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There are two types of IFs in MySQL: the IF statement and the IF function. Both are different from each other. In this article, we will explain their diversities and show usage examples. Also, we will review other MySQL functions. Contents MySQL IF statements MySQL IF-THEN statement MySQL IF-THEN-ELSE statement MySQL IF-THEN-ELSEIF-ELSE statement Examples of […]
The post MySQL IF – Function and Statement (with Examples) appeared first on Devart Blog.
Planet MySQL
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A critical skill for any rifle shooter, mounting your own scope will save you time, money, and teach a core skill for long range shooting.Recoil
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In today’s world, it’s difficult to find unbiased news and get a true sense of what’s going on around you. This applies to widespread topics, like politics or science, as well as more personalized topics, like gaming, sports, or film.
Luckily, you don’t have to scour individual news sites anymore. There are apps dedicated to collecting news from different sources, making it easy for you to keep up with everything you’re interested in and get different viewpoints. Flipboard and Feedly are two of the most popular apps for keeping track of new info, but which is better? Let’s check it out!
Download: Flipboard for Android | iOS (Free)
Download: Feedly for Android | iOS (Free, in-app purchases available)
Overall, Flipboard has a more intuitive user interface that seems more fleshed out for the average, everyday user when compared to Feedly.
Articles and topics of interest are displayed with a large square image that’s more aesthetically pleasing. Flipboard also lets you flip through content on the home screen, similar to the flipping motion of reading an actual magazine.
There’s nothing overly special about Feedly’s user interface. It’s straightforward and fairly easy to use, but a little boring, at least compared to Flipboard. When you see articles on the home screen, there’s less of a focus on the featured image for the article.
Instead, the article title is bolded, there’s sometimes a brief sentence displayed under the title, and then there’s a small image to the right.
When you first download Flipboard and set up your account, you’ll be asked to select a variety of hashtags based on what your interests are. You can select as many as you want to, but you have to select at least three.
Then, your home page, or pages, are personalized to the content you’re interested in seeing. You can flip through content on the home page, or head over to your Following tab to see articles with specific hashtags you follow. Being able to navigate the news this way within the Flipboard app makes it much more easily personalized than what Feedly offers.
Feedly does a good job of displaying popular news stories that interest you on the home screen, but you have to do a lot of work behind the scenes to get your home screen looking the way you want it. Whereas Flipboard allows you to add topics by hashtags, Feedly lets you favorite or follow specific websites within a niche.
For example, if you’re interested in keeping up with the latest gaming news, you could search that topic and find multiple sites related to that industry. Then, you need to personally select the sites that you want to read stories from to fill your feed.
If you don’t feel like putting in all the effort to personalize your feed, you can browse through the Explore tab to read some of the most popular stories. Since you browse news by the sites you choose to follow, it’s a bit harder to find fair and balanced news on Feedly than it is on Flipboard.
Both apps let you share articles on almost every platform you can think of. Want to send a quick link to your mom with a recipe you think she’ll like? Or send the latest sports news to a friend to see what they thought of the game last night?
On Flipboard, when you open an article and tap the share button, you’ll see a list of all your sharing-compatible apps pop up. Select an app and it’ll share the article title and a shortened link.
When you tap the share button on Feedly, you’ll see your most recent or most popular apps show up to quickly share the article. You can, of course, always scroll to the end to view others, but they’re not readily displayed like in the Flipboard app.
It’s not always possible to read every story that piques your interest as soon as you see it. Luckily, both Flipboard and Feedly allow you to save stories to read them when you find time. You can also use this feature to bookmark articles you want to save for the future or eventually show to a family member or friend.
Flipboard lets you organize articles into your own personal “magazines.” You can customize the titles of your magazines to make it easy to find articles later, as well as reset the cover image to reflect the last article you added.
You can add as many magazines as you want. If you select the Profile tab all the way to the right on the bottom navigation bar, you’ll see all your magazines displayed how you have them organized. By tapping and holding a magazine cover, you can drag it around the screen to reorder it.
You can create magazines simply for collecting and saving stories for you or your followers, for sharing among friends and family, or for mixing together content from Twitter feeds, blogs, and other news sources.
