Oracle to MariaDB Migration - Oracle Compatibility Mode

SQLines provides tools to help you transfer data, convert database schema (DDL), views, stored procedures, functions, packages, triggers, queries and SQL scripts from Oracle to MariaDB:

  • SQLines Data - Data transfer, schema migration and validation tool
  • SQLines SQL Converter - SQL scripts assessment and conversion tool

Databases:

  • Oracle 19c, 18c, 12c, 11g, 10g and 9i
  • MariaDB 10.x

Starting from MariaDB 10.3 there is the Oracle compatibility mode that allows MariaDB to understand a subset of Oracle's PL/SQL language. To enable this mode, use:

set sql_mode=oracle;

This reference documents Oracle to MariaDB migration issues in the Oracle compatibility mode. For migration to the MariaDB native SQL language, see Oracle to MariaDB Migration.

Migration Reference

SQL Language Elements

Converting SQL language elements:

Oracle MariaDB - Oracle Compatibility Mode
1 -- comment Single line comment -- comment A blank is required after --

Oracle DATE arithmetic:

Oracle MariaDB - Oracle Compatibility Mode
1 SYSDATE + 1 Add 1 day DATE_ADD(SYSDATE(), INTERVAL 1 DAY)
2 SYSDATE + 1/24 Add 1 hour DATE_ADD(SYSDATE(), INTERVAL 1 HOUR)
3 SYSDATE + 1/1440 Add 1 minute DATE_ADD(SYSDATE(), INTERVAL 1 MINUTE)
4 SYSDATE + 1/86400 Add 1 second DATE_ADD(SYSDATE(), INTERVAL 1 SECOND)

Operators and predicates:

Oracle MariaDB - Oracle Compatibility Mode
1 (start1, end1) OVERLAPS (start2, end2) Check if two datetime
intervals overlap
(start2 < end1 AND end2 > start1)

Data Types

Character data types:

Oracle MariaDB - Oracle Compatibility Mode
1 CLOB Character large object, <= 4G LONGTEXT
2 LONG Character data, <= 2G LONGTEXT
3 VARCHAR2(n [BYTE | CHAR]) Variable-length string
1 <= n <= 4000
(MAX_STRING_SIZE = STANDARD)

1 <= n <= 32767
(MAX_STRING_SIZE = EXTENDED)
since Oracle 12c
VARCHAR2(n) BYTE and CHAR semantics
cannot be specified

Unicode character data types:

Oracle MariaDB - Oracle Compatibility Mode
1 NCHAR(n) Fixed-length Unicode string, n <= 2000 NCHAR(n) n <= 255
NVARCHAR(n) n > 255
2 NVARCHAR2(n) Variable-length Unicode string, n <= 4000 NVARCHAR(n) n <= 65,535
3 NCLOB Unicode large character object LONGTEXT

Numeric data types:

Oracle MariaDB - Oracle Compatibility Mode
1 BINARY_INTEGER 32-bit signed integer number, PL/SQL only INTEGER
2 NUMBER(p,s) Fixed-point number, s > 0 NUMBER(p,s)
NUMBER(*,s) Fixed-point number DECIMAL(38,s)
NUMBER Floating-point number NUMBER
3 PLS_INTEGER 32-bit signed integer number, PL/SQL only INTEGER

Binary data types:

Oracle MariaDB - Oracle Compatibility Mode
1 BLOB Binary large object, ⇐ 4G LONGBLOB
2 RAW(n) Variable-length binary data, 1 ⇐ n ⇐ 2000 RAW(n)
3 LONG RAW Binary data, < 2G LONGBLOB

Other data types:

Oracle MariaDB - Oracle Compatibility Mode
1 ROWID Physical row address CHAR(10)
2 XMLTYPE XML data LONGTEXT

Built-in SQL Functions

Converting string functions:

Oracle MariaDB - Oracle Compatibility Mode
1 REPLACE(str, search) Remove search-string REPLACE(str, search, ")
REPLACE(str, search, replace) Replace search-string REPLACE(str, search, replace)

Converting date and time functions:

Oracle MariaDB - Oracle Compatibility Mode
1 ADD_MONTHS(date, num) Add num months to date TIMESTAMPADD(MONTH, num, date)
2 LAST_DAY(datetime) Get last day of the month,
includes time
LAST_DAY(datetime) Returns date only
3 SYSDATE Get current date and time SYSDATE() Returns time, but () are required
4 TO_CHAR(datetime, format) Convert datetime to string DATE_FORMAT(datetime, format)
5 TO_DATE(string, format) Convert string to datetime STR_TO_DATE(string, format)
6 TRUNC(datetime) Truncate datetime value CAST and DATE_FORMAT

Converting case functions:

Oracle MariaDB - Oracle Compatibility Mode
1 DECODE(exp, when, then, …) Evaluate conditions DECODE(exp, when, then, …)

Views

CREATE VIEW and ALTER VIEW statements:

Oracle MariaDB - Oracle Compatibility Mode
1 CREATE OR REPLACE VIEW name Create a view CREATE OR REPLACE VIEW name
2 CREATE FORCE VIEW name Create a view even if base tables
do not exist or no privileges on them
FORCE removed, not supported
3 CREATE MATERIAZED VIEW name Create a materiazed view Not supported
4 EDITIONABLE Editioning view keyword Not supported

Sequences

CREATE SEQUENCE and ALTER SEQUENCE statements:

