from __future__ import annotations
import array
import functools
import hashlib
import json
import logging
import os
import uuid
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
Iterable,
List,
Optional,
Tuple,
Type,
TypeVar,
Union,
cast,
)
if TYPE_CHECKING:
from oracledb import Connection
import numpy as np
from langchain_core.documents import Document
from langchain_core.embeddings import Embeddings
from langchain_core.vectorstores import VectorStore
from langchain_community.vectorstores.utils import (
DistanceStrategy,
maximal_marginal_relevance,
)
logger = logging.getLogger(__name__)
log_level = os.getenv("LOG_LEVEL", "ERROR").upper()
logging.basicConfig(
level=getattr(logging, log_level),
format="%(asctime)s - %(levelname)s - %(message)s",
)
# Define a type variable that can be any kind of function
T = TypeVar("T", bound=Callable[..., Any])
def _handle_exceptions(func: T) -> T:
@functools.wraps(func)
def wrapper(*args: Any, **kwargs: Any) -> Any:
try:
return func(*args, **kwargs)
except RuntimeError as db_err:
# Handle a known type of error (e.g., DB-related) specifically
logger.exception("DB-related error occurred.")
raise RuntimeError(
"Failed due to a DB issue: {}".format(db_err)
) from db_err
except ValueError as val_err:
# Handle another known type of error specifically
logger.exception("Validation error.")
raise ValueError("Validation failed: {}".format(val_err)) from val_err
except Exception as e:
# Generic handler for all other exceptions
logger.exception("An unexpected error occurred: {}".format(e))
raise RuntimeError("Unexpected error: {}".format(e)) from e
return cast(T, wrapper)
def _table_exists(client: Connection, table_name: str) -> bool:
try:
import oracledb
except ImportError as e:
raise ImportError(
"Unable to import oracledb, please install with "
"`pip install -U oracledb`."
) from e
try:
with client.cursor() as cursor:
cursor.execute(f"SELECT COUNT(*) FROM {table_name}")
return True
except oracledb.DatabaseError as ex:
err_obj = ex.args
if err_obj[0].code == 942:
return False
raise
def _compare_version(version: str, target_version: str) -> bool:
# Split both version strings into parts
version_parts = [int(part) for part in version.split(".")]
target_parts = [int(part) for part in target_version.split(".")]
# Compare each part
for v, t in zip(version_parts, target_parts):
if v < t:
return True # Current version is less
elif v > t:
return False # Current version is greater
# If all parts equal so far, check if version has fewer parts than target_version
return len(version_parts) < len(target_parts)
@_handle_exceptions
def _index_exists(client: Connection, index_name: str) -> bool:
# Check if the index exists
query = """
SELECT index_name
FROM all_indexes
WHERE upper(index_name) = upper(:idx_name)
"""
with client.cursor() as cursor:
# Execute the query
cursor.execute(query, idx_name=index_name.upper())
result = cursor.fetchone()
# Check if the index exists
return result is not None
def _get_distance_function(distance_strategy: DistanceStrategy) -> str:
# Dictionary to map distance strategies to their corresponding function
# names
distance_strategy2function = {
DistanceStrategy.EUCLIDEAN_DISTANCE: "EUCLIDEAN",
DistanceStrategy.DOT_PRODUCT: "DOT",
DistanceStrategy.COSINE: "COSINE",
}
# Attempt to return the corresponding distance function
if distance_strategy in distance_strategy2function:
return distance_strategy2function[distance_strategy]
# If it's an unsupported distance strategy, raise an error
raise ValueError(f"Unsupported distance strategy: {distance_strategy}")
def _get_index_name(base_name: str) -> str:
unique_id = str(uuid.uuid4()).replace("-", "")
return f"{base_name}_{unique_id}"
@_handle_exceptions
def _create_table(client: Connection, table_name: str, embedding_dim: int) -> None:
cols_dict = {
"id": "RAW(16) DEFAULT SYS_GUID() PRIMARY KEY",
"text": "CLOB",
"metadata": "CLOB",
"embedding": f"vector({embedding_dim}, FLOAT32)",
}
if not _table_exists(client, table_name):
with client.cursor() as cursor:
ddl_body = ", ".join(
f"{col_name} {col_type}" for col_name, col_type in cols_dict.items()
)
ddl = f"CREATE TABLE {table_name} ({ddl_body})"
cursor.execute(ddl)
logger.info("Table created successfully...")
else:
logger.info("Table already exists...")
