This commit adds `bit` vector support by adding `element_type: bit` for
vectors. This new element type works for indexed and non-indexed
vectors. Additionally, it works with `hnsw` and `flat` index types. No
quantization based codec works with this element type, this is
consistent with `byte` vectors.
`bit` vectors accept up to `32768` dimensions in size and expect vectors
that are being indexed to be encoded either as a hexidecimal string or a
`byte[]` array where each element of the `byte` array represents `8`
bits of the vector.
`bit` vectors support script usage and regular query usage. When
indexed, all comparisons done are `xor` and `popcount` summations (aka,
hamming distance), and the scores are transformed and normalized given
the vector dimensions. Note, indexed bit vectors require `l2_norm` to be
the similarity.
For scripts, `l1norm` is the same as `hamming` distance and `l2norm` is
`sqrt(l1norm)`. `dotProduct` and `cosineSimilarity` are not supported.
Note, the dimensions expected by this element_type are always to be
divisible by `8`, and the `byte[]` vectors provided for index must be
have size `dim/8` size, where each byte element represents `8` bits of
the vectors.
closes: https://github.com/elastic/elasticsearch/issues/48322
This adds `hamming` distances, the pop-count of `xor` byte vectors as a
first class citizen in painless.
For byte vectors, this means that we can compute hamming distances via
script_score (aka, brute-force).
The implementation of `hamming` is the same that is available in Lucene,
and when lucene 9.11 is merged, we should update our logic where
applicable to utilize it.
NOTE: this does not yet add hamming distance as a metric for indexed
vectors. This will be a future PR after the Lucene 9.11 upgrade.
Removes `testenv` annotations and related code. These annotations originally let you skip x-pack snippet tests in the docs. However, that's no longer possible.
Relates to #79309, #31619
Allow direct access to a dense_vector' values in script
through the following functions:
- getVectorValue – returns a vector's value as an array of floats
- getMagnitude – returns a vector's magnitude
Closes#51964
Follow up to #48368. This PR removes support for `sparse_vector` on new
indices. On 7.x indices a `sparse_vector` can still be defined, but it is not
possible to index or search on it.
Previously the functions accepted a doc values reference, whereas they now
accept the name of the vector field. Here's an example of how a vector function
was called before and after the change.
```
Before: cosineSimilarity(params.query_vector, doc['field'])
After: cosineSimilarity(params.query_vector, 'field')
```
This seems more intuitive, since we don't allow direct access to vector doc
values and the the meaning of `doc['field']` is unclear.
The PR makes the following changes (broken into distinct commits):
* Add new function signatures of the form `function(params.query_vector,
'field')` and deprecates the old ones. Because Painless doesn't allow two
methods with the same name and number of arguments, we allow a generic `Object`
to be passed in to the function and decide on the behavior through an
`instanceof` check.
* Refactor the class bindings so that the document field is passed to the
constructor instead of the instance method. This allows us to avoid retrieving
the vector doc values on every function invocation, which gives a tiny speed-up
in benchmarks.
Note that this PR adds new signatures for the sparse vector functions too, even
though sparse vectors are deprecated. It seemed simplest to understand (for both
us and users) to keep everything symmetric between dense and sparse vectors.
We have not seen much adoption of this experimental field type, and don't see a
clear use case as it's currently designed. This PR deprecates the field type in
7.x. It will be removed from 8.0 in a follow-up PR.
* Add l1norm and l2norm distances for vectors
Add L1norm - Manhattan distance
Add L2norm - Euclidean distance
relates to #37947
* Address Christoph's feedback
- organize vector functions as a separate doc
- increase precision in tests calculations
- add a separate test when sparse doc dims
are bigger and less than query vector dims
* Made examples more realistic
