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Consistent transactions between storage engines
Posted 4 hours, 45 minutes ago via Planet MySQL
You may not realize it, but in MariaDB 5.2 and earlier and in MySQL up to version 5.5, START TRANSACTION WITH CONSISTENT SNAPSHOT does not give any guarantees of consistency between different storage engines.
For example, suppose you have two transactions which run in parallel:
Transaction T1:
BEGIN;
SET @t = NOW();
UPDATE xtradb_table SET a= @t WHERE id = 5;
UPDATE pbxt_table SET b= @t WHERE id = 5;
COMMIT;
Transaction T2:
SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
START TRANSACTION WITH CONSISTENT SNAPSHOT;
SELECT t1.a, t2.b
FROM xtradb_table t1 INNER JOIN pbxt_table t2 ON t1.id=t2.id
WHERE t1.id = 5;
In the above case, it is possible, even with a "consistent" snapshot, to see the changes in a transaction only in InnoDB/XtraDB tables, and not in PBXT tables.
Naturally, it would be much better if the changes were visible no matter the storage engine used by the table. Thankfully this is possible, thanks to the introduction in MariaDB 5.3
of group commit
and an enhanced storage engine API for COMMIT which allows storage engines to coordinate commit ordering and visibility with each other and with the binary log.
With these improvements, the START TRANSACTION WITH CONSISTENT SNAPSHOT statement in MariaDB 5.3 has been enhanced to ensure consistency in-between storage engines which support the new API. Currently the storage engines which support this are XtraDB (MariaDB's enhanced version of InnoDB) and PBXT. In addition, the binary log, while not a storage engine as such, also supports the new API and can provide a binlog position consistent with storage engine transaction snapshots.
This means that with transaction isolation level at least REPEATABLE READ, the START TRANSACTION WITH CONSISTENT SNAPSHOT statement can be used to ensure that queries will see a transaction-consistent view of the database between storage engines.
No longer is it possible for a query to see the changes from some transaction T in XtraDB tables without also seeing the changes T makes to PBXT tables.
More information on this can be found in the AskMonty Knowledgebase
.
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Covering Lots of Things
Posted 6 hours, 17 minutes ago via Poker Blog
I was hoping for a no drama 2012, but the early part of 2012 has tested me so far...
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Breaking news! We’re changing up our weekly Party Hard gif dump where instead of throwing them all up here, we’ll be posting them to our Party Hard-only Cheez Site, Party Hardest! We’ll put all the party-inducing (and sometimes seizure-inducing) gifs over there from here on in, so all the party times can be in one convenient place. It’s already loaded with some of the very best of previous Party Hard posts, so go check it out!
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ARM-Based MacBook Air Unlikely Based on Analyst Talk with Tim Cook
Posted 7 hours ago via MacRumors: Mac News and Rumors - Front Page
There had been some interesting claims last year that Apple had been actively testing an ARM (A5) based MacBook Air. The ARM processor is the same one that is used in the iPhone and iPad. An ARM-based MacBook Air, however, would raise a number of questions about what kind of device it might actually be. Would it run OS X, or iOS? Would it be closer to a Mac or an iOS device? One of the main advantages of using an ARM processor would be a reduction in power-requirements, but with a corresponding drop in computing power. Using ARM, however, would abandon binary compatibility with existing Mac OS X applications.
CNet reports on a research note from Citigroup analyst Richard Gardner who was able to meet with Apple CEO Tim Cook and CFO Peter Oppenheimer on Thursday. Gardner addresses this question in his note with the following:
"Tim Cook reiterated his view that rapid innovation on the iOS platform (and mobile OS platforms in general) will significantly broaden the use case for tablets, eventually pushing annual tablet volumes above those of traditional PCs. We have wondered whether Apple might offer an ARM-based version of MacBook Air at some point; we walked away from this meeting with the impression that Apple feels iPad satisfies--or will soon satisfy--the needs of those who might have been interested in such a product."
Based on his conversations with the Apple executives, it seems Gardner believes that the iPad will evolve to meet any needs that might be met with an ARM-based MacBook air.
Rumors have suggested that the iPad will likely be getting a significant upgrade in the near future, with a faster processor, improved graphics capabilities and the long rumored Retina display. Of course, Cook is unlikely to divulge specific product plans at analyst meetings, but a complete Apple transition to ARM processors seemed an unlikely prospect regardless.
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So awesome, I’m powerless to do anything but deal with it.
