PREFACE
Hello everyone, this is Fly Balloon, from Singapore, a tiny tropical island, which has been described by Jules Verne in his great novel <> in 19th century as thus:
Pepper plants replaced the prickly hedges of European fields; ... Agile and grinning bands of monkeys skipped about in the trees, nor were tigers wanting in the jungles.
Now there is no more monkey and tiger wanting around; the pepper plants were replaced by concrete forest, inside which live some intelligent creatures such as DBAs. Fogg is one of them, as a fan of Jules Verne, he is always dreaming to explore the experience of traveling around world in most natural and ancient ways. One day with his perfect database skill he managed to connect to the matrix database and issue a recover command, amazingly, the time return back to a hundred years ago...
Mr. Phileas Fogg lived, in 1872, at No. 7, Saville Row, Burlington Gardens. At half-past eleven in the morning, he reached the Reform Club where his usual partners at whist for the Standard.
"The journey round the world in eighty days?"
"A true Englishman doesn't joke when he is talking about so serious a thing as a wager," replied Phileas Fogg, solemnly. "I will bet twenty thousand pounds against anyone who wishes that I will make the tour of the world in eighty days or less; Do you accept?"
"We accept," replied Messrs. Stuart, Fallentin, Sullivan, Flanagan, and Ralph, after consulting each other.
"Good," said Mr. Fogg. "The train leaves for Dover at a quarter before nine. I will take it."
? From Jules Verne, <>
Chapter One Oracle Database Architecture
Fogg decided to travel the world by hot air balloon in order to speed up the journey. Passepartout was excited about the decision and worked hard to load fuel and food into the basket. However, the basket had weight limitation and cannot load with too much water. The French young man showed up his talent by invented a condensing pipe which can extract water from vapor in atmosphere.
Fogg in the meantime, found no time to help Passepartout but dedicated himself to learn Geography and Meteorology at the last minute and currently was concentrating on a world water circulation map.
Few yet noticed that Fogg actually had a very strong mathematics background. He preferred to express whatever he learnt in data-based manners.
1.1. Client Requests and Server Processes
When the balloon[client]* need water[data], condensing pipe can be used to extract from vapor[server process] in the atmosphere. If there happened to be cloud[database buffer] nearby, then the job became easy - just to extract the water from cloud. Otherwise, the only way to get water from ocean was make use of sunlight and vapor the water from ocean, which was quite energy[disk wring] consuming.
1.2. Datafiles and Database Buffer
Ocean[data files], as the primary source of water[data] , when heated by the Sunlight [disk read I/O], vapor the water to make up the cloud[database buffer];
On the contrary way, rain[ database writer] dropped the condensed water[dirty data] from cloud[database buffer] back to ocean[data files];
1.3. Redo Log File And Redo Log Buffer
Water[redo data] flowed from river[redo log buffer] into sea[redo log file] by gravity[log writer process].
* Oracle Terminology
1.4. Database Buffer And Redo Log Buffer
When cloud[database buffer] has grown to be too heavy, condensed water would be dropped into the river by the rain, therefore , river[redo log buffer] was reflecting the changes in cloud[database buffer].
1.5. Checkpoints
The trip was delayed for one day because of a heavy rain. Even so, Fogg was still very excited on the starting day because the sky was extremely clean after the rain and ideal for traveling. He marked a checkpoint on his dairy, "On the starting day, we cannot see any dirty cloud in the whole sky after the rain".
[Database writer process to flush dirty buffer to data file and checkpoint process to update data file header and control file with system change number].
1.6. Archive Mode Vs. Noarchivelog Mode
1.7. Database Creation
Due to his religion, Fogg believed that the world was created by the God. How did the God create the earth at first place? He was not able to find the answer in his Geography books but he imaged that the powerful supernatural made our world in the following steps:
Step One,
To write down the structure of atmosphere[SGA] on a piece of board, this board was call "init.ora";
Step Two,
With the parameters written on the board[init.ora], he built up atmosphere[SGA] including air [shared pool] and cloud[database buffer]. [Instance started by startup no mount command].
Step Three,
With atmosphere setup , he created earth sharp [create control file , contains data/log files names and locations, log sequence number and checkpoint information]. The earth sharp[control files] decided the characteristic of ocean[data files] and sea[log files].
Step Four,
With earth sharp built, he put the ocean[data files] and sea[log files] in place [Mount database], and then added/dropped/renamed ocean[data files] and sea[redo log files] at this stage.
Step five,
With all above ready, he opened the earth to all lives[open database], which means any living creatures [user with the create session privilege] could live on the earth[login to the database].
Fogg's balloon journey was quite smooth all the time until one of the most insurmountable barrier - Himalaya Mountains came into their way. When landed, they found themselves arrive in the wonderful land India.
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