feat: add initial support for DDL and data modification operator (#128)

proto/substrait/algebra.proto

@@ -364,6 +364,76 @@ message Rel {
   }
 }
 
+// A base table for writing. The list of string is used to represent namespacing (e.g., mydb.mytable).
+// This assumes shared catalog between systems exchanging a message.
+// it also includes a base schema, and default values
+message NamedTableWrite {
+  repeated string names = 1;
+  // The columns that will be modified (representing after-image of a schema change)
+  NamedStruct base_schema = 2;
+  // The default values for the columns (representing after-image of a schema change)
+  repeated Expression.Literal defaults = 3;
+
+  substrait.extensions.AdvancedExtension advanced_extension = 10;
+}
+
+message DdlRel {
+  // Definition of which type of scan operation is to be performed
+  oneof write_type {
+    NamedTableWrite named_table = 1;
+    ReadRel.ExtensionTable extension_table = 2;
+  }
+
+  //TODO add constraints/indexes/etc..?
+
+  // The type of operation to perform
+  DdlOp op = 3;
+
+  // The body of the CREATE VIEW / CTAS
+  Rel input = 4;
+
+  enum DdlOp {
+    DDL_OP_UNSPECIFIED = 0;
+    DDL_OP_CREATE_TABLE = 1;
+    DDL_OP_DROP_TABLE = 2;
+    DDL_OP_ALTER_TABLE = 3;
+
+    DDL_OP_CREATE_VIEW = 4;
+    DDL_OP_CREATE_OR_REPLACE = 5;
+    DDL_OP_DROP_VIEW = 6;
+  }
+}
+
+// The operator that modifies the schema/content of a database
+message WriteRel {
+  // Definition of which type of write operation is to be performed
+  oneof write_type {
+    NamedTableWrite named_table = 1;
+    ReadRel.LocalFiles local_files = 2;
+    ReadRel.ExtensionTable extension_table = 3;
+  }
+
+  // The type of operation to perform
+  WriteOp op = 4;
+
+  // The relation that determines the tuples to add/remove/modify
+  // remaining columns are left as-is or to default (for INSERT).
+  Rel input = 5;
+
+  // The rel that specifies the output of the operator. It allows references
+  // to DELETED.<col_name> or INSERTED.<col_name>. It can also compute simply count of
+  // affected tuples (per common behavior of most RDBMS). Defaults to no output.
+  Rel output = 6;
+
+  enum WriteOp {
+    WRITE_OP_UNSPECIFIED = 0;
+    WRITE_OP_INSERT = 1;
+    WRITE_OP_INSERT_OR_REPLACE = 2;
+    WRITE_OP_DELETE = 3;
+    WRITE_OP_UPDATE = 4;
+  }
+}
+
 // The argument of a function
 message FunctionArgument {
   oneof arg_type {

site/docs/relations/logical_relations.md

@@ -300,17 +300,16 @@ The aggregate operation groups input data on one or more sets of grouping keys,
 %%% proto.algebra.AggregateRel %%%
     ```
 
-
 ## Write Operator
 
 The write operator is an operator that consumes one output and writes it to storage. A simple example would be writing Parquet files. It is expected that many types of writes will be added over time.
 
-| Signature            | Value           |
-| -------------------- | --------------- |
-| Inputs               | 1               |
-| Outputs              | 0               |
-| Property Maintenance | N/A (no output) |
-| Direct Output Order  | N/A (no output) |
+| Signature            | Value                |
+| -------------------- |----------------------|
+| Inputs               | 1                    |
+| Outputs              | 1                    |
+| Property Maintenance | N/A (no output)      |
+| Direct Output Order  | Unchanged from input |
 
 ### Write Properties
 
@@ -326,6 +325,13 @@ The write operator is an operator that consumes one output and writes it to stor
 
 Write definition types are built by the community and added to the specification. This is a portion of specification that is expected to grow rapidly.
 
+
+=== "WriteRel Message"
+
+    ```proto
+%%% proto.algebra.WriteRel %%%
+    ```
+
 #### Virtual Table
 
 | Property | Description                                                  | Required                     |
@@ -343,7 +349,25 @@ Write definition types are built by the community and added to the specification
 | Format   | Enumeration of available formats. Only current option is PARQUET. | Required |
 
 
+## DDL Operator
+
+The operator that defines modifications of a database schema (CREATE/DROP/ALTER for TABLE and VIEWS).
+
+| Signature            | Value           |
+| -------------------- |-----------------|
+| Inputs               | 1               |
+| Outputs              | 0               |
+| Property Maintenance | N/A (no output) |
+| Direct Output Order  | N/A             |
+
+=== "DdlRel Message"
+
+    ```proto
+%%% proto.algebra.DdlRel %%%
+    ```
 
 ## Discussion Points
 
 * How to handle correlated operations?
+
+