While Flipboard allows you to create custom magazines in addition to a “Save For Later” magazine, the Feedly app only lets you bookmark articles to read later. There’s no way to organize the articles you save. Instead, everything is saved in one long list.
You can change what the article looks like in this list, like a card with a picture, a magazine list, or just text from the article. But you can’t organize articles by topic or create a separate section for recipes, as an example, that you can simply save forever.
Once you’ve read an article that you saved to read later, you can remove the bookmark to take it off your reading list instantly. Or, you can read through all the articles on your list and then mark all of them as read at once.
Both Flipboard and Feedly make it easy for users to find news on topics that interest them, whether you want to find out what’s going on in other countries or what’s going on in the industry you work in. With such a variety of sources, it’s easy to find balanced stories that offer different opinions on even the most controversial topics.
With either app, you can collect news relevant to you instead of always perusing a single site to find your news.
Browsing an individual site almost always means skipping over stories that just don’t interest you, but by using a personalized app, everything you see will be based on your interests! Between Flipboard and Feedly, I’d say Flipboard is the better news app because it’s more personalized and easier to use.
MUO – Feed
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Home defense is a hot topic in the firearms community, with newbies and seasoned pros debating the merits of different platforms.
But what should you consider when setting up a home defense or bedside gun?
Well, I’m here to help. I’m going to try and dial in on some suggestions of things I would consider essential in home defense, as well as looking at the stats behind home invasions.
I will preface this by saying that everything contained in this article is meant as a general picture and in no way should be construed as an all-inclusive, gospel, or a cookie-cutter response to fit every person or scenario.
There are simply too many variables to account for in one article in dealing with a home defense scenario and what the correct tool for the job is.
But I’ve done my best to offer a broad perspective that should at least get you started. So keep reading to learn more!
Table of Contents
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One of the common misconceptions in the firearms community is that we must prepare to fight off waves of invaders in a home defense situation.
Could that happen? Sure. Is it likely? Reading through recent home invasion stories reported to the police, no.
Local statistics in Las Vegas are that the likelihood is one or two (average was 1.5) persons will attempt to gain entry, though more are possibly outside in supporting roles.
This can vary from area to area, but lower-income locations typically see more burglaries and attempts.
Per the FBI’s Criminal Justice Information Services Division, a break-in occurs once every 26 seconds in the United States.
Of those break-ins, 61% of offenders were unarmed at the time of the offense, and only 12% of all violent break-ins involved the offender having a firearm. Often, the offenders were known to the victims, and an assault occurred in only 5% of the break-ins reported.
So, what does all that have to do with setting up your home defense? First and foremost, the best deterrent you can have to prevent a home invasion is a security system — 83% of would-be burglars check for some sort of security system before breaking in.
If you choose to defend yourself, your home, and your family with a firearm, you need to understand that you may know the person attempting to break in, they may or may not be armed, and that the likelihood is that they want to get in and get out with cash or goods, not hurt you.
In short, make sure you understand your local laws VERY well.
This is a very complicated answer, and there isn’t a blanket “this works best for everyone” response.
Instead of going into a nuanced answer, I’m going to attempt to give some information that will highlight the strengths and weaknesses of different firearms for home defense.
Ultimately you will have to decide what will work best based on your level of familiarity and comfort with a particular platform, the layout of your house, availability of defensive ammo, and many other variables.
Why does the layout of your house matter? Defending a one-bedroom apartment will be a vastly different scenario than trying to defend a 10,000-square-foot ranch house on 27 acres of land.
The key here is realizing that you are legally responsible for everything a bullet does once it exits the muzzle of your firearm after being discharged.
Sending a round through a wall into your neighboring townhouse means you are responsible for any damages or injuries it causes. Different tools will excel in different environments, so figure out what will do the best for you.
Investing in some deterrents can often prevent the need to use force.
We already saw that potential burglars check for a security system, so that is the first thing you should be investing in. (Or take a look at our article on the Best Ways to Secure Your Home for more tips!)
Beyond that, what’s the next step to deterring a burglary without escalating to force? A good-quality handheld flashlight and properly using it.
