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https://issues.apache.org/jira/browse/HAWQ-465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15206996#comment-15206996
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ASF GitHub Bot commented on HAWQ-465:
-------------------------------------
Github user hornn commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/479#discussion_r57044521
--- Diff: src/backend/utils/adt/pxf_functions.c ---
@@ -0,0 +1,164 @@
+/*
+ * 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 "catalog/external/externalmd.h"
+#include "postgres.h"
+#include "fmgr.h"
+#include "funcapi.h"
+#include "utils/builtins.h"
+
+
+typedef struct ObjectContext
+{
+ ListCell *current_object;
+ ListCell *current_field;
+} ObjectContext;
+
+ListCell* pxf_object_fields_enum_start(text *profile, text *pattern);
+ObjectContext* pxf_object_fields_enum_next(ObjectContext *object_context);
+void pxf_object_fields_enum_end(void);
+
+ListCell*
+pxf_object_fields_enum_start(text *profile, text *pattern)
+{
+ List *objects = NIL;
+
+ char *profile_cstr = text_to_cstring(profile);
+ char *pattern_cstr = text_to_cstring(pattern);
+
+ objects = get_pxf_object_metadata(profile_cstr, pattern_cstr, NULL);
+
+ return list_head(objects);
+}
+
+ObjectContext*
+pxf_object_fields_enum_next(ObjectContext *object_context)
+{
+
+ //first time call
+ if (object_context->current_object && !object_context->current_field)
+ object_context->current_field = list_head(((PxfItem *)
lfirst(object_context->current_object))->fields);
+
+ //next field for the same object
+ else if lnext(object_context->current_field)
+ object_context->current_field =
lnext(object_context->current_field);
+ //next table
+ else if lnext(object_context->current_object)
+ {
+ object_context->current_object =
lnext(object_context->current_object);
+ object_context->current_field = list_head(((PxfItem *)
lfirst(object_context->current_object))->fields);
+
+ //no objects, no fields left
+ } else
+ object_context = NULL;
+
+ return object_context;
+}
+
+void pxf_object_fields_enum_end(void)
+{
+ //cleanup
+}
+
+Datum pxf_get_object_fields(PG_FUNCTION_ARGS)
+{
+ MemoryContext oldcontext;
+ FuncCallContext *funcctx;
+ HeapTuple tuple;
+ Datum result;
+ Datum values[4];
+ bool nulls[4];
+
+ ObjectContext *object_context;
+
+ text *profile = PG_GETARG_TEXT_P(0);
+ text *pattern = PG_GETARG_TEXT_P(1);
+
+ /* stuff done only on the first call of the function */
+ if (SRF_IS_FIRSTCALL())
+ {
+ TupleDesc tupdesc;
+
+ /* create a function context for cross-call persistence */
+ funcctx = SRF_FIRSTCALL_INIT();
+
+ /*
+ * switch to memory context appropriate for multiple function
calls
+ */
+ oldcontext =
MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+ /* initialize object fileds metadata scanning code */
+ object_context = (ObjectContext *)
palloc0(sizeof(ObjectContext));
+ object_context->current_object =
pxf_object_fields_enum_start(profile, pattern);
+ funcctx->user_fctx = (void *) object_context;
+
+ /*
+ * build tupdesc for result tuples. This must match this
function's
+ * pg_proc entry!
+ */
+ tupdesc = CreateTemplateTupleDesc(4, false);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 1, "path",
+ TEXTOID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 2, "objectname",
+ TEXTOID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 3, "columnname",
+ TEXTOID, -1, 0);
+ TupleDescInitEntry(tupdesc, (AttrNumber) 4, "columntype",
--- End diff --
what about the modifiers? are they included in the type?
> Implement stored procedure to return fields metainfo from PXF
> -------------------------------------------------------------
>
> Key: HAWQ-465
> URL: https://issues.apache.org/jira/browse/HAWQ-465
> Project: Apache HAWQ
> Issue Type: Sub-task
> Components: Hcatalog, PXF
> Reporter: Oleksandr Diachenko
> Assignee: Oleksandr Diachenko
> Fix For: 2.0.0
>
>
> User should be able to call built-in function:
> {code}
> select pxf_get_object_fields('source_name', 'container_name', 'object_name');
> pxf_get_object_fields
> {code}
> to retrieve all metadata for given source, container, object.
> Input parameters:
> ||Name||Type||Mode||
> |profile|text|IN|
> |pattern|text|IN|
> |path|text|OUT|
> |objectname|text|OUT|
> |fieldname|text|OUT|
> |fieldtype|text|OUT|
> |fieldmodifiers|text|OUT|
> Example:
> {noformat}
> # select * from pxf_get_object_fields('Hive', 'default/tab*');
> path | objectname | fieldname | fieldtype | fieldmodifiers |
> ---------+-----------------+------------------
> +----------------+-------------------+
> default | table1 | col1 | int4 | not
> null |
> default | table1 | col2 | text |
> |
> default | table2 | col1 | int4 | not
> null |
> default | table2 | col2 | text |
> |
> (4 rows)
> {noformat}
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