Chapter 4. Data types

4.1. Runtime types

Data Virtualization works with a core set of runtime types. Runtime types can be different from semantic types that are defined in type fields at design time. The runtime type can also be specified at design time or it will be automatically chosen as the closest base type to the semantic type.

Note

Even if a type is declared with a length, precision, or scale argument, those restrictions are effectively ignored by the runtime system, but may be enforced/reported at the edge by OData, ODBC, JDBC. Geospatial types act in a similar manner. Extension metadata might be needed for SRID, type, and number of dimensions for consumption by tools/OData, but it is not yet enforced. In some instances you might need to use the ST_SETSRID function to ensure the SRID is associated.

Table 4.1. Data Virtualization runtime types
Type	Description	Java runtime class	JDBC type	ODBC type
string or varchar	Variable length character string with a maximum length of 4000.	java.lang.String	VARCHAR	VARCHAR
varbinary	Variable length binary string with a nominal maximum length of 8192.	byte[] [1]	VARBINARY	VARBINARY
char	A single 16 bit character - which cannot represent a value beyond the Basic Multilingual Plane. This limitation also applies to functions/expressions that expect a single character such as trim, textagg, texttable, and like escape.	java.lang.Character	CHAR	CHAR
boolean	A single bit, or Boolean, that can be true, false, or null (unknown)	java.lang.Boolean	BIT	SMALLINT
byte or tinyint	Numeric, integral type, signed 8-bit	java.lang.Byte	TINYINT	SMALLINT
short or smallint	Numeric, integral type, signed 16-bit	java.lang.Short	SMALLINT	SMALLINT
integer or serial	Numeric, integral type, signed 32-bit. The serial type also implies not null and has an auto-incrementing value that starts at 1. serial types are not automatically UNIQUE.	java.lang.Integer	INTEGER	INTEGER
long or bigint	Numeric, integral type, signed 64-bit	java.lang.Long	BIGINT	NUMERIC
biginteger	Numeric, integral type, arbitrary precision of up to 1000 digits	java.math.BigInteger	NUMERIC	NUMERIC
float or real	Numeric, floating point type, 32-bit IEEE 754 floating-point numbers	java.lang.Float	REAL	FLOAT
double	Numeric, floating point type, 64-bit IEEE 754 floating-point numbers	java.lang.Double	DOUBLE	DOUBLE
bigdecimal or decimal	Numeric, floating point type, arbitrary precision of up to 1000 digits.	java.math.BigDecimal	NUMERIC	NUMERIC
date	Datetime, representing a single day (year, month, day)	java.sql.Date	DATE	DATE
time	Datetime, representing a single time (hours, minutes, seconds)	java.sql.Time	TIME	TIME
timestamp	Datetime, representing a single date and time (year, month, day, hours, minutes, seconds, fractional seconds).	java.sql.Timestamp	TIMESTAMP	TIMESTAMP
object	Any arbitrary Java object, must implement java.lang.Serializable.	Any	JAVA_OBJECT	VARCHAR
blob	Binary large object, representing a stream of bytes.	java.sql.Blob [2]	BLOB	VARCHAR
clob	Character large object, representing a stream of characters.	java.sql.Clob [3]	CLOB	VARCHAR
xml	XML document	java.sql.SQLXML[4]	JAVA_OBJECT	VARCHAR
geometry	Geospatial Object	java.sql.Blob [5]	BLOB	BLOB
geography (11.2+)	Geospatial Object	java.sql.Blob [6]	BLOB	BLOB
json (11.2+)	Character large object, representing a stream of JSON characters.	java.sql.Clob [7]	CLOB	VARCHAR

The runtime type is org.teiid.core.types.BinaryType. Translators will need to explicitly handle BinaryType values. UDFs will instead have a byte[] value passed.
The concrete type is expected to be org.teiid.core.types.BlobType
The concrete type is expected to be org.teiid.core.types.ClobType
The concrete type is expected to be org.teiid.core.types.XMLType
The concrete type is expected to be org.teiid.core.types.GeometryType
The concrete type is expected to be org.teiid.core.types.GeographyType
The concrete type is expected to be org.teiid.core.types.JsonType

Note

Character, String, and character large objects (CLOB) types are not limited to ASCII/extended ASCII values. Character can hold codes up to 2^16-1 and String/CLOB can hold any value.

Arrays

An array of any type is designated by adding [] for each array dimension to the type declaration.

Example: Array types

string[]

integer[][]

Note

Array handling is typically in memory. It is not advisable to rely on the usage of large array values. Arrays of large objects (LOBs) are typically not handled correctly when serialized.

4.2. Type conversions

Data types may be converted from one form to another either explicitly or implicitly. Implicit conversions automatically occur in criteria and expressions to ease development. Explicit datatype conversions require the use of the CONVERT function or CAST keyword.

