feat: update operator to update a table (#734)

proto/substrait/algebra.proto

@@ -531,6 +531,7 @@ message Rel {
     ReferenceRel reference = 21;
     WriteRel write = 19;
     DdlRel ddl = 20;
+    UpdateRel update = 22;
     // Physical relations
     HashJoinRel hash_join = 13;
     MergeJoinRel merge_join = 14;
@@ -664,6 +665,31 @@ message WriteRel {
   }
 }
 
+// The operator that modifies the columns of a table
+message UpdateRel {
+  oneof update_type {
+    NamedTable named_table = 1;
+  }
+
+  NamedStruct table_schema = 2; // The full schema of the named_table
+  Expression condition = 3; // condition to be met for the update to be applied on a record
+
+  // The list of transformations to apply to the columns of the named_table
+  repeated TransformExpression transformations = 4;
+
+  message TransformExpression {
+    Expression transformation = 1; // the transformation to apply
+    int32 column_target = 2; // index of the column to apply the transformation to
+  }
+}
+
+// A base table. The list of string is used to represent namespacing (e.g., mydb.mytable).
+// This assumes shared catalog between systems exchanging a message.
+message NamedTable {
+  repeated string names = 1;
+  substrait.extensions.AdvancedExtension advanced_extension = 10;
+}
+
 // Hash joins and merge joins are a specialization of the general join where the join
 // expression is an series of comparisons between fields that are ANDed together.  The
 // behavior of this comparison is flexible

site/docs/relations/logical_relations.md

@@ -474,6 +474,32 @@ Write definition types are built by the community and added to the specification
 | Format   | Enumeration of available formats. Only current option is PARQUET. | Required |
 
 
+## Update Operator
+
+The update operator applies a set of column transformations on a named table and writes to a storage. 
+
+| Signature            | Value                                 |
+| -------------------- |---------------------------------------|
+| Inputs               | 0                                     |
+| Outputs              | 1                                     |
+| Property Maintenance | Output is number of modified records  |
+
+### Update Properties
+
+| Property               | Description                                                                          | Required                                         |
+|------------------------|--------------------------------------------------------------------------------------|--------------------------------------------------|
+| Update Type            | Definition of which object we are operating on (e.g., a fully-qualified table name). | Required                                         |
+| Table Schema           | The names and types of all the columns of the input table                            | Required                                         |
+| Update Condition       | The condition that must be met for a record to be updated.                           | Required                                         |
+| Update Transformations | The set of column updates to be applied to the table.                                | Required                                         |
+
+=== "UpdateRel Message"
+
+    ```proto
+%%% proto.algebra.UpdateRel %%%
+    ```
+
+
 ## DDL (Data Definition Language) Operator
 
 The operator that defines modifications of a database schema (CREATE/DROP/ALTER for TABLE and VIEWS).