org.apache.hadoop.hive.common
Interface ValidTxnList

All Known Implementing Classes:

ValidTxnListImpl

public interface ValidTxnList

Models the list of transactions that should be included in a snapshot. It is modelled as a high water mark, which is the largest transaction id that has been committed and a list of transactions that are not included.

Nested Class Summary

static class

ValidTxnList.RangeResponse The response to a range query.

Field Summary

static String

VALID_TXNS_KEY Key used to store valid txn list in a Configuration object.

Method Summary

long	getHighWatermark() Get the largest committed transaction id.
long[]	getOpenTransactions() Get the list of transactions under the high water mark that are still open.
boolean	isTxnCommitted(long txnid) Indicates whether a given transaction has been committed and should be viewed as valid for read.
ValidTxnList.RangeResponse	isTxnRangeCommitted(long minTxnId, long maxTxnId) Find out if a range of transaction ids have been committed.
void	readFromString(String src) Populate this validTxnList from the string.
String	writeToString() Write this validTxnList into a string.

Field Detail

VALID_TXNS_KEY

static final String VALID_TXNS_KEY

Key used to store valid txn list in a Configuration object.

See Also:

Constant Field Values

Method Detail

isTxnCommitted

boolean isTxnCommitted(long txnid)

Indicates whether a given transaction has been committed and should be viewed as valid for read.

Parameters:

txnid - id for the transaction

Returns:

true if committed, false otherwise

isTxnRangeCommitted

ValidTxnList.RangeResponse isTxnRangeCommitted(long minTxnId,
                                               long maxTxnId)

Find out if a range of transaction ids have been committed.

Parameters:

minTxnId - minimum txnid to look for, inclusive

maxTxnId - maximum txnid to look for, inclusive

Returns:

Indicate whether none, some, or all of these transactions have been committed.

writeToString

String writeToString()

Write this validTxnList into a string. This should produce a string that can be used by readFromString(String) to populate a validTxnsList.

readFromString

void readFromString(String src)

Populate this validTxnList from the string. It is assumed that the string was created via writeToString().

Parameters:

src - source string.

getHighWatermark

long getHighWatermark()

Get the largest committed transaction id.

Returns:

largest committed transaction id

getOpenTransactions

long[] getOpenTransactions()

Get the list of transactions under the high water mark that are still open.

Returns:

a list of open transaction ids