com.orindasoft.pub
Class QueryStatement

java.lang.Object
  com.orindasoft.pub.StatementParameters2
      com.orindasoft.pub.DmlStatement
          com.orindasoft.pub.QueryStatement

All Implemented Interfaces:

OracleResourceUser, StatsInterface

public class QueryStatement
extends DmlStatement
implements OracleResourceUser, StatsInterface

A SELECT statement with caching.

This class implements a parameterized SQL statement with query result caching that continues to exist even if the connection it uses is withdrawn. It extends DMLStatement

(c) Copyright 2003 - 2012 Orinda Software Ltd

Since:

2.0.1477: execute() will now attempt to reparse if the first attempt at execution fails

Version:

6.0

Author:

Orinda Software

Field Summary

static int	CACHE_FOREVER Constant for caching data for the life of the class.
static int	CACHE_NEVER Constant for not caching data.
static int	DEFAULT_QUERIES_CACHED Default value for how many different queries we can cache...
static int	DEFAULT_QUERY_ROWS Default value for how many rows returned by a query we actually use...

Constructor Summary

QueryStatement(java.lang.String statementSqlText, LogInterface theLog)
Create a DML Statement object.

QueryStatement(java.lang.String statementSqlText, LogInterface theLog, java.sql.Connection theConnection)
Create a DML Statement object and give it a connection

Method Summary

void	clearCache() Clear the cache.
ReadOnlyRowSet	execute() Execute the statement and return a ReadOnlyRowSet If caching is in use the cache will be checked and a cached copy returned if possible.
int	getBufferSize() Get current file io buffer size
int	getCacheSize() Return the number of queries currently in the cache.
long	getErrors() Return counter containing number of errors.
long	getExecutions() Return counter containing number of executions.
long	getExecutionTime() Return counter containing time spent executing statement in milliseconds.
boolean	getKeepFiles() Get keepFiles flag
boolean	getKeepLobs() Get keepLobs
java.lang.String	getLatestQuerySignature() Return an up to date signature of the query parameters.
long	getParses() Return counter containing number of parses.
long	getParseTime() Return counter containing time spent parsing in milliseconds.
long	getReleases() Return counter containing number of releases.
long	getRetrievalTime() Return counter containing time spent retrieving data in milliseconds.
java.io.File	getTempDir() Get temporary directory
java.lang.String	getTempFilePrefix() Get the prefix used for generating temporary files
java.lang.String	getTempFileSuffix() Get the suffix used for generating temporary files
boolean	getUseByteArraysForLongsAndLOBS() Get keepLobs
int	purgeExpiredCacheEntries(int howManyMilliseconds) Remove entries that are too old from the cache
int	purgeUnderusedCacheEntries(int minAcceptableReuses, int howManyMilliseconds) Remove entries that have not been reused from the cache
void	resetStatsCounters() Reset all stats counters to 0.
void	setBufferSize(int bufferSize) Set new file io buffer size
void	setCacheRows(int newCacheRows) Specify how many results will be cached.
void	setCacheSeconds(int newCacheSeconds) Specify how long results will be cached.
void	setKeepFiles(boolean keepFiles) Set keepFiles
void	setKeepLobs(boolean keepLobs) Set keepLobs
void	setQueryRows(int newQueryRows) Specify how many rows can be brought back
void	setTempDir(java.io.File tempFileDir) Set temporary directory
void	setTempFilePrefix(java.lang.String tempFilePrefix) Set the prefix used for generating temporary files
void	setTempFileSuffix(java.lang.String tempFileSuffix) Set the suffix used for generating temporary files
void	setUseByteArraysForLongsAndLOBS(boolean useByteArraysForLongsAndLOBS) SetUseByteArraysForLongsAndLOBS

Methods inherited from class com.orindasoft.pub.DmlStatement

connectionIsUsable, freeConnection, getUnderlyingStatement, hasResources, releaseResources, setConnection

Methods inherited from class com.orindasoft.pub.StatementParameters2

bindParameters, checkBuild, checkSet, clearParameters, getParam, getParamCount, getParameters, getSignature, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setParam, setPlSqlTableArrayParam

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.orindasoft.pub.OracleResourceUser

hasResources, releaseResources

Field Detail

DEFAULT_QUERY_ROWS

public static final int DEFAULT_QUERY_ROWS

Default value for how many rows returned by a query we actually use...

