Re: PostgreSQL

PostgreSQL and Oracle are two different databases.

Both implement most of the SQL standards, and both contain their own specific implementations for all kinds of things. This is true for anything that directly is defined by the SQL standard, and anything beyond that.

PostgreSQL contains a procedural language extension, plpgsql, that has similarities with Oracle's PLSQL.

Out of the available general databases, I do believe PostgreSQL is most close to Oracle SQL and PLSQL.

A few differences:

- PostgreSQL relies on the operating system page cache for datafile buffering, and thus strictly employs buffered reads for these.
- There is no equivalence of the shared pool: every backend (database connection) has to build its own dictionary cache, SQL cache, row cache.
- The implementation of consistency differs between Oracle and PostgreSQL. Although the general way they deal with it is obvious and alike, there are nuanced implementation differences between the two.

Oracle would perform better at huge scale with very specific configuration. In reality, most products using the database use it in a very basic way, and for these PostgreSQL can probably quite easily replace Oracle, provided you can change the SQL, the driver, etc. In fact, this is happening in a lot of places.

Frits

> On 6 Jan 2023, at 13:36, Terrian Thomas J CTR DLA INFO OPERATIONS ("Tom.Terrian.ctr") <dmarc-noreply_at_freelists.org> wrote:
>
> Here are some open ended question for the group…We are starting to look at migrating our databases from Oracle to PostgreSQL. I know nothing about PostgreSQL.
>
> Has anyone done a pro’s and con’s list of Oracle vs. PostgreSQL?
> Anyone have a lesson’s learned list from migrating from Oracle to PostgreSQL?
> Any thoughts/comments on PostgreSQL?
> I kind of think that you get what you pay for…wouldn’t that mean that Oracle would outperform PostgreSQL in every way?
>
> Any comments would be appreciated.
>
> Tom

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