Let’s face facts; if something goes bump in the night, most of the time, there isn’t a need to point a gun at it.
The use of a flashlight to investigate what is skulking around your property allows you to make an informed decision on whether the use of force is necessary or if you simply caught your teenage kid sneaking back into the house.
If you spot a would-be burglar, the threat of being caught and detained statistically shows they are less likely to stay.
In that 5% of break-ins that turn into an assault, however, use of force may be needed, and that is where other tools are more suitable for the job.
I’m not getting into a debate over semi-automatic vs. revolver or a debate on which caliber is the best.
The correct answer is finding a gun that you will train to become more proficient with, that can add the features you work best with, and ensure you are confident in its use.
I will not recommend a .22 LR as a defensive handgun, but if that is all you have, you better make it work for you.
Generally, any caliber from .380 and up that offers hollow-point rounds can be suitable for a defensive gun. Each caliber will have some advantages and disadvantages.
Quality matters for defensive guns. Right now, finding quality guns can be both difficult and expensive, but you have to ask yourself what your life is worth.
Stick to brands with proven track records of success and quality like Glock, CZ, H&K, Smith & Wesson, Sig Sauer, FN, etc.
Set your gun up for dominance and success.
Let’s face it, in the middle of the night; you should have the advantage in your home over a stranger. You know the layout better, you know where obstacles typically are, and you are just generally more familiar. Why not press that advantage with your firearm?
If you find yourself in a dark house trying to defend yourself, getting positive target identification and getting sights on target are the two things with which you need to be concerned — speaking in terms of operating the gun itself, not considering things like finding and using cover, etc.
To this end, I do recommend a weapon-mounted light of good quality — Streamlight, Surefire, Modlite, etc.
Additionally, I am a huge advocate for adding an optic to your pistol. Optics allow you to be threat-focused, rather than requiring you to switch to sight focus beyond a certain distance.
Prices accurate at time of writing
Prices accurate at time of writing
Optics allow you to acquire your aiming device regardless of lighting conditions and permit faster follow-up shots with more consistency, regardless of shooting experience.
Can’t night sights/fiber optic sights do the same thing? Yes and no. They will allow you to find your sights faster, but you are still limited by lighting conditions to get sights on target, and iron sights still require sight focus vs. being target focused.
The last component is ammo. Find good quality, consistent hollow points that will get the job done.
Examples of this would include but are not limited to Speer Gold Dot, Hornady Critical Duty, or Federal HST for larger handguns like the Glock G17 and G19.
For shorter barreled guns like Glock G43x, S&W Shield, or Sig P365, Hornady Critical Defense or Federal Punch are better options.
Prices accurate at time of writing
Prices accurate at time of writing
Speaking with Chuck Haggard of Agile/Training & Consulting, he mentioned that shorter barreled handguns lead to the round not fully expanding on some of the duty grade hollow points.
His testing and experience showed that Critical Defense was a much better choice in that scenario.
Make sure your gun is rated for any +P or +P+ ammo you intend to shoot, and then shoot a magazine worth through your gun to make sure it cycles without any issue.
Pistols do have their limits, and you need to know them.
Depending on the handgun you’ve selected, you will have between six and 17 rounds to use for your defense without reloading.
Looking back at the average number of attackers, that is between three and eight shots at each adversary.
Add in adrenaline and the high stress of the situation, and you now have a scenario where you are likely reverting to your lowest proficiency and training to put hits on target.
Many, myself included, choose to use a rifle or pistol version of a rifle for home defense.
Rifles offer a more stable, more forgiving firing platform than handguns due to the increased points of body contact with the gun.
Additionally, they typically offer more ammunition to feed and, in most cases, provide increased velocity over handguns.
So, when will a rifle be an advantage over a handgun? If your house is laid out in such a manner that you can create distance, a rifle is going to generally be better than a handgun.
I want to clarify this in that shot placement matters; either way, people can generally fire a rifle better than a handgun at low skill levels. At 15 to 20 yards, both can be effective; it will come down to training and comfort.
In my case, my entire family is housed on the second floor of our home. I can then use a rifle to defend against people coming upstairs and know that it will be effective.
Much like handguns, some definite upgrades are recommended.
