org.apache.drill.exec.util

Class EncodedSchemaPathSet

java.lang.Object

org.apache.drill.exec.util.EncodedSchemaPathSet

public class EncodedSchemaPathSet
extends Object

This class provided utility methods to encode and decode a set of user specified SchemaPaths to a set of encoded SchemaPaths with the following properties.

1. Valid Drill identifier as per its grammar with only one, root name segment.
2. A single identifier can not exceed 1024 characters in length.

Format of the encoded SchemaPath:

$$ENC\d\dlt;base32 encoded input paths>

We use Base-32 over Base-64 because the later's charset includes '\' and '+'.

Field Summary

Fields

Modifier and Type	Field and Description
static String	ENCODED_STAR_COLUMN

Constructor Summary

Constructors

Constructor and Description
EncodedSchemaPathSet()

Method Summary

Modifier and Type	Method and Description
static Collection<SchemaPath>	decode(Collection<SchemaPath> encodedPaths) Returns the decoded Collection of SchemaPath from the input which may contain a mix of encoded and non-encoded SchemaPaths.
static String[]	decode(String... encodedPaths) Returns the decoded array of SchemaPath strings from the input which may contain a mix of encoded and non-encoded SchemaPaths.
static String[]	encode(String... schemaPaths) Returns the encoded array of SchemaPath identifiers from the input array of SchemaPath.
static boolean	isEncodedSchemaPath(SchemaPath schemaPath)
static boolean	isEncodedSchemaPath(String schemaPath)

Methods inherited from class java.lang.Object

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

Field Detail

ENCODED_STAR_COLUMN

public static final String ENCODED_STAR_COLUMN

Constructor Detail

EncodedSchemaPathSet

public EncodedSchemaPathSet()

Method Detail

encode

public static String[] encode(String... schemaPaths)

Returns the encoded array of SchemaPath identifiers from the input array of SchemaPath.

The returned identifiers have the following properties:

• Each SchemaPath identifier in the array has only one single root NameSegment.
• Maximum length of each such identifier is equal to the maximum length of Drill identifier (currently 1024).

We take advantage of the fact that Java's modified utf-8 encoding can never contain embedded null byte.

See Also:

http://docs.oracle.com/javase/8/docs/api/java/io/DataInput.html#modified-utf-8

isEncodedSchemaPath

public static boolean isEncodedSchemaPath(SchemaPath schemaPath)

isEncodedSchemaPath

public static boolean isEncodedSchemaPath(String schemaPath)

decode

public static Collection<SchemaPath> decode(Collection<SchemaPath> encodedPaths)

Returns the decoded Collection of SchemaPath from the input which may contain a mix of encoded and non-encoded SchemaPaths.

The size of returned Collection is always equal to or greater than the input array.

The non-encoded SchemaPaths are collated in the beginning to the returned array, in the same order as that of the input array.

decode

public static String[] decode(String... encodedPaths)

Returns the decoded array of SchemaPath strings from the input which may contain a mix of encoded and non-encoded SchemaPaths.

The size of returned array is always equal to or greater than the input array.

The non-encoded SchemaPaths are collated in the beginning to the returned array, in the same order as that of the input array.