exec/colserde: add arrow format serialization/deserialization

This commit is heavily based off of #34763 (thanks @danhhz!).

It adds a colserde pkg to serialize and deserialize arrow batches using
flatbuffers into the standard Arrow IPC format
(https://arrow.apache.org/docs/format/IPC.html) allowing for
zero-allocation serialization. The goal here is to only support the
necessary subset for columnar execution to send data batches so
messages such as schema information are not supported and left up
to the caller to provide.

Release note: None

Author: asubiotto

Gopkg.lock

@@ -0,0 +1,20 @@
+// Copyright 2019 The Cockroach Authors.
+//
+// Licensed 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.
+
+// Package arrowserde contains the flatbuffer generated code used for Apache
+// Arrow serialization (and some small helpers associated with the generated
+// code).
+//
+// Generated by: flatc --go --gen-onefile --go-namespace arrowserde -o . *.fbs
+package arrowserde

pkg/sql/exec/colserde/arrowserde/doc.go

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+// 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.
+
+include "schema.fbs";
+
+namespace org.apache.arrow.flatbuf;
+
+/// ----------------------------------------------------------------------
+/// Arrow File metadata
+///
+
+table Footer {
+  version: org.apache.arrow.flatbuf.MetadataVersion;
+
+  schema: org.apache.arrow.flatbuf.Schema;
+
+  dictionaries: [ Block ];
+
+  recordBatches: [ Block ];
+}
+
+struct Block {
+
+  /// Index to the start of the RecordBlock (note this is past the Message header)
+  offset: long;
+
+  /// Length of the metadata
+  metaDataLength: int;
+
+  /// Length of the data (this is aligned so there can be a gap between this and
+  /// the metatdata).
+  bodyLength: long;
+}
+
+root_type Footer;

pkg/sql/exec/colserde/arrowserde/file.fbs

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+// 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.
+
+include "schema.fbs";
+include "tensor.fbs";
+
+namespace org.apache.arrow.flatbuf;
+
+/// ----------------------------------------------------------------------
+/// Data structures for describing a table row batch (a collection of
+/// equal-length Arrow arrays)
+
+/// Metadata about a field at some level of a nested type tree (but not
+/// its children).
+///
+/// For example, a List<Int16> with values [[1, 2, 3], null, [4], [5, 6], null]
+/// would have {length: 5, null_count: 2} for its List node, and {length: 6,
+/// null_count: 0} for its Int16 node, as separate FieldNode structs
+struct FieldNode {
+  /// The number of value slots in the Arrow array at this level of a nested
+  /// tree
+  length: long;
+
+  /// The number of observed nulls. Fields with null_count == 0 may choose not
+  /// to write their physical validity bitmap out as a materialized buffer,
+  /// instead setting the length of the bitmap buffer to 0.
+  null_count: long;
+}
+
+/// A data header describing the shared memory layout of a "record" or "row"
+/// batch. Some systems call this a "row batch" internally and others a "record
+/// batch".
+table RecordBatch {
+  /// number of records / rows. The arrays in the batch should all have this
+  /// length
+  length: long;
+
+  /// Nodes correspond to the pre-ordered flattened logical schema
+  nodes: [FieldNode];
+
+  /// Buffers correspond to the pre-ordered flattened buffer tree
+  ///
+  /// The number of buffers appended to this list depends on the schema. For
+  /// example, most primitive arrays will have 2 buffers, 1 for the validity
+  /// bitmap and 1 for the values. For struct arrays, there will only be a
+  /// single buffer for the validity (nulls) bitmap
+  buffers: [Buffer];
+}
+
+/// For sending dictionary encoding information. Any Field can be
+/// dictionary-encoded, but in this case none of its children may be
+/// dictionary-encoded.
+/// There is one vector / column per dictionary, but that vector / column
+/// may be spread across multiple dictionary batches by using the isDelta
+/// flag
+
+table DictionaryBatch {
+  id: long;
+  data: RecordBatch;
+
+  /// If isDelta is true the values in the dictionary are to be appended to a
+  /// dictionary with the indicated id
+  isDelta: bool = false;
+}
+
+/// ----------------------------------------------------------------------
+/// The root Message type
+
+/// This union enables us to easily send different message types without
+/// redundant storage, and in the future we can easily add new message types.
+///
+/// Arrow implementations do not need to implement all of the message types,
+/// which may include experimental metadata types. For maximum compatibility,
+/// it is best to send data using RecordBatch
+union MessageHeader {
+  Schema, DictionaryBatch, RecordBatch, Tensor, SparseTensor
+}
+
+table Message {
+  version: org.apache.arrow.flatbuf.MetadataVersion;
+  header: MessageHeader;
+  bodyLength: long;
+}
+
+root_type Message;