[cctalk] Re: Little Databases

[Gavin Scott via cctalk]

On Fri, Aug 18, 2023 at 9:21 PM Grant Taylor via cctalk
 wrote:
>
> On 8/18/23 9:06 PM, Adam Thornton wrote:
> > So it doesn't support concurrent access by multiple users,
>
> I used to think the same thing.
>
> But, I seem to recall reading an authoritative article, likely on
> SQLite's site, talking about how it is possible to have multiple
> processes but the same and / or different users access the same SQLite
> database file (almost) concurrently.

My understanding is:

Concurrent access is fine, except that as soon as one writer begins
updating things SQLite will take a lock on the whole database so
another writer is going to wait until the first transaction is
committed or rolled back before its own transaction can proceed. This
also means you can't get a locking issue that could roll back your
transaction unexpectedly due to a conflict.

And there is now the BEGIN CONCURRENT option which defers locking
until COMMIT time, so multiple concurrent writers can just go at it,
but it only works well if each writer is changing different data
(records that don't share index pages etc.). At COMMIT time, it checks
to see if any of the database pages that the transaction was based on
(read or written) have changed since the start of the transaction and
if so, the COMMIT fails and you have to roll back and try again which
of course makes the application code more complex.

https://www.sqlite.org/cgi/src/doc/begin-concurrent/doc/begin_concurrent.md

Overall, I think SQLite is one of the best things ever. Not even Open
Source licensed, it's explicitly in the Public Domain. It now
implements the vast majority of the SQL standards and you're unlikely
to find something you need that it can't do. If you don't need
client-server access and don't need a zillion concurrent users, then
it's often the best choice. Just the lack of any installation,
configuration, startup/shutdown or other management requirements makes
it pretty much "implement and forget". It has billions of
installations and on the order of a trillion databases in use.

The O'Reilly SQL Pocket Guide (4th Ed.) covers SQLite, SQL Server,
Oracle, and PostgreSQL making it a handy resource for comparing those
systems.

[cctalk] Re: Little Databases

[Grant Taylor via cctalk]

On 8/18/23 9:06 PM, Adam Thornton wrote:

Have you considered sqlite3?


Yes, I have considered SQLite many times over many years and multiple 
versions.  I'm quite happy with it.



It's a SQL engine, but the backend is just a file.


Yep.


So it doesn't support concurrent access by multiple users,


I question the veracity of that statement.

I used to think the same thing.

But, I seem to recall reading an authoritative article, likely on 
SQLite's site, talking about how it is possible to have multiple 
processes but the same and / or different users access the same SQLite 
database file (almost) concurrently.


My take away at the time is that SQLite didn't support multiple 
/concurrent/ updates.  Or that updates were an exclusive activity.  But 
multiple concurrent reads were fully supported.


There is also the question of what is concurrency.  Especially if you 
consider that an exclusive lock can be acquired only for an INSERT / 
UPDATE / DELETE query and released thereafter.  Thereby allowing 
multiple processes / users to have almost concurrent access to an SQLite 
database, each of which can make updates (I/U/D queries) as long as they 
aren't doing it at exactly the same time.


At least that's what I recall.  If I'm wrong, please correct me.


but if that's not a concern,
I remember walking away from what I read thinking that I could use 
SQLite between multiple processes / users on the same system with each 
user being able to make an update as close as a second after the 
previous user did.


So, likely not a problem for any use case I would have.

it gives you the ability to do real SQL queries without the bother 
of setting up an RDBMS.


The last time I looked, SQLite wasn't completely /proper/ SQL when you 
got into fancier queries / joins / views / etc.  But that it was 
exceedingly good if you wanted to do mainstream and maybe one degree 
less mainstream things.


SQLite is a really impressive database.  The only reason that I'd step 
up to a more traditional RDBMS is when I wanted network based 
connectivity and / or needed actual concurrent write ability to multiple 
tables in the same database.  Nothing I do comes close to that.


