Oracle connector#

The Oracle connector allows querying and creating tables in an external Oracle database. Connectors let Trino join data provided by different databases, like Oracle and Hive, or different Oracle database instances.

Requirements#

To connect to Oracle, you need:

  • Oracle 12 or higher.

  • Network access from the Trino coordinator and workers to Oracle. Port 1521 is the default port.

Configuration#

To configure the Oracle connector as the oracle catalog, create a file named oracle.properties in etc/catalog. Include the following connection properties in the file:

connector.name=oracle
connection-url=jdbc:oracle:thin:@example.net:1521/ORCLCDB
connection-user=root
connection-password=secret

Note

Oracle does not expose metadata comment via REMARKS column by default in JDBC driver. You can enable it using oracle.remarks-reporting.enabled config option. See Additional Oracle Performance Extensions for more details.

By default, the Oracle connector uses connection pooling for performance improvement. The below configuration shows the typical default values. To update them, change the properties in the catalog configuration file:

oracle.connection-pool.max-size=30
oracle.connection-pool.min-size=1
oracle.connection-pool.inactive-timeout=20m

To disable connection pooling, update properties to include the following:

oracle.connection-pool.enabled=false

Multiple Oracle servers#

If you want to connect to multiple Oracle servers, configure another instance of the Oracle connector as a separate catalog.

To add another Oracle catalog, create a new properties file. For example, if you name the property file sales.properties, Trino creates a catalog named sales.

Querying Oracle#

The Oracle connector provides a schema for every Oracle database.

Run SHOW SCHEMAS to see the available Oracle databases:

SHOW SCHEMAS FROM oracle;

If you used a different name for your catalog properties file, use that catalog name instead of oracle.

Note

The Oracle user must have access to the table in order to access it from Trino. The user configuration, in the connection properties file, determines your privileges in these schemas.

Examples#

If you have an Oracle database named web, run SHOW TABLES to see the tables it contains:

SHOW TABLES FROM oracle.web;

To see a list of the columns in the clicks table in the web database, run either of the following:

DESCRIBE oracle.web.clicks;
SHOW COLUMNS FROM oracle.web.clicks;

To access the clicks table in the web database, run the following:

SELECT * FROM oracle.web.clicks;

Type mapping#

Both Oracle and Trino have types that are not supported by the Oracle connector. The following sections explain their type mapping.

Oracle to Trino type mapping#

Trino supports selecting Oracle database types. This table shows the Oracle to Trino data type mapping:

Oracle to Trino type mapping#

Oracle database type

Trino type

Notes

NUMBER(p, s)

DECIMAL(p, s)

See Mapping numeric types

NUMBER(p)

DECIMAL(p, 0)

See Mapping numeric types

FLOAT[(p)]

DOUBLE

BINARY_FLOAT

REAL

BINARY_DOUBLE

DOUBLE

VARCHAR2(n CHAR)

VARCHAR(n)

VARCHAR2(n BYTE)

VARCHAR(n)

NVARCHAR2(n)

VARCHAR(n)

CHAR(n)

CHAR(n)

NCHAR(n)

CHAR(n)

CLOB

VARCHAR

NCLOB

VARCHAR

RAW(n)

VARBINARY

BLOB

VARBINARY

DATE

TIMESTAMP

See Mapping datetime types

TIMESTAMP(p)

TIMESTAMP

See Mapping datetime types

TIMESTAMP(p) WITH TIME ZONE

TIMESTAMP WITH TIME ZONE

See Mapping datetime types

Trino to Oracle type mapping#

Trino supports creating tables with the following types in an Oracle database. The table shows the mappings from Trino to Oracle data types:

Note

For types not listed in the table below, Trino can’t perform the CREATE TABLE <table> AS SELECT operations. When data is inserted into existing tables Oracle to Trino type mapping is used.

Trino to Oracle Type Mapping#

Trino type

Oracle database type

Notes

TINYINT

NUMBER(3)

SMALLINT

NUMBER(5)

INTEGER

NUMBER(10)

BIGINT

NUMBER(19)

DECIMAL(p, s)

NUMBER(p, s)

REAL

BINARY_FLOAT

DOUBLE

BINARY_DOUBLE

VARCHAR

NCLOB

VARCHAR(n)

VARCHAR2(n CHAR) or NCLOB

See Mapping character types

CHAR(n)

CHAR(n CHAR) or NCLOB

See Mapping character types

VARBINARY

BLOB

DATE

DATE

See Mapping datetime types

TIMESTAMP

TIMESTAMP(3)

See Mapping datetime types

TIMESTAMP WITH TIME ZONE

TIMESTAMP(3) WITH TIME ZONE

See Mapping datetime types

Mapping numeric types#

An Oracle NUMBER(p, s) maps to Trino’s DECIMAL(p, s) except in these conditions:

  • No precision is specified for the column (example: NUMBER or NUMBER(*)), unless oracle.number.default-scale is set.

