Learn Oracle Feelingsjust before contacting Oracle database, I saw a story about Oracle system knowledge from the Internet, called "Sid's House". , reading with interest, did not expect that the story is very good, for beginners to understand the Oracle database system is very helpful. and in the subsequent learning process, learning to different stages of Oracle, read again, there will be different sentiment. The story is related to what the Oracle database does, and it's very well-connected. Dedicated to beginners who want to learn Oracle database.
-_-(actually has been out for many years, but can not help but want to promote to the Oracle database, because I just because this story into the world of Oracle)
Excerpt from the----Oracle Backup and Recovery
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A man named Sid has a passion for filming, saving and organizing photos. Sid's wife, named Debbie, had three sons, Logan, Archie and Chuck. He had a big house with the butler Simon and the maid Pam. I will introduce his family, his house and his hobbies: filming, collecting and showing off his photos.
Now, Sid lives happily-family, friends and vacations. He took pictures from time to times. In fact, he always carries his camera with him. He doesn't want to miss anything. Every breakfast, lunch and dinner will be photographed. When the children go home from school, the camera takes their greetings to their father. When the children do their homework, "card cha, card cha, card Cha", the camera's shutter rang nonstop. At the baseball game, every throw of his son Archie was filmed. At the school ball, Chuck's father filmed every slow step and conversation next to 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 were destroyed and some changed. Sid has a magicalsystemTo process these photos. 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 is shot with a special camera. Every time his camera was shot, he produced a photograph and a film. He never had to change the film (it's a sci-fiTechnology）。 The photos are affixed to the walls of the room, and the negatives are kept in a safe place.
1.1.1 Sid's Home
Have I introduced Sid's home 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 photos were hung on the wall, some were hidden in the photo album, some were inserted into the scrapbook, and some were placed in a box in the storeroom without being skimmed. All of these photos were placed somewhere in his home. 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. The walls in the room are the physical structure of the photos stored in the photo space.
1.1.2 Debbie of Housework
Because SID was busy shooting and processing photos, he didn't have enough energy to place and store them-that was her wife's job. The full name of Debbie is Debra Wrider. She's got dbwr-on her t-shirt. This is a family tradition-label everything.
It's a huge job to put all these photos in order, but Sid and Debbie have built a system. When the SID shot was over, he put the photos on a specific shelf in the kitchen. That particular shelf is called "Db_buffer_cache". Debbie always check the shelf to see if there are any new photos. During the day, she places the photos retrieved from the shelves into the corresponding photo space. In fact, at a baseball game or school ball, Sid makes photos too fast. So that Debbie almost can't keep up. This is a special situation where SID takes photos and places them on that particular shelf, debbie them in a scrapbook, hangs on a wall or inserts a photo album.
When Sid enters the kitchen with photos and negatives, there may be a conversation between him and his wife:
Sid: "Honey, guess what I brought back for you?" ”
Debbie: "You took a lot of pictures again, didn't you?" You know how much I like to organize pictures. ”
Sid: "Of course, Archie's baseball team won the last inning." He won in the nineth inning with two two bases, and I filmed all of them. ”
Debbie: "Great, the photos are in the motion class of the wall 9th of the photo space, and it looks great." I can't wait to place them, I will invite all the neighbours to watch. ”
Sid: "Archie is also very happy. OK, I'll take some more photos, 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, goodbye. ”
To make it easy to manage photos, frames, and logs, he uses a special number to create a directory called the SID's directory number. He uses these unique, increasing numbers to track the operation of all the photos in the house. SIDs and Debbie have been tired of looking up directory numbers for SIDS. Sid wrote "Sid's catalogue number" on all photos, videotapes and negatives, and got tired of cramping. Finally, they shrink the "Sid directory Number" to a slightly SCN. Remember that Scn,sid life revolves around it.
Now, the whole family knows that this number is simply called SCN. You can see the SCN in every place. The SID wrote them on the negatives, and then he wrote the SCN of the low and high highs out of every bag of negatives. Debbie wrote them where she placed the photos. These numbers are particularly important in the complex family life of SIDS.
Debbie put the picture in the frame, each frame in the house is the same size. Some frames save only one photo, while some frames hold several photos. Some particularly large photos occupy multiple frames. The SID has a photograph of the same size as the original, which was filmed in the air after skydiving, which occupies two frames. When a photo crosses a frame, the SID is called the photo chain.
At any time, as soon as Debbie changes the picture in the frame, she writes the SCN on the frame. Every picture in the house has a unique number. They say this number is the photo ID. These photo IDs help the SID manage all the photos on the wall in the home. If he needs to find a photo as soon as possible, he can do it by photo ID. With photo Id,sid, you can quickly find walls and frames to save photos.
