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
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.
The internet remembers everything: Middelfart, Denmark, 2006:
December 9, 2025 at 12:46 PM
The internet remembers everything: Middelfart, Denmark, 2006:
Only 48 hours until UKOUG Discover 2025 starts. I'll be in the audience for "Super Sunday", and presenting at the break of day (nearly) on the Monday.
jonathanlewis.wordpress.com/public-appea...
jonathanlewis.wordpress.com/public-appea...
November 28, 2025 at 9:49 AM
Only 48 hours until UKOUG Discover 2025 starts. I'll be in the audience for "Super Sunday", and presenting at the break of day (nearly) on the Monday.
jonathanlewis.wordpress.com/public-appea...
jonathanlewis.wordpress.com/public-appea...
Lifted all my dahlias a few days ago, just before the overnight temperature dropped to -4C. It's taking ages to clean off all the earth so that they can dry properly for overwintering.
November 24, 2025 at 3:45 PM
Lifted all my dahlias a few days ago, just before the overnight temperature dropped to -4C. It's taking ages to clean off all the earth so that they can dry properly for overwintering.
Here's a golden oldie that MIGHT still be causing some errors in early versions of 19c - a POSSIBLE case appeared a few days ago on the Oracle database forum:
jonathanlewis.wordpress.com/2015/11/09/w...
jonathanlewis.wordpress.com/2015/11/09/w...
November 24, 2025 at 10:48 AM
Here's a golden oldie that MIGHT still be causing some errors in early versions of 19c - a POSSIBLE case appeared a few days ago on the Oracle database forum:
jonathanlewis.wordpress.com/2015/11/09/w...
jonathanlewis.wordpress.com/2015/11/09/w...
Only two weeks to go #ukougdiscover25 - don't stay up too late on Sunday night if you're thinking of coming to this one:
November 18, 2025 at 10:35 AM
Only two weeks to go #ukougdiscover25 - don't stay up too late on Sunday night if you're thinking of coming to this one:
Now reading: "Blue Machine - How the ocean shapes our world" by @helenczerski.bsky.social
A fascinating mix of scientific and historical detail, told in an enjoyable narrative style.
Bought it after attending the 2nd in her series of lectures at Gresham College: www.gresham.ac.uk/watch-now/se...
A fascinating mix of scientific and historical detail, told in an enjoyable narrative style.
Bought it after attending the 2nd in her series of lectures at Gresham College: www.gresham.ac.uk/watch-now/se...
Notes from a Large Planet: a citizen’s guide to the Earth
A six-part
www.gresham.ac.uk
November 17, 2025 at 8:02 PM
Now reading: "Blue Machine - How the ocean shapes our world" by @helenczerski.bsky.social
A fascinating mix of scientific and historical detail, told in an enjoyable narrative style.
Bought it after attending the 2nd in her series of lectures at Gresham College: www.gresham.ac.uk/watch-now/se...
A fascinating mix of scientific and historical detail, told in an enjoyable narrative style.
Bought it after attending the 2nd in her series of lectures at Gresham College: www.gresham.ac.uk/watch-now/se...
Reference point for @oraclebase.bsky.social and @martinwidlake.bsky.social : the 2017 Ig Nobel prize for Physics was awarded to the author of a paper discussing whether cats are solids or liquids or both:
live.stemfellowship.org/the-ig-nobel...
live.stemfellowship.org/the-ig-nobel...
The Ig Nobel Prize: Why are Cats Liquid? - Stem Fellowship
By Angela Zhu Did you know that there exists an amusing prize for the funniest scientists and their comical findings? In this series, we will explore the famous Ignoble Nobel Prize (abbreviated as “Ig...
live.stemfellowship.org
November 17, 2025 at 9:26 AM
Reference point for @oraclebase.bsky.social and @martinwidlake.bsky.social : the 2017 Ig Nobel prize for Physics was awarded to the author of a paper discussing whether cats are solids or liquids or both:
live.stemfellowship.org/the-ig-nobel...
live.stemfellowship.org/the-ig-nobel...
