Load OSM extension in retention background worker to drop tiered chunks

src/chunk.c

@@ -60,6 +60,7 @@
 #include "hypercube.h"
 #include "hypertable.h"
 #include "hypertable_cache.h"
+#include "loader/loader.h"
 #include "osm_callbacks.h"
 #include "partitioning.h"
 #include "process_utility.h"
@@ -3954,6 +3955,15 @@ ts_chunk_do_drop_chunks(Hypertable *ht, int64 older_than, int64 newer_than, int3
 	{
 		hypertable_drop_chunks_hook_type osm_drop_chunks_hook =
 			ts_get_osm_hypertable_drop_chunks_hook();
+
+		/*
+		 * OSM library may not be loaded at the moment if `ts_chunk_do_drop_chunks`
+		 * is called from the a background worker. If this is the case try to
+		 * load it now.
+		 */
+		if (!osm_drop_chunks_hook && ts_try_load_osm())
+			osm_drop_chunks_hook = ts_get_osm_hypertable_drop_chunks_hook();
+
 		if (osm_drop_chunks_hook)
 		{
 			ListCell *lc;

src/extension_constants.h

@@ -16,6 +16,7 @@
 #define EXTENSION_SO TS_LIBDIR "" EXTENSION_NAME
 #define EXTENSION_TSL_SO TS_LIBDIR TSL_LIBRARY_NAME "-" TIMESCALEDB_VERSION_MOD
 #define TS_HYPERCORE_TAM_NAME "hypercore"
+#define OSM_EXTENSION_NAME "timescaledb_osm"
 
 #define MAKE_EXTOPTION(NAME) (EXTENSION_NAMESPACE "." NAME)
 

src/loader/loader.c

@@ -187,6 +187,12 @@ ts_loader_extension_version(void)
 	return extension_version(EXTENSION_NAME);
 }
 
+TSDLLEXPORT char *
+ts_osm_extension_version(void)
+{
+	return extension_version(OSM_EXTENSION_NAME);
+}
+
 extern bool
 ts_loader_extension_exists(void)
 {

src/loader/loader.h

@@ -13,6 +13,8 @@ extern bool ts_loader_extension_exists(void);
 
 extern void ts_loader_extension_check(void);
 
+extern char *ts_osm_extension_version(void);
+
 /* WaitLatch expects a long, so make sure to cast the value */
 /* Default value for timescaledb.launcher_poll_time */
 #ifdef TS_DEBUG

src/osm_callbacks.c

@@ -5,8 +5,13 @@
  */
 #include "osm_callbacks.h"
 
+#include <commands/extension.h>
 #include <fmgr.h>
 
+#include "export.h"
+#include "extension_constants.h"
+#include "loader/loader.h"
+
 #define OSM_CALLBACKS "osm_callbacks"
 #define OSM_CALLBACKS_VAR_NAME "osm_callbacks_versioned"
 
@@ -74,3 +79,48 @@ ts_get_osm_hypertable_drop_chunks_hook()
 		return ptr->hypertable_drop_chunks_hook;
 	return NULL;
 }
+
+TSDLLEXPORT bool
+ts_try_load_osm(void) {
+	bool res = false;
+	Oid osm_extension_oid = get_extension_oid(OSM_EXTENSION_NAME, true);
+
+	if (OidIsValid(osm_extension_oid))
+	{
+		MemoryContext old_mcxt = CurrentMemoryContext;
+
+		PG_TRY();
+		{
+			char version[MAX_VERSION_LEN];
+			char soname[MAX_SO_NAME_LEN];
+
+			// Form library path
+			strlcpy(version, ts_osm_extension_version(), MAX_VERSION_LEN);
+			snprintf(soname, MAX_SO_NAME_LEN, "%s%s-%s",
+				TS_LIBDIR,
+				OSM_EXTENSION_NAME,
+				version);
+
+			// Load library
+			load_external_function(soname, "pfdw_handler_wrapper", false, NULL);
+			res = true;
+		}
+		PG_CATCH();
+		{
+			ErrorData *error;
+
+			/* Switch to the original context & copy edata */
+			MemoryContextSwitchTo(old_mcxt);
+			error = CopyErrorData();
+			FlushErrorState();
+
+			elog(LOG, "failed to load OSM extension: %s", error->message);
+
+			/* Finally, free error data */
+			FreeErrorData(error);
+		}
+		PG_END_TRY();
+	}
+
+	return res;
+}

src/osm_callbacks.h

@@ -42,3 +42,4 @@ typedef struct
 extern chunk_insert_check_hook_type ts_get_osm_chunk_insert_hook(void);
 extern hypertable_drop_hook_type ts_get_osm_hypertable_drop_hook(void);
 extern hypertable_drop_chunks_hook_type ts_get_osm_hypertable_drop_chunks_hook(void);
+extern bool ts_try_load_osm(void);

tsl/src/planner.c

@@ -31,8 +31,6 @@
 
 #include <math.h>
 
-#define OSM_EXTENSION_NAME "timescaledb_osm"
-
 static int osm_present = -1;
 
 static bool