From 8b6f87614b1817e5d97cf88f966ed2f582f8670e Mon Sep 17 00:00:00 2001
From: Jeff Davis <jefdavi@microsoft.com>
Date: Tue, 15 Mar 2022 16:52:05 -0700
Subject: [PATCH] external funcs

---
 src/backend/distributed/Makefile              |  2 --
 src/backend/distributed/shared_library_init.c | 36 ++++++++++++++++---
 src/include/distributed/shared_library_init.h |  2 ++
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/src/backend/distributed/Makefile b/src/backend/distributed/Makefile
index 30d733ba9..ef47a79bf 100644
--- a/src/backend/distributed/Makefile
+++ b/src/backend/distributed/Makefile
@@ -19,8 +19,6 @@ DATA_built = $(generated_sql_files)
 
 # directories with source files
 SUBDIRS = . commands connection ddl deparser executor metadata operations planner progress relay safeclib test transaction utils worker
-# columnar modules
-SUBDIRS += ../columnar
 # enterprise modules
 SUBDIRS +=
 
diff --git a/src/backend/distributed/shared_library_init.c b/src/backend/distributed/shared_library_init.c
index 35909dad9..2047bfade 100644
--- a/src/backend/distributed/shared_library_init.c
+++ b/src/backend/distributed/shared_library_init.c
@@ -360,6 +360,11 @@ _PG_init(void)
 	 */
 	load_file(COLUMNAR_LIB_NAME, false);
 
+	/*
+	 * Now, acquire symbols from columnar module. First, acquire
+	 * the address of the set options hook, and set it so that we
+	 * can propagate options changes.
+	 */
 	ColumnarTableSetOptions_hook_type **ColumnarTableSetOptions_hook_ptr =
 		(ColumnarTableSetOptions_hook_type **) find_rendezvous_variable(
 			"ColumnarTableSetOptions_hook");
@@ -368,11 +373,34 @@ _PG_init(void)
 	Assert(ColumnarTableSetOptions_hook_ptr != NULL);
 	Assert(*ColumnarTableSetOptions_hook_ptr != NULL);
 
-	/*
-	 * Set the hook, so that when the options change on a columnar
-	 * table, we propagate the changes to shards.
-	 */
 	**ColumnarTableSetOptions_hook_ptr = ColumnarTableSetOptionsHook;
+
+	/*
+	 * Next, acquire symbols for columnar functions that citus
+	 * needs to call.
+	 */
+	void *handle = NULL;
+	ColumnarSupportsIndexAM = (ColumnarSupportsIndexAM_type)
+	  load_external_function(COLUMNAR_LIB_NAME, "ColumnarSupportsIndexAM",
+				 true, &handle);
+	CompressionTypeStr = (CompressionTypeStr_type)
+	  load_external_function(COLUMNAR_LIB_NAME, "CompressionTypeStr",
+				 true, &handle);
+	IsColumnarAmTable = (IsColumnarAmTable_type)
+	  load_external_function(COLUMNAR_LIB_NAME, "IsColumnarAmTable",
+				 true, &handle);
+	ReadColumnarOptions = (ReadColumnarOptions_type)
+	  load_external_function(COLUMNAR_LIB_NAME, "ReadColumnarOptions",
+				 true, &handle);
+
+	/*
+	 * Finally, acquire symbols the "pass through" to columnar so
+	 * that a SQL function declared on the citus module can be
+	 * defined in the columnar module. This helps with the upgrade
+	 * transition, where some columnar functions
+	 * (e.g. columnar_handler) are declared in SQL to be in the
+	 * citus module.
+	 */
 }
 
 
diff --git a/src/include/distributed/shared_library_init.h b/src/include/distributed/shared_library_init.h
index b5bc09da3..1ca5d9f78 100644
--- a/src/include/distributed/shared_library_init.h
+++ b/src/include/distributed/shared_library_init.h
@@ -11,6 +11,8 @@
 #ifndef SHARED_LIBRARY_INIT_H
 #define SHARED_LIBRARY_INIT_H
 
+#include "columnar/columnar.h"
+
 #define GUC_STANDARD 0
 #define MAX_SHARD_COUNT 64000
 #define MAX_SHARD_REPLICATION_FACTOR 100