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.
This metric represents the percentage of parse requests where the cursor was already in the cursor cache compared to the number of total parses. This ratio provides an indication as to how often the application is parsing statements that already reside in the cache as compared to hard parses of statements that are not in the cache.
This test checks the percentage of soft parse requests to total parse requests. If the value is less 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 |
Only %value%%% of parses are soft parses. |
|
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 |
((DeltaParseCountTotal - DeltaParseCountHard) / DeltaParseCountTotal) * 100 where:
DeltaParseCountTotal: difference in 'select value from v$sysstat where name='parse count (total)'' between sample end and start
DeltaParseCountHard: difference in 'select value from v$sysstat where name='parse count (hard)'' between sample end and start
Soft parses consume less resources than hard parses, so the larger the value for this item, the better. But many soft parses indicate the application is using SQL inefficiently. Reparsing the statement, even if it is a soft parse, requires a network round trip from the application to the database, as well as requiring the processing time to locate the previously compiled statement in the cache. Reducing network round trips and unnecessary processing will improve application performance.
If this metric value is below 80% you should look at the Top Sessions page sorted by Hard Parses. This page lists the sessions that are currently performing the most hard parses. Starting with these sessions and the SQL statements they are executing will indicate which applications and corresponding SQL statements are being used inefficiently.
If the metric is currently showing a high value, the expensive hard parses are not occurring but the application can still be tuned by reducing the amount of soft parses. Visit the Top SQL page sorted by Parses to identify the SQL statements that have been most parsed. This will allow you to quickly identify SQL that is being re-parsed unnecessarily. You should investigate these statements first for possible application logic changes such that cursors are opened once, and executed or fetched from many times.
Related Topics
About Alerts
About the Metric Detail Page
Editing Thresholds
Understanding Line Charts
Copyright © 1996, 2009, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its affiliates.
Other names may be trademarks of their respective owners.