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AT&T Starts Throttling Unlimited Data Users after 2GB of Monthly Usage
Posted 8 hours ago via MacRumors: Mac News and Rumors - Front Page
In October, AT&T announced that they would start throttling data usage amongst mobile Unlimited Data Plan users. While AT&T no longer offers an Unlimited Data plan to new customers, many of the original iPhone purchasers are still grandfathered into that plan. Those iPhone users have been able to retain these Unlimited plans, even though AT&T has since moved to a tiered data plan structure.
When AT&T announced their plan to start throttling users, the company said that they would only be throttling the top 5% of users. Early reports of affected users had pointed to 10GB-12GB per month users as the initially affected.
It seems that ceiling has decreased significantly over the past few months, at least for some regions. John Cozen reports that he received his top 5% data usage warning after reaching only 2.1GB of data for January.
I received a message during my last billing cycle, warning I was in the top 5% of my region and would experience reduced data speeds next time I reach that level of data use. I immediately checked my data usage on the AT&T iOS app.
2.1 GB. Less than I expected considering AT&T offers a 3GB plan for $30 a month. The same amount I’ve paid for the unlimited data plan since signing up with them many years ago. AT&T no longer offers an unlimited data plan, anyone still on it has been grandfathered in.
Cozen contacted AT&T to make sure it wasn't a mistake, and after several back and forth exchanges, it seems clear that it wasn't a mistake. The AT&T representatives seemed to confirm that 2.1GB did fall in the 5% range and the only option to avoid throttling was to move to a tiered plan.
Cozen was understandably upset since AT&T even offers an unthrottled 3GB plan for the same price he is paying at $30 month.
AT&T's top 5% measurement seems to be region-specific, as some users are continuing to see higher than 2GB usage without throttling.
Recent Mac and iOS Blog Stories
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Apple Releases iBooks 2.0.1 to Address Issue with Textbooks Not Opening
•
Id Software's RAGE Arrives on Mac App Store
•
'The Daily' Reports 100,000 Paying Subs on One-Year Anniversary
•
Safari 5.1.4 with JavaScript and PDF Handling Improvements Seeded to Developers
•
Apple Grabs Another Gaming PR Executive for App Store
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Apple Revises Snow Leopard Security Update and Pulls 10.7.3 Delta Update
Posted 8 hours, 23 minutes ago via MacRumors: Mac News and Rumors - Front Page
After a couple of issues with some software updates, Apple has made some quiet revisions to address the problems.
The first was a Snow Leopard security update which inadvertently caused problems with Apple's PowerPC emulation layer Rosetta. Macworld notes that Apple has since released Security Update 2012-001, version 1.1 for Snow Leopard. The new version seems to fix the PowerPC crashing issues described with the original update.
Meanwhile, the crashing/CUI errors with 10.7.3 Delta updater has also been addressed by Apple. 9to5Mac notes that Apple has responded by pulling the Delta update altogether, leaving the Combo updater alone.
The different between the Delta and Combo updaters is normally just download size alone. The Delta updater is a smaller download since it just includes the changes, while the Combo updater includes everything and weighs in at 1.3GB. The Combo updater should be available at this support page for direct download, but the page is presently not working. The direct download (1.3GB) link is still working at this time.
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• Apple Releases iBooks 2.0.1 to Address Issue with Textbooks Not Opening
• Id Software's RAGE Arrives on Mac App Store
• 'The Daily' Reports 100,000 Paying Subs on One-Year Anniversary
• Safari 5.1.4 with JavaScript and PDF Handling Improvements Seeded to Developers
• Apple Grabs Another Gaming PR Executive for App Store
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Converting transparency sheets to an LCD monitor
Posted 10 hours, 23 minutes ago via Hack a Day
Apparently, there’s some sort of sporting event being televised this weekend that has been historically used as an excuse to buy a big-screen TV. [Joel] wanted a huge-screen TV on the cheap, so he converted an overhead projector to something he can use with his XBox.
Using a bare LCD panel with an overhead projector is a decades-old hack we’ve covered before. The basic idea is fairly simple, but we’ve never seen anything that could be considered a semi-permanent build. [Joel] started his project by picking up a surplus overhead projector for $25 and routing a cutting board to mount the LCD in. The bulb in the projector added a lot of heat, so three small fans are used to blow air between the projector glass and the LCD display.
[Joel] started off looking at the LumenLab DIY projector project, but considered that to be a terrible amount of work with a fairly high initial investment. If you don’t count the few LCDs [Joel] burned through while building his project, his projector was built for under $100. We’re loving the result and are sure it will be much appreciated at [Joel]‘s LAN parties.
