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admin:optimization:plans:example [2012/02/03 19:47] doc |
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| === Step 2: Process the HOUSEHOLDS table's criteria === | === Step 2: Process the HOUSEHOLDS table's criteria === | ||
| - | Omnidex will perform index qualifications to process the criteria in the HOUSEHOLDS table, paying attention to Boolean operators and parentheses to insure the correct result. Once this is done, Omnidex will have isolated the rows that meet this criteria, identified by a temporary file containing index pointers. | + | Omnidex will perform index qualifications to process the criteria in the HOUSEHOLDS table, paying attention to Boolean operators and parentheses to insure the correct result. Once this is done, Omnidex will have isolated index pointers for the rows that meet this criteria. |
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| === Step 3: Join from HOUSEHOLDS to INDIVIDUALS === | === Step 3: Join from HOUSEHOLDS to INDIVIDUALS === | ||
| - | Omnidex will join from the HOUSEHOLDS table to the INDIVIDUALS table. Omnidex has several techniques for optimizing table joins. In this case, it will use the primary key values in HOUSEHOLDS as criteria against thed HOUSEHOLD index in the INDIVIDUALS table. Once this is done, Omnidex will have isolated rows in the INDIVIDUALS table that meet the criteria from the HOUSEHOLDS table. | + | Omnidex will join from the HOUSEHOLDS table to the INDIVIDUALS table. Omnidex has several techniques for optimizing table joins. In this case, it will use the primary key values in HOUSEHOLDS as criteria against thed HOUSEHOLD index in the INDIVIDUALS table. Omnidex will then have isolated index pointers for rows in the INDIVIDUALS table that link to the previously qualified HOUSEHOLDS rows. |
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| === Step 4: Process the INDIVIDUALS table's criteria === | === Step 4: Process the INDIVIDUALS table's criteria === | ||
| - | Omnidex will perform index qualifications to process the criteria in the INDIVIDUALS table. This will further refine the index pointers already identified by processing in the HOUSEHOLDS table. | + | Omnidex will perform index qualifications to process the criteria in the INDIVIDUALS table. This will further refine the index pointers so that they reflect criteria from both tables, as well as the table join itself. |
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| === Step 5: Aggregate counts in the INDIVIDUALS table=== | === Step 5: Aggregate counts in the INDIVIDUALS table=== | ||
| - | Omnidex will aggregate counts in the INDIVIDUALS table by scanning its indexes and filering the results using the index pointers set aside from the previous steps. | + | Omnidex will aggregate counts in the INDIVIDUALS table using indexes on the GROUP BY columns, while also intersecting with the index pointers that were isolated while processing criteria and table joins. |
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| === Step 6: Return the final result set === | === Step 6: Return the final result set === | ||
| - | Omnidex will finally return the result set of the query. When possible, Omnidex will return the first rows as soon as they are available, even if the later rows are still being processed. This speeds query execution, and also helps when only the first screenfuls of data are going to be requested. | + | Omnidex will finally return the result set of the query. When possible, Omnidex will return the first rows as soon as they are available, even if the later rows are still being processed. This speeds query execution, and also helps when only the first screenfuls of data are going to be viewed. |
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