Monthly Archives: September 2012
Life of an Oracle DBA – The Basics Access Paths: Index Skip Scan
Normally for Oracle to use an index, the leading column in the index must be in the predicate. There are conditions, where the leading edge of the index is not in the predicate but the remaining columns in the index … Continue reading
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Life of an Oracle DBA – The Basics Access Paths: Index Range Scan
A index range scan gets the rowid by getting the adjacent index entries. Once Oracle has gathered the rowid’s the rows are returned in ascending order. Unless you use sort descending. From our previous example we saw that if you … Continue reading
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Life of an Oracle DBA – The Basics Access Paths: Index Unique Scan
The index unique scan is good for getting one row from and index and returning the rowid. You will get a index unique scan if you have a unique index or primary key on a table. In this example; we … Continue reading
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Life of an Oracle DBA – The Basics Access Paths: Table Access By Rowid.
Dang, that just sounds fast, and it is. Rowid points to the datafile:block:location in block. So, what is this good for? How do you get Oracle to access by rowid? If you want to access a specific row or set … Continue reading
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Life of an Oracle DBA – The Basics Access Paths: Full Table Scan
For the next few weeks I am going to be going over some of the basics of what you need to know to be a good Oracle DBA. Feel Free to speak up if there is something you think I … Continue reading
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