Add github pages (#25)

* Add doc

* Add api reference

* Add news

* Add getting-started.md

* Clean up

* Only enable doc build on pushing to main

.github/workflows/doc.yml

@@ -0,0 +1,32 @@
+name: documentation
+
+on: 
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+      - name: Install dependencies
+        run: |
+          cp -r media doc/markdown
+          pip install sphinx sphinx_rtd_theme myst_parser
+      - name: Sphinx build
+        run: |
+          sphinx-build doc _build
+      - name: Deploy to GitHub Pages
+        uses: peaceiris/actions-gh-pages@v3
+        if: ${{ (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/main' }}
+        with:
+          publish_branch: gh-pages
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: _build/
+          force_orphan: true

README.md

@@ -61,8 +61,20 @@ vector_from_json(json_string) -- converts a json array of type TEXT into BLOB(a
 vector_to_json(vector_blob) -- converts a vector of type BLOB(c-style float32 array) into a json array of type TEXT
 vector_distance(vector_blob1, vector_blob2, distance_type_str) -- calculate vector distance between two vectors, distance_type_str could be 'l2', 'cosine', 'ip' 
 ```
+In fact, one can easily implement brute force searching using `vector_distance`, which returns 100% accurate search results:
+```sql
+-- use a normal sqlite table
+create table my_table(rowid integer primary key, embedding blob);
+
+-- insert 
+insert into my_table(rowid, embedding) values (0, {your_embedding});
+-- search for 10 nearest neighbors using l2 squared distance
+select rowid from my_table order by vector_distance({query_vector}, embedding, 'l2') asc limit 10
+
+```
+
 ### Virtual Table
-The core of vectorlite is the [virtual table](https://www.sqlite.org/vtab.html) module, which is used to hold vector index.
+The core of vectorlite is the [virtual table](https://www.sqlite.org/vtab.html) module, which is used to hold vector index and way faster than brute force approach at the cost of not being 100% accurate.
 A vectorlite table can be created using:
 