Type conversion considerations

Any type may be implicitly converted to the OBJECT type.
The OBJECT type can be explicitly converted to any other type.
The NULL value can be converted to any type.
Any valid implicit conversion is also a valid explicit conversion.
In scenarios where literal values would normally require explicit conversions, you can apply implicit conversions if no loss of information occurs.
If widenComparisonToString is false (the default), Data Virtualization raises an exception if it detects that an explicit conversion cannot be applied implicitly in criteria.
If widenComparisonToString is true, then depending upon the comparison, a widening conversion is applied or the criteria are treated as false. For more information about widenComparisonToString, see System properties in the Administrator’s Guide.
Example
```
SELECT * FROM my.table WHERE created_by = 'not a date'
```
If widenComparisonToString is false, and created_by is a date, not a date cannot be converted to a date value, and an exception results.
Explicit conversions that are not allowed between two types will result in an exception before execution. Allowed explicit conversions can still fail during processing if the runtime values are not actually convertible.

Warning

The Data Virtualization conversions of float/double/bigdecimal/timestamp to string rely on the JDBC/Java defined output formats. Pushdown behavior attempts to mimic these results, but can vary depending upon the actual source type and conversion logic. It is best not to assume use of the string form in criteria or other places where variations might lead to different results.

Table 4.2. Type conversions
Source type	Valid implicit target types	Valid explicit target types
string	clob	char, boolean, byte, short, integer, long, biginteger, float, double, bigdecimal, xml ^[a]
char	string
boolean	string, byte, short, integer, long, biginteger, float, double, bigdecimal
byte	string, short, integer, long, biginteger, float, double, bigdecimal	boolean
short	string, integer, long, biginteger, float, double, bigdecimal	boolean, byte
integer	string, long, biginteger, double, bigdecimal	boolean, byte, short, float
long	string, biginteger, bigdecimal, float ^[b], double ^[b]	boolean, byte, short, integer, float, double
biginteger	string, bigdecimal float ^[b], double ^[b]	boolean, byte, short, integer, long, float, double
bigdecimal	string, float ^[b], double ^[b]	boolean, byte, short, integer, long, biginteger, float, double
float	string, bigdecimal, double	boolean, byte, short, integer, long, biginteger
double	string, bigdecimal, float ^[b]	boolean, byte, short, integer, long, biginteger, float
date	string, timestamp
time	string, timestamp
timestamp	string	date, time
clob		string
json	clob	string
xml		string ^[c]
geography		geometry
^[a] string to xml is equivalent to XMLPARSE(DOCUMENT exp). For more information, see XMLPARSE in XML functions. ^[b] Implicit conversion to float/double only occurs for literal values. ^[c] xml to string is equivalent to XMLSERIALIZE(exp AS STRING). For more information, see XMLSERIALIZE in XML functions.

4.3. Special conversion cases

Conversion of string literals

Data Virtualization automatically converts string literals within a SQL statement to their implied types. This typically occurs in a criteria comparison where an expression with a different datatype is compared to a literal string. For example:

SELECT * FROM my.table WHERE created_by = '2016-01-02'

In the preceding example, if the created_by column has the data type of date, Data Virtualization automatically converts the data type of the string literal to a date.

Converting to Boolean

Data Virtualization can automatically convert literal strings and numeric type values to Boolean values as shwon in the following table:

Table 4.3. Boolean conversions
Type	Literal value	Boolean value
String	'false'	false
	'unknown'	null
	other	true
Numeric	0	false
	other	true

Date and time conversions

Data Virtualization can implicitly convert properly formatted literal strings to their associated date-related data types as shown in the following table:

Table 4.4. Date and time conversions
String literal format	Possible implicit conversion type
yyyy-mm-dd	DATE
hh:mm:ss	TIME
yyyy-mm-dd[ hh:mm:ss.[fff…]]	TIMESTAMP

The preceding formats are those expected by the JDBC date types. For information about using other formats, see the functions PARSEDATE, PARSETIME, and PARSETIMESTAMP in Date and time functions.

4.4. Escaped literal syntax

Rather than relying on implicit conversion, you can define data type values directly in SQL by using escape syntax. The string values that you supply must match the expected format exactly, or an exception will occur.

Datatype	Escaped syntax	Standard literal
BOOLEAN	{b 'true'}	TRUE
DATE	{d 'yyyy-mm-dd'}	DATE 'yyyy-mm-dd'
TIME	{t 'hh-mm-ss'}	TIME 'hh-mm-ss'
TIMESTAMP	{ts 'yyyy-mm-dd[ hh:mm:ss.[fff…]]'}	TIMESTAMP 'yyyy-mm-dd[ hh:mm:ss.[fff…]]'

4.1. Runtime types

4.2. Type conversions

4.3. Special conversion cases

4.4. Escaped literal syntax

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