Package com.inductiveautomation.historian.gateway.query.execution

Class AbstractHistoryQueryExecutor

java.lang.Object

com.inductiveautomation.historian.gateway.query.execution.AbstractHistoryLoader<IndexedQualifiedValue>

com.inductiveautomation.historian.gateway.query.execution.AbstractHistoryQueryExecutor

All Implemented Interfaces:

HistoryQueryExecutor

Direct Known Subclasses:

Query, SimulatorHistorianQuery

public abstract class AbstractHistoryQueryExecutor
extends AbstractHistoryLoader<IndexedQualifiedValue>

This can be a base for simple historical query executors. It manages the column nodes, and the sub type only has to read the data and provide data types. Remember when implementing that if you need boundary values, you need to load those and call setSeed/Post values.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractHistoryQueryExecutor.ColumnDataType	Holds the datatype of a column.

Field Summary

Fields inherited from class com.inductiveautomation.historian.gateway.query.execution.AbstractHistoryLoader

endTime, startTime

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractHistoryQueryExecutor(QueryController controller, List<ColumnQueryDefinition> paths, LoggerEx logger, QueryMetrics metrics)

Method Summary

Modifier and Type	Method	Description
protected ValueBasedResultNode	buildRealNode(int index, ColumnQueryDefinition def, AbstractHistoryQueryExecutor.ColumnDataType dtype)
List<? extends ResultNode>	getColumnNodes()	Returns the HistoryNodes of this executor.
int	getEffectiveWindowSizeMS()	When "natural" results are requested, this will be called to let the query executors say what they think "natural" means.
LoggerEx	getLogger()
protected long	getTimestampFor(IndexedQualifiedValue value)
protected long	loadValue(IndexedQualifiedValue value)	Puts the value into the appropriate column.
protected final void	primeRead()	This function starts the read process, and gets the system ready for the first call to readNextFromSource
protected abstract List<AbstractHistoryQueryExecutor.ColumnDataType>	startReadingData(List<QualifiedPath> paths)	Should do the following: 1) Start reading the data.

Methods inherited from class com.inductiveautomation.historian.gateway.query.execution.AbstractHistoryLoader

closeRead, endReading, getController, getEndTime, getQueryId, getSeedValues, getStartTime, hasMore, initialize, nextTime, pathToString, processData, readNext, readNextFromSource, setErrored, setPostValues, setSeedValues, shouldReadBoundaryValues, startReading

Methods inherited from class java.lang.Object

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

Constructor Details

AbstractHistoryQueryExecutor

protected AbstractHistoryQueryExecutor(QueryController controller,
 List<ColumnQueryDefinition> paths,
 LoggerEx logger,
 QueryMetrics metrics)

Method Details

getLogger

public LoggerEx getLogger()

Specified by:

getLogger in class AbstractHistoryLoader<IndexedQualifiedValue>

getEffectiveWindowSizeMS

public int getEffectiveWindowSizeMS()

Description copied from interface: HistoryQueryExecutor

When "natural" results are requested, this will be called to let the query executors say what they think "natural" means. If a query executor does not support natural results, it should return -1. If all of the query executors return -1, a raw query will be performed.

getColumnNodes

public List<? extends ResultNode> getColumnNodes()

Description copied from interface: HistoryQueryExecutor

Returns the HistoryNodes of this executor. There MUST be one for every tag path, and they must be in the same order as the paths provided to the executor when it was created. Also, these values must be available as soon as the executor is created. However, they won't be consulted for their data type until after initialize is called, so the normal procedure is to create and return DelegatingResultNodes, which get filled in later.

getTimestampFor

protected long getTimestampFor(IndexedQualifiedValue value)

Specified by:

getTimestampFor in class AbstractHistoryLoader<IndexedQualifiedValue>

primeRead

protected final void primeRead()
                        throws Exception

Description copied from class: AbstractHistoryLoader

This function starts the read process, and gets the system ready for the first call to readNextFromSource

Specified by:

primeRead in class AbstractHistoryLoader<IndexedQualifiedValue>

Throws:

Exception

startReadingData

protected abstract List<AbstractHistoryQueryExecutor.ColumnDataType> startReadingData(List<QualifiedPath> paths)
                                                                               throws Exception

Should do the following: 1) Start reading the data. Values should be produced with a 1-to-1 index into these paths. If there are boundary values, those maps should be set with calls to setSeed/PostValues 2) Collect and return the data types of the paths/columns.

Throws:

Exception

buildRealNode

protected ValueBasedResultNode buildRealNode(int index,
 ColumnQueryDefinition def,
 AbstractHistoryQueryExecutor.ColumnDataType dtype)

loadValue

protected long loadValue(IndexedQualifiedValue value)

Description copied from class: AbstractHistoryLoader

Puts the value into the appropriate column.

Specified by:

loadValue in class AbstractHistoryLoader<IndexedQualifiedValue>