Jonathan Lewis
@jloracle.bsky.social
Nearly-retired Oracle performance specialist. 50 years using computers, 40 years self-employed, 35 years as a freelance Oracle specialist.
Pinned
Jonathan Lewis
@jloracle.bsky.social
· Nov 21
https://web.archive.org/web/20181213051606/http://www.jlcomp.demon.co.uk/
t.co
Copying from ex-Twitter, and pinning:
The demon subdomain, including my old website disappeared a while ago, but there is a copy from December 2018 on the Wayback machine starting at: t.co/D9qBXqwJTu
The demon subdomain, including my old website disappeared a while ago, but there is a copy from December 2018 on the Wayback machine starting at: t.co/D9qBXqwJTu
Pulled the last of the leeks from the "big leek" bed ready for lunch tomorrow, then picked a small handful of kalettes - the first I've harvested - to eat today. Much nicer than both kale and brussel sprouts, so going to grow more this season. Purple sprouting broccoli also just ready for picking.
February 7, 2026 at 3:16 PM
Pulled the last of the leeks from the "big leek" bed ready for lunch tomorrow, then picked a small handful of kalettes - the first I've harvested - to eat today. Much nicer than both kale and brussel sprouts, so going to grow more this season. Purple sprouting broccoli also just ready for picking.
Today's tasks, come rain or sun: feed and mulch the fruit trees, weed, feed and mulch the killer gooseberry bush after putting on the gauntlets and giving it a ferocious pruning.
February 6, 2026 at 8:53 AM
Today's tasks, come rain or sun: feed and mulch the fruit trees, weed, feed and mulch the killer gooseberry bush after putting on the gauntlets and giving it a ferocious pruning.
Local weather forecast said it was going to rain today, starting at 3:00 am, non-stop until 3:00pm TOMORROW - so I worked at home, raking, shredding and bagging a huge pile of decomposing oak leaves, repotting plants ... no rain
Got ready to head out to the allotment at 3:00 pm: it started to rain.
Got ready to head out to the allotment at 3:00 pm: it started to rain.
February 5, 2026 at 10:01 PM
Local weather forecast said it was going to rain today, starting at 3:00 am, non-stop until 3:00pm TOMORROW - so I worked at home, raking, shredding and bagging a huge pile of decomposing oak leaves, repotting plants ... no rain
Got ready to head out to the allotment at 3:00 pm: it started to rain.
Got ready to head out to the allotment at 3:00 pm: it started to rain.
Went to an excellent @greshamcollege.bsky.social lecture by Prof. Chris Lintott on Exoplanets last night.
Informative and entertaining; including an introduction to the Planet Hunters - allowing to find potential exoplanets by analysing data from TESS.
science.nasa.gov/citizen-scie...
Informative and entertaining; including an introduction to the Planet Hunters - allowing to find potential exoplanets by analysing data from TESS.
science.nasa.gov/citizen-scie...
Planet Hunters TESS - NASA Science
Join the Planet Hunters Coffee Chat video series! Project leads cover relevant topics in a friendly, fun format. Want to see what you’ve missed? check out the
science.nasa.gov
February 5, 2026 at 8:59 PM
Went to an excellent @greshamcollege.bsky.social lecture by Prof. Chris Lintott on Exoplanets last night.
Informative and entertaining; including an introduction to the Planet Hunters - allowing to find potential exoplanets by analysing data from TESS.
science.nasa.gov/citizen-scie...
Informative and entertaining; including an introduction to the Planet Hunters - allowing to find potential exoplanets by analysing data from TESS.
science.nasa.gov/citizen-scie...
Reposted by Jonathan Lewis
It's not quite what you would write manually
The QUALIFY clauses get wrapped as a Boolean expression. So if you have
QUALIFY p1 AND p2 AND p3
it becomes
SELECT * FROM (
SELECT ( p1 AND p2 AND p3 ) qexpr ...
) WHERE qexpr IS TRUE
So yes, a manual rewrite may give better optimizations
The QUALIFY clauses get wrapped as a Boolean expression. So if you have
QUALIFY p1 AND p2 AND p3
it becomes
SELECT * FROM (
SELECT ( p1 AND p2 AND p3 ) qexpr ...
) WHERE qexpr IS TRUE
So yes, a manual rewrite may give better optimizations
February 5, 2026 at 2:01 PM
It's not quite what you would write manually
The QUALIFY clauses get wrapped as a Boolean expression. So if you have
QUALIFY p1 AND p2 AND p3
it becomes
SELECT * FROM (
SELECT ( p1 AND p2 AND p3 ) qexpr ...
