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java.lang.Objectorg.apache.cayenne.dba.JdbcPkGenerator
public class JdbcPkGenerator
Default primary key generator implementation. Uses a lookup table named "AUTO_PK_SUPPORT" to search and increment primary keys for tables.
Field Summary | |
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static int |
DEFAULT_PK_CACHE_SIZE
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protected static java.lang.String |
NEXT_ID
Deprecated. Since 1.2 unused. |
protected static ObjAttribute[] |
objDesc
Deprecated. Since 1.2 unused. |
protected java.util.Map |
pkCache
|
protected int |
pkCacheSize
|
protected static DbAttribute[] |
resultDesc
Deprecated. Since 1.2 unused. |
Constructor Summary | |
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JdbcPkGenerator()
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Method Summary | |
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protected boolean |
autoPkTableExists(DataNode node)
Checks if AUTO_PK_TABLE already exists in the database. |
protected byte[] |
binaryPK(DbEntity entity)
|
void |
createAutoPk(DataNode node,
java.util.List dbEntities)
Generates necessary database objects to provide automatic primary key support. |
java.util.List |
createAutoPkStatements(java.util.List 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,
java.util.List dbEntities)
Drops table named "AUTO_PK_SUPPORT" if it exists in the database. |
java.util.List |
dropAutoPkStatements(java.util.List dbEntities)
Returns SQL string needed to drop database objects associated with automatic primary key generation. |
protected java.lang.String |
dropAutoPkString()
|
java.lang.Object |
generatePkForDbEntity(DataNode node,
DbEntity ent)
Generates new (unique and non-repeating) primary key for specified dbEntity. |
java.lang.String |
generatePkForDbEntityString(DbEntity ent)
Deprecated. Since 1.2 corresponding interface method is deprecated. |
int |
getPkCacheSize()
Returns a size of the entity primary key cache. |
protected java.lang.String |
pkCreateString(java.lang.String entName)
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protected java.lang.String |
pkDeleteString(java.util.List dbEntities)
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protected int |
pkFromDatabase(DataNode node,
DbEntity ent)
Performs primary key generation ignoring cache. |
protected java.lang.String |
pkSelectString(java.lang.String entName)
|
protected java.lang.String |
pkTableCreateString()
|
protected java.lang.String |
pkUpdateString(java.lang.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,
java.lang.String sql)
Runs JDBC update over a Connection obtained from DataNode. |
void |
setPkCacheSize(int pkCacheSize)
Sets the size of the entity primary key cache. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final int DEFAULT_PK_CACHE_SIZE
protected static final java.lang.String NEXT_ID
protected static final ObjAttribute[] objDesc
protected static final DbAttribute[] resultDesc
protected java.util.Map pkCache
protected int pkCacheSize
Constructor Detail |
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public JdbcPkGenerator()
Method Detail |
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public void createAutoPk(DataNode node, java.util.List dbEntities) throws java.lang.Exception
PkGenerator
createAutoPk
in interface PkGenerator
node
- node that provides access to a DataSource.dbEntities
- a list of entities that require primary key autogeneration
support
java.lang.Exception
public java.util.List createAutoPkStatements(java.util.List dbEntities)
PkGenerator
createAutoPkStatements
in interface PkGenerator
public void dropAutoPk(DataNode node, java.util.List dbEntities) throws java.lang.Exception
dropAutoPk
in interface PkGenerator
node
- node that provides access to a DataSource.dbEntities
- a list of entities whose primary key autogeneration support
should be dropped.
java.lang.Exception
public java.util.List dropAutoPkStatements(java.util.List dbEntities)
PkGenerator
dropAutoPkStatements
in interface PkGenerator
protected java.lang.String pkTableCreateString()
protected java.lang.String pkDeleteString(java.util.List dbEntities)
protected java.lang.String pkCreateString(java.lang.String entName)
protected java.lang.String pkSelectString(java.lang.String entName)
protected java.lang.String pkUpdateString(java.lang.String entName)
protected java.lang.String dropAutoPkString()
protected boolean autoPkTableExists(DataNode node) throws java.sql.SQLException
java.sql.SQLException
public int runUpdate(DataNode node, java.lang.String sql) throws java.sql.SQLException
java.sql.SQLException
- in case of query failure.public java.lang.String generatePkForDbEntityString(DbEntity ent)
PkGenerator
generatePkForDbEntityString
in interface PkGenerator
public java.lang.Object generatePkForDbEntity(DataNode node, DbEntity ent) throws java.lang.Exception
Generates new (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.
generatePkForDbEntity
in interface PkGenerator
ent
- DbEntity for which automatic PK is generated.
java.lang.Exception
protected byte[] binaryPK(DbEntity entity)
protected int pkFromDatabase(DataNode node, DbEntity ent) throws java.lang.Exception
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".
java.lang.Exception
public int getPkCacheSize()
public void setPkCacheSize(int pkCacheSize)
pkCacheSize
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.
public void reset()
PkGenerator
reset
in interface PkGenerator
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