Advanced Database Persistence for Java

Examples & Reference Manual
 

PostgreSQL

The HotRod PostgreSQL adapter automatically maps known database column types to DAO Java types. In most of the cases this default Java type is well suited to handle the database values. However, when needed the default Java type of a property can be overridden by a custom type if it's provided by the developer.

Default Java Types

If a custom Java type is not specified HotRod will use the following rules to decide which Java type to use for each PostgreSQL column. In yellow is the DAO property type. In parenthesis the actual object type returned by the PostgreSQL JDBC driver, that on occasions may be different.

Please note that the Java types for the PostgreSQL columns may vary depending on the specific version and variant of the RDBMS, the operating system where the database engine is running, and the JDBC driver version.

PostgreSQL Column Type Default Java Type
SMALLINT,
INT2,
SMALLSERIAL 		java.lang.Short
INTEGER,
INT,
INT4,
SERIAL 		java.lang.Integer
BIGINT,
INT8,
BIGSERIAL 		java.lang.Long
DECIMAL(p,s),
NUMERIC(p,s) 		If neither p or s are specified:
  • java.math.BigDecimal
If s is specified and different from zero the Java type is:
  • java.math.BigDecimal
if s is not specified or specified with a value of zero:
  • if p <= 2: java.lang.Byte
  • if 2 < p <= 4: java.lang.Short
  • if 4 < p <= 9: java.lang.Integer
  • if 8 < p <= 18: java.lang.Long
  • if p > 18: java.math.BigInteger
REAL java.lang.Float
DOUBLE PRECISION java.lang.Double
MONEY java.math.BigDecimal
CHAR(n),
CHARACTER(n),
VARCHAR(n),
CHARACTER VARYING(n), 		java.lang.String
TEXT java.lang.String
BYTEA byte[]
DATE java.sql.Date
TIMESTAMP(n),
TIMESTAMP(n) WITHOUT TIME ZONE,
TIMESTAMPTZ(n),
TIMESTAMP(n) WITH TIME ZONE 		java.sql.Timestamp
TIME(n),
TIME(n) WITHOUT TIME ZONE,
TIMETZ(n),
TIME(n) WITH TIME ZONE 		java.sql.Timestamp *
BOOLEAN,
BOOL 		java.lang.Boolean
INTERVAL <fields> (n) No default HotRod data type
XML No default HotRod data type
POINT,
LINE,
LSEG,
BOX,
PATH,
POLYGON,
CIRCLE 		No default HotRod data type
CIDR,
INET,
MACADDR 		No default HotRod data type
BIT(n),
BIT VARYING(n) 		No default HotRod data type
UUID java.lang.Object **
JSON,
JSONB 		No default HotRod data type
(arrays, such as)
INTEGER[],
CHAR[][],
INTEGER ARRAY 		No default HotRod data type
INT4RANGE,
INT8RANGE,
NUMRANGE,
TSRANGE,
TSTZRANGE,
DATERANGE 		No default HotRod data type
(enum data types) No default HotRod data type
(composite types) No default HotRod data type
OID,
REGPROC,
REGPROCEDURE,
REGOPER,
REGOPERATOR,
REGCLASS,
REGTYPE,
REGROLE,
REGNAMESPACE,
REGCONFIG,
REGDICTIONARY 		No default HotRod data type

* In the special case of a precision of zero, a  java.sql.Time type would be enough to store any time of the day without fractional seconds. However, since the majority of cases will have a different precision this type defaults to java.sql.Timestamp in all cases; this type can handle up to 9 decimal places.
** Even though, the java.util.UUID type is able to save a value into the database, apparently it cannot read from the database into a Java program. Therefore, the java.lang.Object type is safer, but you'll need to cast it after retrieving a value.

Custom Java Types

To override the default Java type see the reference section for the tables, views, and selects. The Example 19 - Custom DAO Property Java Types shows a case where a custom type overrides the default type. To override the default type add a <column> tag in a <table> , <view> , or <select> definition.