From d3beb981c11d084bd02bd97cf0e4654018b3afa0 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 7 Jan 2021 17:06:49 +0100
Subject: [PATCH 1/5] ARROW-11163: [C++] Fix reading of compressed IPC/Feather
 files written with Arrow 0.17

---
 cpp/src/arrow/ipc/reader.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cpp/src/arrow/ipc/reader.cc b/cpp/src/arrow/ipc/reader.cc
index 3d855425c7a..7d8e7e28aca 100644
--- a/cpp/src/arrow/ipc/reader.cc
+++ b/cpp/src/arrow/ipc/reader.cc
@@ -49,6 +49,7 @@
 #include "arrow/util/key_value_metadata.h"
 #include "arrow/util/logging.h"
 #include "arrow/util/parallel.h"
+#include "arrow/util/string.h"
 #include "arrow/util/ubsan.h"
 #include "arrow/visitor_inline.h"
 
@@ -535,8 +536,10 @@ Status GetCompressionExperimental(const flatbuf::Message* message,
     RETURN_NOT_OK(internal::GetKeyValueMetadata(message->custom_metadata(), &metadata));
     int index = metadata->FindKey("ARROW:experimental_compression");
     if (index != -1) {
+      // Arrow 0.17 stored string in upper case, internal utils now require lower case
+      auto name = arrow::internal::AsciiToLower(metadata->value(index));
       ARROW_ASSIGN_OR_RAISE(*out,
-                            util::Codec::GetCompressionType(metadata->value(index)));
+                            util::Codec::GetCompressionType(name));
     }
     return internal::CheckCompressionSupported(*out);
   }

From a6c907e9e6ac1e0149f878c395f7afdbd591c2e4 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 7 Jan 2021 17:42:14 +0100
Subject: [PATCH 2/5] format

---
 cpp/src/arrow/ipc/reader.cc | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/cpp/src/arrow/ipc/reader.cc b/cpp/src/arrow/ipc/reader.cc
index 7d8e7e28aca..a3cb67add9d 100644
--- a/cpp/src/arrow/ipc/reader.cc
+++ b/cpp/src/arrow/ipc/reader.cc
@@ -52,7 +52,6 @@
 #include "arrow/util/string.h"
 #include "arrow/util/ubsan.h"
 #include "arrow/visitor_inline.h"
-
 #include "generated/File_generated.h"  // IWYU pragma: export
 #include "generated/Message_generated.h"
 #include "generated/Schema_generated.h"
@@ -538,8 +537,7 @@ Status GetCompressionExperimental(const flatbuf::Message* message,
     if (index != -1) {
       // Arrow 0.17 stored string in upper case, internal utils now require lower case
       auto name = arrow::internal::AsciiToLower(metadata->value(index));
-      ARROW_ASSIGN_OR_RAISE(*out,
-                            util::Codec::GetCompressionType(name));
+      ARROW_ASSIGN_OR_RAISE(*out, util::Codec::GetCompressionType(name));
     }
     return internal::CheckCompressionSupported(*out);
   }

From 6feba1c1459e4f2529d467206643e336b1fb95e3 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Mon, 11 Jan 2021 14:01:32 +0100
Subject: [PATCH 3/5] add tiny test

---
 .../v0.17.0.version=2-compression=lz4.feather | Bin 0 -> 594 bytes
 python/pyarrow/tests/test_feather.py          |  21 ++++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 python/pyarrow/tests/data/feather/v0.17.0.version=2-compression=lz4.feather

