An Oracle-compatible PostgreSQL working toward 1.0, built around measured evidence of where compatibility ends.
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An Oracle-compatible PostgreSQL, built around one honest promise: we can tell you exactly where compatibility ends (for your code, with measured evidence) and close the gaps that matter to you.
Paritas is PostgreSQL 18 with an Oracle mode that compiles and runs real PL/SQL: packages, triggers, collections and exceptions. It is working toward 1.0 against eight published acceptance criteria, and every figure on this page comes from a dated run against Oracle Database 21c.
When a company moves off Oracle, everyone focuses on converting the code, the visible half. The invisible half is that PostgreSQL is not Oracle: in places it computes a different answer to the same expression. Not an error. A different number.
Three real results, each measured on live engines. Every one converts cleanly, and none raises an error you would see at build time.
The moat is not the database. Anyone can fork one. It's a differential test harness: Oracle Database 21c, stock PostgreSQL and the unmodified open-source base Paritas is built on, all running beside Paritas. The same code goes to each engine and every answer is compared against Oracle's. A difference is only real once it is measured on a live engine, never assumed from a manual: on 9 October 2026 two fixes written from Oracle's own manual gave the wrong answer on a real Oracle 21c.
762 cases of SQL and PL/SQL, each with the answer a real Oracle instance returned. Every engine runs every case, and every verdict is kept from run to run, so a change that fixes one answer and breaks another shows up in the next run.
591 units and 92,000 lines of real PL/SQL from nine schemas, among them the Alexandria, Logger, utPLSQL and PL/JSON libraries and Oracle's HR and OE samples, compiled unchanged. It ranks what breaks, so the most common blocker is fixed first.
170 stress cases, an AddressSanitizer build in continuous integration, and a 24-hour soak with flat memory on the release candidate. A database that gives Oracle's answers and then falls over is not compatible.
The bar for 1.0 was set in advance, as numbers rather than adjectives. Here is where each stood on 12 October 2026 (the call-site count is from 8 October).
Each item below is tested against Oracle 21c's measured answers, and most arrived in the last few weeks because the gauntlet ranked them first.
Specification and body, with state kept per session · Package records, constants, cursors and initialization sections · Types, subtypes and exceptions declared in a package and used from other code · Private body items, and recursion that keeps each caller's values
SUBTYPE, and 13 predefined subtypes such as POSITIVE and NATURAL · PLS_INTEGER, SIMPLE_INTEGER, SYS_REFCURSOR and cursor attributes · SELECT INTO, EXECUTE IMMEDIATE, and procedure calls without CALL · FOR ... IN REVERSE in Oracle's order
User-defined and predefined exceptions, raised and caught by name · PRAGMA EXCEPTION_INIT with Oracle's scope and codes · RAISE_APPLICATION_ERROR, and SQLCODE and SQLERRM in handlers
Nested tables, VARRAY and INDEX BY PLS_INTEGER collections, with EXTEND · BULK COLLECT, TABLE() in a query, and pipelined functions · Schema-level object types (attributes) and collection types, with constructors
Oracle's trigger syntax: the body in the statement, :new and :old, INSERTING, UPDATING, DELETING, REFERENCING · MINUS, Oracle's set-operator order, and ROWNUM in single-table queries · IEEE arithmetic for BINARY_FLOAT and BINARY_DOUBLE · DBMS_OUTPUT, DBMS_LOB, UTL_RAW and part of DBMS_UTILITY
One server, two dialects: Oracle mode on its own port beside PostgreSQL's, so no session has to switch · Backup and restore of Oracle-mode databases with pg_dump · Builds on Linux and on Windows, where three Oracle-mode tests still fail
Any architect will test a compatibility claim within an hour. Say "Oracle compatible" without limits and you lose the account the moment they find the first gap. So we write down where it ends: our list of limitations runs to more than 140 entries, each saying what happens, and most what to do instead. The headlines are below.
Object types with methods: type bodies, member functions, UNDER, REF · Autonomous transactions: refused when the code compiles, because a fake would be a trap · The network packages (UTL_HTTP, UTL_TCP, UTL_SMTP, UTL_MAIL) · The XML packages (DBMS_XMLGEN, DBMS_XMLDOM, DBMS_XMLPARSER) · DBMS_SCHEDULER and DBMS_JOB · Optimizer hints, which are read as comments
Integer division truncates: SELECT 10/4 is 2, where Oracle, which has no integer type, gives 2.5 · A number turned into text keeps its leading zero: TO_CHAR(0.5) is 0.5, where Oracle gives .5 · INDEX BY VARCHAR2 collections and FORALL · ROWNUM in joins and in the nested pagination idiom; FETCH FIRST works · The (+) outer join, which pgrecon rewrites to LEFT JOIN · DBMS_SQL, UTL_FILE and four more packages, planned for 1.0
pgrecon tells you what your Oracle estate contains and what a migration will cost. The Paritas harness tells you which of that estate behaves differently on the destination (measured, per expression). The two already share their plumbing: the tables the gauntlet compiles real PL/SQL against are extracted and converted by pgrecon itself. Know the scope, then know the risk, before you commit.
We would rather you hear the limits now than in six months.
The harness: the corpus, the gauntlet and the stress suite, with a dated run behind every figure here · Paritas builds, installs and runs as PostgreSQL 18 with an Oracle mode, fully rebranded · Every change passes a gate (a build with zero warnings and the full regression suites) and independent review · Every expected answer in its tests is Oracle 21c's, measured, never copied from a manual
Paritas builds on Apache-2.0-licensed open-source technology, so it is fully legal, with proper attribution files. Where we find a defect that belongs upstream, we send it back with a reproduction the maintainers can run, building credibility in the PostgreSQL world rather than maintaining a private fork of everything. It is working: the floating-point fix above was merged into the upstream open-source project on 3 September 2026. Since then we have filed eleven more issue reports with reproductions and opened ten pull requests with fixes, all still under review on 13 October 2026. Paritas carries its own fix for each of those pull requests meanwhile, and drops it when upstream's version arrives.
Paritas cannot be bought today, and we give no date: 1.0 ships when the eight criteria hold, not before.
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