[docs]@_handle_exceptions
def create_index(
client: Connection,
vector_store: OracleVS,
params: Optional[dict[str, Any]] = None,
) -> None:
"""Create an index on the vector store.
Args:
client: The OracleDB connection object.
vector_store: The vector store object.
params: Optional parameters for the index creation.
Raises:
ValueError: If an invalid parameter is provided.
"""
if params:
if params["idx_type"] == "HNSW":
_create_hnsw_index(
client, vector_store.table_name, vector_store.distance_strategy, params
)
elif params["idx_type"] == "IVF":
_create_ivf_index(
client, vector_store.table_name, vector_store.distance_strategy, params
)
else:
_create_hnsw_index(
client, vector_store.table_name, vector_store.distance_strategy, params
)
else:
_create_hnsw_index(
client, vector_store.table_name, vector_store.distance_strategy, params
)
return
@_handle_exceptions
def _create_hnsw_index(
client: Connection,
table_name: str,
distance_strategy: DistanceStrategy,
params: Optional[dict[str, Any]] = None,
) -> None:
defaults = {
"idx_name": "HNSW",
"idx_type": "HNSW",
"neighbors": 32,
"efConstruction": 200,
"accuracy": 90,
"parallel": 8,
}
if params:
config = params.copy()
# Ensure compulsory parts are included
for compulsory_key in ["idx_name", "parallel"]:
if compulsory_key not in config:
if compulsory_key == "idx_name":
config[compulsory_key] = _get_index_name(
str(defaults[compulsory_key])
)
else:
config[compulsory_key] = defaults[compulsory_key]
# Validate keys in config against defaults
for key in config:
if key not in defaults:
raise ValueError(f"Invalid parameter: {key}")
else:
config = defaults
# Base SQL statement
idx_name = config["idx_name"]
base_sql = (
f"create vector index {idx_name} on {table_name}(embedding) "
f"ORGANIZATION INMEMORY NEIGHBOR GRAPH"
)
# Optional parts depending on parameters
accuracy_part = " WITH TARGET ACCURACY {accuracy}" if ("accuracy" in config) else ""
distance_part = f" DISTANCE {_get_distance_function(distance_strategy)}"
parameters_part = ""
if "neighbors" in config and "efConstruction" in config:
parameters_part = (
" parameters (type {idx_type}, neighbors {"
"neighbors}, efConstruction {efConstruction})"
)
elif "neighbors" in config and "efConstruction" not in config:
config["efConstruction"] = defaults["efConstruction"]
parameters_part = (
" parameters (type {idx_type}, neighbors {"
"neighbors}, efConstruction {efConstruction})"
)
elif "neighbors" not in config and "efConstruction" in config:
config["neighbors"] = defaults["neighbors"]
parameters_part = (
" parameters (type {idx_type}, neighbors {"
"neighbors}, efConstruction {efConstruction})"
)
# Always included part for parallel
parallel_part = " parallel {parallel}"
# Combine all parts
ddl_assembly = (
base_sql + accuracy_part + distance_part + parameters_part + parallel_part
)
# Format the SQL with values from the params dictionary
ddl = ddl_assembly.format(**config)
# Check if the index exists
if not _index_exists(client, config["idx_name"]):
with client.cursor() as cursor:
cursor.execute(ddl)
logger.info("Index created successfully...")
else:
logger.info("Index already exists...")
