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new 45aa81347 add csv registration and sql query (#2825)
45aa81347 is described below
commit 45aa813478701612c5af3e910e1e2b28928f75ae
Author: Wei-Ting Kuo <[email protected]>
AuthorDate: Mon Jul 4 03:22:59 2022 +0800
add csv registration and sql query (#2825)
---
docs/source/python/index.rst | 60 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
diff --git a/docs/source/python/index.rst b/docs/source/python/index.rst
index 3cafc550b..167e66b9f 100644
--- a/docs/source/python/index.rst
+++ b/docs/source/python/index.rst
@@ -66,6 +66,66 @@ Simple usage:
assert result.column(1) == pyarrow.array([-3, -3, -3])
+We can also execute a query against data stored in CSV
+
+.. code-block:: bash
+
+ echo "a,b\n1,4\n2,5\n3,6" > example.csv
+
+
+.. code-block:: python
+
+ import datafusion
+ from datafusion import functions as f
+ from datafusion import col
+ import pyarrow
+
+ # create a context
+ ctx = datafusion.SessionContext()
+
+ # register a CSV
+ ctx.register_csv('example', 'example.csv')
+
+ # create a new statement
+ df = ctx.table('example').select(
+ col("a") + col("b"),
+ col("a") - col("b"),
+ )
+
+ # execute and collect the first (and only) batch
+ result = df.collect()[0]
+
+ assert result.column(0) == pyarrow.array([5, 7, 9])
+ assert result.column(1) == pyarrow.array([-3, -3, -3])
+
+
+And how to execute a query against a CSV using SQL:
+
+
+.. code-block:: python
+
+ import datafusion
+ from datafusion import functions as f
+ from datafusion import col
+ import pyarrow
+
+ # create a context
+ ctx = datafusion.SessionContext()
+
+ # register a CSV
+ ctx.register_csv('example', 'example.csv')
+
+ # create a new statement via SQL
+ df = ctx.sql("SELECT a+b, a-b FROM example")
+
+ # execute and collect the first (and only) batch
+ result = df.collect()[0]
+
+ assert result.column(0) == pyarrow.array([5, 7, 9])
+ assert result.column(1) == pyarrow.array([-3, -3, -3])
+
+
+
UDFs
----
