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admin:indexing:strategies:aggregations [2012/01/30 18:03] doc |
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| The advantage of this optimization approach is that a small number of indexes can support nearly any combination of GROUP BY columns, providing high performance at little cost. | The advantage of this optimization approach is that a small number of indexes can support nearly any combination of GROUP BY columns, providing high performance at little cost. | ||
| - | There are some situations in which specialized index is better for optimizing a query. When the GROUP BY column have especially high cardinality, such as over 64,000 distinct values, it will be necessary to create a multi-column index as described below. Additionally, if the same GROUP BY columns are used repeatedly, a multi-column index will perform faster. | + | There are some situations in which specialized indexes are better for optimizing a query. When a GROUP BY column has especially high cardinality, such as over 64,000 distinct values, it is necessary to create a multi-column index as described below. Additionally, if the same GROUP BY columns are used frequently, a multi-column index will provide even faster performance. |
| ==== Optimizing Other Aggregations ==== | ==== Optimizing Other Aggregations ==== | ||