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Posted to github@arrow.apache.org by "lidavidm (via GitHub)" <gi...@apache.org> on 2023/07/11 15:13:35 UTC
[GitHub] [arrow-adbc] lidavidm commented on a diff in pull request #883: feat(c/driver/postgresql): Handle NUMERIC type by converting to string
lidavidm commented on code in PR #883:
URL: https://github.com/apache/arrow-adbc/pull/883#discussion_r1258885026
##########
c/driver/postgresql/postgres_copy_reader.h:
##########
@@ -211,6 +212,172 @@ class PostgresCopyNetworkEndianFieldReader : public PostgresCopyFieldReader {
}
};
+// Converts COPY resulting from the Postgres NUMERIC type into a string.
+// Rewritten based on the Postgres implementation of NUMERIC cast to string in
+// src/backend/utils/adt/numeric.c : get_str_from_var() (Note that in the initial source,
+// DEC_DIGITS is always 4 and DBASE is always 10000).
+//
+// Briefly, the Postgres representation of "numeric" is an array of int16_t ("digits")
+// from most significant to least significant. Each "digit" is a value between 0000 and
+// 9999. There are weight + 1 digits before the decimal point and dscale digits after the
+// decimal point. Both of those values can be zero or negative. A "sign" component
+// encodes the positive or negativeness of the value and is also used to encode special
+// values (inf, -inf, and nan).
+class PostgresCopyNumericFieldReader : public PostgresCopyFieldReader {
+ public:
+ ArrowErrorCode Read(ArrowBufferView* data, int32_t field_size_bytes, ArrowArray* array,
+ ArrowError* error) override {
+ // -1 for NULL
+ if (field_size_bytes < 0) {
+ return ArrowArrayAppendNull(array, 1);
+ }
+
+ // Read the input
+ if (data->size_bytes < static_cast<int64_t>(4 * sizeof(int16_t))) {
+ ArrowErrorSet(error,
+ "Expected at least %d bytes of field data for numeric copy data but "
+ "only %d bytes of input remain",
+ static_cast<int>(4 * sizeof(int16_t)),
+ static_cast<int>(data->size_bytes)); // NOLINT(runtime/int)
+ return EINVAL;
+ }
+
+ int16_t ndigits = ReadUnsafe<int16_t>(data);
+ int16_t weight = ReadUnsafe<int16_t>(data);
+ uint16_t sign = ReadUnsafe<uint16_t>(data);
+ uint16_t dscale = ReadUnsafe<uint16_t>(data);
+
+ if (data->size_bytes < static_cast<int64_t>(ndigits * sizeof(int16_t))) {
+ ArrowErrorSet(error,
+ "Expected at least %d bytes of field data for numeric digits copy "
+ "data but only %d bytes of input remain",
+ static_cast<int>(ndigits * sizeof(int16_t)),
+ static_cast<int>(data->size_bytes)); // NOLINT(runtime/int)
+ return EINVAL;
+ }
+
+ digits_.clear();
+ for (int16_t i = 0; i < ndigits; i++) {
+ digits_.push_back(ReadUnsafe<int16_t>(data));
+ }
+
+ // Handle special values
+ std::string special_value;
+ switch (sign) {
+ case kNumericNAN:
+ special_value = std::string("nan");
+ break;
+ case kNumericPinf:
+ special_value = std::string("inf");
+ break;
+ case kNumericNinf:
+ special_value = std::string("-inf");
+ break;
+ case kNumericPos:
+ case kNumericNeg:
+ special_value = std::string("");
+ break;
+ default:
+ ArrowErrorSet(error,
+ "Unexpected value for sign read from Postgres numeric field: %d",
+ static_cast<int>(sign));
+ return EINVAL;
+ }
+
+ if (special_value.size() > 0) {
Review Comment:
nit: `!special_value.empty()`
##########
c/driver/postgresql/postgres_copy_reader.h:
##########
@@ -211,6 +212,172 @@ class PostgresCopyNetworkEndianFieldReader : public PostgresCopyFieldReader {
}
};
+// Converts COPY resulting from the Postgres NUMERIC type into a string.
+// Rewritten based on the Postgres implementation of NUMERIC cast to string in
+// src/backend/utils/adt/numeric.c : get_str_from_var() (Note that in the initial source,
+// DEC_DIGITS is always 4 and DBASE is always 10000).
+//
+// Briefly, the Postgres representation of "numeric" is an array of int16_t ("digits")
+// from most significant to least significant. Each "digit" is a value between 0000 and
+// 9999. There are weight + 1 digits before the decimal point and dscale digits after the
+// decimal point. Both of those values can be zero or negative. A "sign" component
+// encodes the positive or negativeness of the value and is also used to encode special
+// values (inf, -inf, and nan).
+class PostgresCopyNumericFieldReader : public PostgresCopyFieldReader {
+ public:
+ ArrowErrorCode Read(ArrowBufferView* data, int32_t field_size_bytes, ArrowArray* array,
+ ArrowError* error) override {
+ // -1 for NULL
+ if (field_size_bytes < 0) {
+ return ArrowArrayAppendNull(array, 1);
+ }
+
+ // Read the input
+ if (data->size_bytes < static_cast<int64_t>(4 * sizeof(int16_t))) {
+ ArrowErrorSet(error,
+ "Expected at least %d bytes of field data for numeric copy data but "
+ "only %d bytes of input remain",
+ static_cast<int>(4 * sizeof(int16_t)),
+ static_cast<int>(data->size_bytes)); // NOLINT(runtime/int)
+ return EINVAL;
+ }
+
+ int16_t ndigits = ReadUnsafe<int16_t>(data);
+ int16_t weight = ReadUnsafe<int16_t>(data);
+ uint16_t sign = ReadUnsafe<uint16_t>(data);
+ uint16_t dscale = ReadUnsafe<uint16_t>(data);
+
+ if (data->size_bytes < static_cast<int64_t>(ndigits * sizeof(int16_t))) {
+ ArrowErrorSet(error,
+ "Expected at least %d bytes of field data for numeric digits copy "
+ "data but only %d bytes of input remain",
+ static_cast<int>(ndigits * sizeof(int16_t)),
+ static_cast<int>(data->size_bytes)); // NOLINT(runtime/int)
+ return EINVAL;
+ }
+
+ digits_.clear();
+ for (int16_t i = 0; i < ndigits; i++) {
+ digits_.push_back(ReadUnsafe<int16_t>(data));
+ }
+
+ // Handle special values
+ std::string special_value;
+ switch (sign) {
+ case kNumericNAN:
+ special_value = std::string("nan");
+ break;
+ case kNumericPinf:
+ special_value = std::string("inf");
+ break;
+ case kNumericNinf:
+ special_value = std::string("-inf");
+ break;
+ case kNumericPos:
+ case kNumericNeg:
+ special_value = std::string("");
+ break;
+ default:
+ ArrowErrorSet(error,
+ "Unexpected value for sign read from Postgres numeric field: %d",
+ static_cast<int>(sign));
+ return EINVAL;
+ }
+
+ if (special_value.size() > 0) {
+ NANOARROW_RETURN_NOT_OK(
+ ArrowBufferAppend(data_, special_value.data(), special_value.size()));
+ NANOARROW_RETURN_NOT_OK(ArrowBufferAppendInt32(offsets_, data_->size_bytes));
+ return AppendValid(array);
+ }
+
+ // Calculate string space requirement
+ int64_t max_chars_required = std::max<int64_t>(1, weight + 1 * kDecDigits);
Review Comment:
is the `1 *` necessary?
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