org.postgresql.core.v3.adaptivefetch

Class AdaptiveFetchCache

java.lang.Object

org.postgresql.core.v3.adaptivefetch.AdaptiveFetchCache

public class AdaptiveFetchCache
extends 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.

Constructor Summary

Constructors

Constructor and Description
AdaptiveFetchCache(long maximumResultBufferSize, Properties info)

Method Summary

Modifier and Type	Method and Description
void	addNewQuery(boolean adaptiveFetch, @NonNull Query query) Add query to being cached and computing adaptive fetch size.
boolean	getAdaptiveFetch() Get state of adaptive fetch.
int	getFetchSizeForQuery(boolean adaptiveFetch, @NonNull Query query) Get adaptive fetch size for given query.
void	removeQuery(boolean adaptiveFetch, @NonNull Query query) Remove query information from caching.
void	setAdaptiveFetch(boolean adaptiveFetch) Set state of adaptive fetch.
void	updateQueryFetchSize(boolean adaptiveFetch, @NonNull 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

Constructor Detail

AdaptiveFetchCache

public AdaptiveFetchCache(long maximumResultBufferSize,
                          Properties info)
                   throws SQLException

Throws:

SQLException

Method Detail

addNewQuery

public void addNewQuery(boolean adaptiveFetch,
                        @NonNull 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,
                                 @NonNull 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,
                                @NonNull 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,
                        @NonNull 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

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