  • Scale (s ) is greater than precision.

  • Precision (p ) is greater than 38.

  • Scale is negative and the difference between p and s is greater than 38, unless oracle.number.rounding-mode is set to a different value than UNNECESSARY.

If s is negative, NUMBER(p, s) maps to DECIMAL(p + s, 0).

For Oracle NUMBER (without precision and scale), you can change oracle.number.default-scale=s and map the column to DECIMAL(38, s).

Mapping datetime types#

Selecting a timestamp with fractional second precision (p) greater than 3 truncates the fractional seconds to three digits instead of rounding it.

Oracle DATE type may store hours, minutes, and seconds, so it is mapped to Trino TIMESTAMP.

Warning

Due to date and time differences in the libraries used by Trino and the Oracle JDBC driver, attempting to insert or select a datetime value earlier than 1582-10-15 results in an incorrect date inserted.

Mapping character types#

Trino’s VARCHAR(n) maps to VARCHAR2(n CHAR) if n is no greater than 4000. A larger or unbounded VARCHAR maps to NCLOB.

Trino’s CHAR(n) maps to CHAR(n CHAR) if n is no greater than 2000. A larger CHAR maps to NCLOB.

Using CREATE TABLE AS to create an NCLOB column from a CHAR value removes the trailing spaces from the initial values for the column. Inserting CHAR values into existing NCLOB columns keeps the trailing spaces. For example:

CREATE TABLE vals AS SELECT CAST('A' as CHAR(2001)) col;
INSERT INTO vals (col) VALUES (CAST('BB' as CHAR(2001)));
SELECT LENGTH(col) FROM vals;
 _col0
-------
  2001
     1
(2 rows)

Attempting to write a CHAR that doesn’t fit in the column’s actual size fails. This is also true for the equivalent VARCHAR types.

General configuration properties#

The following properties can be used to configure how data types from the connected data source are mapped to Trino data types and how the metadata is cached in Trino.

Property name

Description

Default value

unsupported-type-handling

Configure how unsupported column data types are handled:

  • IGNORE, column is not accessible.

  • CONVERT_TO_VARCHAR, column is converted to unbounded VARCHAR.

The respective catalog session property is unsupported_type_handling.

IGNORE

jdbc-types-mapped-to-varchar

Allow forced mapping of comma separated lists of data types to convert to unbounded VARCHAR

case-insensitive-name-matching

Support case insensitive database and collection names

False

case-insensitive-name-matching.cache-ttl

1 minute

metadata.cache-ttl

Duration for which metadata, including table and column statistics, is cached

0 (disabled caching)

metadata.cache-missing

Cache the fact that metadata, including table and column statistics, is not available

False

Number to decimal configuration properties#

Configuration property name

Session property name

Description

Default

oracle.number.default-scale

number_default_scale

Default Trino DECIMAL scale for Oracle NUMBER (without precision and scale) date type. When not set then such column is treated as not supported.

not set

oracle.number.rounding-mode

number_rounding_mode

Rounding mode for the Oracle NUMBER data type. This is useful when Oracle NUMBER data type specifies higher scale than is supported in Trino. Possible values are:

  • UNNECESSARY - Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary.

  • CEILING - Rounding mode to round towards positive infinity.

  • FLOOR - Rounding mode to round towards negative infinity.

  • HALF_DOWN - Rounding mode to round towards nearest neighbor unless both neighbors are equidistant, in which case rounding down is used.

  • HALF_EVEN - Rounding mode to round towards the nearest neighbor unless both neighbors are equidistant, in which case rounding towards the even neighbor is performed.

  • HALF_UP - Rounding mode to round towards nearest neighbor unless both neighbors are equidistant, in which case rounding up is used

  • UP - Rounding mode to round towards zero.

  • DOWN - Rounding mode to round towards zero.

UNNECESSARY

Synonyms#

Based on performance reasons, Trino disables support for Oracle SYNONYM. To include SYNONYM, add the following configuration property:

oracle.synonyms.enabled=true

Pushdown#

The connector supports pushdown for a number of operations:

Limitations#

The following SQL statements are not supported: