com.google.cloud.spanner

Interface ResultSet

All Superinterfaces:

AutoCloseable, StructReader

All Known Implementing Classes:

ForwardingResultSet

public interface ResultSet
extends AutoCloseable, StructReader

Provides access to the data returned by a Cloud Spanner read or query. ResultSet allows a single row to be inspected at a time through the methods from the StructReader interface, in the order that the rows were returned by the read or query. The result set can be positioned over the next row, if one exists, by calling next(); this method returns false when all rows returned have been seen. The result set is initially positioned before the first row, so a call to next() is required before the first row can be inspected.

ResultSet implementations may buffer data ahead and/or maintain a persistent streaming connection to the remote service until all data has been returned or the resultSet closed. As such, it is important that all uses of ResultSet either fully consume it (that is, call next() until false is returned or it throws an exception) or explicitly call close(): failure to do so may result in wasted work or leaked resources.

ResultSet implementations are not required to be thread-safe: if methods are called from multiple threads, external synchronization must be used.

Method Summary

Modifier and Type	Method and Description
void	close() Explicitly close the result set, releasing any associated resources.
Struct	getCurrentRowAsStruct() Creates an immutable version of the row that the result set is positioned over.
com.google.spanner.v1.ResultSetStats	getStats() Returns the ResultSetStats for the query only if the query was executed in either the PLAN or the PROFILE mode via the ReadContext.analyzeQuery(Statement, com.google.cloud.spanner.ReadContext.QueryAnalyzeMode) method or for DML statements in ReadContext#executeQuery(Statement, QueryOption...).
boolean	next() Advances the result set to the next row, returning false if no such row exists.

Methods inherited from interface com.google.cloud.spanner.StructReader

getBoolean, getBoolean, getBooleanArray, getBooleanArray, getBooleanList, getBooleanList, getBytes, getBytes, getBytesList, getBytesList, getColumnCount, getColumnIndex, getColumnType, getColumnType, getDate, getDate, getDateList, getDateList, getDouble, getDouble, getDoubleArray, getDoubleArray, getDoubleList, getDoubleList, getLong, getLong, getLongArray, getLongArray, getLongList, getLongList, getString, getString, getStringList, getStringList, getStructList, getStructList, getTimestamp, getTimestamp, getTimestampList, getTimestampList, getType, isNull, isNull

Method Detail

next

boolean next()
      throws SpannerException

Advances the result set to the next row, returning false if no such row exists. This method may block.

Throws:

SpannerException

getCurrentRowAsStruct

Struct getCurrentRowAsStruct()

Creates an immutable version of the row that the result set is positioned over. This may involve copying internal data structures, and so converting all rows to Struct objects is generally more expensive than processing the ResultSet directly.

close

void close()

Explicitly close the result set, releasing any associated resources. This must always be called when disposing of a ResultSet before next() has returned false or raised an exception. Calling close() is also allowed if the result set has been fully consumed, so a recommended practice is to unconditionally close the result set once it is done with, typically using a try-with-resources construct.

Specified by:

close in interface AutoCloseable

getStats

@Nullable
com.google.spanner.v1.ResultSetStats getStats()

Returns the ResultSetStats for the query only if the query was executed in either the PLAN or the PROFILE mode via the ReadContext.analyzeQuery(Statement, com.google.cloud.spanner.ReadContext.QueryAnalyzeMode) method or for DML statements in ReadContext#executeQuery(Statement, QueryOption...). Attempts to call this method on a ResultSet not obtained from analyzeQuery or executeQuery will return a null ResultSetStats. This method must be called after next() has returned @{code false}. Calling it before that will result in null ResultSetStats too.