DuckDB-python的api的汇总

python-duckddb

  DuckDBPyConnection  DuckDBPyRelation
   duckdb.ExplainType  duckdb.Expression duckdb.Statement  duckdb.StatementType
   _duckdb.typing.DuckDBPyType

duckdb

duckdb.read_csv()
duckdb.sql(sql_query).fetch_arrow_table()
        duckdb.sql(sql_query).arrow()   .df()    .fetchall() .fetchnumpy()
		duckdb.sql(sql_query).write_csv("out.csv") ) .write_parquet("out.parquet")  
num_rows = duckdb.sql(f"select count(*) as num_rows from {self.sql_query_fragment()}").fetchall()

duckdb.create_function()
duckdb.ColumnExpression
duckdb.StarExpression
duckdb.ConstantExpression

conn:DuckDBPyConnection

conn: duckdb.DuckDBPyConnection = None,
conn.sql(sql_query).fetch_arrow_table()
con.close()
con.table("test").show()
con.create_function()

duckdb.DuckDBPyRelation

    Transformation	
Relational API
       sql() query() sql_query() from_csv_auto()  ()read_csv   table()  view()
	   
Python DB API
       con.execute() con.executemany()

####run DuckDB in parallel, each thread must have its own connection:
def good_use():
    con = duckdb.connect()
    # uses new connection
    con.sql("SELECT 1").fetchall()   
 DuckDBPyConnection.cursor() method
 
 DuckDBPyConnection.register() function. 
 
 rel.types

typing

 DuckDBPyType  
 duckdb.sqltypes.DuckDBPyType
 duckdb.typing.DuckDBPyType
 duckdb.sqltypes import VARCHAR
 from duckdb.sqltypes import BIGINT
 
 Python object types to DuckDB Logical Types:
    str     → VARCHAR
    bool    → BOOLEAN 
    bytearray   → BLOB
    memoryview  → BLOB
    uuid.UUID   → UUID
	None  → NULL
    int   →  BIGINT INTEGER  UBIGINT  UINTEGER  DOUBLE
	float → DOUBLE FLOAT
	bytes → BLOB BITSTRING
	list  → LIST  VARCHAR[]
	dict  → STRUCT(...) or MAP(..., ...)
	tuple → LIST STRUCT
	 → 
	 → 
	 → 
	datetime.timedelta → INTERVAL 
	decimal.Decimal    → DECIMAL / DOUBLE
	datetime.date datetime.time datetime.datetime  →
  NumPy         : fetchnumpy()
  Pandas        : df()     fetch_df() fetchdf() fetch_df_chunk(vector_multiple)
  Apache Arrow  : arrow()  fetch_arrow_table()  fetch_record_batch(chunk_size)
  Polars        : pl()

加载扩展

命令行式
 con = duckdb.connect()
 con.install_extension("h3", repository="community")
 con.load_extension("h3")

###类的方式
class DuckDbExtensionContext(UDFContext):
    def __init__(self, name: str, extension_path: str) -> None:
        self.name = name
        self.extension_path = extension_path

    def __str__(self) -> str:
        return f"{self.name}@{self.extension_path}"

    __repr__ = __str__

    def bind(self, conn: duckdb.DuckDBPyConnection):
        conn.load_extension(self.extension_path)

参考

https://duckdb.org/docs/stable/clients/python/reference/    
https://github.com/duckdb/duckdb/tree/main
https://github.com/duckdb/duckdb-python/tree/main/src/duckdb_py