Oracle Usage Oracle Data Types and PostgreSQL Data Types PostgreSQL Usage Migration of Oracle Data Types to PostgreSQL Data Types

Common Data Types

Feature compatibility	AWS SCT / AWS DMS automation level	AWS SCT action code index	Key differences
		Data Types	PostgreSQL doesn’t support `BFILE`, `ROWID`, `UROWID`.

Oracle Usage

Oracle provides a set of primitive data types for defining table columns and PL/SQL code variables. The assigned data types for table columns or PL/SQL code (such as stored procedures and triggers) define the valid values each column or argument can store.

Oracle Data Types and PostgreSQL Data Types

Character data types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
CHAR(n)	Maximum size of 2000 bytes	Yes	CHAR(n)
CHARACTER(n)	Maximum size of 2000 bytes	Yes	CHARACTER(n)
NCHAR(n)	Maximum size of 2000 bytes	No	CHAR(n)
VARCHAR(n)	Maximum size of 2000 bytes	Yes	VARCHAR(n)
NCHAR VARYING (n)	Varying-length UTF-8 string, maximum size of 4000 bytes	No	CHARACTER VARYING(n)
VARCHAR2(n) 11g	Maximum size of 4000 bytes. Maximum size of 32KB in PL/SQL.	No	VARCHAR(n)
VARCHAR2(n) 12g	Maximum size of 32767 bytes. MAX_STRING_SIZE=EXTENDED	No	VARCHAR(n)
NVARCHAR2(n)	Maximum size of 4000 bytes	No	VARCHAR(n)
LONG	Maximum size of 2GB	No	TEXT
RAW(n)	Maximum size of 2000 bytes	No	BYTEA
LONG RAW	Maximum size of 2GB	No	BYTEA

Numeric data types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
NUMBER	Floating-point number	No	DOUBLE PRECISION
NUMBER(*)	Floating-point number	No	DOUBLE PRECISION
NUMBER(p,s)	Precision can range from 1 to 38, scale can range from -84 to 127	No	DECIMAL(p,s)
NUMERIC(p,s)	Precision can range from 1 to 38	Yes	NUMERIC(p,s)
FLOAT(p)	Floating-point number	No	DOUBLE PRECISION
DEC(p,s)	Fixed-point number	Yes	DEC(p,s)
DECIMAL(p,s)	Fixed-point number	Yes	DECIMAL(p,s)
INT	38 digits integer	Yes	INTEGER or NUMERIC(38,0)
INTEGER	38 digits integer	Yes	INTEGER or NUMERIC(38,0)
SMALLINT	38 digits integer	Yes	SMALLINT
REAL	Floating-point number	No	DOUBLE PRECISION
DOUBLE PRECISION	Floating-point number	Yes	DOUBLE PRECISION

Date and time data types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
DATE	DATE data type stores date and time data (year, month, day, hour, minute and second)	Yes	TIMESTAMP(0)
TIMESTAMP(p)	Date and time with fraction	Yes	TIMESTAMP(p)
TIMESTAMP(p) WITH TIME ZONE	Date and time with fraction and time zone	Yes	TIMESTAMP(p) WITH TIME ZONE
INTERVAL YEAR(p) TO MONTH	Date interval	Yes	INTERVAL YEAR TO MONTH
INTERVAL DAY(p) TO SECOND(s)	Day and time interval	Yes	INTERVAL DAY TO SECOND(s)

LOB data types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
BFILE	Pointer to binary file, maximum file size of 4 GB	No	VARCHAR (255) or CHARACTER VARYING (255)
BLOB	Binary large object, maximum file size of 4 GB	No	BYTEA
CLOB	Character large object, maximum file size of 4 GB	No	TEXT
NCLOB	Variable-length Unicode string, maximum file size of 4 GB	No	TEXT

ROWID data types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
ROWID	Physical row address	No	CHARACTER (255)
UROWID(n)	Universal row id, logical row addresses	No	CHARACTER VARYING