Just like with handguns, a rifle will benefit from a weapon-mounted light. Target identification is still a priority, even more so at greater distances.
Some form of quality optic is needed as well. I prefer red dots that I can leave on like an Aimpoint CompM5 or T2 so that my gun is ready when I pick it up. I know others that run low-power variable scopes and are very effective.
Prices accurate at time of writing
Prices accurate at time of writing
I would avoid using just iron sights, as you still suffer the same limitations as handgun sights. Invest in a quality optic, stay away from knocks-offs and low-quality products, and prosper.
Lastly, a sling is a must-have for a defensive rifle. This allows the user to retain possession of the weapon if hand to hand occurs and allows for retention of the rifle if you need your hands free to pick something or someone up to help.
Prices accurate at time of writing
Prices accurate at time of writing
Rifles are not without their drawbacks, though. That sling that I just mentioned means that the gun is attached to you to some extent. A knowledgeable attacker can use that as leverage against you to control your body and/or throw you.
In closer quarters or houses with lots of turns, a longer barrel can be a hindrance in terms of maneuverability.
Ammo selection, along with good shot placement, also plays a huge role in the effectiveness of a rifle. Once again, something like Speer Gold Dot, Federal LE Tactical, or Hornady TAP FDP that are made to have a hollow or soft point allow for better defensive use than a full metal jacket round.
TAP and other fragmenting rounds are especially worth considering if over-penetration is a concern in smaller living spaces. Please understand that fragmenting rounds are different than frangible rounds, and under no circumstances are frangible rounds a go-to for personal protection.
Going back to our average number of people in the break-in, rifles offer more rounds to put on target.
An AR-15 magazine comes in 10-round, 20-round, and 30-round magazines as the most common options. You can get larger capacity drum magazines, but many tend to be lower quality, finicky, and not reliable to consider for a self-defense scenario.
As I mentioned above, it may take more than one round to stop someone from attacking you, so having more ammunition to expend in that pursuit is a good thing.
Shotguns for home defense use have become a more heated topic in the last few years.
Search any gun forum or message board, and you’ll encounter people saying…shotguns are the best defensive gun ever, you just need to rack the action to scare away every bad guy in a 3-mile radius, you don’t have to aim, etc.
The truth is that shotguns have their place in home defense, but like anything else, they aren’t a blanket answer to a problem. Sometimes shotguns will be the optimal choice and other times they won’t.
The first thing to consider is the gun itself…
Remington 870s or Mossberg 590s are the go-to pump-action shotguns.
If semi-automatic shotguns are more your thing, the Beretta 1301, Benelli M2 or M4, and the Mossberg 940 will do.
Prices accurate at time of writing
Prices accurate at time of writing
Once you have a good-quality, reliable shotgun, the next step is patterning your ammo.
This involves getting the ammo you intend to use and shooting it at various distances to see how the pellets spread and pattern on a target.
This is important, as using different types of buckshot with different guns will get you different results. As you are responsible for everything your ammo does after it is fired, you need to know exactly where these pellets will fly, where they end up, and if you will face any unintended damage.
There are two viable shotgun rounds for defense, buckshot, and slugs. Birdshot and snakeshot are not suitable for self-defense, and their use could leave you facing an angry opponent that is still able to function.
Buckshot utilizes larger pellets that are ideally suited for home defense, but not all of them pattern the same. Depending on your barrel and if you are running a choke or not, Federal Flight Control may be an option, and generally, 8-pellet buckshot is going to be superior to 9-pellet.
Slugs are your other option for self-defense. Slugs utilize a solid projectile instead of pellets and were originally designed for use on larger game.
Think of firing a softball instead of marbles. Slugs will be a better choice for defensive rounds at longer distances, as buckshot patterns will spread out more there. Inside of 10 yards, though, buckshot will be better.
Distance is generally going to be the enemy of a shotgun beyond 30 yards or so. Inside of that range, a shotgun is a devastating tool that will very quickly end engagements.
Contrary to popular myth, you still have to aim a shotgun for it to be effective. To that end, a good quality light for target identification is worth considering. As with other platforms, mounting an optic is not a bad idea.
