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 JdbcAdapter
adapter
static int
DEFAULT_PK_CACHE_SIZE
protected ConcurrentMap<String,Queue<Long>>
pkCache
protected int
pkCacheSize
protected long
pkStartValue
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Constructor Summary
Constructors Constructor Description JdbcPkGenerator(JdbcAdapter adapter)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected boolean
autoPkTableExists(DataNode node)
Checks if AUTO_PK_TABLE already exists in the database.void
createAutoPk(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.void
dropAutoPk(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 String
dropAutoPkString()
Object
generatePk(DataNode node, DbAttribute pk)
Generates a unique and non-repeating primary key for specified dbEntity.JdbcAdapter
getAdapter()
int
getPkCacheSize()
Returns a size of the entity primary key cache.protected long
longPkFromDatabase(DataNode node, DbEntity entity)
Performs primary key generation ignoring cache.protected String
pkCreateString(String entName)
protected String
pkDeleteString(List<DbEntity> dbEntities)
protected String
pkSelectString(String entName)
protected String
pkTableCreateString()
protected String
pkUpdateString(String entName)
void
reset()
Resets any cached primary keys forcing generator to go to the database next time id generation is requested.int
runUpdate(DataNode node, String sql)
Runs JDBC update over a Connection obtained from DataNode.void
setPkCacheSize(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(JdbcAdapter adapter)
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Method Detail
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getAdapter
public JdbcAdapter getAdapter()
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createAutoPk
public void createAutoPk(DataNode node, List<DbEntity> dbEntities) throws Exception
Description copied from interface:PkGenerator
Generates necessary database objects to provide automatic primary key support.- Specified by:
createAutoPk
in 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:PkGenerator
Returns 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:
createAutoPkStatements
in 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:
dropAutoPk
in 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:PkGenerator
Returns SQL string needed to drop database objects associated with automatic primary key generation. No actual database operations are performed.- Specified by:
dropAutoPkStatements
in 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:
generatePk
in interfacePkGenerator
- Throws:
Exception
- Since:
- 3.0
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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. IfpkCacheSize
parameter 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:PkGenerator
Resets 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:
reset
in interfacePkGenerator
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