) WHERE qexpr IS TRUE
So yes, a manual rewrite may give better optimizations
The QUALIFY clauses get wrapped as a Boolean expression. So if you have
QUALIFY p1 AND p2 AND p3
it becomes
SELECT * FROM (
SELECT ( p1 AND p2 AND p3 ) qexpr ...
) WHERE qexpr IS TRUE
So yes, a manual rewrite may give better optimizations
I've finally taken advantage of one of the most significant benefits brought to us by Brexit.
I've bought a packer of TimTams from the local supermarket.
I've bought a packer of TimTams from the local supermarket.
February 4, 2026 at 2:59 PM
I've finally taken advantage of one of the most significant benefits brought to us by Brexit.
I've bought a packer of TimTams from the local supermarket.
I've bought a packer of TimTams from the local supermarket.
Reposted by Jonathan Lewis
The QUALIFY clause enables you to filter rows using window functions
e.g. get the top ranked rows with
SELECT ... FROM ...
QUALIFY RANK () OVER ( ORDER BY ... ) = ...
@danischnider.bsky.social looks at how it works in Oracle AI Database 26ai
e.g. get the top ranked rows with
SELECT ... FROM ...
QUALIFY RANK () OVER ( ORDER BY ... ) = ...
@danischnider.bsky.social looks at how it works in Oracle AI Database 26ai
QUALIFY: The WHERE Condition for Analytic Functions
Filtering analytic functions was not straight-forward in Oracle and most other databases. Oracle 26ai now supports the QUALIFY clause in SQL. It works like a WHERE condition, but can be used for an…
buff.ly
February 4, 2026 at 12:01 PM
The QUALIFY clause enables you to filter rows using window functions
e.g. get the top ranked rows with
SELECT ... FROM ...
QUALIFY RANK () OVER ( ORDER BY ... ) = ...
@danischnider.bsky.social looks at how it works in Oracle AI Database 26ai
e.g. get the top ranked rows with
SELECT ... FROM ...
QUALIFY RANK () OVER ( ORDER BY ... ) = ...
@danischnider.bsky.social looks at how it works in Oracle AI Database 26ai
Reposted by Jonathan Lewis
1Password not mincing words here:
"If you are experimenting with OpenClaw, do not do it on a company device. Full stop."
"If you have already run OpenClaw on a work device, treat it as a potential incident and engage your security team immediately."
1password.com/blog/from-ma...
"If you are experimenting with OpenClaw, do not do it on a company device. Full stop."
"If you have already run OpenClaw on a work device, treat it as a potential incident and engage your security team immediately."
1password.com/blog/from-ma...
From magic to malware: How OpenClaw's agent skills become an attack surface | 1Password
The same capabilities that make OpenClaw a groundbreaking tool also make it an urgent security risk. This blog contains confirmed examples of agent skills being used as malware vectors, and advice on ...
1password.com
February 3, 2026 at 1:12 PM
1Password not mincing words here:
"If you are experimenting with OpenClaw, do not do it on a company device. Full stop."
"If you have already run OpenClaw on a work device, treat it as a potential incident and engage your security team immediately."
1password.com/blog/from-ma...
"If you are experimenting with OpenClaw, do not do it on a company device. Full stop."
"If you have already run OpenClaw on a work device, treat it as a potential incident and engage your security team immediately."
1password.com/blog/from-ma...
Reposted by Jonathan Lewis
Congrats to the winners in the Oracle Dev Gym championships!
1st Andrey Zaytsev
2nd mentzel.iudith
3rd [email protected]
🏆🍾
👏 to all competitors; we hope you enjoyed the challenge
Thanks to @kibeha.dk and @anthony-harper.bsky.social for writing & reviewing quizzes
blogs.oracle.com/sql/announci...
1st Andrey Zaytsev
2nd mentzel.iudith
3rd [email protected]
🏆🍾
👏 to all competitors; we hope you enjoyed the challenge
Thanks to @kibeha.dk and @anthony-harper.bsky.social for writing & reviewing quizzes
blogs.oracle.com/sql/announci...
blogs.oracle.com
February 2, 2026 at 4:19 PM
Congrats to the winners in the Oracle Dev Gym championships!
