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admin:indexing:indexes:groups [2011/01/24 03:53] els |
admin:indexing:indexes:groups [2016/06/28 22:38] (current) |
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| ==== Index Groups ==== | ==== Index Groups ==== | ||
| - | Index Groups are used to combine multiple indexes into one single index. This allows a search against any one index within the group to automatically search all indexes within the group. For example, if a table has three lines, ADDRESS_LINE_1, ADDRESS_LINE_2 and ADDRESS_LINE_3, they can be indexed as an Index Group. Criteria against any one of those three columns will automatically search all address lines. | + | Index Groups are used to combine multiple indexes into one single index. This allows a search against any one index within the group to automatically search all indexes within the group. For example, if a table has three lines, ADDRESS_LINE_1, ADDRESS_LINE_2, and ADDRESS_LINE_3, they can be indexed as an Index Group. Criteria against any one of those three columns will automatically search all address lines. |
| In the example below, a row displays an address: | In the example below, a row displays an address: | ||
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| If these three columns are added to an Index Group, then the following search will locate the row: | If these three columns are added to an Index Group, then the following search will locate the row: | ||
| - | <code sql> | + | <code> |
| select NAME, ADDRESS_LINE_1, ADDRESS_LINE_2, ADDRESS_LINE_3 | select NAME, ADDRESS_LINE_1, ADDRESS_LINE_2, ADDRESS_LINE_3 | ||
| from CUSTOMERS | from CUSTOMERS | ||
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| Care should be taken when considering where to use Index Groups. When indexes are combined into an Index Group, they lose the ability to distinguish which column originally contained the values. This can lead to confusion. For example, the following search will also locate the row: | Care should be taken when considering where to use Index Groups. When indexes are combined into an Index Group, they lose the ability to distinguish which column originally contained the values. This can lead to confusion. For example, the following search will also locate the row: | ||
| - | <code sql> | + | <code> |
| select NAME, ADDRESS_LINE_1, ADDRESS_LINE_2, ADDRESS_LINE_3 | select NAME, ADDRESS_LINE_1, ADDRESS_LINE_2, ADDRESS_LINE_3 | ||
| from CUSTOMERS | from CUSTOMERS | ||
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| === Common Uses of Index Groups === | === Common Uses of Index Groups === | ||
| - | Index Groups can be used in many different situations. Here is a little of common situation where Index Groups are used: | + | Index Groups can be used in many different situations. Here is a common situation where Index Groups are used: |
| * Combining indexes for multiple address lines | * Combining indexes for multiple address lines | ||
| * Combining indexes for a short-description column and a long-description column. | * Combining indexes for a short-description column and a long-description column. | ||
| - | * Combining indexes for given names, nicknames and aliases | + | * Combining indexes for given names, nicknames, and aliases |
| * Combining indexes for multiple telephone numbers | * Combining indexes for multiple telephone numbers | ||
| * Combining indexes for multiple email addresses | * Combining indexes for multiple email addresses | ||
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| If HOUSEHOLDS.HOME_PHONE and INDIVIDUALS.MOBILE_PHONE were added to an Index Group, then this household would be returned in the following query. Note that the query searches the indexes in the INDIVIDUALS table **even though the INDIVIDUALS table is not referenced in the query.** | If HOUSEHOLDS.HOME_PHONE and INDIVIDUALS.MOBILE_PHONE were added to an Index Group, then this household would be returned in the following query. Note that the query searches the indexes in the INDIVIDUALS table **even though the INDIVIDUALS table is not referenced in the query.** | ||
| - | <code sql> | + | <code> |
| select HOUSEHOLD, ADDRESS, CITY, STATE, ZIP | select HOUSEHOLD, ADDRESS, CITY, STATE, ZIP | ||
| from HOUSEHOLDS | from HOUSEHOLDS | ||
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| </code> | </code> | ||
| - | As discussed above, care should be taken when considering where to use Index Groups across tables. It can be confusing that when a table is searched without it being included in the SQL statement. A row can also be qualified when a portion of the criteria exists in the parent and another portion exists in a child row. For example, the following search will also locate this household: | + | As discussed above, care should be taken when considering where to use Index Groups across tables. It can be confusing when a table is actually searched without it being referenced in the SQL statement. A row can also be qualified when a portion of the criteria exists in the parent and another portion exists in a child row. For example, the following search will also locate this household: |
| - | <code sql> | + | <code> |
| select HOUSEHOLD, ADDRESS, CITY, STATE, ZIP | select HOUSEHOLD, ADDRESS, CITY, STATE, ZIP | ||
| from HOUSEHOLDS | from HOUSEHOLDS | ||