 ```sql
@@ -102,6 +114,8 @@ select rowid, distance from my_vectorlite_table where knn_search(vector_name, kn
 ```
 
 ## Benchmark
+Please note only small datasets(with 3000 or 20000 vectors) are used because it would be unfair to benchmark against [sqlite-vec](https://github.com/asg017/sqlite-vec) using larger datasets. Sqlite-vec only uses brute-force, which doesn't scale with large datasets, while vectorlite uses ANN(approximate nearest neighbors), which scales to large datasets at the cost of not being 100% accurate.
+
 How the benchmark is done:
 1. Insert 3000/20000 randomly-generated vectors of dimension 128,512,1536 and 3000 into a vectorlite table with HNSW parameters ef_construction=100, M=30.
 2. Randomly generate 100 vectors and then query the table with them for 10 nearest neighbors with ef=10,50,100 to see how ef impacts recall rate.

doc/Makefile

@@ -0,0 +1,20 @@
+# Minimal makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line, and also
+# from the environment for the first two.
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+SOURCEDIR     = .
+BUILDDIR      = _build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+.PHONY: help Makefile
+
+# Catch-all target: route all unknown targets to Sphinx using the new
+# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
+%: Makefile
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

doc/conf.py

@@ -0,0 +1,28 @@
+# Configuration file for the Sphinx documentation builder.
+#
+# For the full list of built-in configuration values, see the documentation:
+# https://www.sphinx-doc.org/en/master/usage/configuration.html
+
+# -- Project information -----------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
+
+project = 'vectorlite'
+copyright = 'vectorlite contributors'
+author = '[email protected]'
+release = '0.2.0'
+
+
+# -- General configuration ---------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
+
+extensions = ['myst_parser']
+
+templates_path = ['_templates']
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+
+
+# -- Options for HTML output -------------------------------------------------
+# https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
+
+html_theme = 'sphinx_rtd_theme'
+html_static_path = ['_static']

doc/index.rst

@@ -0,0 +1,16 @@
+.. Example documentation master file, created by
+   sphinx-quickstart on Sat Sep 23 20:35:12 2023.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+Welcome to vectorlite's documentation!
+===================================
+
+.. toctree::
+   :maxdepth: 3
+   :caption: Contents:
+
+   markdown/overview.md
+   markdown/api.md
+   markdown/getting-started.md
+   markdown/news.md

doc/make.bat

@@ -0,0 +1,35 @@
+@ECHO OFF
+
+pushd %~dp0
+
+REM Command file for Sphinx documentation
+
+if "%SPHINXBUILD%" == "" (
+	set SPHINXBUILD=sphinx-build
+)
+set SOURCEDIR=.
+set BUILDDIR=_build
+
+%SPHINXBUILD% >NUL 2>NUL
+if errorlevel 9009 (
+	echo.
+	echo.The 'sphinx-build' command was not found. Make sure you have Sphinx
+	echo.installed, then set the SPHINXBUILD environment variable to point
+	echo.to the full path of the 'sphinx-build' executable. Alternatively you
+	echo.may add the Sphinx directory to PATH.
+	echo.
+	echo.If you don't have Sphinx installed, grab it from
+	echo.https://www.sphinx-doc.org/
+	exit /b 1
+)
+
+if "%1" == "" goto help
+
+%SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+goto end
+
+:help
+%SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+
+:end
+popd

doc/markdown/api.md

@@ -0,0 +1,62 @@
+# API reference
+Vectorlite provides the following APIs. 
+Please note vectorlite is currently in beta. There could be breaking changes.
+## Free-standing Application Defined SQL functions
+The following functions can be used in any context.
+``` sql
+vectorlite_info() -- prints version info and some compile time info. e.g. Is SSE, AVX enabled.
+vector_from_json(json_string) -- converts a json array of type TEXT into BLOB(a c-style float32 array)
+vector_to_json(vector_blob) -- converts a vector of type BLOB(c-style float32 array) into a json array of type TEXT
+vector_distance(vector_blob1, vector_blob2, distance_type_str) -- calculate vector distance between two vectors, distance_type_str could be 'l2', 'cosine', 'ip' 
+```
+
+In fact, one can easily implement brute force searching using `vector_distance`, which returns 100% accurate search results:
+```sql
+-- use a normal sqlite table
+create table my_table(rowid integer primary key, embedding blob);
+
+-- insert 
+insert into my_table(rowid, embedding) values (0, {your_embedding});
+-- search for 10 nearest neighbors using l2 squared distance
+select rowid from my_table order by vector_distance({query_vector}, embedding, 'l2') asc limit 10
+
+```
+## Virtual Table
+The core of vectorlite is the [virtual table](https://www.sqlite.org/vtab.html) module, which is used to hold vector index and way faster than brute force approach at the cost of not being 100% accurate.
+A vectorlite table can be created using:
+
+```sql
+-- Required fields: table_name, vector_name, dimension, max_elements
+-- Optional fields:
+-- 1. distance_type: defaults to l2
+-- 2. ef_construction: defaults to 200
+-- 3. M: defaults to 16
+-- 4. random_seed: defaults to 100
+-- 5. allow_replace_deleted: defaults to true
+-- 6. index_file_path: no default value. If not provided, the table will be memory-only. If provided, vectorlite will try to load index from the file and save to it when db connection is closed.
+create virtual table {table_name} using vectorlite({vector_name} float32[{dimension}] {distance_type}, hnsw(max_elements={max_elements}, {ef_construction=200}, {M=16}, {random_seed=100}, {allow_replace_deleted=true}), {index_file_path});
+```
+You can insert, update and delete a vectorlite table as if it's a normal sqlite table. 
+```sql
+-- rowid is required during insertion, because rowid is used to connect the vector to its metadata stored elsewhere. Auto-generating rowid doesn't makes sense.