@_handle_exceptions
def _create_ivf_index(
client: Connection,
table_name: str,
distance_strategy: DistanceStrategy,
params: Optional[dict[str, Any]] = None,
) -> None:
# Default configuration
defaults = {
"idx_name": "IVF",
"idx_type": "IVF",
"neighbor_part": 32,
"accuracy": 90,
"parallel": 8,
}
if params:
config = params.copy()
# Ensure compulsory parts are included
for compulsory_key in ["idx_name", "parallel"]:
if compulsory_key not in config:
if compulsory_key == "idx_name":
config[compulsory_key] = _get_index_name(
str(defaults[compulsory_key])
)
else:
config[compulsory_key] = defaults[compulsory_key]
# Validate keys in config against defaults
for key in config:
if key not in defaults:
raise ValueError(f"Invalid parameter: {key}")
else:
config = defaults
# Base SQL statement
idx_name = config["idx_name"]
base_sql = (
f"CREATE VECTOR INDEX {idx_name} ON {table_name}(embedding) "
f"ORGANIZATION NEIGHBOR PARTITIONS"
)
# Optional parts depending on parameters
accuracy_part = " WITH TARGET ACCURACY {accuracy}" if ("accuracy" in config) else ""
distance_part = f" DISTANCE {_get_distance_function(distance_strategy)}"
parameters_part = ""
if "idx_type" in config and "neighbor_part" in config:
parameters_part = (
f" PARAMETERS (type {config['idx_type']}, neighbor"
f" partitions {config['neighbor_part']})"
)
# Always included part for parallel
parallel_part = f" PARALLEL {config['parallel']}"
# Combine all parts
ddl_assembly = (
base_sql + accuracy_part + distance_part + parameters_part + parallel_part
)
# Format the SQL with values from the params dictionary
ddl = ddl_assembly.format(**config)
# Check if the index exists
if not _index_exists(client, config["idx_name"]):
with client.cursor() as cursor:
cursor.execute(ddl)
logger.info("Index created successfully...")
else:
logger.info("Index already exists...")
[docs]@_handle_exceptions
def drop_table_purge(client: Connection, table_name: str) -> None:
"""Drop a table and purge it from the database.
Args:
client: The OracleDB connection object.
table_name: The name of the table to drop.
Raises:
RuntimeError: If an error occurs while dropping the table.
"""
if _table_exists(client, table_name):
cursor = client.cursor()
with cursor:
ddl = f"DROP TABLE {table_name} PURGE"
cursor.execute(ddl)
logger.info("Table dropped successfully...")
else:
logger.info("Table not found...")
return
[docs]@_handle_exceptions
def drop_index_if_exists(client: Connection, index_name: str) -> None:
"""Drop an index if it exists.
Args:
client: The OracleDB connection object.
index_name: The name of the index to drop.
Raises:
RuntimeError: If an error occurs while dropping the index.
"""
if _index_exists(client, index_name):
drop_query = f"DROP INDEX {index_name}"
with client.cursor() as cursor:
cursor.execute(drop_query)
logger.info(f"Index {index_name} has been dropped.")
else:
logger.exception(f"Index {index_name} does not exist.")
return
[docs]class OracleVS(VectorStore):
"""`OracleVS` vector store.
To use, you should have both:
- the ``oracledb`` python package installed
- a connection string associated with a OracleDBCluster having deployed an
Search index
Example:
.. code-block:: python
from langchain.vectorstores import OracleVS
from langchain.embeddings.openai import OpenAIEmbeddings
import oracledb
with oracledb.connect(user = user, passwd = pwd, dsn = dsn) as
connection:
print ("Database version:", connection.version)
embeddings = OpenAIEmbeddings()
query = ""
vectors = OracleVS(connection, table_name, embeddings, query)
"""
[docs] def __init__(
self,
client: Connection,
embedding_function: Union[
Callable[[str], List[float]],
Embeddings,
],
table_name: str,
distance_strategy: DistanceStrategy = DistanceStrategy.EUCLIDEAN_DISTANCE,
query: Optional[str] = "What is a Oracle database",
params: Optional[Dict[str, Any]] = None,
):
try:
import oracledb
except ImportError as e:
raise ImportError(
"Unable to import oracledb, please install with "
"`pip install -U oracledb`."