diff --git a/python/pyarrow/tests/data/feather/v0.17.0.version=2-compression=lz4.feather b/python/pyarrow/tests/data/feather/v0.17.0.version=2-compression=lz4.feather
new file mode 100644
index 0000000000000000000000000000000000000000..562b0b2c53d8684fcb2b0417bad36877d92af53e
GIT binary patch
literal 594
zcmcJMy-osA5QS&=E^tFOWRtakhQe4_N@7JUpx2ntnAiZpElA`iU_nW&d=wwa(l^oX
z+}#Zpw4UV5&%HBq&(4k~lgFol*$+6FSq9D8mRi#q=7~V$$c@Znlge^Tb^$Z2r@j@c
zvT8;YUsd-BUhv#|sx$>eBN;e{djAXGg(W(~rG|{Yjt-r(7o4=*C<p2<wWUFsW{cOb
z56AkxVR6_NyXC4_zs+B#i_L1gEB5>4X3a=y?w@b5ZQd(q=$r4LcF}+};yO6vYdyM>
zroVkUlO7?teCW<b?>)kt!aVYp$Iy8@)_YQ&_8~6~Df?}P?P(K&3;HxuJ$mm03g5w=
R_EV+7{pbJt<b|;7!7tnxDSrR}

literal 0
HcmV?d00001

diff --git a/python/pyarrow/tests/test_feather.py b/python/pyarrow/tests/test_feather.py
index b3348269e4a..f01ac292ddf 100644
--- a/python/pyarrow/tests/test_feather.py
+++ b/python/pyarrow/tests/test_feather.py
@@ -39,6 +39,11 @@
     pass
 
 
+@pytest.fixture(scope='module')
+def datadir(base_datadir):
+    return base_datadir / 'feather'
+
+
 def random_path(prefix='feather_'):
     return tempfile.mktemp(prefix=prefix)
 
@@ -769,3 +774,19 @@ def test_nested_types(compression):
 @h.given(past.all_tables, st.sampled_from(["uncompressed", "lz4", "zstd"]))
 def test_roundtrip(table, compression):
     _check_arrow_roundtrip(table, compression=compression)
+
+
+def test_feather_v017_experimental_compression_backward_compatibility(datadir):
+    # ARROW-11163 - ensure newer pyarrow versions can read the old feather
+    # files from version 0.17.0 with experimental compression support (before
+    # it was officially added to IPC format in 1.0.0)
+
+    # file generated with:
+    #     table = pa.table({'a': range(5)})
+    #     from pyarrow import feather
+    #     feather.write_feather(
+    #         table, "v0.17.0.version=2-compression=lz4.feather",
+    #         compression="lz4", version=2)
+    expected = pa.table({'a': range(5)})
+    result = read_table(datadir / "v0.17.0.version=2-compression=lz4.feather")
+    assert result.equals(expected)

From 4af31cef83204f57e19b332ff676e071f73399e9 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Mon, 11 Jan 2021 14:04:06 +0100
Subject: [PATCH 4/5] add R news note

---
 r/NEWS.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/r/NEWS.md b/r/NEWS.md
index a606c03b9cf..69223c29570 100644
--- a/r/NEWS.md
+++ b/r/NEWS.md
@@ -43,6 +43,7 @@
 * `write_parquet()` can now write RecordBatches
 * Reading a Table from a RecordBatchStreamReader containing 0 batches no longer crashes
 * `readr`'s `problems` attribute is removed when converting to Arrow RecordBatch and table to prevent large amounts of metadata from accumulating inadvertently [ARROW-10624](https://issues.apache.org/jira/browse/ARROW-10624)
+* Fixed reading of compressed Feather files written with Arrow 0.17 [ARROW-10850](https://issues.apache.org/jira/browse/ARROW-10850)
 
 ## Packaging and installation
 

From cf023b3394633ac00bf77c8d3c87b3958f96d6ce Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Mon, 11 Jan 2021 14:05:20 +0100
Subject: [PATCH 5/5] undo whitespace change

---
 cpp/src/arrow/ipc/reader.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/cpp/src/arrow/ipc/reader.cc b/cpp/src/arrow/ipc/reader.cc
index a3cb67add9d..e20208a14dc 100644
--- a/cpp/src/arrow/ipc/reader.cc
+++ b/cpp/src/arrow/ipc/reader.cc
@@ -52,6 +52,7 @@
 #include "arrow/util/string.h"
 #include "arrow/util/ubsan.h"
 #include "arrow/visitor_inline.h"
+
 #include "generated/File_generated.h"  // IWYU pragma: export
 #include "generated/Message_generated.h"
 #include "generated/Schema_generated.h"