roughsealtd

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@bishupoonia5106 6 жыл бұрын

Extremely useful for beginners. Great explanation. Now I can do better on my exams today. I just don't understand why would anyone dislike this video?

@smbaxter12650 6 жыл бұрын

You are funny. I enjoyed your book plug. Thank you for this video

@JP-td8gt 6 жыл бұрын

Bravo! Indeed, these fundamentally effective methods work like a charm.

@iPhoneJerry 6 жыл бұрын

Thank you

@click2vikash 7 жыл бұрын

Very well explained.Amazing

@xxx4651 7 жыл бұрын

Ok, so the back ground music makes me uncomfortable but I will still finish watching.

@maheshwaranparamasivan5177 7 жыл бұрын

Very Crisp and to the point. Also Thanks for the captions :)

@nelsonthekinger 7 жыл бұрын

great job sir :)

@ThomasJeff4s0n 7 жыл бұрын

Great video. Your accent is great. I used the automatic youtube captions and they worked perfectly as well. Thank you for the information.

@zes7215 7 жыл бұрын

not understanding of this to perfox, not everyx, idt nerx

@UttamSingh-ib5on 7 жыл бұрын

wow............amazing

@chmercuri 8 жыл бұрын

Excelente video, ficou claro sobre a arquitetura do banco Oracle. --------------------- Excellent video, it was clear about the architecture of the Oracle database.

@robheusd 8 жыл бұрын

If two queries are functionally the same (returning same resultset) but not litterally the same, they get parsed as different queries? (for example: differences in whitespace between tokens, and differences in case of keywords in queries, or alternate syntax forms which are functionally the same).

@roughsealtd 8 жыл бұрын

I'm not too sure about spaces, case is indifferent, but different aliases and even comments change the "signature" of a query. And of course you have multiple ways of returning the same result with different queries; joins can be written in different ways, and can be replaced by subqueries. Only the text counts for signatures, it's not thought for interactive queries but for prepared queries in programs that are executed repeatedly.

@robheusd 8 жыл бұрын

So, oracle would not create an abstract syntax tree in the soft parse phase? If the query has a bind variable, the signature does not depend on the value of the bindvar? The excution plan might differ for different values of a bindvar due to statistics.

@roughsealtd 8 жыл бұрын

Exactly, the signature only depends on text. Concerning bind variables, you have put the finger of one of the major performance stability issues. Oracle tries to anticipate problems when statistics hint at a distribution of values that may be hazardous, and may put queries under watch, checking actual against expected performance, but it only notices it after one query has gone wrong. Dynamic sampling may help.

@shihabma 6 жыл бұрын

yes

@PravinJanjal92 8 жыл бұрын

Awesome

@hnuniyal 8 жыл бұрын

Excellant

@GodGod1337 8 жыл бұрын

fking boring and catch no balls =_=

@roughsealtd 8 жыл бұрын

Try this kzbin.info/www/bejne/Z4fYfpeCopWWmbc instead.

@GodGod1337 8 жыл бұрын

XD thats cute !! :D

@descendentofthemystc 8 жыл бұрын

The video was great up until the last two minutes. It's great to explain advanced technical terms at a basic level for people to understand if the people actually understood what the guy is saying. And then let's have CAPTIONS AVAILABLE IF I FEEL LIKE IT at the top just to tease everyone. "Full transcript available for a small fee" Like sorry you're not french and I half assed my english pronunciations, if you want to understand me give me money. What a fucking joke.

@shivrajkadam3172 8 жыл бұрын

interesting.....

@kmsunil87 8 жыл бұрын

Good starter video..... Thanks

@PradyumnaNadig 9 жыл бұрын

Excellent, precise.

@ulysses_grant 9 жыл бұрын

Great information, the best video I've seen in this subject. Thanks a lot!

@kaisbenrhouma 9 жыл бұрын

Le son est trop faible :/

@jamsjams3083 9 жыл бұрын

Really Nice information,, Good Architecture part..

@djnihal2 9 жыл бұрын

good and decent explanation... job well done.. thank you :D

@felipeserial 9 жыл бұрын

Hello dear, I appreciate a lot this video, but it's from 2009, still update this structure nowadays? I mean, is it the same?

@SalahYoumir 9 жыл бұрын

6:50 .. étapes d’exécution de requête

@InvestWithRishi 9 жыл бұрын

Have an interview tomorrow. Now feeling confident !!! ... thanks!!!