See Also:

Constant Field Values

DEFAULT_QUERIES_CACHED

public static final int DEFAULT_QUERIES_CACHED

Default value for how many different queries we can cache...

See Also:

Constant Field Values

CACHE_FOREVER

public static final int CACHE_FOREVER

Constant for caching data for the life of the class. Usage: setCacheSeconds(CACHE_FOREVER);

See Also:

Constant Field Values

CACHE_NEVER

public static final int CACHE_NEVER

Constant for not caching data. Usage: setCacheSeconds(CACHE_NEVER);

See Also:

Constant Field Values

Constructor Detail

QueryStatement

public QueryStatement(java.lang.String statementSqlText,
                      LogInterface theLog,
                      java.sql.Connection theConnection)

Create a DML Statement object and give it a connection

QueryStatement

public QueryStatement(java.lang.String statementSqlText,
                      LogInterface theLog)

Create a DML Statement object.

Method Detail

setCacheSeconds

public void setCacheSeconds(int newCacheSeconds)

Specify how long results will be cached. Setting this to a non-zero value turns caching on.

Parameters:

int - newCacheSeconds

setCacheRows

public void setCacheRows(int newCacheRows)

Specify how many results will be cached. By default this is DEFAULT_QUERIES_CACHED.

Parameters:

int - newCacheSeconds

getCacheSize

public int getCacheSize()

Return the number of queries currently in the cache.

clearCache

public void clearCache()

Clear the cache.

setQueryRows

public void setQueryRows(int newQueryRows)

Specify how many rows can be brought back

Parameters:

int - newQueryRows

execute

public ReadOnlyRowSet execute()
                       throws CSException

Execute the statement and return a ReadOnlyRowSet If caching is in use the cache will be checked and a cached copy returned if possible.

Returns:

ReadOnlyRowSet The results from this query

Throws:

CSException

Since:

2.0.1477: execute() will now attempt to reparse if the first attempt at execution fails, 5.0.2314 'useByteArraysForLongsAndLOBS' added.

purgeExpiredCacheEntries

public int purgeExpiredCacheEntries(int howManyMilliseconds)

Remove entries that are too old from the cache

Parameters:

int - howManyMilliseconds The maximum amount of time to be spent removing entries.

Returns:

int How many entries were removed.

purgeUnderusedCacheEntries

public int purgeUnderusedCacheEntries(int minAcceptableReuses,
                                      int howManyMilliseconds)

Remove entries that have not been reused from the cache

Parameters:

int - minAcceptableReuses How many times an entry must have been used to avoid deletion.

int - howManyMilliseconds The maximum amount of time to be spent removing entries.

Returns:

int How many entries were removed.

getLatestQuerySignature

public java.lang.String getLatestQuerySignature()

Return an up to date signature of the query parameters.

getBufferSize

public int getBufferSize()

Get current file io buffer size

Returns:

int bufferSize Buffersize in bytes.

getKeepFiles

public boolean getKeepFiles()

Get keepFiles flag

Returns:

int true if temporary files are kept after the JVM exits.

getTempDir

public java.io.File getTempDir()

Get temporary directory

getTempFilePrefix

public java.lang.String getTempFilePrefix()

Get the prefix used for generating temporary files

getTempFileSuffix

public java.lang.String getTempFileSuffix()

Get the suffix used for generating temporary files

setBufferSize

public void setBufferSize(int bufferSize)

Set new file io buffer size

Parameters:

int - bufferSize A new Buffersize in bytes.

setKeepFiles

public void setKeepFiles(boolean keepFiles)

Set keepFiles

Parameters:

boolean - keepFiles Keep generated files after JVM exits

setKeepLobs

public void setKeepLobs(boolean keepLobs)

Set keepLobs

Parameters:

boolean - keepLobs Keep LOB objects such as CLOB, BLOB and BFILE as LOBS instead of turning them into files on retrieval.

