| Licensing | Processor Value Unit (PVU) or per-user licensing models | Completely free and open source under PostgreSQL License with no licensing fees or usage limitations | Eliminates licensing costs through automated migration from expensive DB2 LUW editions to PostgreSQL |
| Ownership | IBM DB2 LUW is fully owned and managed by IBM Corporation | Open source project maintained by PostgreSQL Global Development Group | Ispirer LLC |
| SQL Language | Uses IBM's SQL implementation with extensions to ANSI SQL standard; supports SPL (Stored Procedure Language) | Uses standard SQL with PL/pgSQL procedural language and supports multiple procedural languages including PL/Python, PL/Perl, and PL/Tcl | The Ispirer toolkit automatically converts IBM SQL extensions and SPL (Stored Procedure Language) stored procedures to PostgreSQL-compatible PL/pgSQL, handling complex SQL syntax transformations with up to 90% automation level |
| Basic Data Types | Rich set including BSON, JSON, BIGINT, BIGSERIAL, BYTE, CHAR, DATE, DATETIME, DECIMAL, FLOAT, INTEGER, INTERVAL, MONEY, TEXT, VARCHAR, and specialized types | Extensive data types including NUMERIC, INTEGER variants, native arrays, JSON, JSONB, UUID, geometric types, and custom user-defined types | Provides intelligent data type mapping and conversion, automatically handling DB2 LUW specific types (BSON, BIGSERIAL, BYTE, DATETIME, MONEY) to PostgreSQL equivalents with customizable mapping rules |
| Indexing Options | B-tree (default), bitmap indexes, function-based indexes, reverse key indexes, and specialized DataBlade module indexes for user-defined data | B-tree (default), GIN, GiST, BRIN, SP-GiST indexes; supports partial/conditional indexes and specialized indexing for various data types | Converts DB2 LUW indexes to appropriate PostgreSQL index types |