Oracle MariaDB - Oracle Compatibility Mode
1 CREATE SEQUENCE seqname CREATE [OR REPLACE] SEQUENCE seqname
2 ALTER SEQUENCE seqname ALTER SEQUENCE [IF EXISTS] seqname
3 INCREMENT BY num Positive or negative increment, default is 1 INCREMENT BY num
4 START WITH num Initial value START WITH num
5 MAXVALUE num Maximum value is num MAXVALUE num
NOMAXVALUE System limit NOMAXVALUE
6 MINVALUE num Minimum value is num MINVALUE num
NOMINVALUE System limit NOMINVALUE
7 CYCLE Reuse values after reaching the limit CYCLE
NOCYCLE No reuse, this is default NOCYCLE
8 CACHE num Cache num values, default is 20 CACHE num Default is 1000
NOCACHE Values are not preallocated NOCACHE
9 ORDER Guarantee numbers in order of requests Option not supported, commented
NOORDER No guarantee, this is default Option not supported, removed as it is default
10 NOKEEP Do not keep value during replay Option not supported, removed as it is default
11 NOSCALE Disable sequence scalability Option not supported, removed as it is default
12 GLOBAL A regular sequence visible to all sessions Option not supported, removed as it is default

Referencing sequence values:

Oracle MariaDB - Oracle Compatibility Mode
1 seqname.CURRVAL The current value of seqname seqname.CURRVAL
2 seqname.NEXTVAL The next value of seqname seqname.NEXTVAL

DROP SEQUENCE statement:

Oracle MariaDB - Oracle Compatibility Mode
1 DROP SEQUENCE seqname DROP SEQUENCE [IF EXISTS] seqname

CREATE INDEX Statement

Converting CREATE INDEX statement keywords and clauses:

Oracle MariaDB - Oracle Compatibility Mode
1 CREATE INDEX schema.index_name CREATE INDEX index_name Can contain index name only

SELECT Statement

Converting SQL SELECT statement and its clauses:

Oracle MariaDB - Oracle Compatibility Mode
1 t1 JOIN t2 USING (column_name) USING clause for joins t1 JOIN t2 USING (column_name)
2 CONNECT BY PRIOR Hierarchical queries Recursive Common Table Expressions (CTE)

Rownum pseudo-column conditions:

Oracle MariaDB Oracle mode - Before 10.6.1 MariaDB Oracle mode - Since 10.6.1
1 ROWNUM = 1 Return 1 row only LIMIT 1 ROWNUM = 1
ROWNUM <= n Row limit LIMIT n ROWNUM <= n
ROWNUM < n LIMIT n - 1 ROWNUM < n

INSERT Statement

Converting SQL INSERT statement and its clauses:

Oracle MariaDB - Oracle Compatibility Mode
1 INSERT INTO table
VALUES rowtype_var
Insert a record from
%ROWTYPE variable
INSERT INTO table VALUES
(rowtype_var.col1, rowtype_var.col2, …)
Columns have to be
explicitly defined

CREATE FUNCTION Statement

Converting user-defined functions from Oracle to MariaDB:

Oracle MariaDB - Oracle Compatibility Mode
1 CREATE OR REPLACE FUNCTION name DELIMITER //
CREATE OR REPLACE FUNCTION name
2 param IN | OUT | IN OUT datatype Parameter definition param datatype Length can be skipped,
it is derived from the caller
3 RETURN datatype Return value RETURN datatype RETURNS not allowed

PL/SQL Statements

Converting PL/SQL statements:

Oracle MariaDB - Oracle Compatibility Mode
1 CURSOR cur (param IN type, … ) IS … Cursor declaration CURSOR cur (param type, … ) IS … IN not allowed

Flow of control statements:

Oracle MariaDB - Oracle Compatibility Mode
1 RETURN; Return from a stored procedure RETURN;
2 RETURN exp; Return from a user-defined function RETURN exp;

Other statements:

Oracle MariaDB - Oracle Compatibility Mode
1 NULL; “no-op” (no operation) NULL;

Exception Block

Predefined exceptions handlers:

Oracle MariaDB - Oracle Compatibility Mode
1 ACCESS_INTO_NULL Assign attribute of NULL object Not supported
2 CASE_NOT_FOUND No condition met in CASE Not supported
3 COLLECTION_IS_NULL Assigning to NULL collection Not supported
4 CURSOR_ALREADY_OPEN Cursor already open Not supported
5 DUP_VAL_ON_INDEX Insert duplicate values DUP_VAL_ON_INDEX
6 INVALID_CURSOR Operation on non-open cursor Not supported
7 INVALID_NUMBER String does not represent valid number Not supported
8 LOGIN_DENIED Invalid user name or password Not supported
9 NO_DATA_FOUND SELECT INTO returns no rows NO_DATA_FOUND
10 NO_DATA_NEEDED Early exit from pipelined function Not supported
11 NOT_LOGGED_ON Not connected Not supported
12 OTHERS All other conditions OTHERS
13 PROGRAM_ERROR Internal error Not supported
14 ROWTYPE_MISMATCH Incompatible types Not supported
15 SELF_IS_NULL Invoke method of NULL instance Not supported
16 STORAGE_ERROR Out of memory Not supported
17 SUBSCRIPT_BEYOND_COUNT Index number too large Not supported
18 SUBSCRIPT_OUTSIDE_LIMIT Index number is out of range Not supported
19 SYS_INVALID_ROWID Invalid rowid Not supported
20 TIMEOUT_ON_RESOURCE Timeout Not supported
21 TOO_MANY_ROWS SELECT INTO returns more than one row TOO_MANY_ROWS
22 VALUE_ERROR Expression error Not supported
23 ZERO_DIVIDE Divide a number by zero Not supported

SQL Statements

SQL statements and clauses:

Oracle MariaDB - Oracle Compatibility Mode
1 COMMENT ON COLUMN table.column IS 'string' Not supported , should be moved to COMMENT in CREATE TABLE
2 COMMENT ON TABLE table IS 'string' ALTER TABLE table COMMENT 'string'