Why does performance degrade when many UPDATE, INSERT, or DELETEstatements are issued on a table that has an associated bitmap index?
Bitmap indexes in currently ''supported'' versions of Oracle are maintained in a much more efficient manner than they were previously, to the point where the need for frequently rebuilds has been much reduced, even in tables in which such indexes are not dropped during heavy loads.
That said, Bitmap indexes are still unsuitable in OLTP type environments (even in 11g or later) due to the locking implications associated with them.
Note: bitmap indexes are only suitable for static tables and materialized views which are updated at nigh and rebuilt after batch row loading.
Not B: Like b-tree indexes, bitmap indexes should be rebuilt (ALTER INDEX . . . REBUILD) if there is a lot of DML (UPDATE, INSERT, DELETE) activity.
Not A: Since 10g,Oracle issignificantly more efficient and where possible will simply adjust the current rowidrange of the Bitmap index entry and modify the bitmap string accordingly to accommodatea new row value (resulting in an overall increase of just 2 bytes overall in this example) rather than create a totally new index entry (which required an additional 21 bytes in the 9i example).
Examine the table:
Table name: PRODUCTS
Schema: SCOTT
Tablespace: USERS
Organization: Standard (Heap Organized)
This table contains 20 rows. In the data that has been entered, the PROD_ID column contains only single-digit values, PROD_NAME has a maximum of five characters, and PROD_RATE has four-digit values for all rows.
Which two statements are true regarding the modifications that can be performed to the structure of the PRODUCTS table?
John is a CDB administrator, and Mike and Tim are PDB administrators of their respective databases- John takes a complete CDB backup by using RMAN>Backup Database. Mike and Tim may need point-in-time recovery of their PDBs. Which statement is true?
Your customer has two CDBs: one for Production and one for development. You are asked to create a new development PDB (salesdev) from an existing production PDB (salesprd). Which two options would accomplish this?
A: Creating a PDB Using the Seed
You can use the CREATE PLUGGABLE DATABASE statement to create a PDB in a CDB using the files of the seed.
D: Plugging In an Unplugged PDB
To plug in an unplugged PDB, the following prerequisites must be met:
* Complete the prerequisites described in 'Preparing for PDBs'.
* The XML file that describes the PDB must exist in a location that is accessible to the CDB.
The USING clause must specify the XML file.
Etc
Real-Time ADDM detects a high-load performance issue within the database. Which condition triggered it?
http://docs.oracle.com/cd/E16655_01/server.121/e15857/pfgrf_diag.htm#TGDBA95369 (table 7-1)
