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Given the following (incomplete) fragment table:
| id | parent_id | anchor_id | xpath |
|---|---|---|---|
| 1 | NULL | 3 | /bookstore |
| 2 | 1 | 3 | /bookstore/categories[@code='1'] |
| 3 | 2 | 3 | /bookstore/categories[@code='1']/books[@title='Matilda'] |
| 4 | 2 | 3 | /bookstore/categories[@code='1']/books[@title='The Gruffalo'] |
| 5 | 1 | 3 | /bookstore/categories[@code='2'] |
| 6 | 5 | 3 | /bookstore/categories[@code='2']/books[@title='Good Omens'] |
| 7 | 5 | 3 | /bookstore/categories[@code='2']/books[@title='The Colour of Magic'] |
| 8 | NULL | 4 | /dmi-registry |
| 9 | 8 | 4 | /dmi-registry/cm-handles[@id='d99ef4cc8d744a749490cceefd4c469e'] |
Here is a visualization of both algorithms:
| Existing solution | Proposed solution |
|---|
| Because the existing solution uses a regex, |
| all fragments in anchor 3 need to be examined, so see if they match the regex. | Because the proposed solution uses sub-queries to look up |
| each path component, only relevant fragments are examined. | |
|
|
A note on fetching descendant nodes
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