/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

syntax = 'proto3';

package spark.connect;

import "google/protobuf/any.proto";
import "spark/connect/expressions.proto";
import "spark/connect/types.proto";
import "spark/connect/catalog.proto";
import "spark/connect/common.proto";
import "spark/connect/ml_common.proto";

option java_multiple_files = true;
option java_package = "org.apache.spark.connect.proto";
option go_package = "internal/generated";

// The main [[Relation]] type. Fundamentally, a relation is a typed container
// that has exactly one explicit relation type set.
//
// When adding new relation types, they have to be registered here.
message Relation {
  RelationCommon common = 1;
  oneof rel_type {
    Read read = 2;
    Project project = 3;
    Filter filter = 4;
    Join join = 5;
    SetOperation set_op = 6;
    Sort sort = 7;
    Limit limit = 8;
    Aggregate aggregate = 9;
    SQL sql = 10;
    LocalRelation local_relation = 11;
    Sample sample = 12;
    Offset offset = 13;
    Deduplicate deduplicate = 14;
    Range range = 15;
    SubqueryAlias subquery_alias = 16;
    Repartition repartition = 17;
    ToDF to_df = 18;
    WithColumnsRenamed with_columns_renamed = 19;
    ShowString show_string = 20;
    Drop drop = 21;
    Tail tail = 22;
    WithColumns with_columns = 23;
    Hint hint = 24;
    Unpivot unpivot = 25;
    ToSchema to_schema = 26;
    RepartitionByExpression repartition_by_expression = 27;
    MapPartitions map_partitions = 28;
    CollectMetrics collect_metrics = 29;
    Parse parse = 30;
    GroupMap group_map = 31;
    CoGroupMap co_group_map = 32;
    WithWatermark with_watermark = 33;
    ApplyInPandasWithState apply_in_pandas_with_state = 34;
    HtmlString html_string = 35;
    CachedLocalRelation cached_local_relation = 36;
    CachedRemoteRelation cached_remote_relation = 37;
    CommonInlineUserDefinedTableFunction common_inline_user_defined_table_function = 38;
    AsOfJoin as_of_join = 39;
    CommonInlineUserDefinedDataSource common_inline_user_defined_data_source = 40;
    WithRelations with_relations = 41;
    Transpose transpose = 42;
    UnresolvedTableValuedFunction unresolved_table_valued_function = 43;
    LateralJoin lateral_join = 44;
    ChunkedCachedLocalRelation chunked_cached_local_relation = 45;

    // NA functions
    NAFill fill_na = 90;
    NADrop drop_na = 91;
    NAReplace replace = 92;

    // stat functions
    StatSummary summary = 100;
    StatCrosstab crosstab = 101;
    StatDescribe describe = 102;
    StatCov cov = 103;
    StatCorr corr = 104;
    StatApproxQuantile approx_quantile = 105;
    StatFreqItems freq_items = 106;
    StatSampleBy sample_by = 107;

    // Catalog API (experimental / unstable)
    Catalog catalog = 200;

    // ML relation
    MlRelation ml_relation = 300;

    // This field is used to mark extensions to the protocol. When plugins generate arbitrary
    // relations they can add them here. During the planning the correct resolution is done.
    google.protobuf.Any extension = 998;
    Unknown unknown = 999;
  }
}

// Relation to represent ML world
message MlRelation {
  oneof ml_type {
    Transform transform = 1;
    Fetch fetch = 2;
  }
  // (Optional) the dataset for restoring the model summary
  optional Relation model_summary_dataset = 3;

  // Relation to represent transform(input) of the operator
  // which could be a cached model or a new transformer
  message Transform {
    oneof operator {
      // Object reference
      ObjectRef obj_ref = 1;
      // Could be an ML transformer like VectorAssembler
      MlOperator transformer = 2;
    }
    // the input dataframe
    Relation input = 3;
    // the operator specific parameters
    MlParams params = 4;
  }
}

// Message for fetching attribute from object on the server side.
// Fetch can be represented as a Relation or a ML command
// Command: model.coefficients, model.summary.weightedPrecision which
// returns the final literal result
// Relation: model.summary.roc which returns a DataFrame (Relation)
message Fetch {
  // (Required) reference to the object on the server side
  ObjectRef obj_ref = 1;
  // (Required) the calling method chains
  repeated Method methods = 2;

