetch - desired state of adaptive fetch