XML data type

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
XMLTYPE	XML data	No	XML

Logical data type

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
BOOLEAN	Values `TRUE`, `FALSE`, and `NULL`, can’t be assigned to a database table column	Yes	BOOLEAN

Spatial types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
SDO_GEOMETRY	The geometric description of a spatial object	No	N/A
SDO_TOPO_GEOMETRY	Describes a topology geometry	No	N/A
SDO_GEORASTER	A raster grid or image object is stored in a single row	No	N/A

Media types

Oracle data type	Oracle data type characteristic	PostgreSQL identical compatibility	PostgreSQL corresponding data type
ORDDicom	Supports the storage and management of audio data	No	N/A
ORDDicom	Supports the storage and management of Digital Imaging and Communications in Medicine (DICOM).	No	N/A
ORDDoc	Supports storage and management of any type of media data	No	N/A
ORDImage	Supports the storage and management of image data	No	N/A
ORDVideo	Supports the storage and management of video data	No	N/A

Note

The “PostgreSQL identical compatibility” column indicates if you can use the exact Oracle data type syntax when migrating to Amazon Aurora PostgreSQL.

Oracle Character Column Semantics

Oracle supports both BYTE and CHAR semantics for column size, which determines the amount of storage allocated for CHAR and VARCHAR columns.

If you define a field as VARCHAR2(10 BYTE), Oracle can use up to 10 bytes for storage. However, based on your database codepage and NLS settings, you may not be able to store 10 characters in that field because the physical size of some non-English characters exceeds one byte.
If you define a field as VARCHAR2(10 CHAR), Oracle can store 10 characters no matter how many bytes are required to store each non-English character.

CREATE TABLE table1 (col1 VARCHAR2(10 CHAR), col2 VARCHAR2(10 BYTE));

By default, Oracle uses BYTE semantics. When using a multi-byte character set such as UTF8, use one of the following options.

Use the CHAR modifier in the VARCHAR2 or CHAR column definition.
Modify the session or system parameter NLS_LENGTH_SEMANTICS to change the default from BYTE to CHAR.

ALTER system SET nls_length_semantics=char scope=both;
ALTER system SET nls_length_semantics=byte scope=both;

ALTER session SET nls_length_semantics=char;
ALTER session SET nls_length_semantics=byte;

For more information, see Data Types in the Oracle documentation.

PostgreSQL Usage

PostgreSQL provides multiple data types equivalent to certain Oracle data types. The following table provides the full list of PostgreSQL data types.

Character data types

PostgreSQL data type	PostgreSQL data type characteristic
CHAR	Stores a single character
CHARACTER	Stores a single character
CHAR(n)	Stores exactly (n) characters
VARCHAR(N)	Stores a variable number of characters, up to a maximum of n characters
TEXT	Specific variant of varchar, which doesn’t require you to specify an upper limit on the number of characters

Numeric data types

PostgreSQL data type	PostgreSQL data type characteristic
NUMERIC (P,S)	Exact numeric of selectable precision
REAL	Single precision floating-point number (4 bytes)
DOUBLE PRECISION	Double precision floating-point number (8 bytes)
INT	A signed 4-byte integer that can store from -2147483648 to +2147483647
INTEGER	A signed 4-byte integer that can store from -2147483648 to +2147483647
SMALLINT	A signed 2-byte integer that can store from -32768 to +32767
BIGINT	A signed 8-byte integer, giving approximately 18 digits of precision
BIT	Stores a single bit, 0 or 1
BIT VARYING	Stores a string of bits
MONEY	Equivalent to NUMERIC (9,2), storing 4 bytes of data. Its use is discouraged.

Date and time data types

PostgreSQL data type	PostgreSQL data type characteristic
TIMESTAMP	Stores dates and times from 4713 BC to 1465001 AD, with a resolution of 1 microsecond - 8 bytes
INTERVAL	Stores an interval of approximately 178,000,000 years, with a resolution of 1 microsecond - 16 bytes
DATE	Stores dates from 4713 BC to 32767 AD, with a resolution of 1 day - 4 bytes
TIME	Stores a time of day, from 0 to 23:59:59.99, with a resolution of 1 microsecond - 8 bytes with no timezone, 12 bytes with timezone

Logical data type

PostgreSQL data type	PostgreSQL data type characteristic
BOOLEAN	Holds a truth value. Will accept values such as TRUE, 't','true', 'y', 'yes', and '1' as true. Uses 1 byte of storage, and can store NULL. You can use this type upon table creation.

