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Google El Carro Oracle Operator offers a way to run Oracle databases in Kubernetes as a portable, open source, community driven, no vendor lock-in container orchestration system. El Carro provides a powerful declarative API for comprehensive and consistent configuration and deployment as well as for real-time operations and monitoring. Extend your Oracle database’s capabilities to build AI-powered experiences by leveraging the El Carro LangChain integration.
This guide goes over how to use El Carro LangChain integration to save, load and delete langchain documents with ElCarroLoader and ElCarroDocumentSaver. This integration works for any Oracle database, regardless of where it is running. Learn more about the package on GitHub. Open In Colab

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Before You Begin

Please complete the Getting Started section of the README to set up your El Carro Oracle database.

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🦜🔗 Library Installation

The integration lives in its own langchain-google-el-carro package, so we need to install it. 
pip install -qU langchain-google-el-carro

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Basic Usage

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Set Up Oracle Database Connection

Fill out the following variable with your Oracle database connections details. 
# @title Set Your Values Here { display-mode: "form" }
HOST = "127.0.0.1"  # @param {type: "string"}
PORT = 3307  # @param {type: "integer"}
DATABASE = "my-database"  # @param {type: "string"}
TABLE_NAME = "message_store"  # @param {type: "string"}
USER = "my-user"  # @param {type: "string"}
PASSWORD = input("Please provide a password to be used for the database user: ")
If you are using El Carro, you can find the hostname and port values in the status of the El Carro Kubernetes instance. Use the user password you created for your PDB. Example Ouput: 
kubectl get -w instances.oracle.db.anthosapis.com -n db
NAME   DB ENGINE   VERSION   EDITION      ENDPOINT      URL                DB NAMES   BACKUP ID   READYSTATUS   READYREASON        DBREADYSTATUS   DBREADYREASON

mydb   Oracle      18c       Express      mydb-svc.db   34.71.69.25:6021   ['pdbname']            TRUE          CreateComplete     True            CreateComplete

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ElCarroEngine Connection Pool

ElCarroEngine configures a connection pool to your Oracle database, enabling successful connections from your application and following industry best practices. 
from langchain_google_el_carro import ElCarroEngine

elcarro_engine = ElCarroEngine.from_instance(
    db_host=HOST,
    db_port=PORT,
    db_name=DATABASE,
    db_user=USER,
    db_password=PASSWORD,
)

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Initialize a table

Initialize a table of default schema via elcarro_engine.init_document_table(<table_name>). Table Columns:
  • page_content (type: text)
  • langchain_metadata (type: JSON)
elcarro_engine.drop_document_table(TABLE_NAME)
elcarro_engine.init_document_table(
    table_name=TABLE_NAME,
)

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Save documents

Save langchain documents with ElCarroDocumentSaver.add_documents(<documents>). To initialize ElCarroDocumentSaver class you need to provide 2 things:
  1. elcarro_engine - An instance of a ElCarroEngine engine.
  2. table_name - The name of the table within the Oracle database to store langchain documents.
from langchain_core.documents import Document
from langchain_google_el_carro import ElCarroDocumentSaver

doc = Document(
    page_content="Banana",
    metadata={"type": "fruit", "weight": 100, "organic": 1},
)

saver = ElCarroDocumentSaver(
    elcarro_engine=elcarro_engine,
    table_name=TABLE_NAME,
)
saver.add_documents([doc])

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Load documents

Load langchain documents with ElCarroLoader.load() or ElCarroLoader.lazy_load(). lazy_load returns a generator that only queries database during the iteration. To initialize ElCarroLoader class you need to provide:
  1. elcarro_engine - An instance of a ElCarroEngine engine.
  2. table_name - The name of the table within the Oracle database to store langchain documents.
from langchain_google_el_carro import ElCarroLoader

loader = ElCarroLoader(elcarro_engine=elcarro_engine, table_name=TABLE_NAME)
docs = loader.lazy_load()
for doc in docs:
    print("Loaded documents:", doc)

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Load documents via query

Other than loading documents from a table, we can also choose to load documents from a view generated from a SQL query. For example: 
from langchain_google_el_carro import ElCarroLoader

loader = ElCarroLoader(
    elcarro_engine=elcarro_engine,
    query=f"SELECT * FROM {TABLE_NAME} WHERE json_value(langchain_metadata, '$.organic') = '1'",
)
onedoc = loader.load()
print(onedoc)
The view generated from SQL query can have different schema than default table. In such cases, the behavior of ElCarroLoader is the same as loading from table with non-default schema. Please refer to section Load documents with customized document page content & metadata.

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Delete documents

Delete a list of langchain documents from an Oracle table with ElCarroDocumentSaver.delete(<documents>). For a table with a default schema (page_content, langchain_metadata), the deletion criteria is: A row should be deleted if there exists a document in the list, such that
  • document.page_content equals row[page_content]
  • document.metadata equals row[langchain_metadata]
docs = loader.load()
print("Documents before delete:", docs)
saver.delete(onedoc)
print("Documents after delete:", loader.load())

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Advanced Usage

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Load documents with customized document page content & metadata

