Обсуждение: PostgreSQL Active-Active Clustering

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> On Jul 15, 2024, at 12:06, Sarkar, Subhadeep <subhadeepsarkar@kpmg.com> wrote:
>
>   • Does the Community edition of PostgreSQL provide NATIVE active-active high availability clustering with
objectivesof scalability, load balancing and high availability without using any extensions or external components or
usageof Kubernetes/Dockers.  
>
>   • In the Community edition of PostgreSQL is it possible to setup a database cluster in load balancing mode and
providevertical and horizontal scalability without repartitioning or changes to the database objects or 3rd party
transactionrouting mechanisms using NATIVE features only (i.e. without using any extensions or external components or
usageof Kubernetes/Dockers). 
>
>   • In the Community edition of PostgreSQL is it possible to setup  a cluster where all the nodes are able to
concurrentlyread-write the underlying database image using NATIVE features (i.e. without using any extensions or
externalcomponents or usage of Kubernetes/Dockers). 

Short answer: No.

The community version of PostgreSQL, without any extensions beyond what is available in the core distribution, supports
noneof these.  I will offer that your client is not being realistic if these are their requirements, and they expect
themto be fulfilled by the core distribution of any open-source database. 

There are commercial extensions to PostgreSQL that provide the first, but PostgreSQL does not do so out of the box.  It
ispossible, now, to build this on top of community PostgreSQL with logical replication, but there is notable
developmentwork involved, and you cannot just drop an existing database into PostgreSQL and expect this to work.  In
anyevent, you will need to make sure the schema is compatible with an active-active model. 

For the second, you can explore open-source projects such as Citus, but some attention to the schema and queries will
berequired.  

No product, either commercial or open-source, provides the last one (read-write shared storage), although there are
commercialproducts that provide for a shared-storage model single-writer, multiple-reader model (for example, Amazon
Aurora).

## Ron Johnson (ronljohnsonjr@gmail.com):

> This "lack of products" puzzles me, because DEC was doing this with VAX
> (then Alpha and Itanium) clusters 40 years ago via a Distributed Lock
> Manager integrated deep into VMS.  Their Rdb and (CODASYL) DBMS products

Tech and trade-offs have changed over the last 40 years :)
These days you can so many cores in one package, while "more than one
processor" was quite a feat in the 80ies ("A dual processor VAX 11/780",
1982 https://dl.acm.org/doi/10.5555/800048.801738; also the 11/782 and
11/784), and you get so much RAM and storage (even fast storage, if
you keep it local) with that package. Response Latency really jumps
if you have to communicate with anything outside your box.
While latency matters, the number of problems where you absolutely
need that distributed lock manager has not really grown that much,
I think.

Regards,
Christoph

-- 
Spare Space

On Mon, Jul 15, 2024 at 3:28 PM Christophe Pettus <xof@thebuild.com> wrote:

> On Jul 15, 2024, at 12:06, Sarkar, Subhadeep <subhadeepsarkar@kpmg.com> wrote:
>

[snip] 

>   • In the Community edition of PostgreSQL is it possible to setup  a cluster where all the nodes are able to concurrently read-write the underlying database image using NATIVE features (i.e. without using any extensions or external components or usage of Kubernetes/Dockers).

[snip] 

No product, either commercial or open-source, provides the last one (read-write shared storage), although there are commercial products that provide for a shared-storage model single-writer, multiple-reader model (for example, Amazon Aurora).

This "lack of products" puzzles me, because DEC was doing this with VAX (then Alpha and Itanium) clusters 40 years ago via a Distributed Lock Manager integrated deep into VMS.  Their Rdb and (CODASYL) DBMS products used those functions extensively.

IMHO IBM did something similar with their shared DASDi back in 70s+. There was serialization mechanism enabling concurrent writes to data sets (meaning files). Not to mention IBM had great VM technology back in the day.

(In the late 1990s, they sold the DLM code to Oracle, which is where RAC comes from.)

It was shared-disk, multiple-writer, because the DLM allowed for locking at the row level.  Thus, a half dozen cluster nodes could hold write locks on different rows on the same data page.

-- 
Achilleas Mantzios IT DEV - HEAD IT DEPT Dynacom Tankers Mgmt (as agents only)

> On Jul 15, 2024, at 12:06, Sarkar, Subhadeep <subhadeepsarkar@kpmg.com> wrote:
>
>  • Does the Community edition of PostgreSQL provide NATIVE active-active high availability clustering with objectives
ofscalability, load balancing and high availability without using any extensions or external components or usage of
Kubernetes/Dockers. 
>
>  • In the Community edition of PostgreSQL is it possible to setup a database cluster in load balancing mode and
providevertical and horizontal scalability without repartitioning or changes to the database objects or 3rd party
transactionrouting mechanisms using NATIVE features only (i.e. without using any extensions or external components or
usageof Kubernetes/Dockers). 
>
>  • In the Community edition of PostgreSQL is it possible to setup  a cluster where all the nodes are able to
concurrentlyread-write the underlying database image using NATIVE features (i.e. without using any extensions or
externalcomponents or usage of Kubernetes/Dockers). 

I do have to add that this list of requirements sounds very much like a set supplied by the sales organization of a
commercialdatabase vendor (in fact, a particular commercial database vendor) in order to exclude open-source software.
Open-sourcesoftware relies very much on a whole ecosystem, rather than attempting to deliver every imaginable feature
inthe core distribution.  This is especially true of projects like PostgreSQL which are not backed by a single company
anddo not have an official commercial distribution.  Can your client articulate why they need these specific features,
andwhy they must be in the core distribution?