) from e
self.insert_mode = "array"
if client.thin is True:
if oracledb.__version__ == "2.1.0":
raise Exception(
"Oracle DB python thin client driver version 2.1.0 not supported"
)
elif _compare_version(oracledb.__version__, "2.2.0"):
self.insert_mode = "clob"
else:
self.insert_mode = "array"
else:
if (_compare_version(oracledb.__version__, "2.1.0")) and (
not (
_compare_version(
".".join(map(str, oracledb.clientversion())), "23.4"
)
)
):
raise Exception(
"Oracle DB python thick client driver version earlier than "
"2.1.0 not supported with client libraries greater than "
"equal to 23.4"
)
if _compare_version(".".join(map(str, oracledb.clientversion())), "23.4"):
self.insert_mode = "clob"
else:
self.insert_mode = "array"
if _compare_version(oracledb.__version__, "2.1.0"):
self.insert_mode = "clob"
try:
"""Initialize with oracledb client."""
self.client = client
"""Initialize with necessary components."""
if not isinstance(embedding_function, Embeddings):
logger.warning(
"`embedding_function` is expected to be an Embeddings "
"object, support "
"for passing in a function will soon be removed."
)
self.embedding_function = embedding_function
self.query = query
embedding_dim = self.get_embedding_dimension()
self.table_name = table_name
self.distance_strategy = distance_strategy
self.params = params
_create_table(client, table_name, embedding_dim)
except oracledb.DatabaseError as db_err:
logger.exception(f"Database error occurred while create table: {db_err}")
raise RuntimeError(
"Failed to create table due to a database error."
) from db_err
except ValueError as val_err:
logger.exception(f"Validation error: {val_err}")
raise RuntimeError(
"Failed to create table due to a validation error."
) from val_err
except Exception as ex:
logger.exception("An unexpected error occurred while creating the index.")
raise RuntimeError(
"Failed to create table due to an unexpected error."
) from ex
@property
def embeddings(self) -> Optional[Embeddings]:
"""
A property that returns an Embeddings instance embedding_function
is an instance of Embeddings, otherwise returns None.
Returns:
Optional[Embeddings]: The embedding function if it's an instance of
Embeddings, otherwise None.
"""
return (
self.embedding_function
if isinstance(self.embedding_function, Embeddings)
else None
)
[docs] def get_embedding_dimension(self) -> int:
# Embed the single document by wrapping it in a list
embedded_document = self._embed_documents(
[self.query if self.query is not None else ""]
)
# Get the first (and only) embedding's dimension
return len(embedded_document[0])
def _embed_documents(self, texts: List[str]) -> List[List[float]]:
if isinstance(self.embedding_function, Embeddings):
return self.embedding_function.embed_documents(texts)
elif callable(self.embedding_function):
return [self.embedding_function(text) for text in texts]
else:
raise TypeError(
"The embedding_function is neither Embeddings nor callable."
)
def _embed_query(self, text: str) -> List[float]:
if isinstance(self.embedding_function, Embeddings):
return self.embedding_function.embed_query(text)
else:
return self.embedding_function(text)
[docs] @_handle_exceptions
def add_texts(
self,
texts: Iterable[str],
metadatas: Optional[List[Dict[Any, Any]]] = None,
ids: Optional[List[str]] = None,
**kwargs: Any,
) -> List[str]:
"""Add more texts to the vectorstore index.
Args:
texts: Iterable of strings to add to the vectorstore.
metadatas: Optional list of metadatas associated with the texts.
ids: Optional list of ids for the texts that are being added to
the vector store.