Thinking small but useful RESETTABLE, a recent (23.26, maybe older) v$ view seems to list resettable parameters:
GV$SYSTEM_RESET_PARAMETER
Name
------
INST_ID
NUM
NAME
TYPE
RESET_VALUE
DISPLAY_RESET_VALUE
ISSYS_RESETTABLE
ISPDB_RESETTABLE
ISINSTANCE_RESETTABLE
UPDATE_COMMENT
CON_ID
GV$SYSTEM_RESET_PARAMETER
Name
------
INST_ID
NUM
NAME
TYPE
RESET_VALUE
DISPLAY_RESET_VALUE
ISSYS_RESETTABLE
ISPDB_RESETTABLE
ISINSTANCE_RESETTABLE
UPDATE_COMMENT
CON_ID
November 10, 2025 at 9:41 AM
Thinking small but useful RESETTABLE, a recent (23.26, maybe older) v$ view seems to list resettable parameters:
GV$SYSTEM_RESET_PARAMETER
Name
------
INST_ID
NUM
NAME
TYPE
RESET_VALUE
DISPLAY_RESET_VALUE
ISSYS_RESETTABLE
ISPDB_RESETTABLE
ISINSTANCE_RESETTABLE
UPDATE_COMMENT
CON_ID
GV$SYSTEM_RESET_PARAMETER
Name
------
INST_ID
NUM
NAME
TYPE
RESET_VALUE
DISPLAY_RESET_VALUE
ISSYS_RESETTABLE
ISPDB_RESETTABLE
ISINSTANCE_RESETTABLE
UPDATE_COMMENT
CON_ID
Reposted by Jonathan Lewis
Small change, but so useful.
RESETTABLE Clause to in Oracle AI Database 26ai
oracle-base.com/articles/26/...
@OracleDatabase #database #26ai
RESETTABLE Clause to in Oracle AI Database 26ai
oracle-base.com/articles/26/...
@OracleDatabase #database #26ai
November 10, 2025 at 8:21 AM
Small change, but so useful.
RESETTABLE Clause to in Oracle AI Database 26ai
oracle-base.com/articles/26/...
@OracleDatabase #database #26ai
RESETTABLE Clause to in Oracle AI Database 26ai
oracle-base.com/articles/26/...
@OracleDatabase #database #26ai
Special day on the allotment tomorrow. My order of raspberry canes has arrived from James McIntyre james-mcintyre.co.uk/product-cate... so I'll be hard at work in the fruit cage
5 x Glen Doll (floricane)
5 x All Gold (primocane)
8 x Joan J (primocane)
with 2 "spare" Joan J for my old raspberry bed
5 x Glen Doll (floricane)
5 x All Gold (primocane)
8 x Joan J (primocane)
with 2 "spare" Joan J for my old raspberry bed
November 8, 2025 at 6:34 PM
Special day on the allotment tomorrow. My order of raspberry canes has arrived from James McIntyre james-mcintyre.co.uk/product-cate... so I'll be hard at work in the fruit cage
5 x Glen Doll (floricane)
5 x All Gold (primocane)
8 x Joan J (primocane)
with 2 "spare" Joan J for my old raspberry bed
5 x Glen Doll (floricane)
5 x All Gold (primocane)
8 x Joan J (primocane)
with 2 "spare" Joan J for my old raspberry bed
Golden oldie time.
From 2007 - and nearly answering a recent question about index sizing: thoughts about space and I/O requests when you are heading for billions of rows in the database.
jonathanlewis.wordpress.com/2007/03/18/t...
From 2007 - and nearly answering a recent question about index sizing: thoughts about space and I/O requests when you are heading for billions of rows in the database.
jonathanlewis.wordpress.com/2007/03/18/t...
November 4, 2025 at 8:24 PM
Golden oldie time.
From 2007 - and nearly answering a recent question about index sizing: thoughts about space and I/O requests when you are heading for billions of rows in the database.
jonathanlewis.wordpress.com/2007/03/18/t...
From 2007 - and nearly answering a recent question about index sizing: thoughts about space and I/O requests when you are heading for billions of rows in the database.
jonathanlewis.wordpress.com/2007/03/18/t...
How do you truncate a partition at the parent end of a referential integrity constraint?
You can't (error ORA-02266) but someone asked how today so I pointed them to a workaround I described in 2012 (after testing to see if it still worked on 19.11)
jonathanlewis.wordpress.com/2012/06/05/t...
You can't (error ORA-02266) but someone asked how today so I pointed them to a workaround I described in 2012 (after testing to see if it still worked on 19.11)
jonathanlewis.wordpress.com/2012/06/05/t...
Truncate Partition
A recent posting on the OTN database forum (which I didn’t answer correctly on my first attempt) raised the problem of truncating partitions when there are referential integrity constraints i…
jonathanlewis.wordpress.com
November 3, 2025 at 7:12 PM
How do you truncate a partition at the parent end of a referential integrity constraint?
You can't (error ORA-02266) but someone asked how today so I pointed them to a workaround I described in 2012 (after testing to see if it still worked on 19.11)
jonathanlewis.wordpress.com/2012/06/05/t...
You can't (error ORA-02266) but someone asked how today so I pointed them to a workaround I described in 2012 (after testing to see if it still worked on 19.11)
jonathanlewis.wordpress.com/2012/06/05/t...
Someone has just sent me a communication through chat. It must be someone I know because I've set chat to respond only to people I follow, and I don't follow many.
But I can't use chat unless I supply my credit card number or a view of my face to an organisation I've never heard of - so no thanks.
But I can't use chat unless I supply my credit card number or a view of my face to an organisation I've never heard of - so no thanks.
