docarray · hanxiao · Feb 2, 2022 · Jan 16, 2022 · Jan 17, 2022 · Jan 18, 2022
diff --git a/docarray/array/document.py b/docarray/array/document.py
@@ -41,6 +41,10 @@ def __new__(cls, *args, storage: str = 'memory', **kwargs) -> 'DocumentArrayLike
                 from .sqlite import DocumentArraySqlite
 
                 instance = super().__new__(DocumentArraySqlite)
+            elif storage == 'pqlite':
+                from .pqlite import DocumentArrayPqlite
+
+                instance = super().__new__(DocumentArrayPqlite)
             elif storage == 'weaviate':
                 from .weaviate import DocumentArrayWeaviate
 

diff --git a/docarray/array/pqlite.py b/docarray/array/pqlite.py
@@ -0,0 +1,7 @@
+from .document import DocumentArray
+from .storage.pqlite import StorageMixins
+
+
+class DocumentArrayPqlite(StorageMixins, DocumentArray):
+    def __new__(cls, *args, **kwargs):
+        return super().__new__(cls)
diff --git a/docarray/array/storage/pqlite/__init__.py b/docarray/array/storage/pqlite/__init__.py
@@ -0,0 +1,10 @@
+from .backend import BackendMixin
+from .getsetdel import GetSetDelMixin
+from .seqlike import SequenceLikeMixin
+from abc import ABC
+
+__all__ = ['StorageMixins']
+
+
+class StorageMixins(BackendMixin, GetSetDelMixin, SequenceLikeMixin, ABC):
+    ...
diff --git a/docarray/array/storage/pqlite/backend.py b/docarray/array/storage/pqlite/backend.py
@@ -0,0 +1,63 @@
+from dataclasses import dataclass, asdict
+from typing import (
+    Union,
+    Dict,
+    Optional,
+    TYPE_CHECKING,
+)
+
+from ..base.backend import BaseBackendMixin
+from ....helper import dataclass_from_dict
+
+if TYPE_CHECKING:
+    from ....types import (
+        DocumentArraySourceType,
+    )
+
+
+@dataclass
+class PqliteConfig:
+    n_dim: int = 1
+    metric: str = 'cosine'
+    serialize_protocol: str = 'pickle'
+    data_path: Optional[str] = None
+
+
+class BackendMixin(BaseBackendMixin):
+    """Provide necessary functions to enable this storage backend. """
+
+    def _init_storage(
+        self,
+        docs: Optional['DocumentArraySourceType'] = None,
+        config: Optional[Union[PqliteConfig, Dict]] = None,
+    ):
+        if not config:
+            config = PqliteConfig()
+        if isinstance(config, dict):
+            config = dataclass_from_dict(PqliteConfig, config)
+
+        self._persist = bool(config.data_path)
+
+        if not self._persist:
+            from tempfile import TemporaryDirectory
+
+            config.data_path = TemporaryDirectory().name
+
+        self._config = config
+
+        from pqlite import PQLite
+        from .helper import OffsetMapping
+
+        config = asdict(config)
+        n_dim = config.pop('n_dim')
+
+        self._pqlite = PQLite(n_dim, **config)
+        self._offset2ids = OffsetMapping(
+            name='docarray',
+            data_path=config['data_path'],
+            in_memory=False,
+        )
+
+        if docs is not None:
+            self.clear()
+            self.extend(docs)
diff --git a/docarray/array/storage/pqlite/getsetdel.py b/docarray/array/storage/pqlite/getsetdel.py
@@ -0,0 +1,88 @@
+from typing import (
+    Sequence,
+    Iterable,
+)
+import numpy as np
+from ...memory import DocumentArrayInMemory
+from ..base.getsetdel import BaseGetSetDelMixin
+from .... import Document
+
+
+class GetSetDelMixin(BaseGetSetDelMixin):
+    """Implement required and derived functions that power `getitem`, `setitem`, `delitem`"""
+
+    # essential methods start
+
+    def _get_doc_by_offset(self, offset: int) -> 'Document':
+        offset = len(self) + offset if offset < 0 else offset
+        doc_id = self._offset2ids.get_id_by_offset(offset)
+        doc = self._pqlite.get_doc_by_id(doc_id) if doc_id else None
+        if doc is None:
+            raise IndexError('index out of range')
+        return doc
+
+    def _get_doc_by_id(self, _id: str) -> 'Document':
+        doc = self._pqlite.get_doc_by_id(_id)
+        if doc is None:
+            raise KeyError(f'Can not find Document with id=`{_id}`')
+        return doc
+
+    def _get_docs_by_offsets(self, offsets: Sequence[int]) -> Iterable['Document']:
+        ids = self._offset2ids.get_ids_by_offsets(offsets)
+        return self._get_docs_by_ids(ids)
+
+    def _get_docs_by_ids(self, ids: str) -> Iterable['Document']:
+        for _id in ids:
+            yield self._get_doc_by_id(_id)
+
+    def _get_docs_by_slice(self, _slice: slice) -> Iterable['Document']:
+        return self._get_docs_by_offsets(range(len(self))[_slice])
+