Sometimes, the SID makes some changes to the photo. If he wants to edit a photo, he lets Debbie find his picture by his photo ID. Debbie give him a copy of the entire frame that includes the desired photo. To prevent the SID from possibly changing his mind and not liking some of the changes he has made, he puts that copy in a storeroom called a "fallback" storage room. When the SID has completed the change and determined, Debbie the changed photo back to the original place on the wall and writes the new SCN on the frame. If the SID does not like his changes, they remove the frame from the "fallback" storeroom and put it back on the wall. As a result, the photos are the same as the SID has not changed before.
1.1.3 Logan's chores.
Debbie was so busy with the photos of SID that she didn'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 on it. Logan has a very simple but very important task. Sid's camera produces the film while producing the negatives, and Logan's task is to put the negatives in the notebook. Another shelf was erected in the kitchen of the home, and the SID on the shelves was labeled to mark the negatives sent to the older son. The label is called "Log_buffer", 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 negatives in his notebook. SIDs call these notebooks "Redo notebooks". He used the name because he could recreate a picture with the negatives. Logan checks his shelves much more often than Debbie. Sid says he can re-create a photo whenever he has a negative. Logan's conversation with his father was brief and warm:
Sid: "Logan, the negatives are on the shelf!" ”
Logan: "You know, I'll take care of it immediately." ”
Logan puts the negatives into a "redo notebook" in the order in which he gets the negatives. Once the current notebook is filled with negatives, he will switch to another new notebook. Every time he changed his "Redo notebook", he made a record on the "Alarm notebook" and informed his brother to do their housework.
Sad, isn't it? Dad and his big son are so absorbed in the negatives!
By the way, not all photos have a corresponding film to save. The SID specifies that some photos do not have to be made into a log, and these photos do not have the corresponding negatives stored in the "Redo Notebook". The SID calls it "no log."
1.1.4 Archie's Chores
Sid's second son, Archibald, had another mission. His shirt was written with arch. Archie the negatives from the redo notebooks, put them in a safe place.
When Archie found that Logan had changed to another redo notebook, he began to act. He took the crane to make the negatives in his notebook and put them in a safe place outside the house. Sid built a basement in the backyard that controls the temperature and humidity. That was the safe place where he kept the negatives. If the storm comes and destroys the house, he can replace the damaged photos with the negatives stored in the basement. Every copy of Logan's "Redo Notebook" is called an 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, now switch notebooks?" ”
Sid: "Yes, he just finished." ”
Archie: "Yes, Dad." I'll copy the negatives and make a new notebook in the basement. Then I'll update the ' Control notebook ' and write a record in the ' Alarm notebook '. ”
Sid: "You're a good boy, I know I can trust you." ”
1.1.5 Chuck's chores.
Sid's youngest son, Chuck, makes sure everything is in sync. His full name is Charles Kenneth Patrick Thomas. The letters on his shirt are ckpt,chuck. The task is to reconcile the number of photos on each wall, photo album, and scrapbook with the numbers in the control notebook. When he got the signal, he began to run in the house, write down the numbers on each wall, and record the same numbers in the control notebook. This makes every thing work together. Here's a conversation between Sid and Chuck:
Sid: "Hi,chuck. ”
Chuck: "Dad, did Logan start changing notebooks again?" ”
Sid: "Yes, son, you know the rules." Go to the room with catalog number 1332935, 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."
Sid: "Don't forget to write 1332935 on the control notebook!" ”
Chuck: "Dad, I know, I've done it hundreds of times in a day." ”
I bet you're tired of reading this crazy Sid home, aren't you? So far, you may have seen that Sid has a dysfunctional family. Functional abnormality? Yes! But it's effective and reliable. Sid likes that.
1.1.6 Control Notebook
How does this family sustain all these activities? Sid, Debbie, Logan, Archie, and Chuck decided that it was necessary to make a lot of detailed notes in order to get the picture collected and organized. Each of them writes their own stuff into a log, called a "control notebook."
The control notebook has a list of family items that record every wall, scrapbook, and photo box in the entire house. If Sid adds a room to put more photos, he makes a record in the control notebook. When Logan replaced the Redo notebook, he made a summary record in the control notebook. Each time Archie made an archived redo notebook into the basement, he wrote the name and the 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 numbers in the house.
1.1.7 Alarm Log
There will always be some surprises, and mistakes may occur. Debbie may have problems when putting pictures in the frame, because there is no more room on the wall. Archie may not be able to fold up the strip because someone sprayed the soda water on it. Sid considering all the possibilities, he bought a spiral-axis notebook and put it in the kitchen drawer. Write "Alarm log" on the face of your notebook. Each member of the family will be confronted with a question written in this log. Not only do they write down the mistakes they make, they also write down the normal course of activities. This alarm log is a convenient place to keep the SID home already and what is about to happen. If they want to explain the extra details in a situation, they make a new "tracking notebook" and record the information inside. In this way, the alarm notebook does not become more cluttered than it originally was.
