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Order by field support FTS (#1132)

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This PR adds support for passing through a set of ordering fields at
index time (unsigned ints that tantivity can use as fast_fields) that at
query time you can sort your results on. This is useful for cases where
you want to get related hits, i.e by keyword, but order those hits by
some other score, such as popularity.

I.e search for songs descriptions that match on "sad AND jazz AND 1920"
and then order those by number of times played. Example usage can be
seen in the fts tests.

---------

Co-authored-by: Nat Roth <natroth@Nats-MacBook-Pro.local>
Co-authored-by: Chang She <759245+changhiskhan@users.noreply.github.com>
This commit is contained in:
natcharacter
2024-03-20 04:27:37 -04:00
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parent befb79c5f9
commit dbdd0a7b4b
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@@ -75,6 +75,36 @@ applied on top of the full text search results. This can be invoked via the fami
table.search("puppy").limit(10).where("meta='foo'").to_list()
```
## Sorting
You can pre-sort the documents by specifying `ordering_field_names` when
creating the full-text search index. Once pre-sorted, you can then specify
`ordering_field_name` while searching to return results sorted by the given
field. For example,
```
table.create_fts_index(["text_field"], ordering_field_names=["sort_by_field"])
(table.search("terms", ordering_field_name="sort_by_field")
.limit(20)
.to_list())
```
!!! note
If you wish to specify an ordering field at query time, you must also
have specified it during indexing time. Otherwise at query time, an
error will be raised that looks like `ValueError: The field does not exist: xxx`
!!! note
The fields to sort on must be of typed unsigned integer, or else you will see
an error during indexing that looks like
`TypeError: argument 'value': 'float' object cannot be interpreted as an integer`.
!!! note
You can specify multiple fields for ordering at indexing time.
But at query time only one ordering field is supported.
## Phrase queries vs. terms queries
For full-text search you can specify either a **phrase** query like `"the old man and the sea"`,