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Documentation
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Known Python Issues
Unfortunately there are some issues that are either beyond our control or are very elusive / hard to track down.
Below is a list of these issues that you might have to be aware of, depending on your workflow.
Numpy Import Multithreading
When making use of multi threading and fetching results either directly as Numpy arrays or indirectly through a Pandas DataFrame, it might be necessary to ensure that numpy.core.multiarray is imported.
If this module has not been imported from the main thread, and a different thread during execution attempts to import it this causes either a deadlock or a crash.
To avoid this, it's recommended to import numpy.core.multiarray before starting up threads.
Running EXPLAIN renders newlines in Jupyter and IPython
When DuckDB is run in Jupyter notebooks or in the IPython shell, the output of the EXPLAIN statement contains hard line breaks (\n):
In [1]: import duckdb
...: duckdb.sql("EXPLAIN SELECT 42 AS x")
Out[1]:
┌───────────────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ explain_key │ explain_value │
│ varchar │ varchar │
├───────────────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ physical_plan │ ┌───────────────────────────┐\n│ PROJECTION │\n│ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ │\n│ x … │
└───────────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
To work around this, print the output of the explain() function:
In [2]: print(duckdb.sql("SELECT 42 AS x").explain())
┌───────────────────────────┐
│ PROJECTION │
│ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ │
│ x │
└─────────────┬─────────────┘
┌─────────────┴─────────────┐
│ DUMMY_SCAN │
└───────────────────────────┘
Please also check out the Jupyter guide for tips on using Jupyter with JupySQL.