"""Vector SQL Database Chain Retriever"""
from __future__ import annotations
from typing import Any, Dict, List, Optional, Sequence, Union
from langchain.chains.llm import LLMChain
from langchain.chains.sql_database.prompt import PROMPT, SQL_PROMPTS
from langchain_community.tools.sql_database.prompt import QUERY_CHECKER
from langchain_community.utilities.sql_database import SQLDatabase
from langchain_core.callbacks.manager import CallbackManagerForChainRun
from langchain_core.embeddings import Embeddings
from langchain_core.language_models import BaseLanguageModel
from langchain_core.output_parsers import BaseOutputParser
from langchain_core.prompts import BasePromptTemplate
from langchain_core.prompts.prompt import PromptTemplate
from langchain_experimental.sql.base import INTERMEDIATE_STEPS_KEY, SQLDatabaseChain
[docs]class VectorSQLOutputParser(BaseOutputParser[str]):
"""Output Parser for Vector SQL.
1. finds for `NeuralArray()` and replace it with the embedding
2. finds for `DISTANCE()` and replace it with the distance name in backend SQL
"""
model: Embeddings
"""Embedding model to extract embedding for entity"""
distance_func_name: str = "distance"
"""Distance name for Vector SQL"""
class Config:
arbitrary_types_allowed = 1
@property
def _type(self) -> str:
return "vector_sql_parser"
[docs] @classmethod
def from_embeddings(
cls, model: Embeddings, distance_func_name: str = "distance", **kwargs: Any
) -> VectorSQLOutputParser:
return cls(model=model, distance_func_name=distance_func_name, **kwargs)
[docs] def parse(self, text: str) -> str:
text = text.strip()
start = text.find("NeuralArray(")
_sql_str_compl = text
if start > 0:
_matched = text[text.find("NeuralArray(") + len("NeuralArray(") :]
end = _matched.find(")") + start + len("NeuralArray(") + 1
entity = _matched[: _matched.find(")")]
vecs = self.model.embed_query(entity)
vecs_str = "[" + ",".join(map(str, vecs)) + "]"
_sql_str_compl = text.replace("DISTANCE", self.distance_func_name).replace(
text[start:end], vecs_str
)
if _sql_str_compl[-1] == ";":
_sql_str_compl = _sql_str_compl[:-1]
return _sql_str_compl
[docs]class VectorSQLRetrieveAllOutputParser(VectorSQLOutputParser):
"""Parser based on VectorSQLOutputParser.
It also modifies the SQL to get all columns.
"""
@property
def _type(self) -> str:
return "vector_sql_retrieve_all_parser"
[docs] def parse(self, text: str) -> str:
text = text.strip()
start = text.upper().find("SELECT")
if start >= 0:
end = text.upper().find("FROM")
text = text.replace(text[start + len("SELECT") + 1 : end - 1], "*")
return super().parse(text)
[docs]def get_result_from_sqldb(db: SQLDatabase, cmd: str) -> Sequence[Dict[str, Any]]:
"""Get result from SQL Database."""
result = db._execute(cmd, fetch="all")
assert isinstance(result, Sequence)
return result
[docs]class VectorSQLDatabaseChain(SQLDatabaseChain):
"""Chain for interacting with Vector SQL Database.
Example:
.. code-block:: python
from langchain_experimental.sql import SQLDatabaseChain
from langchain_community.llms import OpenAI, SQLDatabase, OpenAIEmbeddings
db = SQLDatabase(...)
db_chain = VectorSQLDatabaseChain.from_llm(OpenAI(), db, OpenAIEmbeddings())
*Security note*: Make sure that the database connection uses credentials
that are narrowly-scoped to only include the permissions this chain needs.
Failure to do so may result in data corruption or loss, since this chain may
attempt commands like `DROP TABLE` or `INSERT` if appropriately prompted.
The best way to guard against such negative outcomes is to (as appropriate)
limit the permissions granted to the credentials used with this chain.