Since:

2.0.1505

setUseByteArraysForLongsAndLOBS

public void setUseByteArraysForLongsAndLOBS(boolean useByteArraysForLongsAndLOBS)

SetUseByteArraysForLongsAndLOBS

Parameters:

boolean - useByteArraysForLongsAndLOBS flag that specifies whether lobs such as CLOBS, BLOBS and BFILES and LONG columns will be kept as byte arrays

Since:

JDBCWizard 5.0.2314

getKeepLobs

public boolean getKeepLobs()

Get keepLobs

Returns:

boolean keepLobs Keep LOB objects such as CLOB, BLOB and BFILE as LOBS instead of turning them into files on retrieval.

Since:

2.0.1505

getUseByteArraysForLongsAndLOBS

public boolean getUseByteArraysForLongsAndLOBS()

Get keepLobs

Returns:

boolean useByteArraysForLongsAndLOBS flag that specifies whether lobs such as CLOBS, BLOBS and BFILES and LONG columns will be kept as byte arrays

Since:

JDBCWizard 5.0.2314

setTempDir

public void setTempDir(java.io.File tempFileDir)
                throws CSException

Set temporary directory

Parameters:

java.io.File - tempFileDir a new Temporary Directory

Throws:

CSException - if the directory is not viable

Since:

2.0.879

setTempFilePrefix

public void setTempFilePrefix(java.lang.String tempFilePrefix)

Set the prefix used for generating temporary files

setTempFileSuffix

public void setTempFileSuffix(java.lang.String tempFileSuffix)

Set the suffix used for generating temporary files

resetStatsCounters

public void resetStatsCounters()

Reset all stats counters to 0. Used to implement StatsInterface

Specified by:

resetStatsCounters in interface StatsInterface

See Also:

See StatsInterface - a generic set of performance measuring methods

getParses

public long getParses()

Return counter containing number of parses. Used to implement StatsInterface

Specified by:

getParses in interface StatsInterface

Returns:

long The number of times this statement was parsed.

See Also:

See StatsInterface - a generic set of performance measuring methods

getParseTime

public long getParseTime()

Return counter containing time spent parsing in milliseconds. Used to implement StatsInterface

Specified by:

getParseTime in interface StatsInterface

Returns:

long The length of time this statement has spent parsing in milliseconds

See Also:

See StatsInterface - a generic set of performance measuring methods

getExecutions

public long getExecutions()

Return counter containing number of executions. Used to implement StatsInterface

Specified by:

getExecutions in interface StatsInterface

Returns:

long The number of times this statement was executed.

See Also:

See StatsInterface - a generic set of performance measuring methods

getExecutionTime

public long getExecutionTime()

Return counter containing time spent executing statement in milliseconds. Used to implement StatsInterface

Specified by:

getExecutionTime in interface StatsInterface

Returns:

long The length of time this statement has spent executing in milliseconds

See Also:

See StatsInterface - a generic set of performance measuring methods

getRetrievalTime

public long getRetrievalTime()

Return counter containing time spent retrieving data in milliseconds. Used to implement StatsInterface

Specified by:

getRetrievalTime in interface StatsInterface

Returns:

long The length of time this statement has spent executing in milliseconds

See Also:

See StatsInterface - a generic set of performance measuring methods

getReleases

public long getReleases()

Return counter containing number of releases. Used to implement StatsInterface

Specified by:

getReleases in interface StatsInterface

Returns:

long The number of times this statement was released.

See Also:

See StatsInterface - a generic set of performance measuring methods

getErrors

public long getErrors()

Return counter containing number of errors. Used to implement StatsInterface

Specified by:

getErrors in interface StatsInterface

Returns:

long The number of times an error was generated.

See Also:

See StatsInterface - a generic set of performance measuring methods