com.ibm.di.connector
Class DBChangelogConnector

java.lang.Object
  com.ibm.di.connector.Connector
      com.ibm.di.connector.JDBCConnector
          com.ibm.di.connector.DBChangelogConnector

All Implemented Interfaces:

ChangelogInterface, ConnectorInterface, SkipLookupInterface, VersionInfoInterface

public class DBChangelogConnector
extends JDBCConnector
implements ConnectorInterface, ChangelogInterface

The DBChangelogConnector provides a way to to detect changes in specific RDBMS tables. The Connector connects to the underline database through JDBC driver and creates Entries from specific 'change table' containing one record per modified record in the target table.

The Connector regularly saves current state into the System Store to avoid duplications when retrieving Entries. Records can also be deleted after the retrieving.

Field Summary

Fields inherited from class com.ibm.di.connector.Connector

ALL_MODES, myLog, PROPERTY_MESSAGE, PROPERTY_READER, PROPERTY_WRITER

Fields inherited from interface com.ibm.di.connector.ChangelogInterface

CONN_PARAM_STATE_KEY_PERSISTENCE, PARAM_MERGE_BOTH_NOT_MERGED, PARAM_MERGE_CHANGELOG_AND_DATA, PARAM_MERGE_ONLY_CHANGED_DATA, PARAM_VAL_AFTER_READ, PARAM_VAL_END_OF_CYCLE, PARAM_VAL_MANUAL, SAVE_STATE_AFTER_READ, SAVE_STATE_END_OF_CYCLE, SAVE_STATE_MANUAL

Constructor Summary

DBChangelogConnector()
Constructor for the DBChangelogConnector object.

Method Summary

String	ctString(Object ct) Converts the Object to String.
boolean	doWait() This method sleeps for a number of seconds specified by the 'Sleep Interval' parameter.
Entry	getNextEntry() Gets the next Entry object from the 'change table'.
static int	getNumberOfRecords(String tableName, Connection con) This method extracts the number of records in the changelog table.
Object	getStateKeyObject() This method returns the StateKey used as our Change Detection number.
int	getStateKeySaveMethod() Retrieves the method for storing StateKey.
String	getVersion() Version information.
void	initialize(Object o) Reads Connector parameter's values and initialize the Connector.
void	removeProcessedRows() Removes processed rows from the 'change table'.
void	reselect() Retrieves records from the 'change table' using the current value of the StateKey.
void	saveStateKey() Stores the USN values for the next synchronization.
void	selectEntries() This method prepares the Connector for a sequential read.
String	toHex(int n) Converts integer to Hex String.

Methods inherited from class com.ibm.di.connector.JDBCConnector

alterSession, commit, deleteEntry, execSQL, execSQLSelect, findEntry, getConnection, getNextSQLSelectEntry, getNumSkipLookupAffected, getParameterSubstitution, getPreparedString, getStatement, getSubClause, getWhereClause, isDeltaSupported, isEOCflag, isInsertPaddingDisabled, isIOException, isLookupPaddingDisabled, isUpdatePaddingDisabled, modEntry, putEntry, querySchema, queryTables, rollback, saveMetaData, setCommitMode, setCurrent, setEOCflag, setPaddingInInsert, setPaddingInLookup, setPaddingInUpdate, setParameterSubstitution, setPreparedDeleteStatement, setPreparedFindStatement, setPreparedInsertStatement, setPreparedModifyStatement, setPreparedSelectStatement, setResultSet, setSessionParameters, sqlValue, terminate

Methods inherited from class com.ibm.di.connector.Connector

addFindEntry, allModes, clearFindEntries, debug, debugMode, findEntry, getBoolean, getClassInstance, getConfiguration, getContext, getFindEntryCount, getFirstFindEntry, getLog, getMaxDuplicateEntries, getModes, getModes, getName, getNextClient, getNextFindEntry, getParam, getParser, getProperty, getPushbackEntry, getRawConnectorConfiguration, getRSInterface, getUI, hasConfigValue, hasParser, initParser, isExceptionFatal, logError, logmsg, modEntry, pushback, queryOperations, queryReply, reconnect, reconnect, registerScriptBeans, replyEntry, setConfiguration, setContext, setDebugMode, setLog, setMaxDuplicateEntries, setModes, setModes, setName, setParam, setParser, setProperty, setRSInterface, terminateServer

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.ibm.di.connector.ConnectorInterface

deleteEntry, findEntry, getConfiguration, getContext, getFindEntryCount, getFirstFindEntry, getMaxDuplicateEntries, getName, getNextClient, getNextFindEntry, getParam, getPushbackEntry, getRawConnectorConfiguration, isDeltaSupported, isExceptionFatal, isIOException, modEntry, modEntry, pushback, putEntry, queryOperations, queryReply, querySchema, reconnect, registerScriptBeans, replyEntry, setConfiguration, setContext, setCurrent, setLog, setMaxDuplicateEntries, setName, setParam, setRSInterface, terminate, terminateServer

Constructor Detail

DBChangelogConnector

public DBChangelogConnector()

Constructor for the DBChangelogConnector object.

Method Detail

initialize

public void initialize(Object o)
                throws Exception

Reads Connector parameter's values and initialize the Connector.