I sort of suspect that someone could get SQLite to work as the backend 
for something like SpamAssassin reading preferences for multiple users 
from a singular database.  Especially if updates to preferences were 
done less often than queries therefor.




Grant. . . .

[cctalk] Little Databases

[Adam Thornton via cctalk]

Have you considered sqlite3?  It's a SQL engine, but the backend is just a
file.  So it doesn't support concurrent access by multiple users, but if
that's not a concern, it gives you the ability to do real SQL queries
without the bother of setting up an RDBMS.

Adam

[cctalk] Disposition of stuff

[Adam Thornton via cctalk]

Been thinking about it a little recently, and, no, I definitely don't plan
to send my stuff to a scrapper.  I have some younger friends with an
interest in retrocomputing.  They want my stuff when I'm done with it,
sure.  And if they want _just a little_ of my stuff I'll probably strike a
deal like, "you can have the SGI Indy if that box of IDE drives goes with
it, and you aren't allowed to throw it away until you're somewhere I'm not
going to see it by the side of the road."

Adam

[cctalk] Re: Nixies..

[Mark Linimon via cctalk]

> Kees Stravers, owner of the website about the Evoluon, reports that they were 
> scrapped when the museum closed in 1989.

boo.

mcl

[cctalk] Re: Good Inventory Program for keeping track of my DEC boards, parts, computers, etc?

[Wayne S via cctalk]

Off the original subject but here’s Google’s description of robots.txt and how 
Google can show your page in results.

https://developers.google.com/search/docs/crawling-indexing/robots/intro


Sent from my iPhone

On Aug 18, 2023, at 13:39, Sellam Abraham via cctalk  
wrote:

On Fri, Aug 18, 2023 at 12:35 PM Paul Koning via cctalk <
cctalk@classiccmp.org> wrote:



On Aug 18, 2023, at 12:48 PM, The Doctor via cctalk <
cctalk@classiccmp.org> wrote:

--- Original Message ---
On Thursday, August 17th, 2023 at 13:29, Bill Gunshannon via cctalk <
cctalk@classiccmp.org> wrote:


On 8/17/2023 2:14 PM, John Herron via cctalk wrote:

Why would you give all your data to Google?

They pretty much have it all anyway.  Even if you use /robots.txt to
block
them, they still spider and index pages,

Really?  It would be interesting to have evidence supporting that, because
if so, they could be subjected to pain for violating an explicit order not
to do so.


Not to mention that that could well be a criminal act since it would
constitute unauthorized access of a computer system.

If anyone has actual evidence of this happening now then please show it to
me, and I'll take the necessary legal steps to bring Larry and Sergey to
justice.

Sellam

[cctalk] Re: Good Inventory Program for keeping track of my DEC boards, parts, computers, etc?

[Sellam Abraham via cctalk]

On Fri, Aug 18, 2023 at 12:35 PM Paul Koning via cctalk <
cctalk@classiccmp.org> wrote:

>
>
> > On Aug 18, 2023, at 12:48 PM, The Doctor via cctalk <
> cctalk@classiccmp.org> wrote:
> >
> > --- Original Message ---
> > On Thursday, August 17th, 2023 at 13:29, Bill Gunshannon via cctalk <
> cctalk@classiccmp.org> wrote:
> >
> >
> >> On 8/17/2023 2:14 PM, John Herron via cctalk wrote:
> >>
> >> Why would you give all your data to Google?
> >
> > They pretty much have it all anyway.  Even if you use /robots.txt to
> block
> > them, they still spider and index pages,
>
> Really?  It would be interesting to have evidence supporting that, because
> if so, they could be subjected to pain for violating an explicit order not
> to do so.
>

Not to mention that that could well be a criminal act since it would
constitute unauthorized access of a computer system.

If anyone has actual evidence of this happening now then please show it to
me, and I'll take the necessary legal steps to bring Larry and Sergey to
justice.