+    def _get_docs_by_mask(self, mask: Sequence[bool]):
+        offsets = [i for i, m in enumerate(mask) if m is True]
+        return self._get_docs_by_offsets(offsets)
+
+    def _set_doc_by_offset(self, offset: int, value: 'Document'):
+        offset = len(self) + offset if offset < 0 else offset
+        self._offset2ids.set_at_offset(offset, value.id)
+        docs = DocumentArrayInMemory([value])
+        if docs.embeddings is None:
+            docs.embeddings = np.zeros((1, self._pqlite.dim))
+        self._pqlite.update(docs)
+
+    def _set_doc_by_id(self, _id: str, value: 'Document'):
+        offset = self._offset2ids.get_offset_by_id(_id)
+        self._set_doc_by_offset(offset, value)
+
+    def _set_doc_value_pairs(
+        self, docs: Iterable['Document'], values: Iterable['Document']
+    ):
+        for _d, _v in zip(docs, values):
+            self._set_doc_by_id(_d.id, _v)
+
+    def _del_doc_by_id(self, _id: str):
+        offset = self._offset2ids.get_offset_by_id(_id)
+        self._offset2ids.del_at_offset(offset, commit=True)
+        self._pqlite.delete([_id])
+
+    def _del_doc_by_offset(self, offset: int):
+        offset = len(self) + offset if offset < 0 else offset
+        _id = self._offset2ids.get_id_by_offset(offset)
+        self._offset2ids.del_at_offset(offset)
+        self._pqlite.delete([_id])
+
+    def _del_doc_by_offsets(self, offsets: Sequence[int]):
+        ids = []
+        for offset in offsets:
+            ids.append(self._offset2ids.get_id_by_offset(offset))
+
+        self._offset2ids.del_at_offsets(offsets)
+        self._pqlite.delete(ids)
+
+    def _del_docs_by_slice(self, _slice: slice):
+        offsets = range(len(self))[_slice]
+        self._del_doc_by_offsets(offsets)
+
+    def _del_docs_by_mask(self, mask: Sequence[bool]):
+        offsets = [i for i, m in enumerate(mask) if m is True]
+        self._del_doc_by_offsets(offsets)
diff --git a/docarray/array/storage/pqlite/helper.py b/docarray/array/storage/pqlite/helper.py
@@ -0,0 +1,115 @@
+from typing import Optional, List, Tuple
+
+from pqlite.storage.table import Table
+
+
+class OffsetMapping(Table):
+    def __init__(
+        self,
+        name: str = 'offset2ids',
+        data_path: Optional[str] = None,
+        in_memory: bool = True,
+    ):
+        super().__init__(name, data_path, in_memory)
+        self.create_table()
+        self._size = None
+
+    def create_table(self):
+        sql = f'''CREATE TABLE IF NOT EXISTS {self.name}
+                            (offset INTEGER NOT NULL PRIMARY KEY,
+                             doc_id INTEGER TEXT NOT NULL)'''
+
+        self.execute(sql, commit=True)
+
+    def clear(self):
+        super().clear()
+        self._size = None
+
+    def __len__(self):
+        return self.size
+
+    @property
+    def size(self):
+        if self._size is None:
+            sql = f'SELECT MAX(offset) from {self.name} LIMIT 1;'
+            result = self._conn.execute(sql).fetchone()
+            self._size = result[0] + 1 if result[0] else 0
+
+        return self._size
+
+    def extend_doc_ids(self, doc_ids: List[str], commit: bool = True):
+        offsets = [self.size + i for i in range(len(doc_ids))]
+        offset_ids = list(zip(offsets, doc_ids))
+        self._insert(offset_ids, commit=commit)
+
+    def _insert(self, offset_ids: List[Tuple[int, str]], commit: bool = True):
+        sql = f'INSERT INTO {self.name}(offset, doc_id) VALUES (?, ?);'
+        self.execute_many(sql, offset_ids, commit=commit)
+        self._size = self.size + len(offset_ids)
+
+    def get_id_by_offset(self, offset: int):
+        offset = len(self) + offset if offset < 0 else offset
+        sql = f'SELECT doc_id FROM {self.name} WHERE offset = ? LIMIT 1;'
+        result = self._conn.execute(sql, (offset,)).fetchone()
+        return str(result[0]) if result is not None else None
+
+    def get_ids_by_offsets(self, offsets: List[int]) -> List[str]:
+        return [self.get_id_by_offset(offset) for offset in offsets]
+
+    def get_offsets_by_ids(self, ids: List[str]) -> List[int]:
+        return [self.get_offset_by_id(k) for k in ids]
+
+    def get_offset_by_id(self, doc_id: str):
+        sql = f'SELECT offset FROM {self.name} WHERE doc_id=? LIMIT 1;'
+        result = self._conn.execute(sql, (doc_id,)).fetchone()
+        return result[0] if result else None
+
+    def del_at_offset(self, offset: int, commit: bool = True):
+        offset = len(self) + offset if offset < 0 else offset
+        sql = f'DELETE FROM {self.name} WHERE offset=?'
