It returns the day (day of the month) part of a date or equivalent value. You can convert DATE function to TO_DATE function in PostgreSQL.ĭB2: SELECT DATE ('') FROM SYSIBM.SYSDUMMY1 SELECT CEILING(123.89) FROM SYSIBM.SYSDUMMY1 Scalar Functions: DB2 vs PostgreSQL CEIL/CEILINGĬEIL or CEILING returns the next smallest integer value that is greater than or equal to the input (e.g. PostgreSQL allows a “SELECT” without ”FROM” clause. There is no “SYSIBM.SYSDUMMY1” table in PostgreSQL. GENERATED BY DEFAULT AS IDENTITY (START WITH 1, INCREMENT BY 1, CACHE 20) The IDENTITY column in DB2 can be replaced by Serial column in PostgreSQL. LIMIT 10 GENERATED BY DEFAULT AS IDENTITY In PostgreSQL, you can use LIMIT n which is equivalent to FETCH FIRST n ROWS ONLY. In DB2, you can use FETCH FIRST n ROWS ONLY clause to retrieve no more than n rows. PostgreSQL: TABLESPACE FIRST FETCH n ROWS ONLY TABLESPACE clause defines the name of the tablespace in which the newly created table resides.ĭB2 uses IN clause for TABLESPACE so it should be replaced by TABLESPACE clause in PostgreSQL. Please check the behaviour of DB2 function in PostgreSQL TABLESPACE You can automate them by creating extensions so that you can use the DB2 function as it is in PostgreSQL and you can save your time. There are many incompatibilities present in DB2 and PostgreSQL, you can see some of them here. Some of the data types of IBM DB2 does not match directly with PostgreSQL data types, so you need to change it to corresponding PostgreSQL data type. 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. You can see in the below image that PostgreSQL popularity is increasing over time as compared to DB2. Benefit from open source add-ons to improve database performance.Flexible open source licencing and easy availability from public cloud providers like AWS, Google cloud, Microsoft Azure.
In this blog, we can see some of these incompatibilities. As per the, PostgreSQL is the DBMS of the year 20.Īs you know DB2 and PostgreSQL are RDBMS but there are some incompatibilities. PostgreSQL database has rich feature set and PostgreSQL community is very strong and they are continuously improving the existing features and add new features. PostgreSQL is world’s most widely used advanced open source database. Whether migrating a database or an application from DB2 to PostgreSQL with only one type of database knowledge is not sufficient, there are few things to know about the differences between the two database systems.
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