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SELECT statement Processing in an Oracle Database - DBArch Video 7

282 ratings | 25710 views
You will learn from this video how a SELECT statement is processed in an Oracle Database. You will learn about the a Parse, Execute and Fetch phases in a select statement. Our Upcoming Online Course Schedule is available in the url below https://docs.google.com/spreadsheets/d/1qKpKf32Zn_SSvbeDblv2UCjvtHIS1ad2_VXHh2m08yY/edit#gid=0 Reach us at [email protected]
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Text Comments (32)
Aman Kumar (6 days ago)
Sir ji thanks a lot. You are beyond best. I don't have word to adjectify you. Namaste
Thanks... Enjoy learning
Good overview. Thank you. What happens when a hash is generated and later there is a change in DDL? will the hash be deleted and goes for another hard parse?? Example : 1. hash created for select empid from emp; 2. Query executed and result returned. 3. Ddl executed to drop empid column 4. Reissue the same command.. When step 4 executed hash would be same as step 1.. So it should ideally go for soft parse but how this scenario would be handled.??
+Ramkumar Swaminathan Thank you for clear explanation
On every ddl, typically all depended SQLs in the SQLArea are invalidated and will have to be hard parsed again... Thats why dont execute DDLs in a Production database, unless its an off peak hour...
harisai hari (1 month ago)
nice background music but pls reduce the volume , sometimes its overlapping your voice. Nothing we can say about your teaching skills.hats off
Ramkumar Swaminathan (1 month ago)
Thanks...Enjoy learning... BG music is taken care in new videos
Himanshubhusan Rath (7 months ago)
Really, very nice explanation... You explained such a complex stuff in a very simple manner.. Thank you Sir :)
Ramkumar Swaminathan (7 months ago)
Thanks, enjoy learning...
Dau Bap (7 months ago)
Thank you for your excellent video. I have a question: "How does oracle find table blocks in datafiles ? If table exist in buffer cache, how does oracle find it ?" Thanks.
Ramkumar Swaminathan (7 months ago)
Buffer cache is only a cache of data files...
Dau Bap (7 months ago)
After watching video you have suggested, i understand how oracle find table blocks in storage. But in buffer cache, how oracle find it ? What does oracle base on to find ? Thanks for your quick reply.
Ramkumar Swaminathan (7 months ago)
You can go through my video on Tablespace, Segments, Extents and Blocks https://youtu.be/cp56dkTSSNk All this is maintained and hence when you submit a query, the database is able to identify which blocks belong to the table/s that you are querying... If the block is present in the Buffer Cache then it reads it from there itself... if not it will have to do I/O and read from the data files in the storage...
Rajasekhar Bellapu (8 months ago)
Tq
ashwani mishra (9 months ago)
Best teacher ever... God for dba folks
ashwani mishra (9 months ago)
Ramkumar Swaminathan seriously sir....in my entire schooling college and work life... Never found such an amazing learning exp....thanks a ton 👏
Ramkumar Swaminathan (9 months ago)
Thanks... Enjoy learning
Sir!! I salute you... you know what you are teaching, congratulations
Ramkumar Swaminathan (9 months ago)
Thanks.. enjoy learning
DibyaJyoti Nayak (9 months ago)
Sir, Thank you for this nice video.Very well explained. I have a doubt what will happen if the buffer cache is smaller than the table size. Will it get loaded in the memory? Thanks
Ramkumar Swaminathan (9 months ago)
It will load in parts one after another part(bunch of blocks) of the table and give you the result
digvijay damame (10 months ago)
You are the best :) :) :)
stefan moha (10 months ago)
Best teaching ever seen unbeleivable!!!!! May GOD guide you to the truth about HIM. It is the best gift someone can get in his life.
Ramkumar Swaminathan (10 months ago)
Thanks Stafan.... Enjoy learning...
Shiv Vishnoi (1 year ago)
Thanks you very much. This is very helpful.
Ramkumar Swaminathan (1 year ago)
+Shiv Vishnoi most welcome... Enjoy learning
Dayashankar Sharma (1 year ago)
it's Very Good Videos. explained in simple method. thanks
Ramkumar Swaminathan (1 year ago)
+Dayashankar Sharma thanks
Ashok M (1 year ago)
Thank you so much ...please upload more videos on RAC.and advanced technologies
Ramkumar Swaminathan (1 year ago)
+Ashok M will be coming up... Be subscribed
Pavan B (1 year ago)
Hi Sir , Thank you for all your valuable time & energy for making the videos on the oracle Dba and sharing the knowlede. Request:Please make a video on Multitenant Architecture in 12c . Thanking you in advance.
Nice Sir...Thank you very much your help...

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