This number reflects the total number of parses per second, both hard and soft. A hard parse occurs when a SQL statement has to be loaded into the shared pool. In this case, the Oracle Server has to allocate memory in the shared pool and parse the statement. A soft parse is recorded when the Oracle Server checks the shared pool for a SQL statement and finds a version of the statement that it can reuse.
Each time a particular SQL cursor is parsed, this count will increase by one. There are certain operations which will cause a SQL cursor to be parsed. Parsing a SQL statement breaks it down into atomic steps which the optimizer will evaluate when generating an execution plan for the cursor.
This test checks the number of parse calls per second. If the value is greater than or equal to the threshold values specified by the threshold arguments, and the number of occurrences exceeds the value specified in the "Number of Occurrences" parameter, then a warning or critical alert is generated.
The rest of the information in this section is only valid for this metric when it appears in either the Enterprise Manager Grid Control or the Enterprise Manager Database Control (if applicable).
The following table shows how often the metric's value is collected and compared against the default thresholds. The 'Consecutive Number of Occurrences Preceding Notification' column indicates the consecutive number of times the comparison against thresholds should hold TRUE before an alert is generated.
|
Target Version |
Evaluation and Collection Frequency |
Upload Frequency |
Operator |
Default Warning Threshold |
Default Critical Threshold |
Consecutive Number of Occurrences Preceding Notification |
Alert Text |
|
pre-10g |
Every 5 Minutes |
After Every Sample |
> |
Not Defined |
Not Defined |
2 |
Total parse rate is %value%/sec. |
|
Target Version |
Server Evaluation Frequency |
Collection Frequency |
Upload Frequency |
Operator |
Default Warning Threshold |
Default Critical Threshold |
Consecutive Number of Occurrences Preceding Notification |
Alert Text |
|
10.1.0.x; 10.2.0.x; 11.1.0.x; 11.2.0.x |
Every Minute |
Not Defined |
After Every Sample |
> |
Not Defined |
Not Defined |
2 |
Generated By Database Server |
DeltaParses / Seconds where:
DeltaParses: difference in 'select value from v$sysstat where name='parse count (total)'' between end and start of sample period
Seconds: number of seconds in sample period
If there appears to be excessive time spent parsing, evaluate SQL statements to determine which can be modified to optimize shared SQL pool memory use and avoid unnecessary statement reparsing. This type of problem is commonly caused when similar SQL statements are written which differ in space, case, or some combination of the two. You may also consider using bind variables rather than explicitly specified constants in your statements whenever possible.
The Top Sessions page sorted by Hard Parses will show you which sessions are incurring the most hard parses. Hard parses happen when the server parses a query and cannot find an exact match for the query in the library cache. Hard parses can be avoided by sharing SQL statements efficiently. The use of bind variables instead of literals in queries is one method to increase sharing.
By showing you which sessions are incurring the most hard parses, this page may lead you to the application or programs that are the best candidates for SQL rewrites.
Also, examine SQL statements which can be modified to optimize shared SQL pool memory use and avoid unnecessary statement reparsing. This type of problem is commonly caused when similar SQL statements are written which differ in space, case, or some combination of the two. You may also consider using bind variables rather than explicitly specified constants in your statements whenever possible.
The SHARED_POOL_SIZE initialization parameter controls the total size of the shared pool. Consider increasing the SHARED_POOL_SIZE to decrease the frequency in which SQL requests are being flushed from the shared pool to make room for new requests.
To take advantage of the additional memory available for shared SQL areas, you may also need to increase the number of cursors permitted per session. You can increase this limit by increasing the value of the initialization parameter OPEN_CURSORS.
Related Topics
About Alerts
About the Metric Detail Page
Editing Thresholds
Understanding Line Charts
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