+insert into my_vectorlite_table(rowid, vector_name) values ({your_rowid}, {vector_blob});
+-- Note: update and delete statements that uses rowid filter require sqlite3_version >= 3.38 to run.  
+update my_vectorlite_table set vector_name = {new_vector_blob} where rowid = {your_rowid};
+delete from my_vectorlite_table where rowid = {your_rowid};
+```
+The following functions should be only used when querying a vectorlite table
+```sql
+-- returns knn_parameter that will be passed to knn_search(). 
+-- vector_blob: vector to search
+-- k: how many nearest neighbors to search for
+-- ef: optional. A HNSW parameter that controls speed-accuracy trade-off. Defaults to 10 at first. If set to another value x, it will remain x if not specified again in another query within a single db connection.
+knn_param(vector_blob, k, ef)
+-- Should only be used in the `where clause` in a `select` statement to tell vectorlite to speed up the query using HNSW index
+-- vector_name should match the vectorlite table's definition
+-- knn_parameter is usually constructed using knn_param()
+knn_search(vector_name, knn_parameter)
+-- An example of vector search query. `distance` is an implicit column of a vectorlite table.
+select rowid, distance from my_vectorlite_table where knn_search(vector_name, knn_param({vector_blob}, {k}))
+-- An example of vector search query with pushed-down metadata(rowid) filter, requires sqlite_version >= 3.38 to run.
+select rowid, distance from my_vectorlite_table where knn_search(vector_name, knn_param({vector_blob}, {k})) and rowid in (1,2,3,4,5)
+```

doc/markdown/getting-started.md

@@ -0,0 +1,69 @@
+# Getting started
+The quickest way to get started is to install vectorlite using python.
+```shell
+# Note: vectorlite-py not vectorlite. vectorlite is another project.
+pip install vectorlite-py apsw numpy
+```
+Vectorlite's metadata filter feature requires sqlite>=3.38. Python's builtin `sqlite` module is usually built with old sqlite versions. So `apsw` is used here as sqlite driver, because it provides bindings to latest sqlite. Vectorlite still works with old sqlite versions if metadata filter support is not required.
+Below is a minimal example of using vectorlite. It can also be found in the [examples folder](https://github.com/1yefuwang1/vectorlite/tree/v0.2.0/examples).
+
+```python
+import vectorlite_py
+import apsw
+import numpy as np
+"""
+Quick start of using vectorlite extension.
+"""
+
+conn = apsw.Connection(':memory:')
+conn.enable_load_extension(True) # enable extension loading
+conn.load_extension(vectorlite_py.vectorlite_path()) # load vectorlite
+
+cursor = conn.cursor()
+# check if vectorlite is loaded
+print(cursor.execute('select vectorlite_info()').fetchall())
+
+# Vector distance calculation
+for distance_type in ['l2', 'cosine', 'ip']:
+    v1 = "[1, 2, 3]"
+    v2 = "[4, 5, 6]"
+    # Note vector_from_json can be used to convert a JSON string to a vector
+    distance = cursor.execute(f'select vector_distance(vector_from_json(?), vector_from_json(?), "{distance_type}")', (v1, v2)).fetchone()
+    print(f'{distance_type} distance between {v1} and {v2} is {distance[0]}')
+
+# generate some test data
+DIM = 32 # dimension of the vectors
+NUM_ELEMENTS = 10000 # number of vectors
+data = np.float32(np.random.random((NUM_ELEMENTS, DIM))) # Only float32 vectors are supported by vectorlite for now
+
+# Create a virtual table using vectorlite using l2 distance (default distance type) and default HNSW parameters
+cursor.execute(f'create virtual table my_table using vectorlite(my_embedding float32[{DIM}], hnsw(max_elements={NUM_ELEMENTS}))')
+# Vector distance type can be explicitly set to cosine using:
+# cursor.execute(f'create virtual table my_table using vectorlite(my_embedding float32[{DIM}] cosine, hnsw(max_elements={NUM_ELEMENTS}))')
+
+# Insert the test data into the virtual table. Note that the rowid MUST be explicitly set when inserting vectors and cannot be auto-generated.
+# The rowid is used to uniquely identify a vector and serve as a "foreign key" to relate to the vector's metadata.
+# Vectorlite takes vectors in raw bytes, so a numpy vector need to be converted to bytes before inserting into the table.
+cursor.executemany('insert into my_table(rowid, my_embedding) values (?, ?)', [(i, data[i].tobytes()) for i in range(NUM_ELEMENTS)])
+
+# Query the virtual table to get the vector at rowid 12345. Note the vector needs to be converted back to json using vector_to_json() to be human-readable. 
+result = cursor.execute('select vector_to_json(my_embedding) from my_table where rowid = 1234').fetchone()
+print(f'vector at rowid 1234: {result[0]}')
+
+# Find 10 approximate nearest neighbors of data[0] and there distances from data[0].
+# knn_search() is used to tell vectorlite to do a vector search.
+# knn_param(V, K, ef) is used to pass the query vector V, the number of nearest neighbors K to find and an optional ef parameter to tune the performance of the search.
+# If ef is not specified, ef defaults to 10. For more info on ef, please check https://github.com/nmslib/hnswlib/blob/v0.8.0/ALGO_PARAMS.md
+result = cursor.execute('select rowid, distance from my_table where knn_search(my_embedding, knn_param(?, 10))', [data[0].tobytes()]).fetchall()
+print(f'10 nearest neighbors of row 0 is {result}')
+
+# Find 10 approximate nearest neighbors of the first embedding in vectors with rowid within [1000, 2000) using metadata(rowid) filtering.
+rowids = ','.join([str(rowid) for rowid in range(1000, 2000)])
+result = cursor.execute(f'select rowid, distance from my_table where knn_search(my_embedding, knn_param(?, 10)) and rowid in ({rowids})', [data[0].tobytes()]).fetchall()
+print(f'10 nearest neighbors of row 0 in vectors with rowid within [1000, 2000) is {result}')
+
+conn.close()
+
+```
+
+More examples can be found in [examples](https://github.com/1yefuwang1/vectorlite/tree/v0.2.0/examples) folder.