Filed under:
peripherals hacks,
video hacks 
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Your Phone Use in the Bathroom May Be Influenced by the Phone You Own
Posted 10 hours, 50 minutes ago via Top News
Android users were on the top of the list with 87% of their owners admitting they have used their smartphones while sitting on the throne. 84% of the BlackBerry users admit to doing it (smartphone use in the bathroom) and iPhone users checked in at 77%.
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Reverse Engineering an AC Signal Protocol
Posted 11 hours, 24 minutes ago via Hack a Day
[Arpad] has spent quite a bit of time reverse-engineering a home automation system, and, as he is quick to point out, presents the information learned for informational purposes only. He’s really done his homework (and documented it well), looking into the US patent application, and figuring out how the protocol works.
If you’re wondering how someone is able to send a signal over an AC sine wave, at least one technique is the proprietary [Universal Powerline Bus]. This works by sending precisely times pulses in conjunction with the wave that would exist normally. Given the correct software on the other end, this can then be decoded and used for whatever data transfer is necessary.
Although as engineers and technologists, we certainly don’t condone stealing patents, part of point of one is that others are allowed to learn your secrets in exchange for some legal protection. [Arpad]‘s motivation in doing this is that the technology is only widely available in the US with our puny 120 VAC 60Hz power. With this knowledge, he’s been able to transfer it to work with European 230 VAC 50Hz.
Filed under:
home hacks 
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The Internet makes you stupid, but this app might make you smarter
Posted 11 hours, 38 minutes ago via Top News
Undisputed fact I just made up: The more time we spend online, the dumber and more myopic we get.
Hacker Noah Litvin set out to combat that observable phenomenon with DailyPag.es, an app that wo...
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A.R.T. sorts your recyclables for you
Posted 12 hours, 23 minutes ago via Hack a Day
[Yuhin Wu] wrote in to let us know about the Automated Recycling Sorter that was built with a group of classmates at the University of Toronto. They entered it the school’s student design contest and we’re happy to report that it took first place.
The angled sled has been designed to separate glass, plastic, and metal containers. The first sorting happens at the intake area. A set of moment arms are used to weed out the glass bottles. Since there are several of them in a row, a larger and heavier plastic container will not be falsely sorted and the same goes for smaller glass bottles.
With the glass out of the mix the team goes on to separate metal and plastic. An Arduino was used for this purpose. It senses an electrical disturbance caused by a metal can passing through the chute and actuates a trap door to sort it. Plastic has no effect on this sensor and slides past the trap to its own sorting bin.
Don’t miss both demo videos which we’ve included after the break.
Filed under:
green hacks 
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Apple iPad Split Keyboard Features a Few Hidden Buttons [PIC]
Posted 14 hours, 12 minutes ago via Top News
You may be familiar with the iPad’s split keyboard, introduced along with the roll out of the iOS 5. The wonderful keyboard has some more hidden features...
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OurSQL Episode 77: Removing Evil Queries, part 1
Posted 14 hours, 43 minutes ago via Planet MySQL
Registration for Percona Live: MySQL Conference and Expo is open! The conference is from Tuesday, April 10th through Thursday, April 12th. Early bird pricing ends March 12th, 2012.
Use code PL-pod and save 10% off the early bird prices!.
The 1st Latin American Conference about MySQL, NoSQL and Cloud technologies will be held in Buenos Aires in June. It is called the MariaDB NoSQL & Cloud Latin American Conference and we'll bring you more information as it becomes available.
read more
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We Need Copyright Reform, Not The Anti-Counterfeiting Trade Agreement (ACTA)
Posted 15 hours, 18 minutes ago via Top News
As a Member of the European Parliament, I very much welcome the increased attention the Anti-Counterfeiting Trade Agreement (ACTA) has received in the past weeks. It has taken a while for massive outcry to emerge, but we are seeing protest voices getting louder and louder.
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Polish Protests Put ACTA ‘On Hold’
Posted 1 day ago via Top News
Last week the European Union has officially signed the controversial “anti-piracy” trade agreement ACTA. This brings ACTA a step closer to passing, but individual EU Member States and the European Parliament still have to ratify ACTA later this year. But this may not happen.
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F.B.I. Admits Hacker Group’s Eavesdropping
Posted 1 day, 11 hours ago via Top News
The group known as Anonymous listened in on a call between the bureau, Scotland Yard and other foreign police agencies about their joint investigation of the group and its allies.
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