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Oracle connector

docs/src/main/sphinx/connector/oracle.md

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Oracle connector

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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 23 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 example catalog, create a file named example.properties in etc/catalog. Include the following connection properties in the file:

text
connector.name=oracle
# The correct syntax of the connection-url varies by Oracle version and
# configuration. The following example URL connects to an Oracle SID named
# "orcl".
connection-url=jdbc:oracle:thin:@example.net:1521:orcl
connection-user=root
connection-password=secret

The connection-url defines the connection information and parameters to pass to the JDBC driver. The Oracle connector uses the Oracle JDBC Thin driver, and the syntax of the URL may be different depending on your Oracle configuration. For example, the connection URL is different if you are connecting to an Oracle SID or an Oracle service name. See the Oracle Database JDBC driver documentation for more information.

The connection-user and connection-password are typically required and determine the user credentials for the connection, often a service user. You can use {doc}secrets </security/secrets> to avoid actual values in the catalog properties files.

:::{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:

properties
oracle.connection-pool.max-size=30
oracle.connection-pool.min-size=1
oracle.connection-pool.inactive-timeout=20m
oracle.connection-pool.wait-duration=3s

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

text
oracle.connection-pool.enabled=false
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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.

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(oracle-fte-support)=

Fault-tolerant execution support

The connector supports {doc}/admin/fault-tolerant-execution of query processing. Read and write operations are both supported with any retry policy.

Querying Oracle

The Oracle connector provides a schema for every Oracle database.

Run SHOW SCHEMAS to see the available Oracle databases:

SHOW SCHEMAS FROM example;

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

:::{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 example.web;

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

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

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

SELECT * FROM example.web.clicks;

(oracle-type-mapping)=

Type mapping

Because Trino and Oracle each support types that the other does not, this connector {ref}modifies some types <type-mapping-overview> when reading or writing data. Data types may not map the same way in both directions between Trino and the data source. Refer to the following sections for type mapping in each direction.

Oracle to Trino type mapping

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

:::{list-table} Oracle to Trino type mapping :widths: 30, 25, 50 :header-rows: 1

    • Oracle database type
    • Trino type
    • Notes
    • NUMBER(p, s)
    • DECIMAL(pʹ, sʹ) or NUMBER
    • Maps to Trino DECIMAL when input data can be represented as Trino DECIMAL losslessly. When 1 ≤ p ≤ 38 and 0 ≤ s ≤ p, then pʹ = p and sʹ = s, otherwise, a wider type is used.
      When input cannot be represented as Trino DECIMAL losslessly, maps to NUMBER.
    • NUMBER
    • NUMBER
    • FLOAT[(p)]
    • DOUBLE
    • When p exceeds 53, numeric values may be subject to precision loss. The default precision of the FLOAT data type in Oracle is 53.
    • 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(0)
    • See
    • TIMESTAMP(p)
    • TIMESTAMP(p)
    • See
    • TIMESTAMP(p) WITH TIME ZONE
    • TIMESTAMP WITH TIME ZONE
    • See :::

No other types are supported.

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. :::

:::{list-table} Trino to Oracle Type Mapping :widths: 30, 25, 50 :header-rows: 1

    • Trino type
    • Oracle database type
    • Notes
    • TINYINT
    • NUMBER(3)
    • SMALLINT
    • NUMBER(5)
    • INTEGER
    • NUMBER(10)
    • BIGINT
    • NUMBER(19)
    • DECIMAL(p, s)
    • NUMBER(p, s)
    • NUMBER
    • NUMBER
    • REAL
    • BINARY_FLOAT
    • DOUBLE
    • BINARY_DOUBLE
    • VARCHAR
    • NCLOB
    • VARCHAR(n)
    • VARCHAR2(n CHAR) or NCLOB
    • See
    • CHAR(n)
    • CHAR(n CHAR) or NCLOB
    • See
    • VARBINARY
    • BLOB
    • DATE
    • DATE
    • See
    • TIMESTAMP
    • TIMESTAMP(3)
    • See
    • TIMESTAMP WITH TIME ZONE
    • TIMESTAMP(3) WITH TIME ZONE
    • See :::

No other types are supported.