@katew.361 9 жыл бұрын

Sir, I have watched your tutorials on index and join. Can you clarify a process for me? I have 10 tables. Each table has three fields that together create unique IDs (field1+field2+field3 = uniqueID). I have narrowed Table 1 to only those records I need (this is a type of court case). Now I must join on each of the other tables to select only those records that have IDs matching those in Table 1. My tables are quite large (6 to 120 million records each). I tried my first join but that query has been running for five days. I hope this process will work: I will create an index on those three fields for each table, the run my joins. But, do I need to tell the JOIN queries to use the index? Or is it automatic? Apologies for the long question. Kate

@roughsealtd 9 жыл бұрын

+Kate W. If you state that in each table (field1,field2,field3) is unique (in this order), then an index will be automatically created. I assume, though, that it's not on those three fields that you are joining, because it' would be weird to have 10 tables with the same key (row identifier). Your problem probably comes from the fact that you are having join conditions such as "field2 = ...", without any reference to field1, and in that case the index that starts with field1 cannot be used. If you want to find quickly rows that contain field2, then you should ALSO have an index that starts with field2 or on filed2 alone - but only if field2 is selective (which means that one field2 value returns a small fraction on the rows). With the volumes you mention, people usually start thinking about partitioning. Indexes are great when you know *precisely* what you want. You use an index in a book when you want information on one detail. When you want more information, you read full chapters - partitions are more like chapters.

@katew.361 9 жыл бұрын

+roughsealtd: I'm sorry. I've very new to this. You are correct that my join is seeking to obtain a number of columns from each table where those three columns are the same. Here is an example: CREATE TABLE adrfil_of SELECT adrfil.courtl, adrfil.courtt, adrfil.casnbr, adrfil.relptysid, adrfil.relptyid, adrfil.adrlin1, adrfil.adrlin2, adrfil.city, adrfil.state, adrfil.zipcde FROM adrfil JOIN casfil_of ON adrfil.courtl = casfil_of.courtl AND adrfil.courtt = casfil_of.courtt AND adrfil.casnbr = casfil_of.casnbr So would the proper index for each table (prior to running this join) be: CREATE INDEX adrfil_indx ON ojin.adrfil (courtl, courtt, casnbr) Et merci mille fois et je vous remercie beaucoup pour votre patience!

@roughsealtd 9 жыл бұрын

+Kate W. If every time that you have created your tables you STATED that your three columns are unique, which means that in the CREATE TABLE after the list of indexes you have something that looks like UNIQUE (field1, field2, field3) then you HAVE your index (try inserting three values that already exist. If you succeed, you have no constraint and you should declare it with ALTER TABLE). Now, if you process massive amounts of data, using indexes isn't always the smartest thing to do. A good optimize should be able to decide it, provided that statistics on the tables are up-to-date.

@pradeep200417 9 жыл бұрын

excellent explanation with regards to joins.

@pradeep200417 9 жыл бұрын

excellent video. Especially the way it was presented.

@technologysamrat125 9 жыл бұрын

Really good information about database. Can i use this video in my website.

@roughsealtd 9 жыл бұрын

TechnologySamrat Yes, embedded the video is allowed. As long as you don't edit it and don't try to pretend that you are the author, you can use it wherever you want.

@AryaInk 9 жыл бұрын

Though the information provided is excellent in terms of the value but the title is misleading. The information provided in the video is about pros and cons of indexing and not about how to index ?

@roughsealtd 9 жыл бұрын

Prashant Vikal Was the video titled "how to index"?

@AryaInk 9 жыл бұрын

roughsealtd What you think "SQL indexing" means ?

@roughsealtd 9 жыл бұрын

Prashant Vikal What are indexes, how they work, and, yes, their pros and cons. I should add that in nine minutes you cannot expect an exhaustive review of a topic which is complex; in fact, many young professionals don't quite "get" what is here, which is why I did the video. For a more in-depth analysis, I have written three books on SQL, adding up to about 1,000 pages. And if your concern is the CREATE INDEX syntax, check the docs of your particular DBMS.

@AryaInk 9 жыл бұрын

roughsealtd whatever, I can't convince you and that's not my job. Good luck :/

@salvosuper 7 жыл бұрын

If it were about "how to" it would have included the specific DBMS in the title, since indexing creation syntax is non-standard

@Mi_Fa_Volare 9 жыл бұрын

Can I use remote databases in excel?

@roughsealtd 9 жыл бұрын

***** There is something called ODBC which is a standard way for communicating between a program such as Excel and a database (Google for "ODBC Excel"). If you go to Data/Get External Data in Excel you will see that it's possible to import data from an external database into Excel, although you won't be able to run a sophisticated query. Alternatively, you can format and spool the data resulting from a query to a CSV file and import it into Excel.

@wycherleywilliam4316 9 жыл бұрын

很好的讲解，very nice,

@sivakumarm8033 9 жыл бұрын

Great Explanation.. You nailed it.

@anzodefotouni5618 9 жыл бұрын

This is exactly what I have been looking for since I struggling with oracle architecture. Thanks a bunch. Is it possible to have access to more in depth videos on oracle architecture even if ti cost some money?

@Knot2goodAtIt 9 жыл бұрын

quick question, in the "nested loop" example, is that really an index nested loops join? if it was a simple nested loops join wouldn't you go through every single row of the second relation for every row of the first?

@roughsealtd 9 жыл бұрын

Knot2goodAtIt In theory, "nested loop" is independent from indexing. It may perform well on a textbook-like database ... In practice, you are quite right, and a nested loop is a non-starter if tables are unindexed. However, in 99% of the cases, a column which is either the primary key or unique will be involved in the join, and will be indexed. The question then becomes of how many rows are returned from the first table, because using an index to match zillions of rows isn't particularly efficient.