  // Represents a method with inclusion of method name and its arguments
  message Method {
    // (Required) the method name
    string method = 1;
    // (Optional) the arguments of the method
    repeated Args args = 2;

    message Args {
      oneof args_type {
        Expression.Literal param = 1;
        Relation input = 2;
      }
    }
  }
}

// Used for testing purposes only.
message Unknown {}

// Common metadata of all relations.
message RelationCommon {
  // (Required) Shared relation metadata.
  string source_info = 1 [deprecated=true];

  // (Optional) A per-client globally unique id for a given connect plan.
  optional int64 plan_id = 2;

  // (Optional) Keep the information of the origin for this expression such as stacktrace.
  Origin origin = 3;
}

// Relation that uses a SQL query to generate the output.
message SQL {
  // (Required) The SQL query.
  string query = 1;

  // (Optional) A map of parameter names to literal expressions.
  map<string, Expression.Literal> args = 2 [deprecated=true];

  // (Optional) A sequence of literal expressions for positional parameters in the SQL query text.
  repeated Expression.Literal pos_args = 3 [deprecated=true];

  // (Optional) A map of parameter names to expressions.
  // It cannot coexist with `pos_arguments`.
  map<string, Expression> named_arguments = 4;

  // (Optional) A sequence of expressions for positional parameters in the SQL query text.
  // It cannot coexist with `named_arguments`.
  repeated Expression pos_arguments = 5;
}

// Relation of type [[WithRelations]].
//
// This relation contains a root plan, and one or more references that are used by the root plan.
// There are two ways of referencing a relation, by name (through a subquery alias), or by plan_id
// (using RelationCommon.plan_id).
//
// This relation can be used to implement CTEs, describe DAGs, or to reduce tree depth.
message WithRelations {
  // (Required) Plan at the root of the query tree. This plan is expected to contain one or more
  // references. Those references get expanded later on by the engine.
  Relation root = 1;

  // (Required) Plans referenced by the root plan. Relations in this list are also allowed to
  // contain references to other relations in this list, as long they do not form cycles.
  repeated Relation references = 2;
}

// Relation that reads from a file / table or other data source. Does not have additional
// inputs.
message Read {
  oneof read_type {
    NamedTable named_table = 1;
    DataSource data_source = 2;
  }

  // (Optional) Indicates if this is a streaming read.
  bool is_streaming = 3;

  message NamedTable {
    // (Required) Unparsed identifier for the table.
    string unparsed_identifier = 1;

    // Options for the named table. The map key is case insensitive.
    map<string, string> options = 2;
  }

  message DataSource {
    // (Optional) Supported formats include: parquet, orc, text, json, parquet, csv, avro.
    //
    // If not set, the value from SQL conf 'spark.sql.sources.default' will be used.
    optional string format = 1;

    // (Optional) If not set, Spark will infer the schema.
    //
    // This schema string should be either DDL-formatted or JSON-formatted.
    optional string schema = 2;

    // Options for the data source. The context of this map varies based on the
    // data source format. This options could be empty for valid data source format.
    // The map key is case insensitive.
    map<string, string> options = 3;

    // (Optional) A list of path for file-system backed data sources.
    repeated string paths = 4;

    // (Optional) Condition in the where clause for each partition.
    //
    // This is only supported by the JDBC data source.
    repeated string predicates = 5;
  }
}

// Projection of a bag of expressions for a given input relation.
//
// The input relation must be specified.
// The projected expression can be an arbitrary expression.
message Project {
  // (Optional) Input relation is optional for Project.
  //
  // For example, `SELECT ABS(-1)` is valid plan without an input plan.
  Relation input = 1;

  // (Required) A Project requires at least one expression.
  repeated Expression expressions = 3;
}

// Relation that applies a boolean expression `condition` on each row of `input` to produce
// the output result.
message Filter {
  // (Required) Input relation for a Filter.
  Relation input = 1;

  // (Required) A Filter must have a condition expression.
  Expression condition = 2;
}

// Relation of type [[Join]].
//
// `left` and `right` must be present.
message Join {
  // (Required) Left input relation for a Join.
  Relation left = 1;

  // (Required) Right input relation for a Join.
  Relation right = 2;

  // (Optional) The join condition. Could be unset when `using_columns` is utilized.
  //
  // This field does not co-exist with using_columns.
  Expression join_condition = 3;

  // (Required) The join type.
  JoinType join_type = 4;