(oracle-datetime-mapping)=

Mapping datetime types

Writing a timestamp with fractional second precision (p) greater than 9 rounds the fractional seconds to nine digits.

Oracle DATE type stores hours, minutes, and seconds, so it is mapped to Trino TIMESTAMP(0).

:::{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. :::

(oracle-character-mapping)=

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;
text
 _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.

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Number to decimal configuration properties

:::{list-table} :widths: 20, 20, 50, 10 :header-rows: 1

    • 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 :::

(oracle-sql-support)=

SQL support

The connector provides read access and write access to data and metadata in Oracle. In addition to the globally available and read operation statements, the connector supports the following features:

  • , see also
  • , see also
  • , see also
  • , see also

(oracle-insert)=

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(oracle-update)=

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(oracle-delete)=

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(oracle-alter-table)=

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(oracle-procedures)=

Procedures

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(oracle-table-functions)=

Table functions

The connector provides specific {doc}table functions </functions/table> to access Oracle.

(oracle-query-function)=

query(varchar) -> table

The query function allows you to query the underlying database directly. It requires syntax native to Oracle, because the full query is pushed down and processed in Oracle. This can be useful for accessing native features which are not available in Trino or for improving query performance in situations where running a query natively may be faster.

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As a simple example, query the example catalog and select an entire table:

SELECT
  *
FROM
  TABLE(
    example.system.query(
      query => 'SELECT
        *
      FROM
        tpch.nation'
    )
  );

As a practical example, you can use the MODEL clause from Oracle SQL:

SELECT
  SUBSTR(country, 1, 20) country,
  SUBSTR(product, 1, 15) product,
  year,
  sales
FROM
  TABLE(
    example.system.query(
      query => 'SELECT
        *
      FROM
        sales_view
      MODEL
        RETURN UPDATED ROWS
        MAIN
          simple_model
        PARTITION BY
          country
        MEASURES
          sales
        RULES
          (sales['Bounce', 2001] = 1000,
          sales['Bounce', 2002] = sales['Bounce', 2001] + sales['Bounce', 2000],
          sales['Y Box', 2002] = sales['Y Box', 2001])
      ORDER BY
        country'
    )
  );
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Performance

The connector includes a number of performance improvements, detailed in the following sections.

Synonyms

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

text
oracle.synonyms.enabled=true

(oracle-pushdown)=

Pushdown

The connector supports pushdown for a number of operations:

  • {ref}join-pushdown
  • {ref}limit-pushdown

In addition, the connector supports {ref}aggregation-pushdown for the following functions:

  • {func}avg()
  • {func}count(), also count(distinct x)
  • {func}max()
  • {func}min()
  • {func}sum()

Pushdown is only supported for DOUBLE type columns with the following functions:

  • {func}stddev() and {func}stddev_samp()
  • {func}stddev_pop()
  • {func}var_pop()
  • {func}variance() and {func}var_samp()

Pushdown is only supported for REAL or DOUBLE type column with the following functions:

  • {func}covar_samp()
  • {func}covar_pop()
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(oracle-predicate-pushdown)=

Predicate pushdown support

The connector does not support pushdown of any predicates on columns that use the CLOB, NCLOB, BLOB, or RAW(n) Oracle database types, or Trino data types that {ref}map <oracle-type-mapping> to these Oracle database types.

In the following example, the predicate is not pushed down for either query since name is a column of type VARCHAR, which maps to NCLOB in Oracle:

sql
SHOW CREATE TABLE nation;

--             Create Table
----------------------------------------
-- CREATE TABLE oracle.trino_test.nation (
--    name VARCHAR
-- )
-- (1 row)

SELECT * FROM nation WHERE name > 'CANADA';
SELECT * FROM nation WHERE name = 'CANADA';

In the following example, the predicate is pushed down for both queries since name is a column of type VARCHAR(25), which maps to VARCHAR2(25) in Oracle:

sql
SHOW CREATE TABLE nation;

--             Create Table
----------------------------------------
-- CREATE TABLE oracle.trino_test.nation (
--    name VARCHAR(25)
-- )
-- (1 row)

SELECT * FROM nation WHERE name > 'CANADA';
SELECT * FROM nation WHERE name = 'CANADA';