![]() LINE 1: SELECT CURRENT_TIMESTAMP FROM DUAL Īfter installing Orafce module: postgres=# SELECT CURRENT_TIMESTAMP FROM DUAL Orafce tool have implemented this so you can use Orafce also.Įxample: postgres=# SELECT CURRENT_TIMESTAMP FROM DUAL The Dual table can be created in PostgreSQL as a view to eliminate the porting problem. In PostgreSQL, FROM clause is not mandatory so DUAL table is not necessary. In Oracle FROM clause is mandatory for every SELECT statement so Oracle database uses DUAL table for SELECT statement where table name is not required. Oracle: DELETE FROM table_name WHERE id = 120 The default isolation level of PostgreSQL is Read committed. PostgreSQL database knows all the isolation levels that Oracle database knows. ![]() Even the isolation levels also have no problem. In PostgreSQL, transaction starts when execute BEGIN and end when COMMIT statement executed. In Oracle, the transaction starts when executing any statement and ends when COMMIT statement executed. Oracle database always uses transactions but in PostgreSQL you have to activate that. If the data if above 1 GB then use Large object. PostgreSQL BYTEA stores binary data but only upto 1 GB. BLOB type can store up to 128 terabytes of binary data. In Oracle, BLOB datatype stores unstructured binary data in the database. PostgreSQL TEXT type can store up to 1 GB of text. It is equivalent to Oracle’s Timestamp with local time zone, but this small difference can cause performance issue or application bug. The PostgreSQL type Timestamptz(Timestamp with time zone) is different from the Oracle Timestamp with time zone. NUMBER type can be converted to NUMERIC but if you use SMALLINT, INT and BIGINT then performance would be better.īoth databases has DATE type but Oracle DATE type returns date and time whereas PostgreSQL DATE type return only date no time. In Oracle ‘n’ is number of bytes whereas in PostgreSQL ‘n’ is number of characters Some of the important Data type conversion between Oracle and PostgreSQL is as follow. Please check below some of the important differences you should know before migrating. There is no any tool that can convert 100% Oracle database into PostgreSQL, some manual changes are required. Understand the differences between Oracle and PostgreSQL and convert it using any tool. It connects to the Oracle database, scan it automatically and extracts the data, generating the database migration report. Ora2pg tool is very helpful for migration assessment. Migration AssessmentĪfter preliminary check, the first step of migration is to analyze the application and database object, find out the incompatibilities between both the databases and estimate the time and cost required for migration. Do not waste time replicating data that you don’t need, for example backup data and temporary table from past maintenance. Also, check whether there is any historical data required or not. Do not waste time for migrating objects that are no longer required. It is important to understand which part is to migrate. Benefit from open source add-ons to improve performance.Īs you may know migration from Oracle to PostgreSQL is a costly and time consuming task.Flexible open source licensing and easy availability from public cloud providers like AWS.Cost: As you may know Oracle licence cost is very expensive and there is additional cost for some features like partitioning and high availability.The behaviour of some functions is different between Oracle and PostgreSQL. There are some incompatibilities in Oracle and PostgreSQL. ![]() As per the, PostgreSQL is the DBMS of the year 2017. ![]() PostgreSQL community is very strong and they are continuously improving existing PostgreSQL features and also add new features. PostgreSQL is the world’s most advanced open source database. Whether migrating a database or an application from Oracle to PostgreSQL with only one type of database knowledge, there are few things to know about the differences between the two database systems.
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