This issue shows an example negative outcome if these steps are not taken:
https://github.com/langchain-ai/langchain/issues/5923
"""
sql_cmd_parser: VectorSQLOutputParser
"""Parser for Vector SQL"""
native_format: bool = False
"""If return_direct, controls whether to return in python native format"""
def _call(
self,
inputs: Dict[str, Any],
run_manager: Optional[CallbackManagerForChainRun] = None,
) -> Dict[str, Any]:
_run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
input_text = f"{inputs[self.input_key]}\nSQLQuery:"
_run_manager.on_text(input_text, verbose=self.verbose)
# If not present, then defaults to None which is all tables.
table_names_to_use = inputs.get("table_names_to_use")
table_info = self.database.get_table_info(table_names=table_names_to_use)
llm_inputs = {
"input": input_text,
"top_k": str(self.top_k),
"dialect": self.database.dialect,
"table_info": table_info,
"stop": ["\nSQLResult:"],
}
intermediate_steps: List = []
try:
intermediate_steps.append(llm_inputs) # input: sql generation
llm_out = self.llm_chain.predict(
callbacks=_run_manager.get_child(),
**llm_inputs,
)
sql_cmd = self.sql_cmd_parser.parse(llm_out)
if self.return_sql:
return {self.output_key: sql_cmd}
if not self.use_query_checker:
_run_manager.on_text(llm_out, color="green", verbose=self.verbose)
intermediate_steps.append(
llm_out
) # output: sql generation (no checker)
intermediate_steps.append({"sql_cmd": llm_out}) # input: sql exec
result = get_result_from_sqldb(self.database, sql_cmd)
intermediate_steps.append(str(result)) # output: sql exec
else:
query_checker_prompt = self.query_checker_prompt or PromptTemplate(
template=QUERY_CHECKER, input_variables=["query", "dialect"]
)
query_checker_chain = LLMChain(
llm=self.llm_chain.llm,
prompt=query_checker_prompt,
output_parser=self.llm_chain.output_parser,
)
query_checker_inputs = {
"query": llm_out,
"dialect": self.database.dialect,
}
checked_llm_out = query_checker_chain.predict(
callbacks=_run_manager.get_child(), **query_checker_inputs
)
checked_sql_command = self.sql_cmd_parser.parse(checked_llm_out)
intermediate_steps.append(
checked_llm_out
) # output: sql generation (checker)
_run_manager.on_text(
checked_llm_out, color="green", verbose=self.verbose
)
intermediate_steps.append(
{"sql_cmd": checked_llm_out}
) # input: sql exec
result = get_result_from_sqldb(self.database, checked_sql_command)
intermediate_steps.append(str(result)) # output: sql exec
llm_out = checked_llm_out
sql_cmd = checked_sql_command
_run_manager.on_text("\nSQLResult: ", verbose=self.verbose)
_run_manager.on_text(str(result), color="yellow", verbose=self.verbose)
# If return direct, we just set the final result equal to
# the result of the sql query result (`Sequence[Dict[str, Any]]`),
# otherwise try to get a human readable final answer (`str`).
final_result: Union[str, Sequence[Dict[str, Any]]]
if self.return_direct:
final_result = result
else:
_run_manager.on_text("\nAnswer:", verbose=self.verbose)
input_text += f"{llm_out}\nSQLResult: {result}\nAnswer:"
llm_inputs["input"] = input_text
intermediate_steps.append(llm_inputs) # input: final answer
final_result = self.llm_chain.predict(
callbacks=_run_manager.get_child(),
**llm_inputs,
).strip()
intermediate_steps.append(final_result) # output: final answer
_run_manager.on_text(final_result, color="green", verbose=self.verbose)
chain_result: Dict[str, Any] = {self.output_key: final_result}
if self.return_intermediate_steps:
chain_result[INTERMEDIATE_STEPS_KEY] = intermediate_steps
return chain_result
except Exception as exc:
# Append intermediate steps to exception, to aid in logging and later
# improvement of few shot prompt seeds
exc.intermediate_steps = intermediate_steps # type: ignore
raise exc
@property
def _chain_type(self) -> str:
return "vector_sql_database_chain"
[docs] @classmethod
def from_llm(
cls,
llm: BaseLanguageModel,
db: SQLDatabase,
prompt: Optional[BasePromptTemplate] = None,
sql_cmd_parser: Optional[VectorSQLOutputParser] = None,
**kwargs: Any,
) -> VectorSQLDatabaseChain:
assert sql_cmd_parser, "`sql_cmd_parser` must be set in VectorSQLDatabaseChain."
prompt = prompt or SQL_PROMPTS.get(db.dialect, PROMPT)
llm_chain = LLMChain(llm=llm, prompt=prompt)
return cls(
llm_chain=llm_chain, database=db, sql_cmd_parser=sql_cmd_parser, **kwargs
)
