(orc) branch main updated: ORC-1881: [C++] Populate dstBatch's scale and precision in DecimalConvertColumnReader

[dongjoon]

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dongjoon pushed a commit to branch main
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The following commit(s) were added to refs/heads/main by this push:
     new 44990bd10 ORC-1881: [C++] Populate dstBatch's scale and precision in 
DecimalConvertColumnReader
44990bd10 is described below

commit 44990bd100b8987b3a614e32c9bbd479d0a418d6
Author: zhaokuo03 <zhaoku...@meituan.com>
AuthorDate: Tue Apr 22 18:30:58 2025 +0900

    ORC-1881: [C++] Populate dstBatch's scale and precision in 
DecimalConvertColumnReader
    
    ### What changes were proposed in this pull request?
    
    Set dstBatch's decimal and precision when 
`DecimalConvertColumnReader::next`.
    Fix ORC-1881.
    
    ### Why are the changes needed?
    
    During decimal-to-decimal conversion in `SchemaEvolution`, the target 
decimal's scale and precision are incorrectly initialized to zero, producing a 
corrupted `ColumnVectorBatch`.
    
    ### How was this patch tested?
    
    Unit test.
    
    ### Was this patch authored or co-authored using generative AI tooling?
    
    No.
    
    Closes #2194 from kecookier/fix-decimal-2-decimal.
    
    Authored-by: zhaokuo03 <zhaoku...@meituan.com>
    Signed-off-by: Dongjoon Hyun <dongj...@apache.org>
---
 c++/src/ConvertColumnReader.cc      | 2 ++
 c++/test/TestConvertColumnReader.cc | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/c++/src/ConvertColumnReader.cc b/c++/src/ConvertColumnReader.cc
index a9003bc16..c0f88246e 100644
--- a/c++/src/ConvertColumnReader.cc
+++ b/c++/src/ConvertColumnReader.cc
@@ -579,6 +579,8 @@ namespace orc {
 
       const auto& srcBatch = *SafeCastBatchTo<const 
FileTypeBatch*>(data.get());
       auto& dstBatch = *SafeCastBatchTo<ReadTypeBatch*>(&rowBatch);
+      dstBatch.precision = toPrecision_;
+      dstBatch.scale = toScale_;
       for (uint64_t i = 0; i < numValues; ++i) {
         if (!rowBatch.hasNulls || rowBatch.notNull[i]) {
           convertDecimalToDecimal(dstBatch, i, srcBatch);
diff --git a/c++/test/TestConvertColumnReader.cc 
b/c++/test/TestConvertColumnReader.cc
index 7c5f05bd3..6096fe457 100644
--- a/c++/test/TestConvertColumnReader.cc
+++ b/c++/test/TestConvertColumnReader.cc
@@ -651,6 +651,10 @@ namespace orc {
     auto& readC2 = 
dynamic_cast<Decimal128VectorBatch&>(*readStructBatch.fields[1]);
     auto& readC3 = 
dynamic_cast<Decimal64VectorBatch&>(*readStructBatch.fields[2]);
     auto& readC4 = 
dynamic_cast<Decimal128VectorBatch&>(*readStructBatch.fields[3]);
+    EXPECT_TRUE(9 == readC1.precision && 5 == readC1.scale);
+    EXPECT_TRUE(20 == readC2.precision && 5 == readC2.scale);
+    EXPECT_TRUE(10 == readC3.precision && 3 == readC3.scale);
+    EXPECT_TRUE(19 == readC4.precision && 3 == readC4.scale);
     EXPECT_EQ(TEST_CASES, readBatch->numElements);
     for (int i = 0; i < TEST_CASES / 2; i++) {
       size_t idx = static_cast<size_t>(i);