  // Optional. using_columns provides a list of columns that should present on both sides of
  // the join inputs that this Join will join on. For example A JOIN B USING col_name is
  // equivalent to A JOIN B on A.col_name = B.col_name.
  //
  // This field does not co-exist with join_condition.
  repeated string using_columns = 5;

  enum JoinType {
    JOIN_TYPE_UNSPECIFIED = 0;
    JOIN_TYPE_INNER = 1;
    JOIN_TYPE_FULL_OUTER = 2;
    JOIN_TYPE_LEFT_OUTER = 3;
    JOIN_TYPE_RIGHT_OUTER = 4;
    JOIN_TYPE_LEFT_ANTI = 5;
    JOIN_TYPE_LEFT_SEMI = 6;
    JOIN_TYPE_CROSS = 7;
  }

  // (Optional) Only used by joinWith. Set the left and right join data types.
  optional JoinDataType join_data_type = 6;

  message JoinDataType {
    // If the left data type is a struct.
    bool is_left_struct = 1;
    // If the right data type is a struct.
    bool is_right_struct = 2;
  }
}

// Relation of type [[SetOperation]]
message SetOperation {
  // (Required) Left input relation for a Set operation.
  Relation left_input = 1;

  // (Required) Right input relation for a Set operation.
  Relation right_input = 2;

  // (Required) The Set operation type.
  SetOpType set_op_type = 3;

  // (Optional) If to remove duplicate rows.
  //
  // True to preserve all results.
  // False to remove duplicate rows.
  optional bool is_all = 4;

  // (Optional) If to perform the Set operation based on name resolution.
  //
  // Only UNION supports this option.
  optional bool by_name = 5;

  // (Optional) If to perform the Set operation and allow missing columns.
  //
  // Only UNION supports this option.
  optional bool allow_missing_columns = 6;

  enum SetOpType {
    SET_OP_TYPE_UNSPECIFIED = 0;
    SET_OP_TYPE_INTERSECT = 1;
    SET_OP_TYPE_UNION = 2;
    SET_OP_TYPE_EXCEPT = 3;
  }
}

// Relation of type [[Limit]] that is used to `limit` rows from the input relation.
message Limit {
  // (Required) Input relation for a Limit.
  Relation input = 1;

  // (Required) the limit.
  int32 limit = 2;
}

// Relation of type [[Offset]] that is used to read rows staring from the `offset` on
// the input relation.
message Offset {
  // (Required) Input relation for an Offset.
  Relation input = 1;

  // (Required) the limit.
  int32 offset = 2;
}

// Relation of type [[Tail]] that is used to fetch `limit` rows from the last of the input relation.
message Tail {
  // (Required) Input relation for an Tail.
  Relation input = 1;

  // (Required) the limit.
  int32 limit = 2;
}

// Relation of type [[Aggregate]].
message Aggregate {
  // (Required) Input relation for a RelationalGroupedDataset.
  Relation input = 1;

  // (Required) How the RelationalGroupedDataset was built.
  GroupType group_type = 2;

  // (Required) Expressions for grouping keys
  repeated Expression grouping_expressions = 3;

  // (Required) List of values that will be translated to columns in the output DataFrame.
  repeated Expression aggregate_expressions = 4;

  // (Optional) Pivots a column of the current `DataFrame` and performs the specified aggregation.
  Pivot pivot = 5;

  // (Optional) List of values that will be translated to columns in the output DataFrame.
  repeated GroupingSets grouping_sets = 6;

  enum GroupType {
    GROUP_TYPE_UNSPECIFIED = 0;
    GROUP_TYPE_GROUPBY = 1;
    GROUP_TYPE_ROLLUP = 2;
    GROUP_TYPE_CUBE = 3;
    GROUP_TYPE_PIVOT = 4;
    GROUP_TYPE_GROUPING_SETS = 5;
  }

  message Pivot {
    // (Required) The column to pivot
    Expression col = 1;

    // (Optional) List of values that will be translated to columns in the output DataFrame.
    //
    // Note that if it is empty, the server side will immediately trigger a job to collect
    // the distinct values of the column.
    repeated Expression.Literal values = 2;
  }

  message GroupingSets {
    // (Required) Individual grouping set
    repeated Expression grouping_set = 1;
  }
}

// Relation of type [[Sort]].
message Sort {
  // (Required) Input relation for a Sort.
  Relation input = 1;

  // (Required) The ordering expressions
  repeated Expression.SortOrder order = 2;