Additionally, a sling is a great idea for the same reason discussed earlier. Also, keep in mind that a shotgun will generally be longer and often heavier than an AR-15 or AK-47.
Shotguns do have their drawbacks, though. Like rifles, movement and mobility can be hindered by the size of the gun.
Additionally, recoil mitigation for follow-up shots is something that must be trained, as some people will find the gun awkward and uncomfortable without adjustments made.
Reloading a shotgun is also a bit more involved than slapping a fresh magazine in, so it is a skill that must be trained to be fast and proficient at it.
Applying shotguns to our two-attacker scenario, this is where things are very different.
Depending on which shotgun model you have, the tube may hold between six and eight rounds without extended tubes.
While this leaves only three or four rounds per assailant within a shotgun’s effective range, one round delivered to an attacker is devastating. The shot must still hit, but if it does, there is a very high probability that the fight is now over and your opponent’s behavior has changed.
No two scenarios are the same, and thus no answer will fit universally. Find the self-defense setup that makes sense for you, train with the tools and understand the tactics needed to win the fight.
Also, source out quality information, and do not be afraid to challenge the misconceptions you might have or might have heard.
In the end, defending yourself and those you care about is the only thing that matters, so give yourself as much advantage as possible.
The post Set Up Your Home Defense Gun: Rifle, Shotgun & Pistol [GUIDE] appeared first on Pew Pew Tactical.
Pew Pew Tactical
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With all the recent talk about removing guns from the hands of law-abiding citizens, I think it’s a good time to revisit this video from back in 2019.
Not the Bee
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I am a big fan of Percona Monitoring and Management (PMM) and am happy to report that setting up Percona Platform is as easy to set up and offers a lot of value. Percona Platform reached GA status recently and I think you will find it a handy addition to your infrastructure.
Percona Platform brings together enterprise-level distributions of MySQL, PostgreSQL, and MongoDB plus it includes a range of open source tools for data backup, availability, and management. The core is PMM which provides database management, monitoring, and automated insights, making it easier to manage database deployments. The number of sites with more than 100 separate databases has grown rapidly in the past few years. Being able to have command and control of that many instances from a CLI has become impossible. Businesses need to move faster in increasingly complex environments which puts ever-increasing pressure on database administrators, developers, and everyone involved in database operations. The spiraling levels of demand make it harder to support, manage, and correct issues in database environments.
What Percona Platform provides is a unified view of the health of your entire database environment to quickly visually identify and remediate issues. Developers can now self-service many of their database demands quickly and efficiently so they can easily provision and manage databases on a self-service basis across test and production instances. So you spend fewer resources and time on the management of database complexity.
The two keys to Percona Platform are Query Analytics (QAN), which provides granular insights into database behavior and helps uncover new database performance patterns for in-depth troubleshooting and performance optimization, and Percona Advisors, which are automated insights, created by Percona Experts to identify important issues for remediation such as security vulnerabilities, misconfigurations, performance problems, policy compliance, and database design issues. Automated insights within Percona Monitoring and Management ensure your database performs at its best. The Advisors check for replication inconsistencies, durability issues, password-less users, insecure connections, unstable OS configuration, and search for available performance improvements among other functions.
Percona Platform is a point of control for your database infrastructure and augments PMM to be even more intelligent when connected to the Percona Platform. By connecting PMM with the Percona Platform, you get more advanced Advisors, centralized user account management, access to support tickets, private Database as a Service, Percona Expertise with the fastest SLAs, and more.
The first step is to install PMM by following the Quick Start Guide. You need version 2.2.7 or later.
Second, You will need a Percona Account.
Third, you will need to connect that account to PMM.
I will assume that you will already have PMM installed. Did I mention that PMM is free, open source software?
The signup form allows you to create a new account or use an existing account.
Now you can create a name for your organization.
After creating your username and password, create your organization
Now login to your PMM dashboard and select the Settings / Percona Platform. You will need to get your ‘Public Address’ which the browser can populate the value for you if need be.
The PMM Server ID is automatically generated by PMM. You will need to provide a name for your server, and you will need a second browser window to login into Percona Platform to get the Percona Platform Access Token (this token has a thirty-minute lifetime, so be quick or regenerate another token).
