The happy life of the Oracle family

Oracle
??? A man named Sid, who loves to shoot, save and organize photos. Sid's wife named Debbie, who had three sons, Logan, Archie and Chuck. (SID is an Oracle instance, photo is data)

??? He had a big house with butler Simon and maid Pam. I will introduce his family, his house and his hobbies: shoot, collect and show off his pictures.

Now, Sid lives happily-family, friends and vacations. He takes pictures from time to times. In fact, he always carries a camera with him. He didn't want to miss anything.

Every breakfast, lunch and dinner will be photographed. When the children came home from school, the camera ate their greetings to their father. When the children do homework, "card cha, card cha, card Cha", the camera's shutter rang non-stop.

(Photo only to show that the database is constantly receiving data from outside)

??? Every throw of his son's Archie was filmed at the baseball game. At the school ball, Chuck's father photographed every slow dance and conversation at the soda machine. His dog,--sadie, is the most photographed dog in the world.

He and his family have collected millions of photos. Some of the photos have been destroyed and some have undergone a change. Sid has a magical system to handle these pictures.

Let me tell you something about his family, his house, and how he and his family are committed to developing, organizing and protecting all these photos.

Sid was photographed with a special camera. Every time his camera was taken, a picture and a negative were produced. He never had to change the film (it was a sci-fi technique).

The photos were posted on the walls of the room and the negatives were kept in a safe place.

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1.1.1 Sid's home.

Have I introduced Sid's house yet? Well. It's very big and there are pictures everywhere. Because there are so many photos, Sid has to look for places to put them.

Some of the pictures were hanging on the wall, some were hidden in the album, some were inserted into the scrapbook, and some were placed in a box in the storeroom and would never be skimmed. All these pictures were placed somewhere in his home. (a photo album and a scrapbook should refer to a part of the SGA)

He called the places where the photos were placed as "photo space". A photo space may be a room with a lot of walls, or a scrapbook with many pages. A room is a logical storage unit for photos. (Room is table space)

The walls in the room are the physical structure of the photos in the photo space.

(Walls are data files, rooms are made up of multiple walls)

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1.1 2 Debbie's chores.

Because Sid was busy filming and processing photos, he didn't have enough energy to put and store them-that was her wife's job. Debbie's full name is Debra Wrider. (Write process)

Her t-shirts are dbwr-. It's a family tradition-label everything.

Putting all these pictures in order is a huge job, but Sid and Debbie have built a system. When Sid had finished filming, he put the pictures on a particular shelf in the kitchen. (Shelf is Dbbuffer)

That particular shelf is called "Db_buffer_cache". Debbie often check the shelf to see if there are any new photographs. During the day, she placed the photos retrieved from the shelves into the corresponding photo space.

(There is no description of her job requirements, do anything to be motivated by the conditions, or who do ^_^)

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In fact, at a baseball game or school dance, Sid was making pictures too fast. That Debbie could hardly keep up. This is a special situation where SID takes a picture and then places it on that particular shelf,

Debbie put these pictures in a scrapbook, hang them on a wall or insert a photo album.

When Sid enters the kitchen with photographs and negatives, there may be a conversation between him and his wife:

(Photo is submitted after data, negative for log data)

Sid: "Honey, guess what I brought you back?" ”

Debbie: "You took a lot of pictures again, didn't you?" You know how much I like to organize photos. ”

Sid: "Of course, Archie's baseball team won the last inning." He won two two in the nineth inning, and I shot it all down. ”

Debbie: "Great, those photos are in the sports category on the 9th wall of the photo space, and they look great." I can't wait to put them on, I'll invite all the neighbors to watch. ”

Sid: "Archie is also very happy." OK, I'll take some more photos and I'll be back in 23 milliseconds. Oh, by the way, I just put those pictures on the Db_buffer_cache shelf.

The SID's directory number is now 1332935. "Debbie:" Yes, bye. ”

To ease the management of photos, frames, and logs, he uses a special number to create a directory, called a Sid's directory number. He uses these unique, ever-increasing numbers to track the operation of all the photos in the house. (SCN)

Sid and Debbie have been tired of looking up directory numbers for SIDS. Sid wrote "Sid's catalogue number" on all the photos, videotapes and negatives, and got cramps.