November 2, 2025 at 6:24 PM
Someone has just sent me a communication through chat. It must be someone I know because I've set chat to respond only to people I follow, and I don't follow many.
But I can't use chat unless I supply my credit card number or a view of my face to an organisation I've never heard of - so no thanks.
But I can't use chat unless I supply my credit card number or a view of my face to an organisation I've never heard of - so no thanks.
Here's an article I published 12 years ago about rowids and sorting - if you store and report rowids the you will find that a columnn of type rowid sorts differently from a column where the rowid is stored in its character format.
See: jonathanlewis.wordpress.com/2013/12/01/r...
(Last tested 23.6)
See: jonathanlewis.wordpress.com/2013/12/01/r...
(Last tested 23.6)
Rowids
I have, in the past, used the dbms_rowid package to create rowids from block addresses (typically faking the first and last rowids that could appear in an extent) but I’ve just been sent a pi…
jonathanlewis.wordpress.com
November 2, 2025 at 6:21 PM
Here's an article I published 12 years ago about rowids and sorting - if you store and report rowids the you will find that a columnn of type rowid sorts differently from a column where the rowid is stored in its character format.
See: jonathanlewis.wordpress.com/2013/12/01/r...
(Last tested 23.6)
See: jonathanlewis.wordpress.com/2013/12/01/r...
(Last tested 23.6)
Reposted by Jonathan Lewis
Heads up VirtualBox. If you've updated to 7.2.4 and found that your VMs will no longer start (Error: Failed to load R0 module), then uninstall your existing installation first (or uninstall the 7.2.4 you just installed) and then install 7.2.4 from scratch
November 1, 2025 at 5:50 AM
Heads up VirtualBox. If you've updated to 7.2.4 and found that your VMs will no longer start (Error: Failed to load R0 module), then uninstall your existing installation first (or uninstall the 7.2.4 you just installed) and then install 7.2.4 from scratch
Reposted by Jonathan Lewis
In the multitenant architecture in Oracle AI Database, the container database is essential. If you create it the right way, you can avoid some difficulties later on.
Here's my recommendation for creating container databases.
Here's my recommendation for creating container databases.
How I Think You Should Create Your Container Databases
In the multitenant architecture in Oracle AI Database, the container database is essential. If you create it the right way, you can avoid some difficulties later on. Here's my recommendation for creating container databases.
dohdatabase.com
October 28, 2025 at 6:31 AM
In the multitenant architecture in Oracle AI Database, the container database is essential. If you create it the right way, you can avoid some difficulties later on.
Here's my recommendation for creating container databases.
Here's my recommendation for creating container databases.
Reposted by Jonathan Lewis
Since last week, I can finally use the QUALIFY clause in Oracle. If you never heard of this SQL extension, read my newest blog post:
danischnider.wordpress.com/2025/10/24/q...
danischnider.wordpress.com/2025/10/24/q...
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…
danischnider.wordpress.com
October 24, 2025 at 2:35 PM
Since last week, I can finally use the QUALIFY clause in Oracle. If you never heard of this SQL extension, read my newest blog post:
danischnider.wordpress.com/2025/10/24/q...
danischnider.wordpress.com/2025/10/24/q...
Reposted by Jonathan Lewis
Today I revisited a 4yo post on one of SQLcl’s underrated features: autotrace — shows full session stats for a SQL statement (way beyond SQL*Plus). Still works in latest release. Updated prereqs too. More details here
🔗 martincarstenbach.com/2021/06/10/s...
#Oracle #SQLcl #performance #IKYK
🔗 martincarstenbach.com/2021/06/10/s...
#Oracle #SQLcl #performance #IKYK
SQLcl autotrace is way more than “just” (SQL*Plus) autotrace
As part of the research I did for the 2nd edition of our Exadata book I used session statistics quite heavily. Session statistics can provide additional insights in situations where the wait interf…
martincarstenbach.com
October 21, 2025 at 9:41 AM
Today I revisited a 4yo post on one of SQLcl’s underrated features: autotrace — shows full session stats for a SQL statement (way beyond SQL*Plus). Still works in latest release. Updated prereqs too. More details here
🔗 martincarstenbach.com/2021/06/10/s...
#Oracle #SQLcl #performance #IKYK
🔗 martincarstenbach.com/2021/06/10/s...
#Oracle #SQLcl #performance #IKYK
A new post about parallel DML and how to waste huge amounts of space in your database in no time at all.
jonathanlewis.wordpress.com/2025/10/10/m...
jonathanlewis.wordpress.com/2025/10/10/m...
October 10, 2025 at 12:26 PM
A new post about parallel DML and how to waste huge amounts of space in your database in no time at all.
jonathanlewis.wordpress.com/2025/10/10/m...
jonathanlewis.wordpress.com/2025/10/10/m...