CurtHagenlocher commented on code in PR #3871:
URL: https://github.com/apache/arrow-adbc/pull/3871#discussion_r2710612535
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c/include/arrow-adbc/adbc.h:
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@@ -973,6 +991,95 @@ struct AdbcPartitions {
/// @}
+/// \defgroup adbc-statement-multi Multiple Result Set Execution
+/// Some databases support executing a statement that returns multiple
+/// result sets. This section defines the API for working with such
+/// statements and result sets.
+/// @{
+
+/// \brief A struct for handling a potentially multi-result set execution
+///
+/// This struct is populated by AdbcStatementExecuteMulti and can be used to
iterate
+/// through the result sets of the execution. The caller can use the
NextResultSet or
+/// NextResultSetPartitions functions on the AdbcResultSet struct to iterate
through the
+/// result sets. The caller is responsible for calling the release function
when finished
+/// with the result set.
+///
+/// \since ADBC API revision 1.2.0
+struct ADBC_EXPORT AdbcResultSet {
+ /// \brief opaque implementation-defined state
+ void* private_data;
+
+ /// \brief Release the result set and any associated resources.
+ void (*release)(struct AdbcResultSet* result_set);
+
+ /// \brief Get the next result set from a multi-result-set execution.
+ ///
+ /// The AdbcResultSet must outlive the returned ArrowArrayStream.
+ ///
+ /// The driver can decide whether to allow fetching the next result set
+ /// as a single stream or as a set of partitions. If the driver does not
+ /// support fetching the next result set as a stream (indicating it should
+ /// be fetched as partitions), it should return ADBC_STATUS_NOT_IMPLEMENTED.
+ ///
+ /// To indicate that no additional result sets are available, this should
return
+ /// ADBC_STATUS_OK and set the release callback on out to NULL. The expected
+ /// pattern is that after calling `StatementExecuteMulti`, the caller would
+ /// then call `NextResultSet` repeatedly until it returns ADBC_STATUS_OK and
+ /// sets the release callback to NULL, indicating that there are no more
result sets.
+ /// It is not an error to repeatedly call `NextResultSet` after the last
result set
+ /// has been reached; it should simply continue to return ADBC_STATUS_OK
with a
+ /// NULL release callback.
+ ///
+ /// \param[in] self The result set struct to fetch the next result from.
+ /// \param[out] out The result stream to populate
+ /// \param[out] rows_affected The number of rows affected if known, else -
+ /// \param[out] error An optional location to return an error message if
necessary.
+ ///
+ /// \return ADBC_STATUS_NOT_IMPLEMENTED if the driver only supports fetching
results
+ /// as partitions, ADBC_STATUS_INVALID_STATE if called at an inappropriate
time,
+ /// and ADBC_STATUS_OK (or an appropriate error code) otherwise.
+ AdbcStatusCode (*NextResultSet)(struct AdbcResultSet* self,
Review Comment:
> And/or, some flag or otherwise a way to indicate that you only want the
schema, so the returned ArrowArrayStreams will only have get_schema and won't
return any data.
FWIW, that's the approach that ADO.NET takes. You pass a flag when executing
a command to say "schema only" and then the results you get back look just like
normal query results except that they have no rows.
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