First we prepare an example table with non-default schema, and populate it with some arbitrary data. 
import sqlalchemy

create_table_query = f"""CREATE TABLE {TABLE_NAME} (
    fruit_id NUMBER GENERATED BY DEFAULT AS IDENTITY (START WITH 1),
    fruit_name VARCHAR2(100) NOT NULL,
    variety VARCHAR2(50),
    quantity_in_stock NUMBER(10) NOT NULL,
    price_per_unit NUMBER(6,2) NOT NULL,
    organic NUMBER(3) NOT NULL
)"""
elcarro_engine.drop_document_table(TABLE_NAME)

with elcarro_engine.connect() as conn:
    conn.execute(sqlalchemy.text(create_table_query))
    conn.commit()
    conn.execute(
        sqlalchemy.text(
            f"""
            INSERT INTO {TABLE_NAME} (fruit_name, variety, quantity_in_stock, price_per_unit, organic)
            VALUES ('Apple', 'Granny Smith', 150, 0.99, 1)
            """
        )
    )
    conn.execute(
        sqlalchemy.text(
            f"""
            INSERT INTO {TABLE_NAME} (fruit_name, variety, quantity_in_stock, price_per_unit, organic)
            VALUES ('Banana', 'Cavendish', 200, 0.59, 0)
            """
        )
    )
    conn.execute(
        sqlalchemy.text(
            f"""
            INSERT INTO {TABLE_NAME} (fruit_name, variety, quantity_in_stock, price_per_unit, organic)
            VALUES ('Orange', 'Navel', 80, 1.29, 1)
            """
        )
    )
    conn.commit()
If we still load langchain documents with default parameters of ElCarroLoader from this example table, the page_content of loaded documents will be the first column of the table, and metadata will be consisting of key-value pairs of all the other columns. 
loader = ElCarroLoader(
    elcarro_engine=elcarro_engine,
    table_name=TABLE_NAME,
)
loaded_docs = loader.load()
print(f"Loaded Documents: [{loaded_docs}]")
We can specify the content and metadata we want to load by setting the content_columns and metadata_columns when initializing the ElCarroLoader.
  1. content_columns: The columns to write into the page_content of the document.
  2. metadata_columns: The columns to write into the metadata of the document.
For example here, the values of columns in content_columns will be joined together into a space-separated string, as page_content of loaded documents, and metadata of loaded documents will only contain key-value pairs of columns specified in metadata_columns. 
loader = ElCarroLoader(
    elcarro_engine=elcarro_engine,
    table_name=TABLE_NAME,
    content_columns=[
        "variety",
        "quantity_in_stock",
        "price_per_unit",
        "organic",
    ],
    metadata_columns=["fruit_id", "fruit_name"],
)
loaded_docs = loader.load()
print(f"Loaded Documents: [{loaded_docs}]")

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Save document with customized page content & metadata

In order to save langchain document into table with customized metadata fields we need first create such a table via ElCarroEngine.init_document_table(), and specify the list of metadata_columns we want it to have. In this example, the created table will have table columns:
  • content (type: text): for storing fruit description.
  • type (type VARCHAR2(200)): for storing fruit type.
  • weight (type INT): for storing fruit weight.
  • extra_json_metadata (type: JSON): for storing other metadata information of the fruit.
We can use the following parameters with elcarro_engine.init_document_table() to create the table:
  1. table_name: The name of the table within the Oracle database to store langchain documents.
  2. metadata_columns: A list of sqlalchemy.Column indicating the list of metadata columns we need.
  3. content_column: column name to store page_content of langchain document. Default: "page_content", "VARCHAR2(4000)"
  4. metadata_json_column: column name to store extra JSON metadata of langchain document. Default: "langchain_metadata", "VARCHAR2(4000)".
elcarro_engine.drop_document_table(TABLE_NAME)
elcarro_engine.init_document_table(
    table_name=TABLE_NAME,
    metadata_columns=[
        sqlalchemy.Column("type", sqlalchemy.dialects.oracle.VARCHAR2(200)),
        sqlalchemy.Column("weight", sqlalchemy.INT),
    ],
    content_column="content",
    metadata_json_column="extra_json_metadata",
)
Save documents with ElCarroDocumentSaver.add_documents(<documents>). As you can see in this example,
  • document.page_content will be saved into content column.
  • document.metadata.type will be saved into type column.
  • document.metadata.weight will be saved into weight column.
  • document.metadata.organic will be saved into extra_json_metadata column in JSON format.
doc = Document(
    page_content="Banana",
    metadata={"type": "fruit", "weight": 100, "organic": 1},
)

print(f"Original Document: [{doc}]")

saver = ElCarroDocumentSaver(
    elcarro_engine=elcarro_engine,
    table_name=TABLE_NAME,
    content_column="content",
    metadata_json_column="extra_json_metadata",
)
saver.add_documents([doc])

loader = ElCarroLoader(
    elcarro_engine=elcarro_engine,
    table_name=TABLE_NAME,
    content_columns=["content"],
    metadata_columns=[
        "type",
        "weight",
    ],
    metadata_json_column="extra_json_metadata",
)

loaded_docs = loader.load()
print(f"Loaded Document: [{loaded_docs[0]}]")

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Delete documents with customized page content & metadata

We can also delete documents from table with customized metadata columns via ElCarroDocumentSaver.delete(<documents>). The deletion criteria is: A row should be deleted if there exists a document in the list, such that
  • document.page_content equals row[page_content]
  • For every metadata field k in document.metadata
    • document.metadata[k] equals row[k] or document.metadata[k] equals row[langchain_metadata][k]
  • There is no extra metadata field present in row but not in document.metadata.
loader = ElCarroLoader(elcarro_engine=elcarro_engine, table_name=TABLE_NAME)
saver.delete(loader.load())
print(f"Documents left: {len(loader.load())}")

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More examples

Please look at demo_doc_loader_basic.py and demo_doc_loader_advanced.py for complete code examples.
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