Finally, they shrunk the "Sid directory Number" to the SCN. Remember that Scn,sid's life revolves around it.

Now, the whole family knows that this number is referred to as SCN. You can see the SCN in every place. Sid wrote them on the negatives, then he wrote the SCN at the low and high levels out of each packet of negatives.

Debbie wrote them where she placed the photos. These numbers are particularly important in the complex family life of SIDS.

Debbie the picture in a frame, and every frame in the house is the same size. Some frames save only one photo, and some frames hold several photos. Some of the most significant photos will occupy multiple frames. (Frame is segment)

Sid had a picture of the same size as the original, taking a picture of him in the air after skydiving, which occupied two frames. When a photograph crosses a frame, the SID is called a photo chain.

At any time, as soon as Debbie changes the picture within the frame, she writes the SCN of the photo on the frame. Every picture in the house has a unique number. They call this number the photo ID. (ROWID)

These photo IDs help Sid Manage all the pictures on the walls of the home. If he needs to find a picture as soon as possible, he does it through the photo ID. Through the photo Id,sid can quickly find the walls and save the photo frame.

Sometimes, the SID makes some changes to the photo. If he wants to edit a picture, he lets Debbie find his picture through the photo ID. Debbie gave him a copy of the entire frame that included the required photos. (Image before data changes)

To prevent the SID from changing his mind and not liking some of the changes he had made, he put the copy in a storeroom and called it a "fallback" storeroom. When the SID has made the change and is sure, Debbie the changed photo back to the original place on the wall and writes the new SCN on the frame. If Sid doesn't like his changes, they take the frame out of the "fallback" storeroom and put it back on the wall. (The storeroom is a rollback or undo space)

As a result, the photos are the same as the SID did before.

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1.1.3 Logan's chores.

Debbie has been swamped with photos of Sid, so she doesn't have enough time and energy to deal with Sid's negatives. Sid thought his sons were wasting too much time playing video games and eating potato chips, and he decided to give them a job.

Sid's older son is called Logan William Randolph. Logan's shirt was printed with LGWR. Logan has a very simple but very important task. (LGWR log write process)

While the SID's camera produced the negatives, the Logan's task was to put the negatives in the notebook. There was another shelf in the kitchen, and the SID on the shelf was labeled to mark the negatives that were sent to the older son.

The label is called "Log_buffer," and Logan sits at the kitchen table and observes the special Log_buffer shelf. When the film was put on the shelf, he immediately put the film in The Notebook. (another frame is logbuffer)

Sid calls these notebooks "redo notebooks." He uses the name because he can then recreate a picture with the negatives in it. Logan checks his shelves much more frequently than Debbie.

(LGWR is more frequent than DBWR, but still not named LGWR the trigger condition of the work)

Sid says that if there is a negative, he can recreate a photo at any time. Logan's conversation with his father was brief and warm:

Sid: Logan, the negatives are on the shelves! ”

Logan: Yes, I'll take care of it immediately. ”

Logan put the negatives in a "Redo notebook" in the order he got the negatives. Once the current notebook is full of negatives, he will switch to another new notebook. Every time he replaces the "Redo Notebook",

Make a note on the "Alarm notebook" and notify his brother to do their housework.

(Log switching point log switch, which will be recorded in the alarm log)

Sad, isn't it? Dad and his older son are too focused on the negatives!

By the way, not all photos have a corresponding film to keep. The SID specifies that some photos do not have to be logged, and that the photos have no corresponding negatives stored in the Redo notebook. Sid calls it "no log." (Nolog's case)

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1.1.4 Archie's chores.

Sid's second son, Archibald, has another assignment. His shirt is written on arch. Archie the negatives from the redo notebook and put them in a safe place. (Archive archiving process)

When Archie discovered that Logan had changed to another laptop, he began to move. He took lifting to make the negatives in his notebook and put them in a safe place outside the house.

Sid built a basement in the backyard with a good temperature control. It was a safe place for him to keep the negatives. If the storm comes and destroys the house, he can replace the damaged photos with the negatives kept in the basement.

