PostgreSQL vs Firebird

http://www.amsoftwaredesign.com/pg_vs_fb

PostgreSQL vs Firebird feature comparison (for Enterprise Use)

Feature		PostgreSQL 8.2.x	Firebird 2.0.x
MVCC		Yes	Yes
Row level Locking Available		Yes	Yes
Max Database Size		Unlimited*	Unlimited*
Max table Size		32 TB	~32 TB
Max Row Size		1.6 TB	64 KB
Max Field Size		1 GB Max size for all types including blobs Firebird seems to be a better choice if you need huge blob support.	Depends on Type (Varchar max size is 32k, Max Blob Size is 32GB)
Max Rows per Table		Unlimited*	> 16 Billion
Max Columns Per Table		50 - 1600 depending on column types	Depends on data types used.
Max Indexes Per Table		Unlimited*	65,535
Multi Threaded Architecture Available?		No	Yes (super server)
Ability to re-order table columns without re-creating from a temp table.		No	Yes
Stores Transaction Information in same file as data		No	Yes
Auto Increment Columns		Yes (serial type that uses sequences)	Yes (must use a generator and a trigger)
True Boolean column type		Yes	No
Table Inheritance		Yes	No
Domains		Yes	Yes
Table Partitioning		Yes (basic)	No
Updateable Views		Yes (via rules system)	Yes
Event/Notification System		Yes	Yes
Temporary Tables		Yes	No
Rich Built in Functions		Yes	No
Multi Lang Stored Procedures		Yes (PLPGSQL,PLPerl,PlJava etc)	No
Compiled External Function (UDF) Support		Yes (C,C++, Delphi possible but C headers would have to be ported)	Yes (C,C++,Delphi)
Exception handling in stored procedures		Yes	Yes
2 Phased Commit		Yes	Yes
Native SSL support		Yes	No
Multiple authentication methods (i.e. LDAP)		Yes	No
Compound Indexes		Yes	Yes
Unique Indexes		Yes	Yes
Partial Indexes		Yes	Yes
Functional Indexes		Yes	Yes
Multiple Index Storage Types		Yes (btree,hash etc)	No
Point in Time Recovery		Yes	No
Schema Support		Yes	No
Strongly conforms to ANSI-SQL 92/99		Yes	Yes
Limit/Offset support		Yes	Yes (FIRST/SKIP)
Create user defined types		Yes	No
Create user defined operators		Yes	No
Create user defined Aggregates		Yes	No
Log Shipping		Yes	No
Write ahead logging (Important for Point In Time Recovery and Log Shipping)		Yes	No
Tablespaces		Yes	No
Save Points		Yes	Yes
Open Source Async Replication		Yes (Slony )	No (Commercial solutions available. Database shadowing is also present.)
Online/Hot Backups		Yes	Yes
File System based backups possible		Yes (Postmaster must be stopped)	Yes
Require backup/restore to compact (not just reuse space, but shrink the physical size of the DB)		No	Yes
Fully ACID Compliant		Yes	Yes
Native Win32 Port		Yes (only runs on NTFS files systems)	Yes
Text/Memo field type (Having a type of TEXT or MEMO aids in porting from other databases and in maintaining a abstraction layer)		Yes	Yes (Can store text via BLOB Type 1 While FB can store text it is not referenced in DDL as TEXT or MEMO rather BLOB subtype 1. Can also use a domain to alias blob subtype 1 as TEXT or MEMO. Domain alias must be created by user.)
BLOB support		Yes (limited to the max field size of 1 GB)	Yes (Can be up to 32GB)
UTF8 support		Yes	Yes
Define charactersets/collations per database (default)		Yes (PostgreSQL can also define a characterset for the entire database cluster during the initdb process)	Yes
Define charactersets and collations on a per column level		No	Yes
Foreign Keys		Yes	Yes
Check Constraints		Yes	Yes
Unique Constraints		Yes	Yes
Not Null Constraints		Yes	Yes
Multiple Transaction Isolation levels		Yes	Yes
Fully relational System Catalogs		Yes	Yes
Information Schema		Yes	No (no schema support)
Native GIS support via GIST or other native means		Yes (PostGIS )	No
Open Source Full Text Search (Official part of Project)		Yes	No
Use POSIX Regular Expressions in queries		Yes	No
Database Monitoring		Yes (Supports among other things statement logging at server via config setting. Aids in debugging of client applications)	?
Ability to query databases on other servers local or remote.		Yes (Dblink )	No
Ability to query foreign databases (MS SQL Server, Oracle etc)		Yes (DBI-Link ,DBLink-TDS )	No
Read Only Databases		No	Yes
Regular Version Updates		Yes Major release once per year with frequent minor updates.	No (Often several years between major versions) Minor updates are more frequent. Project is active.