AlenkaF commented on code in PR #41795:
URL: https://github.com/apache/arrow/pull/41795#discussion_r1626055805
##########
docs/source/format/Columnar.rst:
##########
@@ -1078,8 +1078,95 @@ Arrow columnar format. Each logical type uses one of the
above
physical layouts. Nested logical types may have different physical
layouts depending on the particular realization of the type.
-We do not go into detail about the logical types definitions in this
-document as we consider `Schema.fbs`_ to be authoritative.
+.. glossary::
+
+ Null Type
+ Array where all values are null.
+
+ Boolean Type
+ Array of bit-packed values.
+
+ Int Type
+ Array of signed or unsigned integers with 8, 16, 32 or 64 bit width.
+
+ Floating Point Type
+ Array of floating point numbers with half, single or double precision.
+
+ .. TODO: list other types if we agree to keep the glossary
+
+
+Types and their respective Physical Memory Layout
+-------------------------------------------------
+
++--------------------+----------------------------------+------------------------------+
+| Type | Physical Memory Layout | Additional info
stored |
++====================+==================================+==============================+
+| **Primitive** | |
|
++--------------------+----------------------------------+------------------------------+
+| Null | Null Layout | /
|
++--------------------+----------------------------------+------------------------------+
+| Boolean | Fixed-size Primitive Layout | values bit-packed
|
++--------------------+----------------------------------+------------------------------+
+| Int | " (same as above) | | bitWidth
|
+| | | | is_signed
|
++--------------------+----------------------------------+------------------------------+
+| Floating Point | " | precision
|
++--------------------+----------------------------------+------------------------------+
+| Decimal | " | | precision
|
+| | | | scale
|
+| | | | bitWidth
|
++--------------------+----------------------------------+------------------------------+
+| Date | " | | unit
|
++--------------------+----------------------------------+------------------------------+
+| Time | " | | unit
|
+| | | | bitWidth
|
++--------------------+----------------------------------+------------------------------+
+| Timestamp | " | | unit
|
+| | | | timezone
|
++--------------------+----------------------------------+------------------------------+
+| Interval | " | unit
|
++--------------------+----------------------------------+------------------------------+
+| Duration | " | unit
|
++--------------------+----------------------------------+------------------------------+
+| Fixed Size Binary | Fixed-size Binary Layout | byteWidth
|
++--------------------+----------------------------------+------------------------------+
+| Binary | " | /
|
++--------------------+----------------------------------+------------------------------+
+| Large Binary | " | 64-bit offsets
|
++--------------------+----------------------------------+------------------------------+
+| Utf8 | Variable-size Binary Layout | /
|
++--------------------+----------------------------------+------------------------------+
+| Large Utf8 | " | 64-bit offsets
|
++--------------------+----------------------------------+------------------------------+
+| Binary View | " | /
|
++--------------------+----------------------------------+------------------------------+
+| Utf8 View | Variable-size Binary View Layout | /
|
Review Comment:
Oh yes, great catch!
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