+        self._conn.execute(sql, (offset,))
+        self.shift_offset(offset, shift_step=1, direction='left', commit=commit)
+
+        self._size -= 1
+
+    def del_at_offsets(self, offsets: List[int], commit: bool = True):
+        for offset in sorted(offsets, reverse=True):
+            self.del_at_offset(offset, commit=False)
+        if commit:
+            self.commit()
+
+    def insert_at_offset(self, offset: int, doc_id: str, commit: bool = True):
+        offset = len(self) + offset if offset < 0 else offset
+        self.shift_offset(offset - 1, shift_step=1, direction='right', commit=False)
+        self._insert([(offset, doc_id)], commit=commit)
+
+    def set_at_offset(self, offset: int, doc_id: str, commit: bool = True):
+        offset = len(self) + offset if offset < 0 else offset
+        sql = f'UPDATE {self.name} SET doc_id=? WHERE offset = ?'
+        self._conn.execute(
+            sql,
+            (
+                doc_id,
+                offset,
+            ),
+        )
+        if commit:
+            self.commit()
+
+    def shift_offset(
+        self,
+        shift_from: int,
+        shift_step: int = 1,
+        direction: str = 'left',
+        commit: bool = True,
+    ):
+        if direction == 'left':
+            sql = f'UPDATE {self.name} SET offset=offset-{shift_step} WHERE offset > ?'
+        elif direction == 'right':
+            sql = f'UPDATE {self.name} SET offset=offset+{shift_step} WHERE offset > ?'
+        else:
+            raise ValueError(f'The shit_offset directory {direction} is not supported!')
+
+        self._conn.execute(sql, (shift_from,))
+        if commit:
+            self._conn.commit()
diff --git a/docarray/array/storage/pqlite/seqlike.py b/docarray/array/storage/pqlite/seqlike.py
@@ -0,0 +1,80 @@
+from typing import Iterator, Union, Iterable, Sequence, MutableSequence
+import numpy as np
+from .... import Document
+from ...memory import DocumentArrayInMemory
+
+
+class SequenceLikeMixin(MutableSequence[Document]):
+    """Implement sequence-like methods"""
+
+    def insert(self, index: int, value: 'Document'):
+        """Insert `doc` at `index`.
+
+        :param index: Position of the insertion.
+        :param value: The doc needs to be inserted.
+        """
+        if value.embedding is None:
+            value.embedding = np.zeros(self._pqlite.dim, dtype=np.float32)
+
+        self._pqlite.index(DocumentArrayInMemory([value]))
+        self._offset2ids.insert_at_offset(index, value.id)
+
+    def append(self, value: 'Document') -> None:
+        self._pqlite.index(DocumentArrayInMemory([value]))
+        self._offset2ids.extend_doc_ids([value.id])
+
+    def extend(self, values: Iterable['Document']) -> None:
+        docs = DocumentArrayInMemory(values)
+        for doc in docs:
+            if doc.embedding is None:
+                doc.embedding = np.zeros(self._pqlite.dim, dtype=np.float32)
+        self._pqlite.index(docs)
+        self._offset2ids.extend_doc_ids([doc.id for doc in docs])
+
+    def clear(self):
+        """Clear the data of :class:`DocumentArray`"""
+        self._offset2ids.clear()
+        self._pqlite.clear()
+
+    def __del__(self) -> None:
+        if not self._persist:
+            self._offset2ids.clear()
+            self._pqlite.clear()
+
+    def __eq__(self, other):
+        """In pqlite backend, data are considered as identical if configs point to the same database source"""
+        return (
+            type(self) is type(other)
+            and type(self._config) is type(other._config)
+            and self._config == other._config
+        )
+
+    def __len__(self):
+        return self._offset2ids.size
+
+    def __iter__(self) -> Iterator['Document']:
+        for i in range(len(self)):
+            yield self[i]
+
+    def __contains__(self, x: Union[str, 'Document']):
+        if isinstance(x, str):
+            return self._offset2ids.get_offset_by_id(x) is not None
+        elif isinstance(x, Document):
+            return self._offset2ids.get_offset_by_id(x.id) is not None
+        else:
+            return False
+
+    def __bool__(self):
+        """To simulate ```l = []; if l: ...```
+
+        :return: returns true if the length of the array is larger than 0
+        """
+        return len(self) > 0
+
+    def __repr__(self):
+        return f'<DocumentArray[PQLite] (length={len(self)}) at {id(self)}>'
+
+    def __add__(self, other: Union['Document', Sequence['Document']]):
+        v = type(self)(self)
+        v.extend(other)
+        return v
diff --git a/setup.py b/setup.py
@@ -54,6 +54,7 @@
             'fastapi',
             'uvicorn',
             'weaviate-client~=3.3.0',
+            'pqlite>=0.2.1',
         ],
         'test': [
             'pytest',