kwargs: vectorstore specific parameters
"""
texts = list(texts)
if ids:
# If ids are provided, hash them to maintain consistency
processed_ids = [
hashlib.sha256(_id.encode()).hexdigest()[:16].upper() for _id in ids
]
elif metadatas and all("id" in metadata for metadata in metadatas):
# If no ids are provided but metadatas with ids are, generate
# ids from metadatas
processed_ids = [
hashlib.sha256(metadata["id"].encode()).hexdigest()[:16].upper()
for metadata in metadatas
]
else:
# Generate new ids if none are provided
generated_ids = [
str(uuid.uuid4()) for _ in texts
] # uuid4 is more standard for random UUIDs
processed_ids = [
hashlib.sha256(_id.encode()).hexdigest()[:16].upper()
for _id in generated_ids
]
embeddings = self._embed_documents(texts)
if not metadatas:
metadatas = [{} for _ in texts]
docs: List[Tuple[Any, Any, Any, Any]]
if self.insert_mode == "clob":
docs = [
(id_, json.dumps(embedding), json.dumps(metadata), text)
for id_, embedding, metadata, text in zip(
processed_ids, embeddings, metadatas, texts
)
]
else:
docs = [
(id_, array.array("f", embedding), json.dumps(metadata), text)
for id_, embedding, metadata, text in zip(
processed_ids, embeddings, metadatas, texts
)
]
with self.client.cursor() as cursor:
cursor.executemany(
f"INSERT INTO {self.table_name} (id, embedding, metadata, "
f"text) VALUES (:1, :2, :3, :4)",
docs,
)
self.client.commit()
return processed_ids
[docs] def similarity_search(
self,
query: str,
k: int = 4,
filter: Optional[Dict[str, Any]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs most similar to query."""
if isinstance(self.embedding_function, Embeddings):
embedding = self.embedding_function.embed_query(query)
documents = self.similarity_search_by_vector(
embedding=embedding, k=k, filter=filter, **kwargs
)
return documents
[docs] def similarity_search_by_vector(
self,
embedding: List[float],
k: int = 4,
filter: Optional[dict[str, Any]] = None,
**kwargs: Any,
) -> List[Document]:
docs_and_scores = self.similarity_search_by_vector_with_relevance_scores(
embedding=embedding, k=k, filter=filter, **kwargs
)
return [doc for doc, _ in docs_and_scores]
[docs] def similarity_search_with_score(
self,
query: str,
k: int = 4,
filter: Optional[dict[str, Any]] = None,
**kwargs: Any,
) -> List[Tuple[Document, float]]:
"""Return docs most similar to query."""
if isinstance(self.embedding_function, Embeddings):
embedding = self.embedding_function.embed_query(query)
docs_and_scores = self.similarity_search_by_vector_with_relevance_scores(
embedding=embedding, k=k, filter=filter, **kwargs
)
return docs_and_scores
@_handle_exceptions
def _get_clob_value(self, result: Any) -> str:
try:
import oracledb
except ImportError as e:
raise ImportError(
"Unable to import oracledb, please install with "
"`pip install -U oracledb`."
) from e
clob_value = ""
if result:
if isinstance(result, oracledb.LOB):
raw_data = result.read()
if isinstance(raw_data, bytes):
clob_value = raw_data.decode(
"utf-8"
) # Specify the correct encoding
else:
clob_value = raw_data
elif isinstance(result, str):
clob_value = result
else:
raise Exception("Unexpected type:", type(result))
return clob_value
[docs] @_handle_exceptions
def similarity_search_by_vector_with_relevance_scores(
self,
embedding: List[float],
k: int = 4,
filter: Optional[dict[str, Any]] = None,
**kwargs: Any,
) -> List[Tuple[Document, float]]:
docs_and_scores = []
embedding_arr: Any
if self.insert_mode == "clob":
embedding_arr = json.dumps(embedding)
else:
embedding_arr = array.array("f", embedding)
query = f"""
SELECT id,
text,
metadata,
vector_distance(embedding, :embedding,
{_get_distance_function(self.distance_strategy)}) as distance
FROM {self.table_name}
ORDER BY distance
FETCH APPROX FIRST {k} ROWS ONLY
"""
# Execute the query
with self.client.cursor() as cursor:
cursor.execute(query, embedding=embedding_arr)
results = cursor.fetchall()
# Filter results if filter is provided
for result in results:
metadata = json.loads(
self._get_clob_value(result[2]) if result[2] is not None else "{}"
)