Go back into PMM, paste the Access Token into the Percona Platform Access Token field, and click Connect.
On the Percona Platform page, you will see your PMM instances. Congratulations, you are using Percona Platform!
All checks are hosted on Percona Platform. PMM Server automatically downloads them from here when the Advisors and Telemetry options are enabled in PMM under Configuration > Settings > Advanced Settings. Both options are enabled by default.
Depending on the entitlements available for your Percona Account, the set of advisor checks that PMM can download from Percona Platform differ in terms of complexity and functionality.
If your PMM instance is not connected to Percona Platform, PMM can only download the basic set of Anonymous advisor checks. As soon as you connect your PMM instance to Percona Platform, has access to additional checks, available only for Registered PMM instances.
If you are a Percona customer with a Percona Customer Portal account, you also get access to Paid checks, which offer more advanced database health information. A list is provided below.
| Check Name | Description | Tier |
|---|---|---|
| MongoDB Active vs Available Connections | Checks the ratio between Active and Available connections. | Registered, Paid |
| MongoDB Authentication | Warns if MongoDB authentication is disabled. | Anonymous, Registered, Paid |
| MongoDB Security AuthMech | Warns if MongoDB is not using the default SHA-256 hashing as SCRAM authentication method. | Paid |
| MongoDB IP Bindings | Warns if MongoDB network binding is not set as recommended. | Anonymous, Registered, Paid |
| MongoDB CVE Version | Shows an error if MongoDB or Percona Server for MongoDB version is not the latest one with CVE fixes. | Anonymous, Registered, Paid |
| MongoDB Journal Check | Warns if journal is disabled. | Registered, Paid |
| MongoDB Localhost Authentication Bypass is Enabled | Warns if MongoDB localhost bypass is enabled. | Anonymous, Registered, Paid |
| MongoDB Non-Default Log Level | Warns if MongoDB is not using the default log level. | Paid |
| MongoDB Profiling Level | Warns when the MongoDB profile level is set to collect data for all operations. | Registered, Paid |
| MongoDB Read Tickets | Warns if MongoDB is using more than 128 read tickets. | Paid |
| MongoDB Replica Set Topology | Warns if the Replica Set cluster has less than three members. | Registered, Paid |
| MongoDB Version | Warns if MongoDB or Percona Server for MongoDB version is not the latest one. | Anonymous, Registered, Paid |
| MongoDB Write Tickets | Warns if MongoDB network is using more than 128 write tickets. | Paid |
| Check if Binaries are 32-bits | Notifies if version_compatible_machine equals i686. | Anonymous, Registered, Paid |
| MySQL Automatic User Expired Password | Notifies if version_compatible_machine equals i686. | Registered, Paid |
| MySQL InnoDB flush method and File Format check | Checks the following settings: innodb_file_format, innodb_file_format_max, innodb_flush_method and innodb_data_file_path | Registered, Paid |
| MySQL Checks based on values of MySQL configuration variables | Checks the following settings: innodb_file_format,innodb_file_format_max,innodb_flush_method and innodb_data_file_path. | Paid |
| MySQL Binary Logs checks, Local infile and SQL Mode checks | Warns about non-optimal settings for Binary Log, Local Infile and SQL mode. | Registered, Paid |
| MySQL Configuration Check | Warns if parameters are not following Percona best practices, for infile, replication threads, and replica checksum. | Paid |
| MySQL Users With Granted Public Networks Access | Notifies about MySQL accounts allowed to be connected from public networks. | Registered, Paid |
| MySQL User Check | Runs a high-level check on user setup | Registered, Paid |
| MySQL Advanced User Check | Runs a detailed check on user setup | Paid |
| MySQL Security Check | Runs a detailed check on user setup | Paid |
| MySQL Test Database | This check returns a notice if there is a database with name ‘test’ or ‘test_%’. | Registered, Paid |
| MySQL Version | Warns if MySQL, Percona Server for MySQL, or MariaDB version is not the latest one. | Anonymous, Registered, Paid |
| PostgreSQL Archiver is Failing | Verifies if the archiver has failed. | Paid |
| PostgreSQL Cache Hit Ratio | Checks database hit ratio and complains when this is too low. | Paid |
| PostgreSQL Configuration Change Requires Restart/Reload | Warns when a configuration was changed and requires a server restart/reload | Registered, Paid |