Sellam

[cctalk] Re: Good Inventory Program for keeping track of my DEC boards, parts, computers, etc?

[Paul Koning via cctalk]

> On Aug 18, 2023, at 12:48 PM, The Doctor via cctalk  
> wrote:
> 
> --- Original Message ---
> On Thursday, August 17th, 2023 at 13:29, Bill Gunshannon via cctalk 
>  wrote:
> 
> 
>> On 8/17/2023 2:14 PM, John Herron via cctalk wrote:
>> 
>> Why would you give all your data to Google?
> 
> They pretty much have it all anyway.  Even if you use /robots.txt to block
> them, they still spider and index pages, 

Really?  It would be interesting to have evidence supporting that, because if 
so, they could be subjected to pain for violating an explicit order not to do 
so.

paul

[cctalk] Re: Nixies..

[Henk Gooijen via cctalk]

3 feet high is a bit too large, hi, but the pictures on the website brings back 
memories.
I remember the “coffee” machine, but back then (the way I remember it), it had 
vertically
mounted an X / Y slider to generate “coffee!”/ “coffee?” 

I know Kees, a few years ago I helped him a bit moving house after his mother 
died.
Last year I gave him a Siemens T1000 telex machine (5-bit) with reader/punch.
He wanted to set up an RTTY mailbox … must ask him how that went along.
He is a busy guy, I did not know the Evoluon website!


Van: Paul Koning
Verzonden: vrijdag 18 augustus 2023 15:14
Aan: cctalk@classiccmp.org
CC: Henk Gooijen
Onderwerp: Re: [cctalk] Nixies..



> On Aug 17, 2023, at 11:01 AM, Henk Gooijen via cctalk  
> wrote:
>
> Yes, I remember those “nixies”. When you entered the building it was 
> impossible to _not_ see them.
> If you walked under them, you ended up in the restaurant.
>
> The “do-things-yourself” museum is long gone, but the “UFO” saucer building 
> is still there.
> When I am in the office, I can see the building, looking out the window. My 
> work is less than 1 km away.
> I wonder if those “nixies” are still there, and if not, where they ended up …

Kees Stravers, owner of the website about the Evoluon, reports that they were 
scrapped when the museum closed in 1989.

You could of course reproduce them: they aren't actual Nixie tubes but rather a 
set of advertising sign type of neon lights, so any neon light craftsman could 
built such a thing.

paul

[cctalk] Re: Good Inventory Program for keeping track of my DEC boards, parts, computers, etc?

[The Doctor via cctalk]

--- Original Message ---
On Thursday, August 17th, 2023 at 13:29, Bill Gunshannon via cctalk 
 wrote:


> On 8/17/2023 2:14 PM, John Herron via cctalk wrote:
> 
> Why would you give all your data to Google?

They pretty much have it all anyway.  Even if you use /robots.txt to block
them, they still spider and index pages, they just don't show any salient
bits that reflect the user's search query (which probably drops the search
rank to some degree as well).

The Doctor [412/724/301/703/415/510]
WWW: https://drwho.virtadpt.net/
Don't be mean. You don't have to be mean.

[cctalk] Re: Nixies..

[Paul Koning via cctalk]

> On Aug 17, 2023, at 11:01 AM, Henk Gooijen via cctalk  
> wrote:
> 
> Yes, I remember those “nixies”. When you entered the building it was 
> impossible to _not_ see them.
> If you walked under them, you ended up in the restaurant.
> 
> The “do-things-yourself” museum is long gone, but the “UFO” saucer building 
> is still there.
> When I am in the office, I can see the building, looking out the window. My 
> work is less than 1 km away.
> I wonder if those “nixies” are still there, and if not, where they ended up …

Kees Stravers, owner of the website about the Evoluon, reports that they were 
scrapped when the museum closed in 1989.

You could of course reproduce them: they aren't actual Nixie tubes but rather a 
set of advertising sign type of neon lights, so any neon light craftsman could 
built such a thing.

paul