XML data type

PostgreSQL data type	PostgreSQL data type characteristic
XML	XML data

Geometric data types

PostgreSQL data type	PostgreSQL data type characteristic
POINT	The column type to specify when you want to use the following data models
LINE	An (x,y) value
LSEG	A line (pt1, pt2)
BOX	A sequence of points, effectively a closed path
PATH	Collection of POINTs
POLYGON	Collection of LINEs
CIRCLE	Collection of POLYGONs

PotgreSQL data types

PostgreSQL data type	PostgreSQL data type characteristic
JSON	Textual JSON data
JSONB	Binary JSON data, decomposed
SERIAL	A numeric column in a table that increases each time a row is added
OID	An object identifier. Internally, PostgreSQL adds, by default, a hidden oid to each row, and stores a 4-byte integer.
CIDR	Stores a network address of the form x.x.x.x/y where y is the netmask
INET	Similar to cidr, except the host part can be 0
MACADDR	MAC (Media Access Control) address
MACADDR8	MAC (Media Access Control) address in EUI-64 format (PostgreSQL 10)
PG_LSN	PostgreSQL Log Sequence Number
BYTEA	Binary data ("byte array")
TSQUERY	Text search query
TSVECTOR	Text search document
TXID_SNAPSHOT	User-level transaction ID snapshot
UUID	Universally unique identifier

PostgreSQL Character Column Semantics

PostgreSQL only supports CHAR for column size semantics. If you define a field as VARCHAR (10), PostgreSQL can store 10 characters regardless of how many bytes it takes to store each non-English character. VARCHAR(n) stores strings up to n characters (not bytes) in length.

Migration of Oracle Data Types to PostgreSQL Data Types

You can perform automatic migration and conversion of Oracle tables and data types using AWS Schema Conversion Tool (AWS SCT).

Examples

To demonstrate AWS SCT capability for migrating Oracle tables to their PostgreSQL equivalents, a table containing columns representing the majority of Oracle data types was created and converted using AWS SCT.

Source Oracle compatible DDL for creating the DATATYPES table.

CREATE TABLE "DATATYPES"(
  "BFILE"                    BFILE,
  "BINARY_FLOAT"             BINARY_FLOAT,
  "BINARY_DOUBLE"            BINARY_DOUBLE,
  "BLOB"                     BLOB,
  "CHAR"                     CHAR(10 BYTE),
  "CHARACTER"                CHAR(10 BYTE),
  "CLOB"                     CLOB,
  "NCLOB"                    NCLOB,
  "DATE"                     DATE,
  "DECIMAL"                  NUMBER(3,2),
  "DEC"                      NUMBER(3,2),
  "DOUBLE_PRECISION"         FLOAT(126),
  "FLOAT"                    FLOAT(3),
  "INTEGER"                  NUMBER(*,0),
  "INT"                      NUMBER(*,0),
  "INTERVAL_YEAR"            INTERVAL YEAR(4) TO MONTH,
  "INTERVAL_DAY"             INTERVAL DAY(4) TO SECOND(4),
  "LONG"                     LONG,
  "NCHAR"                    NCHAR(10),
  "NCHAR_VARYING"            NVARCHAR2(10),
  "NUMBER"                   NUMBER(9,9),
  "NUMBER1"                  NUMBER(9,0),
  "NUMBER(*)"                NUMBER,
  "NUMERIC"                  NUMBER(9,9),
  "NVARCHAR2"                NVARCHAR2(10),
  "RAW"                      RAW(10),
  "REAL"                     FLOAT(63),
  "ROW_ID"                   ROWID,
  "SMALLINT"                 NUMBER(*,0),
  "TIMESTAMP"                TIMESTAMP(5),
  "TIMESTAMP_WITH_TIME_ZONE" TIMESTAMP(5) WITH TIME ZONE,
  "UROWID"                   UROWID(10),
  "VARCHAR"                  VARCHAR2(10 BYTE),
  "VARCHAR2"                 VARCHAR2(10 BYTE),
  "XMLTYPE"                  XMLTYPE
);

Target PostgreSQL compatible DDL for creating the DATATYPES table migrated from Oracle with AWS SCT.

