com.neeve.rog.log

Interface RogLogQueryEngine

All Superinterfaces:

IdxFieldResolver<RogLog.Entry>, QueryEngine<Long,RogLog.Entry>

public interface RogLogQueryEngine
extends QueryEngine<Long,RogLog.Entry>

The RogLogQueryEngine provides query access to a set of RogLog files. It provides SQL-like query syntax for performing queries. To understand how we query logs we first want to look at the structure of a log. A log is comprised of series of RogLog.Entry object. Each RogLog.Entry is composed of:

• Metadata : Which includes the IRogMetadata including things like transactionId, object id (a UUID), etc which is accessed via RogLog.Entry.getMetadata()
• Object : The logged message or an entity (null for removes) accessed via RogLog.Entry.getObject()
• Entry Fields: Additional fields on the entry itself that come from the entry headers in the log for example RogLog.Entry.getEntryType()

To facility querying in a familiar SQL like manner, we map this structure to a single logical table with one row per RogLog.Entry in the log. Each row is composed of RogLog.Entry fields, Metadata and a column for each Entity and/pr Message type present in the recovery log. For example, in a state replication log we might have objects such as Customer, Address and Order and OrderRequest. We would then have 6 columns in the table which represents this log and any given row of the table will contain the RogLog.Entry fields and Metadata for the log Entry and will have exactly one Entity or Message type column populated, e.g.

Entry	Metadata	Address	Customer	Order	OrderRequest
RogLog.Entry	Metadata	null	Customer(uuid=2)	null	null	null
RogLog.Entry	Address(uuid=1)	null	null	null	null
RogLog.Entry	null	null	null	Order1	null
RogLog.Entry	null	Customer(uuid=2)	null	null	null
RogLog.Entry	null	null	null	null	OrderRequest(uuid=1)

Column Selection

Each of these columns can be selected in a select clause as is:

 SELECT Entry, Metadata, Order FROM "myLog" where Entry.type = 'Put' 
 

and you would get back a RogLogResultSet with three object column that holds the RogLog.Entry, IRogMetadata and Customer

But you can also select individual fields of each of the columns by specifying their bean paths:

  SELECT Entry.type, Metadata.messageSequenceNumber, Customer.customerId FROM "myLog" where Metadata.txnId = '2' 
 

which would return 3 columns with the RogLog.Entry.Type and sequence number and customerId of the entries in transaction 2.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	RogLogQueryEngine.RogLogField<T> Defines an IdxField for a RogLogQueryEngine

Nested classes/interfaces inherited from interface com.neeve.query.QueryEngine

QueryEngine.BackgroundIndexingPolicy

Method Summary

Methods

Modifier and Type	Method and Description
RogLogRepository	addTransactionLogForQuery(File transactionLogFile, String alias) Adds a transaction log as a repository for this query engine.
RogLogQuery	createQuery() Creates an empty Query that can be executed against this QueryEngine.
RogLogQuery	createQuery(String xsql) Creates a Query corresponding to the provided SELECT statement.
void	enableStaticFields(boolean enable) Indicate whether well-known fields such as Entry.timestamp may be implemented via a static field.
void	enableTypeInference(boolean enable) Indicate whether the fields of a given query should be used to filter the log entries by Entry.object.class.
RogLogResultSet	execute(RogLogQuery query) Executes the given log query against the logs added to this RogLogQueryEngine.
RogLogResultSet	execute(String xsql) Executes an xpql query against this QueryEngine.
<T> RogLogQueryEngine.RogLogField<T>	getField(Class<?> objectType, String fieldPath) Resolves a field for the given objectType and field path.
<T> RogLogQueryEngine.RogLogField<T>	getField(Class<?> objectType, String fieldPath, Class<T> fieldType, Class<?>... pathTypes) Gets a field for the given objectType and field path.
<T> RogLogQueryEngine.RogLogField<T>	getField(String columnDefinition) Parses a field using the query engine's parser.
<T> RogLogQueryEngine.RogLogField<T>	getField(String objectTypeName, String fieldPath) Resolves a field for the given objectTypeName and field path.
Collection<RogLogRepository>	getRepositories() Gets this QueryEngine's current RogLogRepositorys.
void	registerFactory(Class<?> factoryClass) Registers a type factory for use in resolving fields.

Methods inherited from interface com.neeve.query.QueryEngine

addRepository, close, createIndex, createIndex, createIndex, dropIndex, dropIndex, execute, executeStatement, getFetchRatioThreshold, getIndexedFields, getNonUniqueIndex, getUniqueIndex, removeRepository, setAutoIndexing, setAutoIndexLimit, setBackgroundIndexingPolicy, setDefaultIndexing, setDefaultPackage, setFetchRatioThreshold, setQueryStatGeneration, setSortAreaInMemoryCardinality, waitForBackgroundIndexing

Method Detail

execute

RogLogResultSet execute(String xsql)

Description copied from interface: QueryEngine

Executes an xpql query against this QueryEngine.

Specified by:

execute in interface QueryEngine<Long,RogLog.Entry>

Parameters:

xsql - The SELECT statement to execute.