1st Andrey Zaytsev
2nd mentzel.iudith
3rd [email protected]
🏆🍾
👏 to all competitors; we hope you enjoyed the challenge
Thanks to @kibeha.dk and @anthony-harper.bsky.social for writing & reviewing quizzes
blogs.oracle.com/sql/announci...
1st Andrey Zaytsev
2nd mentzel.iudith
3rd [email protected]
🏆🍾
👏 to all competitors; we hope you enjoyed the challenge
Thanks to @kibeha.dk and @anthony-harper.bsky.social for writing & reviewing quizzes
blogs.oracle.com/sql/announci...
Reposted by Jonathan Lewis
For those unfamiliar, this arrived in 26ai
January 28, 2026 at 2:43 PM
For those unfamiliar, this arrived in 26ai
Reposted by Jonathan Lewis
It's been a while but I've just written a new blog note. Still subject to checks of typo and grammar, but that will have to wait a couple of days.
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Case Study
This note isn’t a “real” case study, i.e. it’s not going to show you details of the data, indexes, plans etc. from a production system, but it is modelling one aspect of an …
jonathanlewis.wordpress.com
January 27, 2026 at 4:06 PM
It's been a while but I've just written a new blog note. Still subject to checks of typo and grammar, but that will have to wait a couple of days.
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
It's been a while but I've just written a new blog note. Still subject to checks of typo and grammar, but that will have to wait a couple of days.
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Case Study
This note isn’t a “real” case study, i.e. it’s not going to show you details of the data, indexes, plans etc. from a production system, but it is modelling one aspect of an …
jonathanlewis.wordpress.com
January 27, 2026 at 4:06 PM
It's been a while but I've just written a new blog note. Still subject to checks of typo and grammar, but that will have to wait a couple of days.
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Effects of "column is null" on an indexed column, multi-column inlists and index iterators, and an upgrade.
jonathanlewis.wordpress.com/2026/01/27/c...
Oh dear, I can feel a new blog note about indexes, inlists, and "is null" predicates on its way.
Still, it's going to rain (here) all day tomorrow so I won't be going out to dig.
Still, it's going to rain (here) all day tomorrow so I won't be going out to dig.
January 26, 2026 at 2:59 PM
Oh dear, I can feel a new blog note about indexes, inlists, and "is null" predicates on its way.
Still, it's going to rain (here) all day tomorrow so I won't be going out to dig.
Still, it's going to rain (here) all day tomorrow so I won't be going out to dig.
Reposted by Jonathan Lewis
Hidden behind shopfronts on Holborn is a rare survivor from medieval times, Barnard's Inn Hall. Anyone can visit this incredible building, and below its ancient rafters watch a free Gresham lecture about life, the universe and everything londonist.substack.com/p/inside-hol...
Inside Holborn's Tudor Hall
Into Barnard's Inn Hall, home of Gresham College.
londonist.substack.com
January 16, 2026 at 8:02 AM
Hidden behind shopfronts on Holborn is a rare survivor from medieval times, Barnard's Inn Hall. Anyone can visit this incredible building, and below its ancient rafters watch a free Gresham lecture about life, the universe and everything londonist.substack.com/p/inside-hol...
If you want an education in unicode then you should read this thread on the Oracle Developer forum:
forums.oracle.com/ords/apexds/...
forums.oracle.com/ords/apexds/...
January 16, 2026 at 9:33 AM
If you want an education in unicode then you should read this thread on the Oracle Developer forum:
forums.oracle.com/ords/apexds/...
forums.oracle.com/ords/apexds/...
Loved this comparison from Ric van Dyke.
"Parallel lines never meet**, you can't say the same about parallel execution (PX) processes".
** in Euclidean space
Also very keen on his point about distinguishing between parallel and simultaneous (concurrent).
ricramblings.blogspot.com/2026/01/para...
"Parallel lines never meet**, you can't say the same about parallel execution (PX) processes".
** in Euclidean space
Also very keen on his point about distinguishing between parallel and simultaneous (concurrent).
ricramblings.blogspot.com/2026/01/para...
January 13, 2026 at 10:03 AM
Loved this comparison from Ric van Dyke.
"Parallel lines never meet**, you can't say the same about parallel execution (PX) processes".
** in Euclidean space
Also very keen on his point about distinguishing between parallel and simultaneous (concurrent).
ricramblings.blogspot.com/2026/01/para...
"Parallel lines never meet**, you can't say the same about parallel execution (PX) processes".
