westonpace commented on a change in pull request #11982:
URL: https://github.com/apache/arrow/pull/11982#discussion_r809469564
##########
File path: format/FlightSql.proto
##########
@@ -867,6 +867,167 @@ enum SqlSupportsConvert {
SQL_CONVERT_VARCHAR = 19;
}
+enum SqlDataType {
+ SQL_TYPE_UNKNOWN_TYPE = 0;
+ SQL_TYPE_CHAR = 1;
+ SQL_TYPE_NUMERIC = 2;
+ SQL_TYPE_DECIMAL = 3;
+ SQL_TYPE_INTEGER = 4;
+ SQL_TYPE_SMALLINT = 5;
+ SQL_TYPE_FLOAT = 6;
+ SQL_TYPE_REAL = 7;
+ SQL_TYPE_DOUBLE = 8;
+ SQL_TYPE_DATETIME = 9;
+ SQL_TYPE_INTERVAL = 10;
+ SQL_TYPE_VARCHAR = 12;
+}
+
+enum SqlDatetimeSubcode {
+ option allow_alias = true;
+ SQL_SUBCODE_UNKNOWN = 0;
+ SQL_SUBCODE_YEAR = 1;
+ SQL_SUBCODE_DATE = 1;
+ SQL_SUBCODE_TIME = 2;
+ SQL_SUBCODE_MONTH = 2;
+ SQL_SUBCODE_TIMESTAMP = 3;
+ SQL_SUBCODE_DAY = 3;
+ SQL_SUBCODE_TIME_WITH_TIMEZONE = 4;
+ SQL_SUBCODE_HOUR = 4;
+ SQL_SUBCODE_TIMESTAMP_WITH_TIMEZONE = 5;
+ SQL_SUBCODE_MINUTE = 5;
+ SQL_SUBCODE_SECOND = 6;
+ SQL_SUBCODE_YEAR_TO_MONTH = 7;
+ SQL_SUBCODE_DAY_TO_HOUR = 8;
+ SQL_SUBCODE_DAY_TO_MINUTE = 9;
+ SQL_SUBCODE_DAY_TO_SECOND = 10;
+ SQL_SUBCODE_HOUR_TO_MINUTE = 11;
+ SQL_SUBCODE_HOUR_TO_SECOND = 12;
+ SQL_SUBCODE_MINUTE_TO_SECOND = 13;
+ SQL_SUBCODE_INTERVAL_YEAR = 101;
+ SQL_SUBCODE_INTERVAL_MONTH = 102;
+ SQL_SUBCODE_INTERVAL_DAY = 103;
+ SQL_SUBCODE_INTERVAL_HOUR = 104;
+ SQL_SUBCODE_INTERVAL_MINUTE = 105;
+ SQL_SUBCODE_INTERVAL_SECOND = 106;
+ SQL_SUBCODE_INTERVAL_YEAR_TO_MONTH = 107;
+ SQL_SUBCODE_INTERVAL_DAY_TO_HOUR = 108;
+ SQL_SUBCODE_INTERVAL_DAY_TO_MINUTE = 109;
+ SQL_SUBCODE_INTERVAL_DAY_TO_SECOND = 110;
+ SQL_SUBCODE_INTERVAL_HOUR_TO_MINUTE = 111;
+ SQL_SUBCODE_INTERVAL_HOUR_TO_SECOND = 112;
+ SQL_SUBCODE_INTERVAL_MINUTE_TO_SECOND = 113;
+}
+
+enum Nullable {
+ /**
+ * Indicates that the fields does not allow the use of null values.
+ */
+ NULLABILITY_NO_NULLS = 0;
+
+ /**
+ * Indicates that the fields allow the use of null values.
+ */
+ NULLABILITY_NULLABLE = 1;
+
+ /**
+ * Indicates that nullability of the fields can not be determined.
+ */
+ NULLABILITY_UNKNOWN = 2;
+}
+
+enum Searchable {
+ /**
+ * Indicates that column can not be used in a WHERE clause.
+ */
+ SEARCHABLE_NONE = 0;
+
+ /**
+ * Indicates that the column can be used in a WHERE clause if it is using a
+ * LIKE predicate.
+ */
+ SEARCHABLE_CHAR = 1;
+
+ /**
+ * Indicates that the column can be used in a WHERE clause using other
predicates
+ * except for LIKE.
+ *
+ * - Allowed operators: comparison, quantified comparison, BETWEEN,
+ * DISTINCT, IN, MATCH, and UNIQUE.
+ */
+ SEARCHABLE_BASIC = 2;
+
+ /**
+ * Indicates that the column can be used in a WHERE clause using any
operator.
+ */
+ SEARCHABLE_FULL = 3;
+}
+
+/*
+ * Represents a request to retrieve information about data type supported on a
Flight SQL enabled backend.
+ * Used in the command member of FlightDescriptor for the following RPC calls:
+ * - GetSchema: return the schema of the query.
+ * - GetFlightInfo: execute the catalog metadata request.
+ *
+ * The returned schema will be:
+ * <
+ * type_name: utf8 not null (The name of the data type, for example:
VARCHAR, INTEGER, etc),
+ * data_type: int not null (The SQL data type),
+ * column_size: int (The maximum size supported by that column.
+ * In case of numeric types, this represents the maximum
precision.
+ * In case of string types, this represents the character
length.
+ * In case of datetime data types, this represents the
length in characters of the string representation.
+ * NULL is returned for data types where column size is
not applicable.),
+ * literal_prefix: utf8 (Character or characters used to prefix a literal,
NULL is returned for
+ * data types where a literal prefix is not
applicable.),
+ * literal_suffix: utf8 (Character or characters used to terminate a literal,
+ * NULL is returned for data types where a literal
suffix is not applicable.),
+ * create_params: list<utf8 not null>
+ * (A list of keywords corresponding to which
parameters can be used when creating
+ * a column for that specific type.
+ * NULL is returned if there are no parameters for the
data type definition.),
+ * nullable: int not null (Shows if the data type accepts a NULL value. The
possible values can be seen in the
+ * Nullable enum.),
+ * case_sensitive: bool not null (Shows if a character data type is
case-sensitive in collations and comparisons),
+ * searchable: int not null (Shows how the data type is used in a WHERE
clause. The possible values can be seen in the
+ * Searchable enum.),
+ * unsigned_attribute: bool (Shows if the data type is unsigned. NULL is
returned if the attribute is
+ * not applicable to the data type or the data
type is not numeric.),
+ * fixed_prec_scale: bool not null (Shows if the data type has predefined
fixed precision and scale.),
Review comment:
There is also a slight difference in semantics when `fixed_prec_scale`
is true. `MONEY` can generally be thought of as a decimal with precision 19
and scale 4 but consider this example on SQL Server 2017...
```
CREATE TABLE sample (mon MONEY, deci DECIMAL(19, 4));
INSERT INTO sample (mon, deci) VALUES (1, 1);
SELECT mon / 100000, deci / 100000 FROM sample;
```
This will return:
| mon / 100000 | deci / 100000 |
| ------------- | ------------- |
| 0 | 0.00001 |
This is because (I believe) a data type with `fixed_prec_scale = true` is
not allowed to be widened as a natural result of arithmetic operations.
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