Returns:

the QueryResult.

createQuery

RogLogQuery createQuery(String xsql)

Description copied from interface: QueryEngine

Creates a Query corresponding to the provided SELECT statement.

Specified by:

createQuery in interface QueryEngine<Long,RogLog.Entry>

Parameters:

xsql - The query string

createQuery

RogLogQuery createQuery()

Description copied from interface: QueryEngine

Creates an empty Query that can be executed against this QueryEngine.

Specified by:

createQuery in interface QueryEngine<Long,RogLog.Entry>

Returns:

A new Query.

execute

RogLogResultSet execute(RogLogQuery query)

Executes the given log query against the logs added to this RogLogQueryEngine.

Parameters:

query - The query to execute.

Returns:

The RogLogResultSet results.

getField

<T> RogLogQueryEngine.RogLogField<T> getField(String objectTypeName,
                                            String fieldPath)

Resolves a field for the given objectTypeName and field path. The objectTypeName can be:

• 'Entry' meaning the field path is relative the the RogLog.Entry itself
• 'Metadata' meaning that the field path is relative to the node's metadata
• A subclass name of IRogNode e.g. the Message or Entity class, that was logged in which case the field path is relative to that object.

Specified by:

getField in interface IdxFieldResolver<RogLog.Entry>

Parameters:

objectTypeName - The classname of the object. If not fully qualified an attempt will be made to find the field in the engine's registered factories.

fieldPath - The bean path of the field. If null then the field will refer to the object itself

Returns:

The resolved field.

getField

<T> RogLogQueryEngine.RogLogField<T> getField(Class<?> objectType,
                                            String fieldPath)

Resolves a field for the given objectType and field path. The objectType can be:

• RogLog.Entry meaning the field path is relative the the RogLog.Entry itself
• IRogMetadata meaning that the field path is relative to the node's metadata
• A subclass of IRogNode e.g. the Message or Entity class, that was logged in which case the field path is relative to that object.

Specified by:

getField in interface IdxFieldResolver<RogLog.Entry>

Parameters:

objectType - The object whose field should be identified.

fieldPath - The bean path of the field. If null then the field will refer to the object itself

Returns:

The resolved field.

getField

<T> RogLogQueryEngine.RogLogField<T> getField(Class<?> objectType,
                                            String fieldPath,
                                            Class<T> fieldType,
                                            Class<?>... pathTypes)

Gets a field for the given objectType and field path. The objectType can be:

• RogLog.Entry meaning the field path is relative the the RogLog.Entry itself
• IRogMetadata meaning that the field path is relative to the node's metadata
• A subclass of IRogNode e.g. the Message or Entity class, that was logged in which case the field path is relative to that object.

Specified by:

getField in interface IdxFieldResolver<RogLog.Entry>

Parameters:

objectType - The object whose field should be identified.

fieldPath - The bean path of the field. If null then the field will refer to the object itself.

fieldType - Indicates the type of the field refered to by the field path.

pathTypes - For cases where types in the field path are ambiguous, this allows specifying specific types for the intermediate paths. Specifying path types is not generally necessary unless there are ambiguous types in the field path such as Object or if the intent is to specify a specific type for an type in the field path that is polymorphic.

Returns:

The resolved field.

getField

<T> RogLogQueryEngine.RogLogField<T> getField(String columnDefinition)
                                          throws QueryException,
                                                 QueryParseException

Parses a field using the query engine's parser.

Specified by:

getField in interface QueryEngine<Long,RogLog.Entry>

Parameters:

columnDefinition - A field.

Returns:

The resolved field

Throws:

QueryParseException - if the columnDefinition can't be parsed as a valid column name

QueryException - if there is an error resolving the field

registerFactory

void registerFactory(Class<?> factoryClass)

Registers a type factory for use in resolving fields. A RogLogRepository's factories will be added to the factory when it is added to the engine. This method is provided to allow for cases where fields need to be resolved prior to adding a RogLogRepository to the RogLogQueryEngine;

Parameters:

factoryClass - The factory to add.

getRepositories

Collection<RogLogRepository> getRepositories()

Gets this QueryEngine's current RogLogRepositorys. The returned Collection should be considered immutable.

Specified by:

getRepositories in interface QueryEngine<Long,RogLog.Entry>

Returns:

this QueryEngine's current QueryRepositorys.

enableTypeInference

void enableTypeInference(boolean enable)

Indicate whether the fields of a given query should be used to filter the log entries by Entry.object.class.

Parameters:

enable - Whether to enable or disable type inferencing.

enableStaticFields

void enableStaticFields(boolean enable)

Indicate whether well-known fields such as Entry.timestamp may be implemented via a static field. A value of false yields reflection-based fields.

Parameters:

enable - Whether to enable or disable static fields.

addTransactionLogForQuery

RogLogRepository addTransactionLogForQuery(File transactionLogFile,
                                         String alias)
                                           throws OdsException,
                                                  Exception

Adds a transaction log as a repository for this query engine.

Parameters:

transactionLogFile - The transaction log file.

alias - The alias which can be used to identify this log in queries.

Returns:

The opened transaction log repository.

Throws:

OdsException - If there is an error opening the transaction log file.

Exception - If there is an error addint the transaction log for query.