| PostgreSQL fsync is Disabled | Shows an error if the fsync configuration is disabled, as this can result in unrecoverable data corruption. | Anonymous, Registered, Paid |
| PostgreSQL Autovacuum Logging Is Disabled | Shows an error if the fsync configuration is disabled, as this can result in unrecoverable data corruption. | Paid |
| PostgreSQL Checkpoints Logging Is Disabled | Notifies if the log_checkpoints configuration option is not enabled. | Paid |
| PostgreSQL Max_connections is too high | Notifies if the max_connections setting is set above 300. | Anonymous, Registered, Paid |
| PostgreSQL Stale Replication Slot | Warns for stale replication slots since these can lead to WAL file accumulation and DB server outage. | Paid |
| PostgreSQL Super Role | Notifies if there are users with superuser privileges. | Anonymous, Registered, Paid |
| PostgreSQL Version Check | Warns if the PostgreSQL minor or major versions are not the latest, and shows an error if the major version is 9.4 or older. | Anonymous, Registered, Paid |
More Advisors will be added and Perona always welcomes contributions. Check out Percona Platform today!
Percona Database Performance Blog
MySQL Partitioned Tables
Learning Outcomes
Lesson Material
MySQL supports partitioning of tables. It supports range, list, hash, and key partitioning. Range partitioning lets you partition based on column values that fall within given ranges. List partitioning lets you partition based on columns matching one of a set of discrete values. Hash partitioning lets you partition based on the return value from a user-defined expression (the result from a stored SQL/PSM function). Key partitioning performs like hash partitioning, but it lets a user select one or more columns from the set of columns in a table; a hash manages the selection process for you. A hash is a method of organizing keys to types of data, and hashes speed access to read and change data in tables.
Each of the following subsections discusses one of the supported forms of partitioning in MySQL. Naturally, there are differences between other databases and MySQL’s implementation.
List Partitioning
A MySQL list partition works by identifying a column that contains an integer value, the franchise_number in the following example. Partitioning clauses follow the list of columns and constraints and require a partitioning key to be in the primary key or indexed.
The following list partition works with literal numeric values. MySQL uses the IN keyword for list partitions. Note that there’s no primary key designated and an index is on the auto-incrementing surrogate key column. A complete example is provided to avoid confusion on how to index the partitioning key:
CREATE TABLE franchise
( franchise_id INT UNSIGNED AUTO_INCREMENT
, franchise_number INT UNSIGNED
, franchise_name VARCHAR(20)
, city VARCHAR(20)
, state VARCHAR(20)
, index idx (franchise_id))
PARTITION BY LIST(franchise_number)
( PARTITION offshore VALUES IN (49,50)
, PARTITION west VALUES IN (34,45,48)
, PARTITION desert VALUES IN (46,47)
, PARTITION rockies VALUES IN (38,41,42,44));
The inclusion of a PRIMARY KEY constraint on the franchise_id column would trigger an ERROR 1503 when the partitioning key isn’t the primary key. The reason for the error message is that a primary key implicitly creates a unique index, and that index would conflict with the partitioning by list instruction. The use of a non-unique idx index on the franchise_id column is required when you want to partition on a non-primary key column.
Range Partitioning
Range partitioning works only with an integer value or an expression that resolves to an integer against the primary key column. The limitation of the integer drives the necessity of choosing an integer column for range partitioning. You can’t define a range-partitioned table with a PRIMARY KEY constraint unless the primary key becomes your partitioning key, like
the one below.
CREATE TABLE ordering
( ordering_id INT UNSIGNED AUTO_INCREMENT
, item_id INT UNSIGNED
, rental_amount DECIMAL(15,2)
, rental_date DATE
, index idx (ordering_id))
PARTITION BY RANGE(item_id)
( PARTITION jan2011 VALUES LESS THAN (10000) , PARTITION feb2011 VALUES LESS THAN (20000) , PARTITION mar2011 VALUES LESS THAN (30000));
Range partitioning is best suited to large tables that you want to break into smaller pieces based on the integer column. You can also use stored functions that return integers as the partitioning key instead of the numeric literals shown. Few other options are available in MySQL.