Every copy of Logan's "Redo Notebook" is called the "archived Redo Notebook". Maybe one day, you can hear the joke between Sid and his second son:

Sid:: "Archie?" Where are you? ”

Archie: "Dad, I'm in my room, Logan, are you switching notebooks now?" ”

Sid: Yes, he just finished. ”

Archie: Yes, Dad. I'll copy the negatives and make a new notebook in the basement. Then, I will update the ' Control notebook ' and write a record in the ' Alarm notebook '. ”

Sid: "You are a good boy, I know I can trust you." ”

(Archive will update the control file and be credited to the alarm log)

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1.1.5 Chuck's family chores.

Sid's youngest son, Chuck, makes sure everything is synchronized. His full name is Charles Kenneth, Patrick Thomas. The letter on his shirt is ckpt, (CKPT checkpoint process)

Chuck's task is to reconcile each wall, photo album and photo numbers on the clipboard with the numbers in the control notebook. When he got the signal, he started running around the house, writing numbers on each wall,

The same number is also recorded in the control notebook. This makes everything work in harmony. Here's a conversation between Sid and Chuck:

Sid: "Hi,chuck." ”

Chuck: Dad, has Logan started to change his notebook again? ”

Sid: Yes, son, you know the rules. With catalogue number 1332935, go across the room and write this number to the beginning of each wall, the cover of each scrapbook and the top of the photo box. ”

Chuck: "No problem, just give me a few microseconds to finish."

Sid: "Don't forget to write 1332935 on the control notebook!" ”

Chuck: "Dad, I know, the same thing I've done hundreds of times in a day." ”

I bet you're tired of reading this crazy Sid house, aren't you? So far, you may have seen that Sid has a dysfunctional family. Functional disorder? Yes! But it is effective and reliable. Sid likes that.

(The checkpoint process is responsible for updating the header information of the control file, the data file to keep it consistent)

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1.1.6 Control Notebook

How does this family maintain all these activities? Sid, Debbie, Logan, Archie and Chuck conclude that there must be a lot of detailed notes to be done in order to get the picture collected and sorted.

Each of them writes their own stuff into a log called a "Control Notebook". (Control file)

The control notebook has a list of family property items that record every wall, scrapbook, and photo box in the entire house. If Sid adds a room to put more pictures in, he makes a note in the control notebook.

When Logan replaced the Redo notebook, he made a summary record in his control notebook. Every time Archie makes an archived redo notebook into the basement, he writes the name and SCN in the control notebook.

Every time Chuck finishes a lap in the house, he records the details in the control notebook. This special notebook dynamically preserves the assets of all places, and the process of the house being digitally represented.

(The control file contains the database name, data file, log file, archive, checkpoint and SCN, and other related information)

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1.1.7 Alarm Log

From time to time there are always some surprises, and there may be errors. Debbie may have trouble putting photos in the frame, because there is no room left on the wall. Archie may not be able to fold up the film strips,

Because someone sprayed the soda on it. Sid considered all the possibilities, he bought a spiral-axis notebook and put it in the kitchen drawer. Write "Alarm log" on the face of the notebook.

Every family member will have to write the questions in this journal. Not only do they write down the mistakes they make, but they also write down the normal activity process.

This alarm log is a convenient place to keep things that have been and will happen in Sid's home. If they want to explain the extra details of a situation, they create a new "tracking notebook" that records the information.

As a result, the warning notebook does not become more cluttered than it used to be.

(Alarm log records all changes and error messages of the instance)

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1.1.8 Morning Program

The family wakes up together in the morning and always goes to bed at the same time. They call these times "start" and "close" for one day. Here is the morning start program:

Sid starts his day with a cup of coffee up from the bed. On the side of the coffee pot, he kept a series of instructions in his notebook, called the initialization parameter file. Reading this instruction helps him start a new day.

Sipping coffee, he went over to make sure the laptop was in the old place. He was in the house, waking Debbie, Chuck, Logan, Archie, Simon and Pamela (you'll soon meet them).