Specified by:

initialize in interface ConnectorInterface

Overrides:

initialize in class JDBCConnector

Parameters:

o - Socket object, ConnectorMode object or null

Throws:

Exception - If invalid Connector parameter values are supplied.

selectEntries

public void selectEntries()
                   throws Exception

This method prepares the Connector for a sequential read. Retrieves records from 'change table'.

Specified by:

selectEntries in interface ConnectorInterface

Overrides:

selectEntries in class JDBCConnector

Throws:

Exception - If an error occurs while selecting Entries

See Also:

JDBCConnector.getNextEntry()

reselect

public void reselect()
              throws Exception

Retrieves records from the 'change table' using the current value of the StateKey. If StateKey is:

null and 'Remove Processed Row' parameter is true - the processed rows are deleted from the 'change table'

null and 'Remove Processed Row' parameter is false - all entries are retrieved

not null - only entries with ibmsnap_commitseq > StateKey are retrieved

Throws:

Exception - If an error occurs while retrieving records from the database

removeProcessedRows

public void removeProcessedRows()
                         throws Exception

Removes processed rows from the 'change table'. This method deletes all rows with ibmsnap_commitseq <= StateKey. These rows are actually already returned as entries by the getNextEntry() function.

This method is called from the reselect() method only if the parameter 'Removed Processed Rows' is set to true.

Throws:

Exception - If the Connector can not delete processed rows in the database

ctString

public String ctString(Object ct)

Converts the Object to String.

Example:
By using this method you can print the values of the IBMSNAP_COMMITSEQ and IBMSNAP_INTENTSEQ properties of the read entry.

 var csn = conn.getProperty("IBMSNAP_COMMITSEQ");
 task.logmsg("IBMSNAP_COMMITSEQ: "+RDBMS.connector.ctString(csn);
 
 var isn = conn.getProperty("IBMSNAP_INTENTSEQ");
 task.logmsg("IBMSNAP_INTENTSEQ: "+RDBMS.connector.ctString(isn);
 

Parameters:

ct - the Object that need to be converted

Returns:

the converted String

toHex

public String toHex(int n)

Converts integer to Hex String.

Parameters:

n - the integer that need to be converted to Hex String

Returns:

the converted String

getNextEntry

public Entry getNextEntry()
                   throws Exception

Gets the next Entry object from the 'change table'.

Specified by:

getNextEntry in interface ConnectorInterface

Overrides:

getNextEntry in class JDBCConnector

Returns:

The next Entry

Throws:

Exception - If retrieving the next Entry fails.

See Also:

ConnectorInterface.selectEntries()

doWait

public boolean doWait()
               throws Exception

This method sleeps for a number of seconds specified by the 'Sleep Interval' parameter.

It is called by the getNextEntry() method after an entry is retrieved from the 'change table' to make the connector sleep for a specified interval of time before polling for next entry. If no new entries are added to the 'change table' for a timeout value the getNextEntry() method will return null.

Returns:

boolean flag, if true everything is fine, if false maxWait > 0 and (lastWait - firstWait) > maxWait

Throws:

Exception - if an error occurs during sleeping.

getStateKeySaveMethod

public int getStateKeySaveMethod()
                          throws Exception

Retrieves the method for storing StateKey.

Specified by:

getStateKeySaveMethod in interface ChangelogInterface

Returns:

the identifier of the method used for storing the StateKey in the TDI Store.

Throws:

Exception - - never

See Also:

ChangelogInterface.SAVE_STATE_AFTER_READ, ChangelogInterface.SAVE_STATE_END_OF_CYCLE, ChangelogInterface.SAVE_STATE_MANUAL

saveStateKey

public void saveStateKey()
                  throws Exception

Stores the USN values for the next synchronization. This method will skip the storing of the StateKey if the StateKey save method is set to ChangelogInterface.SAVE_STATE_AFTER_READ

Specified by:

saveStateKey in interface ChangelogInterface

Throws:

Exception - - never

getStateKeyObject

public Object getStateKeyObject()
                         throws Exception

This method returns the StateKey used as our Change Detection number. This number shows the last processed record and is retrieved from the ibmsnap_commitseq column in the configured table of the underlying database.

Example:
Here is an example how to print the StateKey using this method.

 key statekey = conn.getStateKeyObject();
 task.logmsg("Iterator State Key: " + thisConnector.connector.ctString(statekey));
 
 

return an Object representing the commit sequence number of the last processed record throws Exception if an error occurs.

Specified by:

getStateKeyObject in interface ChangelogInterface

Returns:

the StateKey, wrapped in some kind of object.

Throws:

Exception - if an error occurs.

See Also:

ChangelogInterface

getVersion

public String getVersion()

Version information.

Specified by:

getVersion in interface VersionInfoInterface

Overrides:

getVersion in class JDBCConnector

Returns:

version information

getNumberOfRecords

public static int getNumberOfRecords(String tableName,
                                     Connection con)
                              throws Exception

This method extracts the number of records in the changelog table.

Parameters:

tableName - name of the changelog table

con - Connection handle for the currently opened session to the database

Returns:

number of records in the specified table

Throws:

Exception -

SQLException - if could not retrieve the number of records

NumberFormatException - if could not parse the returned value