CREATE TABLE IF NOT EXISTS datatypes(
bfile                    character varying(255) DEFAULT NULL,
binary_float             real DEFAULT NULL,
binary_double            double precision DEFAULT NULL,
blob                     bytea DEFAULT NULL,
char                     character(10) DEFAULT NULL,
character                character(10) DEFAULT NULL,
clob                     text DEFAULT NULL,
nclob                    text DEFAULT NULL,
date                     TIMESTAMP(0) without time zone DEFAULT NULL,
decimal                  numeric(3,2) DEFAULT NULL,
dec                      numeric(3,2) DEFAULT NULL,
double_precision         double precision DEFAULT NULL,
float                    double precision DEFAULT NULL,
integer                  numeric(38,0) DEFAULT NULL,
int                      numeric(38,0) DEFAULT NULL,
interval_year            interval year to month(6) DEFAULT NULL,
interval_day             interval day to second(4) DEFAULT NULL,
long                     text DEFAULT NULL,
nchar                    character(10) DEFAULT NULL,
nchar_varying            character varying(10) DEFAULT NULL,
number                   numeric(9,9) DEFAULT NULL,
number1                  numeric(9,0) DEFAULT NULL,
"number(*)"              double precision DEFAULT NULL,
numeric                  numeric(9,9) DEFAULT NULL,
nvarchar2                character varying(10) DEFAULT NULL,
raw                      bytea DEFAULT NULL,
real                     double precision DEFAULT NULL,
row_id                   character(255) DEFAULT NULL,
smallint                 numeric(38,0) DEFAULT NULL,
timestamp                TIMESTAMP(5) without time zone DEFAULT NULL,
timestamp_with_time_zone TIMESTAMP(5) with time zone DEFAULT NULL,
urowid                   character varying DEFAULT NULL,
varchar                  character varying(10) DEFAULT NULL,
varchar2                 character varying(10) DEFAULT NULL,
xmltype                  xml DEFAULT NULL
)
WITH (
OIDS=FALSE
);

AWS SCT converted most of the datatypes. However, a few exceptions were raised for datatypes that AWS SCT is unable to automatically convert and where AWS SCT recommended manual actions.

PostgreSQL doesn’t have a data type BFILE

BFILEs are pointers to binary files.

Recommended actions: Either store a named file with the data and create a routine that gets that file from the file system, or store the data blob inside your database.

PostgreSQL doesn’t have a data type ROWID

ROWIDs are physical row addresses inside Oracle storage subsystems. The ROWID datatype is primarily used for values returned by the ROWID pseudocolumn.

Recommended actions: While PostgreSQL contains a ctid column that is the physical location of the row version within its table, it doesn’t have a comparable data type. However, you can use CHAR as a partial datatype equivalent.

If you use ROWID datatypes in your code, modifications may be necessary.

PostgreSQL doesn’t have a data type UROWID

Universal rowid, or UROWID, is a single Oracle datatype that supports both logical and physical rowids of foreign table rowids such as non-Oracle tables accessed through a gateway.

Recommended actions: PostgreSQL doesn’t have a comparable data type. You can use VARCHAR(n) as a partial datatype equivalent. However, if you are using UROWID datatypes in your code, modifications may be necessary.

For more information, see System Columns and Data Types in the PostgreSQL documentation, and What is the AWS Schema Conversion Tool? in the user guide.

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Document Conventions

Case Sensitivity Differences for Oracle and PostgreSQL

Oracle Read-Only Tables and Partitions and PostgreSQL Aurora Replicas