syntax = "proto2";

package tipb;

option java_multiple_files = true;
option java_package = "com.pingcap.tidb.tipb";

import "expression.proto";
import "schema.proto";

// KeyRange is the encoded index key range, low is closed, high is open. (low <= x < high)
message KeyRange {
	optional bytes low = 1;
	optional bytes high = 2;
}

// ByItem type for group by and order by.
message ByItem {
	optional Expr expr = 1;
	optional bool desc = 2;
}

// SelectRequest works like a simplified select statement.
message SelectRequest {
	// transaction start timestamp.
	optional int64 start_ts = 1;

	// If table_info is not null, it represents a table scan, index_info would be null.
	optional TableInfo table_info = 2;

	// If index_info is not null, it represents an index scan, table_info would be null.
	optional IndexInfo index_info = 3;

	// fields to be selected, fields type can be column reference for simple scan.
	// or aggregation function. If no fields specified, only handle will be returned.
	repeated Expr fields = 4;

	// disjoint handle ranges to be scanned.
	repeated KeyRange ranges = 5;

	// distinct result.
	optional bool distinct = 6;

	// where condition.
	optional Expr where = 7;

	// group by clause.
	repeated ByItem group_by = 8;

	// having clause.
	optional Expr having = 9;

	// order by clause.
	repeated ByItem order_by = 10;

    	// offset of the result.
    	optional int64 offset = 11;

	// limit the result to be returned.
	optional int64 limit = 12;
}

// values are all in text format.
message Row {
	optional bytes handle = 1;
	optional bytes data = 2;
}

message Error {
	optional int32 code = 1;
	optional string msg = 2;
}

// Response for SelectRequest.
message SelectResponse {
	optional Error error = 1;

	// Result rows.
	repeated Row rows = 2;
}