docs(python): Mention stream position issue in doc

py-polars/polars/io/avro.py

@@ -30,6 +30,7 @@ def read_avro(
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
     columns
         Columns to select. Accepts a list of column indices (starting at zero) or a list
         of column names.

py-polars/polars/io/csv/functions.py

@@ -81,6 +81,7 @@ def read_csv(
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance). If `fsspec` is installed, it will be used
         to open remote files.
+        For file-like objects, stream position may not be updated after reading.
     has_header
         Indicate if the first row of the dataset is a header or not. If set to False,
         column names will be autogenerated in the following format: `column_x`, with
@@ -646,6 +647,7 @@ def read_csv_batched(
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance). If `fsspec` is installed, it will be used
         to open remote files.
+        For file-like objects, stream position may not be updated after reading.
     has_header
         Indicate if the first row of the dataset is a header or not. If set to False,
         column names will be autogenerated in the following format: `column_x`, with

py-polars/polars/io/ipc/functions.py

@@ -56,6 +56,7 @@ def read_ipc(
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance). If `fsspec` is installed, it will be used
         to open remote files.
+        For file-like objects, stream position may not be updated after reading.
     columns
         Columns to select. Accepts a list of column indices (starting at zero) or a list
         of column names.
@@ -199,6 +200,7 @@ def read_ipc_stream(
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance). If `fsspec` is installed, it will be used
         to open remote files.
+        For file-like objects, stream position may not be updated after reading.
     columns
         Columns to select. Accepts a list of column indices (starting at zero) or a list
         of column names.
@@ -287,6 +289,7 @@ def read_ipc_schema(source: str | Path | IO[bytes] | bytes) -> dict[str, DataTyp
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
 
     Returns
     -------

py-polars/polars/io/json/read.py

@@ -35,6 +35,7 @@ def read_json(
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
     schema : Sequence of str, (str,DataType) pairs, or a {str:DataType,} dict
         The DataFrame schema may be declared in several ways:
 

py-polars/polars/io/ndjson.py

@@ -37,6 +37,7 @@ def read_ndjson(
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
     schema : Sequence of str, (str,DataType) pairs, or a {str:DataType,} dict
         The DataFrame schema may be declared in several ways:
 

py-polars/polars/io/parquet/functions.py

@@ -63,6 +63,7 @@ def read_parquet(
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance). If the path is a directory, files in that
         directory will all be read.
+        For file-like objects, stream position may not be updated after reading.
     columns
         Columns to select. Accepts a list of column indices (starting at zero) or a list
         of column names.
@@ -273,6 +274,7 @@ def read_parquet_schema(source: str | Path | IO[bytes] | bytes) -> dict[str, Dat
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
 
     Returns
     -------

py-polars/polars/io/spreadsheet/functions.py

@@ -169,6 +169,7 @@ def read_excel(
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
     sheet_id
         Sheet number(s) to convert (set `0` to load all sheets as DataFrames) and
         return a `{sheetname:frame,}` dict. (Defaults to `1` if neither this nor
@@ -383,6 +384,7 @@ def read_ods(
         Path to a file or a file-like object (by "file-like object" we refer to objects
         that have a `read()` method, such as a file handler like the builtin `open`
         function, or a `BytesIO` instance).
+        For file-like objects, stream position may not be updated after reading.
     sheet_id
         Sheet number(s) to convert, starting from 1 (set `0` to load *all* worksheets
         as DataFrames) and return a `{sheetname:frame,}` dict. (Defaults to `1` if