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Table 12-50 Heavy I/O Due to Other Access
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| next | Perform one of the following options: |
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Findings refer to the whole statement - not to a specific execution plan. If a step doesn't exist in the selected execution plan (unless this is the result of an index overhead), switch to another plan and locate the relevant step. |
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Much of the statement I/O is spent on waiting for a lock on the table specified in the Object column.
Table 12-51 Statement State Row Lock
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| next | Select the findings type to examine lock for the statement in the Activity tab. |
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To reduce the lock wait for the table, consider the following solutions: |
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Findings refer to the whole statement - not to a specific execution plan. If a step doesn't exist in the selected execution plan (unless this is the result of an index overhead), switch to another plan and locate the relevant step. |
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Your statement has spent much of its In Oracle time on Buffer Wait. This usually occurs because one of two possible scenarios:
- Contention on a table buffer in Insert statements (Buffer Busy Wait), or
- Lack of free buffers when trying to load blocks from a disk (Free Buffer Wait)
Table 12-52 Buffer Wait Contention
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| next | Perform one of the following options: |
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| Advice | When Buffer Busy Wait is the more dominant Oracle event, consider the following options: |
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When Free Buffer Wait is the more dominant Oracle event, consider the following options: |
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Your statement has spent much of its In Oracle time waiting for Redo Log Wait.
Table 12-53 Redo Log Activity
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| next | Perform one of the following options: |
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To reduce Redo Log Wait, consider the following solution: |
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Your statement has spent much of its In Oracle time waiting for undo.
Table 12-54 Undo Activity
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| next | Perform one of the following options: |
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| Advice | To reduce Undo Wait time, consider the following solutions: |
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Your instance has spent much of its In Oracle time waiting for a RAC activity to complete on the object specified in the Object column.
Table 12-55 RAC Wait
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| next | Select the findings type to see the instances consuming object RAC Wait in the Activity tab. |
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| The object is suffering from a RAC Wait because several instances are using it simultaneously. To solve the problem, identify all programs currently accessing the object and try to avoid accessing it concurrently. |
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Bind sets were collected for the statement.
Table 12-56 Bind Variables Were Collected
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| next | Perform one of the following options: |
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| If the Oracle optimizer finds a better execution plan, try to evaluate one plan in relation to another for a set of captured binds and try to stabilize it by using outlines. |
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More than one real plan was collected for the statement during the selected time frame.
Table 12-57 More Than One Real Plan Was Detected
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| next | Select the findings type and use the All Plans tab to examine the different captured execution plans and their real resource consumption. |
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Try to identify the source for the different execution plans. To resolve the multiple plans, consider the following solutions: |
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The cost for the statement has changed over the last month.
Table 12-58 Costs Have Changed Over the Last Month
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| next | Select the findings type and use the History tab to examine the different costs caught for the statement. |
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Try to identify the source for the different execution plan costs. Go to the History tab to check whether there were any changes (such as schema or statistics changes). |
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Much of the statements In Oracle time is spent on CPU usage, even though the average In Oracle time is low (indicating executions run many times).
Table 12-59 Frequently Executed Statement
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| next | Perform one of the following options: |
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| Try to determine if the large number of executions is valid or if it is derived from redundant executions as a result of inefficient program design (e.g. if the statement is enabled in an inefficient loop). |
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Much of the stats In Oracle time is spent on CPU usage, and the average In Oracle time is high.
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