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Performance and Tuning Guide Volumes 1 - 3 (Online Only) |
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| Chapter 36 Using set showplan |
Chapter 36
This chapter describes each message printed by the showplan utility. showplan displays the steps performed for each query in a batch, the keys and indexes used for the query, the order of joins, and special optimizer strategies.
| Using |
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| Basic showplan messages |
| Query plan delimiter message |
| Step message |
| Query type message |
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| FROM TABLE message |
| TO TABLE message |
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| Update mode messages |
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| Optimized using messages |
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| showplan messages for query clauses |
| GROUP BY message |
| Selecting into a worktable |
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| Grouped aggregate message |
| compute by message |
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| Ungrouped aggregate message |
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| messages for order by and distinct |
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| Sorting messages |
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| Messages describing access methods, caching, and I/O cost |
| Auxiliary scan descriptors message |
| Nested iteration message |
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| Merge join messages |
| Table scan message |
| Clustered index message |
| Index name message |
| Scan direction messages |
| Positioning messages |
| Scanning messages |
| Index covering message |
| Keys message |
| Matching index scans message |
| Dynamic index message (OR strategy) |
| Reformatting Message |
| Trigger Log Scan Message |
| I/O Size Messages |
| Cache strategy messages |
| Total estimated I/O cost message |
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| showplan messages for parallel queries |
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| Executed in parallel messages |
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| showplan messages for subqueries |
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| Output for flattened or materialized subqueries |
| Structure of subquery showplan output |
| Subquery execution message |
| Nesting level delimiter message |
| Subquery plan start delimiter |
| Subquery plan end delimiter |
| Type of subquery |
| Subquery predicates |
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| Internal subquery aggregates |
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| Existence join message |
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