Data Frame Source

A DataSource implementation that wraps a data frame using DuckDB or SQLite for SQL query execution.

Details

This class creates an in-memory database connection and registers the provided data frame as a table. All SQL queries are executed against this database table. See DBISource for the full description of available methods.

By default, DataFrameSource uses the first available engine from duckdb (checked first) or RSQLite. You can explicitly set the engine parameter to choose between "duckdb" or "sqlite", or set the global option querychat.DataFrameSource.engine to choose the default engine for all DataFrameSource instances. At least one of these packages must be installed.

Super classes

DataSource -> DBISource -> DataFrameSource

Methods

Public methods

• DataFrameSource$new()

• DataFrameSource$register_into()

• DataFrameSource$cleanup()

• DataFrameSource$clone()

Inherited methods

• DataSource$get_data_description()
• DBISource$execute_query()
• DBISource$get_data()
• DBISource$get_db_type()
• DBISource$get_schema()
• DBISource$get_schema_result()
• DBISource$get_semantic_views_description()
• DBISource$test_query()

---

DataFrameSource$new()

Create a new DataFrameSource

Usage

DataFrameSource$new(
  df,
  table_name,
  engine = getOption("querychat.DataFrameSource.engine", NULL)
)

Arguments

df

A data frame.

table_name

Name to use for the table in SQL queries. Must be a valid table name (start with letter, contain only letters, numbers, and underscores)

engine

Database engine to use: "duckdb" or "sqlite". Set the global option querychat.DataFrameSource.engine to specify the default engine for all instances. If NULL (default), uses the first available engine from duckdb or RSQLite (in that order).

Returns

A new DataFrameSource object

---

DataFrameSource$register_into()

Register this data frame in a shared DuckDB connection.

Internal hook for joining a shared DuckDBExecutor. The caller owns con and locks it down once all tables are registered.

Usage

DataFrameSource$register_into(con, table_name = self$table_name)

Arguments

con

A DuckDB DBI connection, owned by the caller.

table_name

Name for the table in con. Defaults to the source's own table name.

Returns

NULL (invisibly)

---

DataFrameSource$cleanup()

Disconnect from the database and shut down the DuckDB instance if used.

Usage

DataFrameSource$cleanup()

Returns

NULL (invisibly)

---

DataFrameSource$clone()

The objects of this class are cloneable with this method.

Usage

DataFrameSource$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

# Create a data frame source (uses first available: duckdb or sqlite)
df_source <- DataFrameSource$new(mtcars, "mtcars")
#> duckdb keeps downloaded extensions and secrets in a temporary directory:
#> ℹ /tmp/RtmpZdCyHx/duckdb
#> This is removed when the R session ends.
#> • Extensions are re-downloaded each session.
#> • Secrets are lost.
#> ℹ Run duckdb(shared_home = TRUE) (or create ~/.duckdb) to keep them (suitable for most users).
#> ℹ Run duckdb(shared_home = FALSE) to accept the temporary directory (and silence this message).
#> ℹ See ?duckdb_storage for details and alternatives.

# Get database type
df_source$get_db_type()  # Returns "DuckDB" or "SQLite"
#> [1] "DuckDB"

# Execute a query
result <- df_source$execute_query("SELECT * FROM mtcars WHERE mpg > 25")

# Explicitly choose an engine
df_sqlite <- DataFrameSource$new(mtcars, "mtcars", engine = "sqlite")

# Clean up when done
df_source$cleanup()
df_sqlite$cleanup()