  // (Optional) if this is a global sort.
  optional bool is_global = 3;
}


// Drop specified columns.
message Drop {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) columns to drop.
  repeated Expression columns = 2;

  // (Optional) names of columns to drop.
  repeated string column_names = 3;
}


// Relation of type [[Deduplicate]] which have duplicate rows removed, could consider either only
// the subset of columns or all the columns.
message Deduplicate {
  // (Required) Input relation for a Deduplicate.
  Relation input = 1;

  // (Optional) Deduplicate based on a list of column names.
  //
  // This field does not co-use with `all_columns_as_keys`.
  repeated string column_names = 2;

  // (Optional) Deduplicate based on all the columns of the input relation.
  //
  // This field does not co-use with `column_names`.
  optional bool all_columns_as_keys = 3;

  // (Optional) Deduplicate within the time range of watermark.
  optional bool within_watermark = 4;
}

// A relation that does not need to be qualified by name.
message LocalRelation {
  // (Optional) Local collection data serialized into Arrow IPC streaming format which contains
  // the schema of the data.
  optional bytes data = 1;

  // (Optional) The schema of local data.
  // It should be either a DDL-formatted type string or a JSON string.
  //
  // The server side will update the column names and data types according to this schema.
  // If the 'data' is not provided, then this schema will be required.
  optional string schema = 2;
}

// A local relation that has been cached already.
// CachedLocalRelation doesn't support LocalRelations of size over 2GB.
message CachedLocalRelation {
  // `userId` and `sessionId` fields are deleted since the server must always use the active
  // session/user rather than arbitrary values provided by the client. It is never valid to access
  // a local relation from a different session/user.
  reserved 1, 2;
  reserved "userId", "sessionId";

  // (Required) A sha-256 hash of the serialized local relation in proto, see LocalRelation.
  string hash = 3;
}

// A local relation that has been cached already.
message ChunkedCachedLocalRelation {
  // (Required) A list of sha-256 hashes for representing LocalRelation.data.
  // Data is serialized in Arrow IPC streaming format, each batch is cached on the server as
  // a separate artifact. Each hash represents one batch stored on the server.
  // Hashes are hex-encoded strings (e.g., "a3b2c1d4...").
  repeated string dataHashes = 1;

  // (Optional) A sha-256 hash of the serialized LocalRelation.schema.
  // Scala clients always provide the schema, Python clients can omit it.
  // Hash is a hex-encoded string (e.g., "a3b2c1d4...").
  optional string schemaHash = 2;
}

// Represents a remote relation that has been cached on server.
message CachedRemoteRelation {
  // (Required) ID of the remote related (assigned by the service).
  string relation_id = 1;
}

// Relation of type [[Sample]] that samples a fraction of the dataset.
message Sample {
  // (Required) Input relation for a Sample.
  Relation input = 1;

  // (Required) lower bound.
  double lower_bound = 2;

  // (Required) upper bound.
  double upper_bound = 3;

  // (Optional) Whether to sample with replacement.
  optional bool with_replacement = 4;

  // (Required) The random seed.
  // This field is required to avoid generating mutable dataframes (see SPARK-48184 for details),
  // however, still keep it 'optional' here for backward compatibility.
  optional int64 seed = 5;

  // (Required) Explicitly sort the underlying plan to make the ordering deterministic or cache it.
  // This flag is true when invoking `dataframe.randomSplit` to randomly splits DataFrame with the
  // provided weights. Otherwise, it is false.
  bool deterministic_order = 6;
}

// Relation of type [[Range]] that generates a sequence of integers.
message Range {
  // (Optional) Default value = 0
  optional int64 start = 1;

  // (Required)
  int64 end = 2;

  // (Required)
  int64 step = 3;

  // Optional. Default value is assigned by 1) SQL conf "spark.sql.leafNodeDefaultParallelism" if
  // it is set, or 2) spark default parallelism.
  optional int32 num_partitions = 4;
}

// Relation alias.
message SubqueryAlias {
  // (Required) The input relation of SubqueryAlias.
  Relation input = 1;

  // (Required) The alias.
  string alias = 2;

  // (Optional) Qualifier of the alias.
  repeated string qualifier = 3;
}

// Relation repartition.
message Repartition {
  // (Required) The input relation of Repartition.
  Relation input = 1;

  // (Required) Must be positive.
  int32 num_partitions = 2;

