com.pervasive.datarush.schema

Class PatternBasedDiscovery

java.lang.Object

com.pervasive.datarush.schema.PatternBasedDiscovery

All Implemented Interfaces:

TextRecordDiscoverer

public class PatternBasedDiscovery
extends Object
implements TextRecordDiscoverer

Discovers a schema for delimited text by checking values against a mapping of regular expressions to data types.

Field Summary

Fields

Modifier and Type	Field and Description
static List<TypePattern>	DEFAULT_PATTERNS The default patterns used in discovery when none are specified, in order: TypePattern.INT_PATTERN TypePattern.LONG_PATTERN TypePattern.DOUBLE_PATTERN TypePattern.DATE_PATTERN TypePattern.TIME_PATTERN TypePattern.TIMESTAMP_PATTERN TypePattern.BOOLEAN_PATTERN

Constructor Summary

Constructors

Constructor and Description
PatternBasedDiscovery() Creates a default mapping.
PatternBasedDiscovery(List<TypePattern> patterns) Creates a mapping using the specified patterns.

Method Summary

Modifier and Type	Method and Description
TextRecord	discoverForRead(List<List<String>> rows, boolean containsHeader, TextConversionDefaults defaults) Constructs a schema for reading based on the given file analysis.
TextRecord	generateForWrite(RecordTokenType type, TextConversionDefaults defaults) Constructs a schema for writing based on the given record type.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PATTERNS

public static List<TypePattern> DEFAULT_PATTERNS

The default patterns used in discovery when none are specified, in order:

• TypePattern.INT_PATTERN
• TypePattern.LONG_PATTERN
• TypePattern.DOUBLE_PATTERN
• TypePattern.DATE_PATTERN
• TypePattern.TIME_PATTERN
• TypePattern.TIMESTAMP_PATTERN
• TypePattern.BOOLEAN_PATTERN

Constructor Detail

PatternBasedDiscovery

public PatternBasedDiscovery()

Creates a default mapping. The default mapping detects:

• TextTypes.JAVA_INT
• TextTypes.JAVA_LONG
• TextTypes.JAVA_DOUBLE
• TextTypes.ISO_DATE
• TextTypes.ISO_TIMEOFDAY
• TextTypes.ISO_TIMESTAMP
• TextTypes.TRUE_FALSE

See Also:

DEFAULT_PATTERNS

PatternBasedDiscovery

public PatternBasedDiscovery(List<TypePattern> patterns)

Creates a mapping using the specified patterns. Patterns are tested in the order listed with the first matching pattern used to determine type. Conflicts between records on a field's type are resolved to TextTypes.STRING in most cases. If a field value matches the default null indicator, it is ignored for typing purposes.

Parameters:

patterns - the patterns against which to compare values. The list is in precedence order; the first pattern to match determines the type.

Method Detail

discoverForRead

public TextRecord discoverForRead(List<List<String>> rows,
                                  boolean containsHeader,
                                  TextConversionDefaults defaults)

Description copied from interface: TextRecordDiscoverer

Constructs a schema for reading based on the given file analysis. The analysis may or may not include a header row, as indicated.

Specified by:

discoverForRead in interface TextRecordDiscoverer

Parameters:

rows - the analyzed rows from a text file

containsHeader - indicates whether the first row of the analyzed file is a header

defaults - defaults for the discovered schema

Returns:

a schema appropriate for reading the file.

generateForWrite

public TextRecord generateForWrite(RecordTokenType type,
                                   TextConversionDefaults defaults)

Description copied from interface: TextRecordDiscoverer

Constructs a schema for writing based on the given record type.

Specified by:

generateForWrite in interface TextRecordDiscoverer

Parameters:

type - the record type of the data

defaults - defaults for the discovered schema

Returns:

a schema appropriate for writing data of the given type