@Knot2goodAtIt 9 жыл бұрын

roughsealtd Awesome! That makes sense, most relations do have a primary key...thanks for responding so quickly

@chrispashalis7794 9 жыл бұрын

This is about MySQL NOT SQL

@roughsealtd 9 жыл бұрын

Chris Pashalis SQL = Structured Query Language Invented by IBM, used in DB2, Oracle, MySQL, SQL Server, PostgreSQL ... PDO can work with any database. Change the driver. SQL queries may vary a bit (functions are often different), principles are the same.

@codykonior 9 жыл бұрын

Watching this video as an SQL Server person with no Oracle knowledge some bits were unclear to me. I've made some notes for others in the same situation. At 2:00 alter table and truncate don't commit an explicit transaction in SQL Server, they can be rolled back. That part of the video may be talking about Oracle. At 7:38 you don't need to specify non clustered primary key, if you leave a primary key off entirely then the table is unordered (a heap) in SQL Server. I'm sure you meant that, but just being clear for others. At 9:14 talking about inserting a row between existing rows in a clustered table, that needs some clarification just so that people understand. SQL Server isn't necessarily storing everything on disk in exactly that physical order - that would be disastrous because then inserting a record in the middle would make it move EVERY record forward to make space. What's going on behind the scenes is a page split (which can be small or large but generally only momentarily impacts performance), and then modifying pointers to where it stored the actual data. This fragmentation can reduce read performance over time because it may have to issue extra disk reads to get what you want and you're not getting the full benefit from large disk reads and disk caching.

@roughsealtd 9 жыл бұрын

Cody Konior To be clear rollback never commits :-) - Yes, DDL (CREATE/ALTER/DROP, plus things commands such as TRUNCATE) implicitly commits in Oracle (and PostgreSQL), not in SQL Server.

@codykonior 9 жыл бұрын

roughsealtd Thanks for that yeah I did mean "alter table and truncate" rather than "alter table and rollback", haha. I've gone back and fixed it. That's interesting and a big gotcha for those of us moving SQL Server -> Oracle.

@sudheervlogs 9 жыл бұрын

Very nice explanation

@raju_adapa 9 жыл бұрын

Entraaa maku idhi

@sarthak185 9 жыл бұрын

I love you man, didn't think it would be so easy.

@newkool100 10 жыл бұрын

good one...thanks for the share...

@DJABOU-SUCCESS-MOTIVATION-TV 10 жыл бұрын

Is it a good course ? and do i have to download some soft like MySql on my Win 7 Pro 64 bits to practise ? and how long days or weeks do i need to learn that language : SQL ?, i'd better know it

@roughsealtd 10 жыл бұрын

It System Well, it's as good a course as I could do :-). No, you don't need to download anything, although of course installing MySQL or SQL Server wouldn't hurt. However, the video course is superseded by a book, "SQL Success" - check at edu.konagora.com (no www). Concerning time, I have taught a 4 hour a week course using this book at a State university. By the MidTerm 90% of students were pretty good on SQL, and better than many developers I have met. You won't be good on SQL after 15 minutes, but you can become decent after 30 hours.

@DJABOU-SUCCESS-MOTIVATION-TV 10 жыл бұрын

so i saw this konagora course in french i think ?. And maybe if you can help me to understand faastly what i have to do or begin by which kind of exercice to practise more and understand, because right now i'm just AdminSystem on Win Server 2003

@roughsealtd 10 жыл бұрын

It System There are a few videos in French on this channel, but the book is in English (and the for-pay videos were recorded by a native English speaker). Like anything, you won't learn SQL in 15 minutes. I like to compare it to chess - you acquire the basics very fast, but truly mastering it isn't easy. The book (over 500 pages) goes deep into SQL, and explains things that most people don't understand at all - including some instructors. It contains exercises, which you can run online on the site, and it contains detailed correction of the exercises (you don't have to pay for a website access as with some text books). I think that if you study the book for 5 hours a week, after one month you will be better than many people who claim to know SQL ...

@DJABOU-SUCCESS-MOTIVATION-TV 10 жыл бұрын

hi in french or in english it depends, no problem for me to learn in english....

@lawrenceadams1628 10 жыл бұрын

Brilliant!

@MrPAKISTANI777 10 жыл бұрын

Video and contents are awesome, but the accent is not easy to digest "VERY VARD HARD ACCENT' he would have used other auto speech type of options.

@marischmersahl7062 10 жыл бұрын

Thank you for the explanation. I needed to understand what a Hash Join meant and your explanation was quite helpful. Basically - fields that are being joined are not in the same sorted order. I will remember your dance illustration as I take my exam.

@baoshinchang1750 10 жыл бұрын

Very clear and informative. Thank you!

@cimode99 10 жыл бұрын

<<primary key is completely different from others, because it will used to sort the coulmn values in order>> A primary key is a logical concept and has nothing to do with order physical concept.

@cimode99 10 жыл бұрын

<<would the key be same as the the Primary Key?>> The primary key is a key selected among keys (called also candidate keys), because it it is more robust and familiar than other keys.

@tharindawicky 10 жыл бұрын

thanks

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