Package org.apache.druid.sql.calcite.external

Class Externals

java.lang.Object

org.apache.druid.sql.calcite.external.Externals

public class Externals
extends Object

Conversion functions to-from the SQL, catalog and MSQ representations of external tables.

Field Summary

Fields

Modifier and Type	Field	Description
static final ResourceAction	EXTERNAL_RESOURCE_ACTION

Constructor Summary

Constructors

Constructor	Description
Externals()

Method Summary

Modifier and Type	Method	Description
static ExternalTable	buildExternalTable(ExternalTableSpec spec, com.fasterxml.jackson.databind.ObjectMapper jsonMapper)	Create an MSQ ExternalTable given an external table spec.
static Map<String,Object>	convertArguments(TableFunction fn, List<?> arguments)	Convert the list of Calcite function arguments to a map of non-null arguments.
static List<ColumnSpec>	convertColumns(org.apache.calcite.sql.SqlNodeList schema)	Converts from a list of (identifier, type, ...) pairs to list of column specs.
static List<org.apache.calcite.schema.FunctionParameter>	convertParameters(TableFunction fn)	Convert parameters from Catalog external table definition form to the SQL form used for a table macro and its function.
static List<org.apache.calcite.rel.type.RelDataType>	dataTypes(List<org.apache.calcite.schema.FunctionParameter> parameters)	Extract the data types (only) from a list of SQL parameters.
static ResourceAction	externalRead(String name)
static ExternalTable	toExternalTable(ExternalTableSpec spec, com.fasterxml.jackson.databind.ObjectMapper jsonMapper, com.google.common.base.Supplier<Set<String>> inputSourceTypesSupplier)
static org.apache.calcite.sql.type.SqlOperandMetadata	variadic(List<org.apache.calcite.schema.FunctionParameter> params)	Define a variadic (variable arity) type checker that allows an argument count that ranges from the number of required parameters to the number of available parameters.

Methods inherited from class java.lang.Object

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

Field Details

EXTERNAL_RESOURCE_ACTION

public static final ResourceAction EXTERNAL_RESOURCE_ACTION

Constructor Details

Externals

public Externals()

Method Details

convertParameters

public static List<org.apache.calcite.schema.FunctionParameter> convertParameters(TableFunction fn)

Convert parameters from Catalog external table definition form to the SQL form used for a table macro and its function.

dataTypes

public static List<org.apache.calcite.rel.type.RelDataType> dataTypes(List<org.apache.calcite.schema.FunctionParameter> parameters)

Extract the data types (only) from a list of SQL parameters.

variadic

public static org.apache.calcite.sql.type.SqlOperandMetadata variadic(List<org.apache.calcite.schema.FunctionParameter> params)

Define a variadic (variable arity) type checker that allows an argument count that ranges from the number of required parameters to the number of available parameters. We have to define this because the Calcite form does not allow optional parameters, but we allow any parameter to be optional. We are also not fussy about the type: we catch any type errors from the declared types. We catch missing required parameters at conversion time, where we also catch invalid values, incompatible values, and so on.

convertArguments

public static Map<String,Object> convertArguments(TableFunction fn,
 List<?> arguments)

Convert the list of Calcite function arguments to a map of non-null arguments. The resulting map must be mutable as processing may rewrite values.

convertColumns

public static List<ColumnSpec> convertColumns(org.apache.calcite.sql.SqlNodeList schema)

Converts from a list of (identifier, type, ...) pairs to list of column specs. The schema itself comes from the Druid-specific EXTEND syntax added to the parser.

buildExternalTable

public static ExternalTable buildExternalTable(ExternalTableSpec spec,
 com.fasterxml.jackson.databind.ObjectMapper jsonMapper)

Create an MSQ ExternalTable given an external table spec. Enforces type restructions (which should be revisited.)

externalRead

public static ResourceAction externalRead(String name)

toExternalTable

public static ExternalTable toExternalTable(ExternalTableSpec spec,
 com.fasterxml.jackson.databind.ObjectMapper jsonMapper,
 com.google.common.base.Supplier<Set<String>> inputSourceTypesSupplier)