  // (Optional) Default value is false.
  optional bool shuffle = 3;
}

// Compose the string representing rows for output.
// It will invoke 'Dataset.showString' to compute the results.
message ShowString {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) Number of rows to show.
  int32 num_rows = 2;

  // (Required) If set to more than 0, truncates strings to
  // `truncate` characters and all cells will be aligned right.
  int32 truncate = 3;

  // (Required) If set to true, prints output rows vertically (one line per column value).
  bool vertical = 4;
}

// Compose the string representing rows for output.
// It will invoke 'Dataset.htmlString' to compute the results.
message HtmlString {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) Number of rows to show.
  int32 num_rows = 2;

  // (Required) If set to more than 0, truncates strings to
  // `truncate` characters and all cells will be aligned right.
  int32 truncate = 3;
}

// Computes specified statistics for numeric and string columns.
// It will invoke 'Dataset.summary' (same as 'StatFunctions.summary')
// to compute the results.
message StatSummary {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) Statistics from to be computed.
  //
  // Available statistics are:
  //  count
  //  mean
  //  stddev
  //  min
  //  max
  //  arbitrary approximate percentiles specified as a percentage (e.g. 75%)
  //  count_distinct
  //  approx_count_distinct
  //
  // If no statistics are given, this function computes 'count', 'mean', 'stddev', 'min',
  // 'approximate quartiles' (percentiles at 25%, 50%, and 75%), and 'max'.
  repeated string statistics = 2;
}

// Computes basic statistics for numeric and string columns, including count, mean, stddev, min,
// and max. If no columns are given, this function computes statistics for all numerical or
// string columns.
message StatDescribe {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) Columns to compute statistics on.
  repeated string cols = 2;
}

// Computes a pair-wise frequency table of the given columns. Also known as a contingency table.
// It will invoke 'Dataset.stat.crosstab' (same as 'StatFunctions.crossTabulate')
// to compute the results.
message StatCrosstab {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The name of the first column.
  //
  // Distinct items will make the first item of each row.
  string col1 = 2;

  // (Required) The name of the second column.
  //
  // Distinct items will make the column names of the DataFrame.
  string col2 = 3;
}

// Calculate the sample covariance of two numerical columns of a DataFrame.
// It will invoke 'Dataset.stat.cov' (same as 'StatFunctions.calculateCov') to compute the results.
message StatCov {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The name of the first column.
  string col1 = 2;

  // (Required) The name of the second column.
  string col2 = 3;
}

// Calculates the correlation of two columns of a DataFrame. Currently only supports the Pearson
// Correlation Coefficient. It will invoke 'Dataset.stat.corr' (same as
// 'StatFunctions.pearsonCorrelation') to compute the results.
message StatCorr {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The name of the first column.
  string col1 = 2;

  // (Required) The name of the second column.
  string col2 = 3;

  // (Optional) Default value is 'pearson'.
  //
  // Currently only supports the Pearson Correlation Coefficient.
  optional string method = 4;
}

// Calculates the approximate quantiles of numerical columns of a DataFrame.
// It will invoke 'Dataset.stat.approxQuantile' (same as 'StatFunctions.approxQuantile')
// to compute the results.
message StatApproxQuantile {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The names of the numerical columns.
  repeated string cols = 2;

  // (Required) A list of quantile probabilities.
  //
  // Each number must belong to [0, 1].
  // For example 0 is the minimum, 0.5 is the median, 1 is the maximum.
  repeated double probabilities = 3;

  // (Required) The relative target precision to achieve (greater than or equal to 0).
  //
  // If set to zero, the exact quantiles are computed, which could be very expensive.
  // Note that values greater than 1 are accepted but give the same result as 1.
  double relative_error = 4;
}

// Finding frequent items for columns, possibly with false positives.
// It will invoke 'Dataset.stat.freqItems' (same as 'StatFunctions.freqItems')
// to compute the results.
message StatFreqItems {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The names of the columns to search frequent items in.
  repeated string cols = 2;

  // (Optional) The minimum frequency for an item to be considered `frequent`.
  // Should be greater than 1e-4.
  optional double support = 3;
}


// Returns a stratified sample without replacement based on the fraction
// given on each stratum.
// It will invoke 'Dataset.stat.freqItems' (same as 'StatFunctions.freqItems')
// to compute the results.
message StatSampleBy {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The column that defines strata.
  Expression col = 2;

  // (Required) Sampling fraction for each stratum.
  //
  // If a stratum is not specified, we treat its fraction as zero.
  repeated Fraction fractions = 3;