When everyone wakes up, they open the control notebook. Confirm that according to the contents of the control notebook, all the photos walls are no problem, when all the things have been checked, he opened the house to greet the guests,

and start taking photos. Sid hired a butler, Simon, who helped him in the morning, and Simon's Tuxedo was written with the letter Smon (skipping a letter in the name). Some mornings the house is very messy,

Because at the last bedtime, every member of the family did not clean up their things in time. When Simon was in position, Sid opened the curtains, hung up the phone, opened the door lock, and his family was open and ready to greet the guests.

(performing the necessary system cleanup and instance recovery after startup is Smon a major task)

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Sid and Simon might start the day like this:

Simon: Good morning, sir. What can I do for you today? ”

Sid: "Yes, Simon, Good morning." Looks like we're in a mess here. We had a sudden interruption last night. Can you take care of all these unfinished photos and ' fallback '. ”

Simon: "Of course, all the negatives in the redo notebook are being redesigned and placed in the right frame in a simple order." ”

Sid: "After you've done this, go ahead and deal with ' fallback ', right?" ”

Simon: Of course, sir. I removed the photo frame from the back room and put the old version back where they were. ”

Sid: "Great, when you're done, I'll open the house." "(the instance restore was completed before the database open)

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1.1.9 Night program

The night program at Sid's house is also interesting. When Sid lay down to rest, he asked for all the things in the house to be put, turned off and stopped. The first act of bedtime is to ask all the guests in the house to go home.

Sid has four different moods at night. First, sometimes he was very patient, waiting for all the men and women to leave, and then go to bed; the second, Sid has no patience, he personally supervises every guest,

When the guests finish their respective things (see photos and so on), he gave the guests directions to go out, the third, Sid very impatient, he grabbed the guests to accompany them out of the house, do not let them do what is being done;

The fourth kind, Sid pulls down the gate of the house, yells "Time", the house is a mess. Simon had to clean up the mess the next morning. (Several cases of database shutdown)

When a guest left a mess, Sid called his maid Pamelamonica. She monitors the guests ' activities and handles the aftermath after the guests leave. Her cleaning equipment was labeled Pmon.

(Pmon user Monitoring process, responsible for the cleaning and recycling of user resources)

If the SID doesn't suddenly pull the brake, everyone turns on the lights and cleans them. Synchronize notebooks to complete their tasks. Debbie took all the photos from the Db_buffer_cache shelf and put them on the right wall.

Logan made sure the Log_buffer shelf was empty and all the negatives were in the current redo notebook. Chuck takes a lap in the house and updates the walls and notebooks with the highest and lowest catalogue numbers (SCN).

Archie the last film into the archived redo notebook and put it in the basement of the backyard. Then update the control and alarm notebook. When everyone is done, sid turn off the lights and everybody sleeps.

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The problem with 1.1.10 SID

Sometimes, there are problems with Sid's family. When any of the following events occur, the activity in the House will stop.

When Sid wakes up and he can't find the initialization file, he can't start a day's work.

Sometimes, the SID needs to use Archie to keep the negatives in the basement of the backyard to restore the lost photo if he loses a negative, or if the film is damaged during the recovery process.

He was unable to recover any photos taken after the invalid film.

Sid lost a few negatives at a time. He accidentally opened the camera and exposed the film. It made him so emotionally bad that his world seemed to come to an end. He contacted the camera manufacturers, who provided a special camera,

With two film modules. In this case, if the film is damaged, he can expect the film in the other cabin. SIDs are called mirrors. (cluster?) ）

If the basement of the backyard is full, there is no room for new negatives to be placed in the Archie. Archie just waiting for new space in the basement. This has allowed Sid and Debbie to wait, and the entire SID family activity has stalled. (hang)

If Debbie got the flu, he was ill in bed. Guess what happens: Sid shuts the door madly. Despite these problems and some other family setbacks and dysfunctional

But Sid's family can still handle millions of photos and thousands of simultaneous visitors.

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?? Like me, you might wonder how much time and effort Sid has to do photo collection activities. Doesn't he have a job? Actually, No. Money is not the goal of SID. He doesn't have to work.

He finished a smart investment a few years ago. He bought a large number of computer company shares after 1984, when they were just beginning to be released to the public. The company he invests is headquartered in the Mangrove coast of California State.