Github user jiny2 commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1314#discussion_r154278719
--- Diff: src/include/access/plugstorage.h ---
@@ -0,0 +1,221 @@
+/*
+ * 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.
+ */
+
+/*-------------------------------------------------------------------------
+ *
+ * plugstorage.h
+ *
+ * Pluggable storage definitions. Support external table for now.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef PLUGSTORAGE_H
+#define PLUGSTORAGE_H
+
+#include "postgres.h"
+#include "postgres_ext.h"
+#include "fmgr.h"
+#include "nodes/pg_list.h"
+#include "nodes/plannodes.h"
+#include "nodes/execnodes.h"
+#include "access/sdir.h"
+#include "access/relscan.h"
+#include "access/extprotocol.h"
+#include "access/tupdesc.h"
+#include "access/fileam.h"
+#include "utils/relcache.h"
+#include "executor/tuptable.h"
+
+/* From src/include/access/fileam.h */
+extern char *getExtTblCategoryInFmtOptsStr(char *fmtStr);
+extern char *getExtTblFormatterTypeInFmtOptsStr(char *fmtStr);
+extern char *getExtTblFormatterTypeInFmtOptsList(List *fmtOpts);
+
+
+/*
+ * ExternalTableType
+ *
+ * enum for different types of external tables.
+ *
+ * The different types of external tables can be combinations of
different
+ * protocols and formats. To be specific:
+ * {GPFDIST, GPFDISTS, HTTP, COMMAND, HDFS} X {TEXT, CSV, ORC}
+ *
+ * NOTE:
+ *
+ * The GENERIC external table type is used to simplify the call back
+ * implementation for different combination of external table formats
+ * and protocols. It need to be improved so that each external table
+ * type should get its access method with minimum cost during runtime.
+ *
+ * The fact is that for custom protocol (HDFS), the format types for
+ * TEXT, CSV, and ORC external tables are all 'b' in pg_exttable catalog
+ * table. The formatter information is stored in format options which is
+ * a list strings. Thus, during read and write access of these tables,
+ * there will be performance issue if we get the format type and access
+ * method for them for each tuple.
+ *
+ */
+typedef enum
+{
+ ExternalTableType_GENERIC, /* GENERIC external table format and
protocol */
+ ExternalTableType_PLUG, /* Pluggable format with hdfs protocol,
i.e., ORC */
+ ExternalTableType_Invalid
+} ExternalTableType;
+
+/*
+ * PlugStorageValidatorData is the node type that is passed as fmgr
"context"
+ * info when a function is called by the Pluggable Storage Framework.
+ */
+typedef struct PlugStorageValidatorData
+{
+ /* see T_PlugStorageValidatorData */
+ NodeTag type;
+
+ /* check if format interfaces are implemented in pg_proc */
+ char *format_name;
+
+ /* check if format options and their values are valid */
+ List *format_opts;
+ char *format_str;
+ char *encoding_name;
+ bool is_writable;
+
+ /* check if format data types are supported in table definition */
+ TupleDesc tuple_desc;
+
+} PlugStorageValidatorData;
+
+typedef struct PlugStorageValidatorData *PlugStorageValidator;
+
+/*
+ * PlugStorageData is used to pass args between hawq and pluggable data
formats.
+ */
+typedef struct PlugStorageData
+{
+ NodeTag type; /* see T_PlugStorageData */
+ int ps_table_type;
+ int ps_formatter_type;
+ char *ps_formatter_name;
+ int ps_error_ao_seg_no;
+ Relation ps_relation;
+ PlanState *ps_plan_state;
+ ExternalScan *ps_ext_scan;
+ ScanState *ps_scan_state;
+ ScanDirection ps_scan_direction;
+ FileScanDesc ps_file_scan_desc;
+ ExternalScanState *ps_ext_scan_state;
+ ResultRelSegFileInfo *ps_result_seg_file_info;
+ ExternalInsertDesc ps_ext_insert_desc;
+ ExternalSelectDesc ps_ext_select_desc;
+ bool ps_has_tuple;
+ Oid ps_tuple_oid;
+ TupleTableSlot *ps_tuple_table_slot;
+
+} PlugStorageData;
+
+typedef PlugStorageData *PlugStorage;
+
+
+/*
+ * getExternalTableTypeList
+ * getExternalTableTypeStr
+ *
+ * Return the table type for a given external table
+ *
+ * Currently it is an implementation with performance cost due to the
+ * fact that the format types for TEXT, CSV, and ORC external tables
+ * with customer protocol (HDFS) are all 'b' in pg_exttable catalog
+ * table. It needs to visit the format options to get the table type.
+ */
+void getExternalTableTypeList(const char formatType,
+ List *formatOptions,
+ int *formatterType,
+ char **formatterName);
+
+void getExternalTableTypeStr(const char formatType,
+ char *formatOptions,
+ int *formatterType,
--- End diff --
please double check this format
---