  // (Required) The random seed.
  // This field is required to avoid generating mutable dataframes (see SPARK-48184 for details),
  // however, still keep it 'optional' here for backward compatibility.
  optional int64 seed = 5;

  message Fraction {
    // (Required) The stratum.
    Expression.Literal stratum = 1;

    // (Required) The fraction value. Must be in [0, 1].
    double fraction = 2;
  }
}


// Replaces null values.
// It will invoke 'Dataset.na.fill' (same as 'DataFrameNaFunctions.fill') to compute the results.
// Following 3 parameter combinations are supported:
//  1, 'values' only contains 1 item, 'cols' is empty:
//    replaces null values in all type-compatible columns.
//  2, 'values' only contains 1 item, 'cols' is not empty:
//    replaces null values in specified columns.
//  3, 'values' contains more than 1 items, then 'cols' is required to have the same length:
//    replaces each specified column with corresponding value.
message NAFill {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) Optional list of column names to consider.
  repeated string cols = 2;

  // (Required) Values to replace null values with.
  //
  // Should contain at least 1 item.
  // Only 4 data types are supported now: bool, long, double, string
  repeated Expression.Literal values = 3;
}


// Drop rows containing null values.
// It will invoke 'Dataset.na.drop' (same as 'DataFrameNaFunctions.drop') to compute the results.
message NADrop {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) Optional list of column names to consider.
  //
  // When it is empty, all the columns in the input relation will be considered.
  repeated string cols = 2;

  // (Optional) The minimum number of non-null and non-NaN values required to keep.
  //
  // When not set, it is equivalent to the number of considered columns, which means
  // a row will be kept only if all columns are non-null.
  //
  // 'how' options ('all', 'any') can be easily converted to this field:
  //   - 'all' -> set 'min_non_nulls' 1;
  //   - 'any' -> keep 'min_non_nulls' unset;
  optional int32 min_non_nulls = 3;
}


// Replaces old values with the corresponding values.
// It will invoke 'Dataset.na.replace' (same as 'DataFrameNaFunctions.replace')
// to compute the results.
message NAReplace {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) List of column names to consider.
  //
  // When it is empty, all the type-compatible columns in the input relation will be considered.
  repeated string cols = 2;

  // (Optional) The value replacement mapping.
  repeated Replacement replacements = 3;

  message Replacement {
    // (Required) The old value.
    //
    // Only 4 data types are supported now: null, bool, double, string.
    Expression.Literal old_value = 1;

    // (Required) The new value.
    //
    // Should be of the same data type with the old value.
    Expression.Literal new_value = 2;
  }
}


// Rename columns on the input relation by the same length of names.
message ToDF {
  // (Required) The input relation of RenameColumnsBySameLengthNames.
  Relation input = 1;

  // (Required)
  //
  // The number of columns of the input relation must be equal to the length
  // of this field. If this is not true, an exception will be returned.
  repeated string column_names = 2;
}


// Rename columns on the input relation by a map with name to name mapping.
message WithColumnsRenamed {
  // (Required) The input relation.
  Relation input = 1;


  // (Optional)
  //
  // Renaming column names of input relation from A to B where A is the map key
  // and B is the map value. This is a no-op if schema doesn't contain any A. It
  // does not require that all input relation column names to present as keys.
  // duplicated B are not allowed.
  map<string, string> rename_columns_map = 2 [deprecated=true];

  repeated Rename renames = 3;

  message Rename {
    // (Required) The existing column name.
    string col_name = 1;

    // (Required) The new column name.
    string new_col_name = 2;
  }
}

// Adding columns or replacing the existing columns that have the same names.
message WithColumns {
  // (Required) The input relation.
  Relation input = 1;

  // (Required)
  //
  // Given a column name, apply the corresponding expression on the column. If column
  // name exists in the input relation, then replace the column. If the column name
  // does not exist in the input relation, then adds it as a new column.
  //
  // Only one name part is expected from each Expression.Alias.
  //
  // An exception is thrown when duplicated names are present in the mapping.
  repeated Expression.Alias aliases = 2;
}

message WithWatermark {

  // (Required) The input relation
  Relation input = 1;

  // (Required) Name of the column containing event time.
  string event_time = 2;

