Oracle Arquitetuea

Dúvidas, dicas e truques de SQL, Select, Update, Delete, cláusulas, operações com joins, Funções em SQLs, etc

Poston Wed, 23 Aug 2006 12:35 pm

Good morning guys, I'm with a doubt about Oracle???

What are the components of Oracle architecture affected instructions select, insert, update, delete and commit???

Thanks, Alex
Location: SP

Poston Fri, 05 Jan 2007 2:47 pm

Alex, For these statements you have the following as below: SELECT-UNDOTBS, memory structures (SGA) INSERT-UNDOTBS and redo log files UPDATE-UNDOTBS, memory structures (SGA) and redo log files DELETE-UNDOTBS, memory structures (SGA) and redo log files the Commit you commit changes made to the tables, i.e. after an INSERT, UPDATE, or DELETE, you use the Commit to confirm such tasks.

But you must have surprised UNDOTBS usage in the SELECT statement. Imagine that you're running a SELECT that will return 1,000,000 rows, and during execution, another section ran an UPDATE in one of the tables.

When running Oracle verifies that the rows affected by the UPDATE statement have date of alteration above the first lines \"fetched\". To maintain consistency of information, search the Oracle changed rows of UNDOTBS, and with it the changes are not returned in the SELECT statement.

A good book, which by the way I'm currently reading, is Effective Design by Oracle, the Pope Tom Kyte.

I hope I have clarified some doubts.

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