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Comment by paulryanrogers | Hacker News Reader

> IvorySQL has imported and enhanced the Orafce extension to add support for numerous Oracle compatibility features including built-in PACKAGES, data types, and conversion functions

Sounds and looks like a fork to me.

EnterpriseDB used to offer some Oracle compatibility built on Pg, as a fork IIRC. Don't see it on their site any more though.

EDIT: Much thanks to replies with links to EDB.

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Also, their docs leave me wondering about the level of Oracle compatibility they're claiming. Their page on the subject, https://www.ivorysql.org/docs/compatibillity_features/hierar... , lists a bunch of immediate sore points -- date types and functions, the CONNECT BY query syntax, etc. But there are other things Oracle supports that are not listed, and still potentially serious stumbling blocks -- "fast" (incremental) automatic refresh of materialized views, IGNORE NULLS in window functions, and so forth.

Oddly, I'd take their compatibility claims more seriously if they were more clearly up-front about the limits.

Am I one of the only developers who actually likes the CONNECT BY queries? Often I think they are a very succinct alternative to recursive CTEs.

I'll just fire this up, create some external tables, and use the v7 join syntax to write out my data with utl_file.

Does it need to be a fork, as opposed to just an extension?

I understand why upstream Postgres might not want to put Oracle compatibility in the core, since it would be adding a lot of crud which only a minority of people would benefit from. However, making sure the Postgres core has the extension points necessary to support extensions providing compatibility with Oracle (or DB2, MSSQL, MySQL, etc), is something they might be more willing to entertain.

The postgres 15 manual has a chapter on Oracle compatibility.

I don't know where to find it on their website, but the docs RPM that they provide bundles the PDF.

You are probably thinking of ECPG's "Oracle compatibility mode", which makes it behave more like Oracle Pro*C - https://www.postgresql.org/docs/15/ecpg-oracle-compat.html

However, few people actually use Pro*C nowadays. I spent almost 10 years working for Oracle, and I never once came across anybody using it. I think almost all use of it is in legacy applications which date back to the 1980s, first half of the 1990s at the latest. Obviously still enough use for Oracle to keep on supporting it, even with some occasional minor enhancements, but rather fringe all the same.

I don't think many people use ECPG either. I'm sure some people must, but I myself have never seen it. Probably most use is in porting existing applications from Oracle Pro*C, or its equivalents such as Informix E/SQL. Actually, it is interesting to observe that the section on ECPG's Informix compatibility mode is a lot longer than the Oracle equivalent. I don't know if that's because less compatibility is required (maybe Pro*C is closer to ECPG already), or if that's because Informix compatibility has received more investment.

I've used pro* C for a couple of things (in banking and utilties, 1990s) where people wanted interactive batch functionality for something more complex than you'd generally put in a shell script. I think most of the pro* C usage came from pre Oracle 7 when PL/SQL didn't exist.

EDB PostgreSQL is still very much alive and Oracle compatibility is a big success among enterprises that have chosen to migrate and need to smooth the process.

That was the whole hook for EnterpriseDB. They still sell the product:

https://www.enterprisedb.com/products/edb-enterprise

The difference here is that the EnterpriseDB product is not open source.

IBM Db/2 also bought it, and uses it to implement SQL/PSM.

https://www.enterprisedb.com/resources/ibmr-puts-oracle-swor...

That sounds like the description of a distribution of postgresql to me.

Think of a gnu/linux distro, that gives you some pre-packaged software built with an intended goal (more or less general) and according to a certain set of opinions.

Their Oracle compatibility is still a thing, at least commercially: https://www.enterprisedb.com/products/edb-postgres-advanced-...

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