  // (Required)
  string delay_threshold = 3;
}

// Specify a hint over a relation. Hint should have a name and optional parameters.
message Hint {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) Hint name.
  //
  // Supported Join hints include BROADCAST, MERGE, SHUFFLE_HASH, SHUFFLE_REPLICATE_NL.
  //
  // Supported partitioning hints include COALESCE, REPARTITION, REPARTITION_BY_RANGE.
  string name = 2;

  // (Optional) Hint parameters.
  repeated Expression parameters = 3;
}

// Unpivot a DataFrame from wide format to long format, optionally leaving identifier columns set.
message Unpivot {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) Id columns.
  repeated Expression ids = 2;

  // (Optional) Value columns to unpivot.
  optional Values values = 3;

  // (Required) Name of the variable column.
  string variable_column_name = 4;

  // (Required) Name of the value column.
  string value_column_name = 5;

  message Values {
    repeated Expression values = 1;
  }
}

// Transpose a DataFrame, switching rows to columns.
// Transforms the DataFrame such that the values in the specified index column
// become the new columns of the DataFrame.
message Transpose {
  // (Required) The input relation.
  Relation input = 1;

  // (Optional) A list of columns that will be treated as the indices.
  // Only single column is supported now.
  repeated Expression index_columns = 2;
}

message UnresolvedTableValuedFunction {
  // (Required) name (or unparsed name for user defined function) for the unresolved function.
  string function_name = 1;

  // (Optional) Function arguments. Empty arguments are allowed.
  repeated Expression arguments = 2;
}

message ToSchema {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The user provided schema.
  //
  // The Sever side will update the dataframe with this schema.
  DataType schema = 2;
}

message RepartitionByExpression {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) The partitioning expressions.
  repeated Expression partition_exprs = 2;

  // (Optional) number of partitions, must be positive.
  optional int32 num_partitions = 3;
}

message MapPartitions {
  // (Required) Input relation for a mapPartitions-equivalent API: mapInPandas, mapInArrow.
  Relation input = 1;

  // (Required) Input user-defined function.
  CommonInlineUserDefinedFunction func = 2;

  // (Optional) Whether to use barrier mode execution or not.
  optional bool is_barrier = 3;

  // (Optional) ResourceProfile id used for the stage level scheduling.
  optional int32 profile_id = 4;
}

message GroupMap {
  // (Required) Input relation for Group Map API: apply, applyInPandas.
  Relation input = 1;

  // (Required) Expressions for grouping keys.
  repeated Expression grouping_expressions = 2;

  // (Required) Input user-defined function.
  CommonInlineUserDefinedFunction func = 3;

  // (Optional) Expressions for sorting. Only used by Scala Sorted Group Map API.
  repeated Expression sorting_expressions = 4;

  // Below fields are only used by (Flat)MapGroupsWithState
  // (Optional) Input relation for initial State.
  Relation initial_input = 5;

  // (Optional) Expressions for grouping keys of the initial state input relation.
  repeated Expression initial_grouping_expressions = 6;

  // (Optional) True if MapGroupsWithState, false if FlatMapGroupsWithState.
  optional bool is_map_groups_with_state = 7;

  // (Optional) The output mode of the function.
  optional string output_mode = 8;

  // (Optional) Timeout configuration for groups that do not receive data for a while.
  optional string timeout_conf = 9;

  // (Optional) The schema for the grouped state.
  optional DataType state_schema = 10;

  // Below fields are used by TransformWithState and TransformWithStateInPandas
  // (Optional) TransformWithState related parameters.
  optional TransformWithStateInfo transform_with_state_info = 11;
}

// Additional input parameters used for TransformWithState operator.
message TransformWithStateInfo {
  // (Required) Time mode string for transformWithState.
  string time_mode = 1;

  // (Optional) Event time column name.
  optional string event_time_column_name = 2;

  // (Optional) Schema for the output DataFrame.
  // Only required used for TransformWithStateInPandas.
  optional DataType output_schema = 3;
}

message CoGroupMap {
  // (Required) One input relation for CoGroup Map API - applyInPandas.
  Relation input = 1;

  // Expressions for grouping keys of the first input relation.
  repeated Expression input_grouping_expressions = 2;

  // (Required) The other input relation.
  Relation other = 3;

  // Expressions for grouping keys of the other input relation.
  repeated Expression other_grouping_expressions = 4;

  // (Required) Input user-defined function.
  CommonInlineUserDefinedFunction func = 5;

  // (Optional) Expressions for sorting. Only used by Scala Sorted CoGroup Map API.
  repeated Expression input_sorting_expressions = 6;