# Apply filtering based on the 'filter' dictionary
if filter:
if all(metadata.get(key) in value for key, value in filter.items()):
doc = Document(
page_content=(
self._get_clob_value(result[1])
if result[1] is not None
else ""
),
metadata=metadata,
)
distance = result[3]
docs_and_scores.append((doc, distance))
else:
doc = Document(
page_content=(
self._get_clob_value(result[1])
if result[1] is not None
else ""
),
metadata=metadata,
)
distance = result[3]
docs_and_scores.append((doc, distance))
return docs_and_scores
[docs] @_handle_exceptions
def similarity_search_by_vector_returning_embeddings(
self,
embedding: List[float],
k: int,
filter: Optional[Dict[str, Any]] = None,
**kwargs: Any,
) -> List[Tuple[Document, float, np.ndarray[np.float32, Any]]]:
embedding_arr: Any
if self.insert_mode == "clob":
embedding_arr = json.dumps(embedding)
else:
embedding_arr = array.array("f", embedding)
documents = []
query = f"""
SELECT id,
text,
metadata,
vector_distance(embedding, :embedding, {_get_distance_function(
self.distance_strategy)}) as distance,
embedding
FROM {self.table_name}
ORDER BY distance
FETCH APPROX FIRST {k} ROWS ONLY
"""
# Execute the query
with self.client.cursor() as cursor:
cursor.execute(query, embedding=embedding_arr)
results = cursor.fetchall()
for result in results:
page_content_str = self._get_clob_value(result[1])
metadata_str = self._get_clob_value(result[2])
metadata = json.loads(metadata_str)
# Apply filter if provided and matches; otherwise, add all
# documents
if not filter or all(
metadata.get(key) in value for key, value in filter.items()
):
document = Document(
page_content=page_content_str, metadata=metadata
)
distance = result[3]
# Assuming result[4] is already in the correct format;
# adjust if necessary
current_embedding = (
np.array(result[4], dtype=np.float32)
if result[4]
else np.empty(0, dtype=np.float32)
)
documents.append((document, distance, current_embedding))
return documents # type: ignore
[docs] @_handle_exceptions
def max_marginal_relevance_search_with_score_by_vector(
self,
embedding: List[float],
*,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, Any]] = None,
) -> List[Tuple[Document, float]]:
"""Return docs and their similarity scores selected using the
maximal marginal
relevance.
Maximal marginal relevance optimizes for similarity to query AND
diversity
among selected documents.
Args:
self: An instance of the class
embedding: Embedding to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
fetch_k: Number of Documents to fetch before filtering to
pass to MMR algorithm.
filter: (Optional[Dict[str, str]]): Filter by metadata. Defaults
to None.
lambda_mult: Number between 0 and 1 that determines the degree
of diversity among the results with 0 corresponding
to maximum diversity and 1 to minimum diversity.
Defaults to 0.5.
Returns:
List of Documents and similarity scores selected by maximal
marginal
relevance and score for each.
"""
# Fetch documents and their scores
docs_scores_embeddings = self.similarity_search_by_vector_returning_embeddings(
embedding, fetch_k, filter=filter
)
# Assuming documents_with_scores is a list of tuples (Document, score)
# If you need to split documents and scores for processing (e.g.,
# for MMR calculation)
documents, scores, embeddings = (
zip(*docs_scores_embeddings) if docs_scores_embeddings else ([], [], [])
)
# Assume maximal_marginal_relevance method accepts embeddings and
# scores, and returns indices of selected docs
mmr_selected_indices = maximal_marginal_relevance(
np.array(embedding, dtype=np.float32),
list(embeddings),
k=k,
lambda_mult=lambda_mult,
)
# Filter documents based on MMR-selected indices and map scores
mmr_selected_documents_with_scores = [
(documents[i], scores[i]) for i in mmr_selected_indices
]
return mmr_selected_documents_with_scores
[docs] @_handle_exceptions
def max_marginal_relevance_search_by_vector(
self,
embedding: List[float],
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, Any]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs selected using the maximal marginal relevance.