Columns Partitioning
Columns partitioning is a new variant of range and list partitioning. It is included in MySQL 5.5 and forward. Both range and list partitioning work on an integer-based column (using TINYINT, SMALLINT, MEDIUMINT, INT [alias INTEGER], and BIGINT). Columns partitioning extends those models by expanding the possible data types for the partitioning column to include CHAR, VARCHAR, BINARY, and VARBINARY string data types, and DATE, DATETIME, or TIMESTAMP data types. You still can’t use other number data types such as DECIMAL and FLOAT. The TIMESTAMP data type is also available only in range partitions with the caveat that you use a UNIX_TIMESTAMP function, according to MySQL Bug 42849.
Hash Partitioning
Hash partitions ensure an even distribution of rows across a predetermined number of partitions. It is probably the easiest way to partition a table quickly to test the result of partitioning on a large table. You should base hash partitions on a surrogate or natural primary key.
The following provides a modified example of the ordering table:
CREATE TABLE ordering
( ordering_id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT
, item_id INT UNSIGNED
, rental_amount DECIMAL(15,2)
, rental_date DATE)
PARTITION BY HASH(ordering_id) PARTITIONS 8;
This is the partitioning type that benefits from a PRIMARY KEY constraint because it automatically creates a unique index that can be used by the hash. A non-unique index such as the list partitioning example doesn’t work for a hash partition.
Key Partitioning
Key partitioning is valuable because you can partition on columns that aren’t integers. It performs along the line of hash partitioning, except the MySQL Server uses its own hashing expression.
CREATE TABLE orders_list
( order_list_id INT UNSIGNED AUTO_INCREMENT
, customer_surname VARCHAR(30)
, store_id INT UNSIGNED
, salesperson_id INT UNSIGNED
, order_date DATE
, index idx (order_list_id))
PARTITION BY KEY (order_date) PARTITIONS 8;
This is the only alternative when you want to partition by date ranges. Like the hash partition, it’s easy to deploy. The only consideration is the number of slices that you want to make of the data in the table.
Subpartitioning
The concept of subpartitioning is also known as composite partitioning. You can subpartition range or list partitions with a hash, linear hash, or linear key.
A slight change to the previously created ordering table is required to demonstrate composite partitioning: we’ll add a store_id column to the table definition. The following is an example of a range partition subpartitioned by a hash:
CREATE TABLE ordering
INT UNSIGNED
INT UNSIGNED
DATE
( ordering_id INT UNSIGNED AUTO_INCREMENT
, item_id INT UNSIGNED
, store_id INT UNSIGNED
, rental_amount DECIMAL(15,2)
, rental_date DATE
, index idx (ordering_id))
PARTITION BY RANGE(item_id)
SUBPARTITION BY HASH(store_id) SUBPARTITIONS 4
( PARTITION jan2011 VALUES LESS THAN (10000)
, PARTITION feb2011 VALUES LESS THAN (20000)
, PARTITION mar2011 VALUES LESS THAN (30000));
Composite partitioning is non-trivial and might require some experimentation to achieve optimal results. Plan on making a few tests of different scenarios before you deploy a solution.
Planet MySQL
Some sources of financial data can be expensive or difficult to find. For example, some is only available from exchanges or vendors who charge a hefty fee for access. However, the financial industry is also heavily regulated, and one of its main regulators provides free access to its data. The (U.S. Securities and Exchange Commission)[https://www.sec.gov] … Continue reading An introduction to accessing financial data in EDGAR, using Python
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Planet Python
https://theawesomer.com/photos/2022/05/accurate_stormtroopers_t.jpg
(PG-13: Gore) As Star Wars fans know, stormtroopers have a long history of missing their targets. Corridor imagines how differently things might have turned out if the Empire’s plastic-armored troops just a bit more practice. Bonus VFX points for Han Solo’s mustache.
The Awesomer