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GH-34519: [C++][R] Fix dataset scans that project the same name as a field #34576

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Merged
westonpace merged 1 commit into from
Mar 21, 2023
Merged

GH-34519: [C++][R] Fix dataset scans that project the same name as a field #34576

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24 changes: 11 additions & 13 deletions cpp/src/arrow/dataset/scanner.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -141,19 +141,17 @@ Result<std::shared_ptr<Schema>> GetProjectedSchemaFromExpression(
if (call->function_name != "make_struct") {
return Status::Invalid("Top level projection expression call must be make_struct");
}
for (const compute::Expression& arg : call->arguments) {
if (auto field_ref = arg.field_ref()) {
if (field_ref->IsName()) {
field_names.emplace(*field_ref->name());
} else if (field_ref->IsNested()) {
// We keep the top-level field name.
auto nested_field_refs = *field_ref->nested_refs();
field_names.emplace(*nested_field_refs[0].name());
} else {
return Status::Invalid(
"No projected schema was supplied and we could not infer the projected "
"schema from the projection expression.");
}
for (auto field_ref : compute::FieldsInExpression(projection)) {
if (field_ref.IsName()) {
field_names.emplace(*field_ref.name());
} else if (field_ref.IsNested()) {
// We keep the top-level field name.
auto nested_field_refs = *field_ref.nested_refs();
field_names.emplace(*nested_field_refs[0].name());
} else {
return Status::Invalid(
"No projected schema was supplied and we could not infer the projected "
"schema from the projection expression.");
}
}
}
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22 changes: 19 additions & 3 deletions r/tests/testthat/test-dplyr-query.R
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Original file line number Diff line number Diff line change
Expand Up @@ -740,12 +740,19 @@ test_that("Can use nested field refs", {
collect(),
nested_data
)
})

# Now with Dataset: make sure column pushdown in ScanNode works
test_that("Can use nested field refs with Dataset", {
skip_if_not_available("dataset")
# Now with Dataset: make sure column pushdown in ScanNode works
nested_data <- tibble(int = 1:5, df_col = tibble(a = 6:10, b = 11:15))
tf <- tempfile()
dir.create(tf)
write_dataset(nested_data, tf)
ds <- open_dataset(tf)

expect_equal(
nested_data %>%
InMemoryDataset$create() %>%
ds %>%
mutate(
nested = df_col$a,
times2 = df_col$a * 2
Expand All @@ -759,6 +766,15 @@ test_that("Can use nested field refs", {
) %>%
filter(nested > 7)
)
# Issue #34519: error when projecting same name, but only on file dataset
expect_equal(
ds %>%
mutate(int = as.numeric(int)) %>%
collect(),
nested_data %>%
mutate(int = as.numeric(int)) %>%
collect()
)
})

test_that("Use struct_field for $ on non-field-ref", {
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