Maximal marginal relevance optimizes for similarity to query AND
diversity
among selected documents.
Args:
self: An instance of the class
embedding: Embedding to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
fetch_k: Number of Documents to fetch to pass to MMR algorithm.
lambda_mult: Number between 0 and 1 that determines the degree
of diversity among the results with 0 corresponding
to maximum diversity and 1 to minimum diversity.
Defaults to 0.5.
filter: Optional[Dict[str, Any]]
**kwargs: Any
Returns:
List of Documents selected by maximal marginal relevance.
"""
docs_and_scores = self.max_marginal_relevance_search_with_score_by_vector(
embedding, k=k, fetch_k=fetch_k, lambda_mult=lambda_mult, filter=filter
)
return [doc for doc, _ in docs_and_scores]
[docs] @_handle_exceptions
def max_marginal_relevance_search(
self,
query: str,
k: int = 4,
fetch_k: int = 20,
lambda_mult: float = 0.5,
filter: Optional[Dict[str, Any]] = None,
**kwargs: Any,
) -> List[Document]:
"""Return docs selected using the maximal marginal relevance.
Maximal marginal relevance optimizes for similarity to query AND
diversity
among selected documents.
Args:
self: An instance of the class
query: Text to look up documents similar to.
k: Number of Documents to return. Defaults to 4.
fetch_k: Number of Documents to fetch to pass to MMR algorithm.
lambda_mult: Number between 0 and 1 that determines the degree
of diversity among the results with 0 corresponding
to maximum diversity and 1 to minimum diversity.
Defaults to 0.5.
filter: Optional[Dict[str, Any]]
**kwargs
Returns:
List of Documents selected by maximal marginal relevance.
`max_marginal_relevance_search` requires that `query` returns matched
embeddings alongside the match documents.
"""
embedding = self._embed_query(query)
documents = self.max_marginal_relevance_search_by_vector(
embedding,
k=k,
fetch_k=fetch_k,
lambda_mult=lambda_mult,
filter=filter,
**kwargs,
)
return documents
[docs] @_handle_exceptions
def delete(self, ids: Optional[List[str]] = None, **kwargs: Any) -> None:
"""Delete by vector IDs.
Args:
self: An instance of the class
ids: List of ids to delete.
**kwargs
"""
if ids is None:
raise ValueError("No ids provided to delete.")
# Compute SHA-256 hashes of the ids and truncate them
hashed_ids = [
hashlib.sha256(_id.encode()).hexdigest()[:16].upper() for _id in ids
]
# Constructing the SQL statement with individual placeholders
placeholders = ", ".join([":id" + str(i + 1) for i in range(len(hashed_ids))])
ddl = f"DELETE FROM {self.table_name} WHERE id IN ({placeholders})"
# Preparing bind variables
bind_vars = {
f"id{i}": hashed_id for i, hashed_id in enumerate(hashed_ids, start=1)
}
with self.client.cursor() as cursor:
cursor.execute(ddl, bind_vars)
self.client.commit()
[docs] @classmethod
@_handle_exceptions
def from_texts(
cls: Type[OracleVS],
texts: Iterable[str],
embedding: Embeddings,
metadatas: Optional[List[dict]] = None,
**kwargs: Any,
) -> OracleVS:
"""Return VectorStore initialized from texts and embeddings."""
client = kwargs.get("client")
if client is None:
raise ValueError("client parameter is required...")
params = kwargs.get("params", {})
table_name = str(kwargs.get("table_name", "langchain"))
distance_strategy = cast(
DistanceStrategy, kwargs.get("distance_strategy", None)
)
if not isinstance(distance_strategy, DistanceStrategy):
raise TypeError(
f"Expected DistanceStrategy got " f"{type(distance_strategy).__name__} "
)
query = kwargs.get("query", "What is a Oracle database")
drop_table_purge(client, table_name)
vss = cls(
client=client,
embedding_function=embedding,
table_name=table_name,
distance_strategy=distance_strategy,
query=query,
params=params,
)
vss.add_texts(texts=list(texts), metadatas=metadatas)
return vss