  // (Optional) Expressions for sorting. Only used by Scala Sorted CoGroup Map API.
  repeated Expression other_sorting_expressions = 7;
}

message ApplyInPandasWithState {
  // (Required) Input relation for applyInPandasWithState.
  Relation input = 1;

  // (Required) Expressions for grouping keys.
  repeated Expression grouping_expressions = 2;

  // (Required) Input user-defined function.
  CommonInlineUserDefinedFunction func = 3;

  // (Required) Schema for the output DataFrame.
  string output_schema = 4;

  // (Required) Schema for the state.
  string state_schema = 5;

  // (Required) The output mode of the function.
  string output_mode = 6;

  // (Required) Timeout configuration for groups that do not receive data for a while.
  string timeout_conf = 7;
}

message CommonInlineUserDefinedTableFunction {
  // (Required) Name of the user-defined table function.
  string function_name = 1;

  // (Optional) Whether the user-defined table function is deterministic.
  bool deterministic = 2;

  // (Optional) Function input arguments. Empty arguments are allowed.
  repeated Expression arguments = 3;

  // (Required) Type of the user-defined table function.
  oneof function {
    PythonUDTF python_udtf = 4;
  }
}

message PythonUDTF {
  // (Optional) Return type of the Python UDTF.
  optional DataType return_type = 1;

  // (Required) EvalType of the Python UDTF.
  int32 eval_type = 2;

  // (Required) The encoded commands of the Python UDTF.
  bytes command = 3;

  // (Required) Python version being used in the client.
  string python_ver = 4;
}

message CommonInlineUserDefinedDataSource {
  // (Required) Name of the data source.
  string name = 1;

  // (Required) The data source type.
  oneof data_source {
    PythonDataSource python_data_source = 2;
  }
}

message PythonDataSource {
  // (Required) The encoded commands of the Python data source.
  bytes command = 1;

  // (Required) Python version being used in the client.
  string python_ver = 2;
}

// Collect arbitrary (named) metrics from a dataset.
message CollectMetrics {
  // (Required) The input relation.
  Relation input = 1;

  // (Required) Name of the metrics.
  string name = 2;

  // (Required) The metric sequence.
  repeated Expression metrics = 3;
}

message Parse {
  // (Required) Input relation to Parse. The input is expected to have single text column.
  Relation input = 1;
  // (Required) The expected format of the text.
  ParseFormat format = 2;

  // (Optional) DataType representing the schema. If not set, Spark will infer the schema.
  optional DataType schema = 3;

  // Options for the csv/json parser. The map key is case insensitive.
  map<string, string> options = 4;
  enum ParseFormat {
    PARSE_FORMAT_UNSPECIFIED = 0;
    PARSE_FORMAT_CSV = 1;
    PARSE_FORMAT_JSON = 2;
  }
}

// Relation of type [[AsOfJoin]].
//
// `left` and `right` must be present.
message AsOfJoin {
  // (Required) Left input relation for a Join.
  Relation left = 1;

  // (Required) Right input relation for a Join.
  Relation right = 2;

  // (Required) Field to join on in left DataFrame
  Expression left_as_of = 3;

  // (Required) Field to join on in right DataFrame
  Expression right_as_of = 4;

  // (Optional) The join condition. Could be unset when `using_columns` is utilized.
  //
  // This field does not co-exist with using_columns.
  Expression join_expr = 5;

  // Optional. using_columns provides a list of columns that should present on both sides of
  // the join inputs that this Join will join on. For example A JOIN B USING col_name is
  // equivalent to A JOIN B on A.col_name = B.col_name.
  //
  // This field does not co-exist with join_condition.
  repeated string using_columns = 6;

  // (Required) The join type.
  string join_type = 7;

  // (Optional) The asof tolerance within this range.
  Expression tolerance = 8;

  // (Required) Whether allow matching with the same value or not.
  bool allow_exact_matches = 9;

  // (Required) Whether to search for prior, subsequent, or closest matches.
  string direction = 10;
}

// Relation of type [[LateralJoin]].
//
// `left` and `right` must be present.
message LateralJoin {
  // (Required) Left input relation for a Join.
  Relation left = 1;

  // (Required) Right input relation for a Join.
  Relation right = 2;

  // (Optional) The join condition.
  Expression join_condition = 3;

  // (Required) The join type.
  Join.JoinType join_type = 4;
}
