Oracle Read-only tablespace more efficient if "select count(*)" issued first - please explain
Page 13-1 of "E10595-06" (Oracle Admin 11gR2 Guide), has the following paragrpaph:
"For better performance while accessing data in a read-only tablespace, you can issue a query that accesses all of the blocks of the tables in the tablespace just before making it read-only. A simple query, such as SELECT COUNT (*), executed against each table ensures that the data blocks in the tablespace can be subsequently accessed most efficiently. This eliminates the need for the database to check the status of the transactions that most recently modified the blocks."
Anybody can explain how a "select count(*)" can make subsequent queries more efficient ?
"For better performance while accessing data in a read-only tablespace, you can issue a query that accesses all of the blocks of the tables in the tablespace just before making it read-only. A simple query, such as SELECT COUNT (*), executed against each table ensures that the data blocks in the tablespace can be subsequently accessed most efficiently. This eliminates the need for the database to check the status of the transactions that most recently modified the blocks."
Anybody can explain how a "select count(*)" can make subsequent queries more efficient ?
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