Class JdbcPkGenerator
- java.lang.Object
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- org.apache.cayenne.dba.JdbcPkGenerator
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- All Implemented Interfaces:
PkGenerator
- Direct Known Subclasses:
FrontBasePkGenerator,MySQLPkGenerator,OpenBasePkGenerator,OraclePkGenerator,SybasePkGenerator
public class JdbcPkGenerator extends Object implements PkGenerator
Default primary key generator implementation. Uses a lookup table named "AUTO_PK_SUPPORT" to search and increment primary keys for tables.
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Field Summary
Fields Modifier and Type Field Description protected JdbcAdapteradapterstatic intDEFAULT_PK_CACHE_SIZEprotected ConcurrentMap<String,Queue<Long>>pkCacheprotected intpkCacheSizeprotected longpkStartValue
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Constructor Summary
Constructors Constructor Description JdbcPkGenerator()JdbcPkGenerator(JdbcAdapter adapter)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected booleanautoPkTableExists(DataNode node)Checks if AUTO_PK_TABLE already exists in the database.voidcreateAutoPk(DataNode node, List<DbEntity> dbEntities)Generates necessary database objects to provide automatic primary key support.List<String>createAutoPkStatements(List<DbEntity> dbEntities)Returns a list of SQL strings needed to generates database objects to provide automatic primary support for the list of entities.voiddropAutoPk(DataNode node, List<DbEntity> dbEntities)Drops table named "AUTO_PK_SUPPORT" if it exists in the database.List<String>dropAutoPkStatements(List<DbEntity> dbEntities)Returns SQL string needed to drop database objects associated with automatic primary key generation.protected StringdropAutoPkString()ObjectgeneratePk(DataNode node, DbAttribute pk)Generates a unique and non-repeating primary key for specified dbEntity.JdbcAdaptergetAdapter()Get an adapter associated with current PkGeneratorintgetPkCacheSize()Returns a size of the entity primary key cache.protected longlongPkFromDatabase(DataNode node, DbEntity entity)Performs primary key generation ignoring cache.protected StringpkCreateString(String entName)protected StringpkDeleteString(List<DbEntity> dbEntities)protected StringpkSelectString(String entName)protected StringpkTableCreateString()protected StringpkUpdateString(String entName)voidreset()Resets any cached primary keys forcing generator to go to the database next time id generation is requested.intrunUpdate(DataNode node, String sql)Runs JDBC update over a Connection obtained from DataNode.voidsetAdapter(DbAdapter adapter)Install the adapter associated with current PkGeneratorvoidsetPkCacheSize(int pkCacheSize)Sets the size of the entity primary key cache.
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Field Detail
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DEFAULT_PK_CACHE_SIZE
public static final int DEFAULT_PK_CACHE_SIZE
- See Also:
- Constant Field Values
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adapter
protected JdbcAdapter adapter
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pkCache
protected ConcurrentMap<String,Queue<Long>> pkCache
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pkCacheSize
protected int pkCacheSize
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pkStartValue
protected long pkStartValue
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Constructor Detail
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JdbcPkGenerator
public JdbcPkGenerator()
- Since:
- 4.1
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JdbcPkGenerator
public JdbcPkGenerator(JdbcAdapter adapter)
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Method Detail
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getAdapter
public JdbcAdapter getAdapter()
Description copied from interface:PkGeneratorGet an adapter associated with current PkGenerator- Specified by:
getAdapterin interfacePkGenerator
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createAutoPk
public void createAutoPk(DataNode node, List<DbEntity> dbEntities) throws Exception
Description copied from interface:PkGeneratorGenerates necessary database objects to provide automatic primary key support.- Specified by:
createAutoPkin interfacePkGenerator- Parameters:
node- node that provides access to a DataSource.dbEntities- a list of entities that require primary key auto-generation support- Throws:
Exception
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createAutoPkStatements
public List<String> createAutoPkStatements(List<DbEntity> dbEntities)
Description copied from interface:PkGeneratorReturns a list of SQL strings needed to generates database objects to provide automatic primary support for the list of entities. No actual database operations are performed.- Specified by:
createAutoPkStatementsin interfacePkGenerator
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dropAutoPk
public void dropAutoPk(DataNode node, List<DbEntity> dbEntities) throws Exception
Drops table named "AUTO_PK_SUPPORT" if it exists in the database.- Specified by:
dropAutoPkin interfacePkGenerator- Parameters:
node- node that provides access to a DataSource.dbEntities- a list of entities whose primary key auto-generation support should be dropped.- Throws:
Exception
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dropAutoPkStatements
public List<String> dropAutoPkStatements(List<DbEntity> dbEntities)
Description copied from interface:PkGeneratorReturns SQL string needed to drop database objects associated with automatic primary key generation. No actual database operations are performed.- Specified by:
dropAutoPkStatementsin interfacePkGenerator
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pkTableCreateString
protected String pkTableCreateString()
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dropAutoPkString
protected String dropAutoPkString()
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autoPkTableExists
protected boolean autoPkTableExists(DataNode node) throws SQLException
Checks if AUTO_PK_TABLE already exists in the database.- Throws:
SQLException
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runUpdate
public int runUpdate(DataNode node, String sql) throws SQLException
Runs JDBC update over a Connection obtained from DataNode. Returns a number of objects returned from update.- Throws:
SQLException- in case of query failure.
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generatePk
public Object generatePk(DataNode node, DbAttribute pk) throws Exception
Generates a unique and non-repeating primary key for specified dbEntity.This implementation is naive since it does not lock the database rows when executing select and subsequent update. Adapter-specific implementations are more robust.
- Specified by:
generatePkin interfacePkGenerator- Throws:
Exception- Since:
- 3.0
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setAdapter
public void setAdapter(DbAdapter adapter)
Description copied from interface:PkGeneratorInstall the adapter associated with current PkGenerator- Specified by:
setAdapterin interfacePkGenerator
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longPkFromDatabase
protected long longPkFromDatabase(DataNode node, DbEntity entity) throws Exception
Performs primary key generation ignoring cache. Generates a range of primary keys as specified by "pkCacheSize" bean property.This method is called internally from "generatePkForDbEntity" and then generated range of key values is saved in cache for performance. Subclasses that implement different primary key generation solutions should override this method, not "generatePkForDbEntity".
- Throws:
Exception- Since:
- 3.0
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getPkCacheSize
public int getPkCacheSize()
Returns a size of the entity primary key cache. Default value is 20. If cache size is set to a value less or equals than "one", no primary key caching is done.
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setPkCacheSize
public void setPkCacheSize(int pkCacheSize)
Sets the size of the entity primary key cache. IfpkCacheSizeparameter is less than 1, cache size is set to "one".Note that our tests show that setting primary key cache value to anything much bigger than 20 does not give any significant performance increase. Therefore it does not make sense to use bigger values, since this may potentially create big gaps in the database primary key sequences in cases like application crashes or restarts.
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reset
public void reset()
Description copied from interface:PkGeneratorResets any cached primary keys forcing generator to go to the database next time id generation is requested. May not be applicable for all generator implementations.- Specified by:
resetin interfacePkGenerator
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