| September 09, 2005 11:19:40 |
#3 |
| praim Sankar |
Member Since: Visitor Total Comments: N/A |
RE: What are the factors causing the reparsing of SQL statements in SGA
|
The Library Cache was introduced because parsing (and validating and checking privileges) is expensive in terms of CPU cycles.
Oracle uses a LRU/MRU mechanism to keep sql statements in cache. When more room is needed in the cache Oracle drops off the LRU block.
When a sql statement is executed Oracle checks the library cache first. If it finds it then there is no need to reparse and it is a hit.
If the statement does not exist in cache then it's a miss and oracle needs to read the data from the data blocks. The statement will be parsed. |
| |