** in Euclidean space
Also very keen on his point about distinguishing between parallel and simultaneous (concurrent).
ricramblings.blogspot.com/2026/01/para...
I've just been browsing through a (private) blog page where I've listed a lot of links to "must-read" articles dating back to the start of the millenium, and it's a bit disappointing how many now point to sites that don't exist - or redirect to domain name sellers.
January 12, 2026 at 4:08 PM
I've just been browsing through a (private) blog page where I've listed a lot of links to "must-read" articles dating back to the start of the millenium, and it's a bit disappointing how many now point to sites that don't exist - or redirect to domain name sellers.
Today's sourdough loaf may look a little different from usual. I got distracted at a critical moment by the need to scare a parakeet off the bird feeder and tipped the flour bowl into the starter/water bowl BEFORE mixing the plain and wholemeal flour. Now wondering if the loaf will turn out marbled.
January 11, 2026 at 11:43 AM
Today's sourdough loaf may look a little different from usual. I got distracted at a critical moment by the need to scare a parakeet off the bird feeder and tipped the flour bowl into the starter/water bowl BEFORE mixing the plain and wholemeal flour. Now wondering if the loaf will turn out marbled.
One for @martinwidlake.bsky.social : science and cats, what more could he want:
x.com/OxUniMaths/s...
x.com/OxUniMaths/s...
January 6, 2026 at 2:35 PM
One for @martinwidlake.bsky.social : science and cats, what more could he want:
x.com/OxUniMaths/s...
x.com/OxUniMaths/s...
Today is the last marmalade day of 2025 - a bit later than in previous years - using up the frozen Seville oranges before the new season's oranges are in the shops.
(Also making a sourdough loaf - because the best marmalade deserves the best bread.)
(Also making a sourdough loaf - because the best marmalade deserves the best bread.)
December 30, 2025 at 11:49 AM
Today is the last marmalade day of 2025 - a bit later than in previous years - using up the frozen Seville oranges before the new season's oranges are in the shops.
(Also making a sourdough loaf - because the best marmalade deserves the best bread.)
(Also making a sourdough loaf - because the best marmalade deserves the best bread.)
Ever had a good idea you wanted to type up, so put the video on hold, stepped into the "office", sat down ... and forgotten what you were going to type?
It's the "Doorway Effect" - though it's not just doorways, and might need more than just a doorway to trigger it
It's the brain's context switch
It's the "Doorway Effect" - though it's not just doorways, and might need more than just a doorway to trigger it
It's the brain's context switch
December 19, 2025 at 11:23 AM
Ever had a good idea you wanted to type up, so put the video on hold, stepped into the "office", sat down ... and forgotten what you were going to type?
It's the "Doorway Effect" - though it's not just doorways, and might need more than just a doorway to trigger it
It's the brain's context switch
It's the "Doorway Effect" - though it's not just doorways, and might need more than just a doorway to trigger it
It's the brain's context switch
Why are brussel sprouts like books? (Possibly only in the UK).
They're available all year round but a ridiculously large percentage of the annual sales happen around christmas.
They're available all year round but a ridiculously large percentage of the annual sales happen around christmas.
December 19, 2025 at 11:03 AM
Why are brussel sprouts like books? (Possibly only in the UK).
They're available all year round but a ridiculously large percentage of the annual sales happen around christmas.
They're available all year round but a ridiculously large percentage of the annual sales happen around christmas.
Reposted by Jonathan Lewis
Running a giant software business used to be fun. Artificial intelligence is now turning that model on its head. Nowhere has the transition been as unsettling as at Oracle
Oracle and the hard truths about software
Running a giant digital business is not as fun as it used to be
econ.st
December 13, 2025 at 6:40 PM
Running a giant software business used to be fun. Artificial intelligence is now turning that model on its head. Nowhere has the transition been as unsettling as at Oracle
So how many seconds does the battery last when you're running the whole lot concurrently?🙂
December 11, 2025 at 9:15 AM
So how many seconds does the battery last when you're running the whole lot concurrently?🙂
It’s taken ages to prepare my Dahlia tubers for winter storage. Down to the last set at last. 4 x Thomas Edison. I started with 3 last year, split off 3, gave way 2, at the start of this year and may have to split off 2 more next year.
December 10, 2025 at 8:04 PM
It’s taken ages to prepare my Dahlia tubers for winter storage. Down to the last set at last. 4 x Thomas Edison. I started with 3 last year, split off 3, gave way 2, at the start of this year and may have to split off 2 more next year.