1.1.8 Morning Program
The whole family wakes up together in the morning and always goes to bed at the same time. They call these times the "start" and "close" of the day. The following is the morning startup program:
Sid get up from bed and end up with a cup of coffee to start his day. On the edge of the coffee pot, he kept a series of instructions in his notebook called Initialization parameters.file。 Read this list of instructions to help him start a new day. Sipping the coffee, he went over and confirmed that the control notebook was in the old place. He wakes up in the house with Debbie, Chuck, Logan, Archie, Simon and Pamela (you'll meet them soon).
When everyone wakes up, turn on the control notebook. Confirm that according to the contents of the control notebook, all the photo walls are fine, when everything has been checked, he opens the house to greet the guests and begins to take pictures. Sid hired a butler, Simon, to help him in the morning, and Simon's Tuxedo was written with the letter Smon (one of the letters in his name omitted). Some mornings are particularly messy, because at the previous bedtime, every member of the family did not clean up their things in time. When Simon was in place, Sid opened the curtains, hung up the phone, unlocked the door, opened his family, and was ready to greet the guests. Sid and Simon may 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 handle all these unfinished photos and ' fallback '. ”
Simon: "Of course, all these negatives are to be recreated in the redo notebooks and then placed in the right frame in a simple order." ”
Sid: "After you've done this, you're going to handle ' fallback," right? ”
Simon: "Of course, sir." I removed the frame from the back of the storeroom and put the old version back in the same place. ”
Sid: "Great, when you're done, I'll open the house." ”
1.1.9 Night program
The Sid Home Night program is also fun. When Sid lay down to rest, he demanded that everything in the house be put, turned off and stopped. The first act of bedtime is to ask all the guests in the house to go home. Sid's mood in the evening has four different situations. First, sometimes he is very patient, waiting for all the male and female guests to leave, and then go to bed; the second, Sid impatient, he personally to supervise each guest, when the guests do their own things (see photos, etc.), he gave the guests directions to go out; third, Sid was very impatient, he grabbed the guests to accompany them to go out To keep them from doing what they were doing; the fourth, Sid pulled down the gate of the house, shouting "time", a mess in the house. Simon had to clean up the chaotic scene the next morning.
When a guest left behind a mess, Sid called his maid Pamelamonica. She monitors the guests ' activities and handles the aftermath after the guests have gone. Her cleaning equipment was labeled Pmon.
If the SID does not suddenly pull off, everyone turns on the lights and cleans. Synchronize your notebooks to complete their tasks. Debbie took all the photos from the Db_buffer_cache shelf and put them on the right wall. Logan is indeed
The Log_buffer shelf is empty and all the negatives are in the current redo notebook. Chuck took a lap in the house and updated the walls and notebooks with the highest and lowest catalogue number (SCN). Archie put the last film in an archived redo notebook and put it in the basement of the backyard. Then update the control and alarm notebooks. When everyone was done, Sid turned off the lights and everybody slept.
Problem with 1.1.10 SID
Sometimes, there are problems with the SID family. When any of the following events occurs, the activity in the house stops.
? When Sid wakes up and he can't find the initialization file, it can't start the day's work.
? Sometimes, Sid needs to use the negatives stored in the backyard basement of Archie to recover lost photos if he loses a negative, or if the negatives are damaged during the recovery process. He could not recover any shot after that void film
All the photos.
? Sid lost several negatives at a time. He accidentally opened the camera and exposed the film. It made him feel very bad, and his world seemed to come to an end. He contacted the camera manufacturers, who provided a special camera with two film cabins. This way, if the film is damaged, he can count on another film in the cabin. The SID is called mirroring.
? If the basement of the backyard is full, Archie has no room to place the new negatives. Archie just waiting for a new space in the basement room. This allows SIDS and Debbie to wait, and the entire SID's family activity is stalled.
If Debbie got the flu, he was sick in bed. Guess what happens: Sid shuts the door wildly. Despite these problems and other family setbacks and dysfunction, Sid's family can still handle millions of photos and thousands of simultaneous visitors.
Like me, you might wonder how Sid had so much time and energy to do photo collection activities. Doesn't he have a job? In fact, No. Money is not the goal of SID. He doesn't have to work. He completed a clever investment a few years ago. He bought a lot of shares in computer companies since 1984, when they were just beginning to be released to the public. The company he invests in is headquartered in the Mangrove coast of California State.
After introducing the SID family, you will find that he has designed the structure for all the activities of the family. Just like this family's activity, OracleDatabaseThere are also spaces, processes, and procedures. With this family analogy in mind, I now briefly describe OracleDataThe library architecture, processes, and operations are part of Oracle data backup and recovery. Maybe you'll find similarities with the SID family.
Dedicated to beginners--the first Story of learning Oracle
