[pgmoneta#5] SQL: CHECKPOINT

cmake/FindPsqlDevel.cmake

@@ -2,19 +2,41 @@
 # postgresql-server-devel Support
 #
 
+find_program(PG_CONFIG pg_config)
+
+if (NOT PG_CONFIG)
+    message(FATAL_ERROR "pg_config executable not found. Ensure PostgreSQL is installed and pg_config is in your PATH.")
+endif()
+
+# Use pg_config to get the include and library directories
+execute_process(COMMAND ${PG_CONFIG} --includedir
+                OUTPUT_VARIABLE PSQLDEVEL_INCLUDE_DIR
+                OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+execute_process(COMMAND ${PG_CONFIG} --libdir
+                OUTPUT_VARIABLE PSQLDEVEL_LIBRARY_DIR
+                OUTPUT_STRIP_TRAILING_WHITESPACE)
+
 find_path(PSQLDEVEL_INCLUDE_DIR
   NAMES libpq-fe.h
-  PATH_SUFFIXES postgresql
+  PATHS ${PSQLDEVEL_INCLUDE_DIR}
 )
 
 find_library(PSQLDEVEL_LIBRARY
   NAMES pq
+  PATHS ${PSQLDEVEL_LIBRARY_DIR}
 )
 
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(PsqlDevel DEFAULT_MSG
                                   PSQLDEVEL_INCLUDE_DIR PSQLDEVEL_LIBRARY)
 
+if (PSQLDEVEL_INCLUDE_DIR AND PSQLDEVEL_LIBRARY)
+  set(PSQLDEVEL_FOUND TRUE)
+else()
+  set(PSQLDEVEL_FOUND FALSE)
+endif()
+
 if (PSQLDEVEL_FOUND)
   set(PSQLDEVEL_INCLUDE_DIRS ${PSQLDEVEL_INCLUDE_DIR})
   set(PSQLDEVEL_LIBRARIES ${PSQLDEVEL_LIBRARY})

doc/manual/user-03-functions.md

@@ -12,3 +12,4 @@ After you create the extension `pgmoneta_ext` using the `postgres` role, you can
 |-----------------------------|-----------|--------------------------------------------------------|
 | `pgmoneta_ext_version()`    |   false   | Return the version number of `pgmoneta_ext` as a Datum.|
 | `pgmoneta_ext_switch_wal()` |   true    | A function for switching to a new WAL file.            |
+| `pgmoneta_ext_checkpoint()` |   true    | A function which forces a checkpoint.                  |

sql/pgmoneta_ext--0.1.0.sql

@@ -7,4 +7,11 @@ CREATE FUNCTION pgmoneta_ext_switch_wal(OUT success bool,
 ) 
 RETURNS record 
 AS 'MODULE_PATHNAME' 
+LANGUAGE C STRICT;
+
+CREATE FUNCTION pgmoneta_ext_checkpoint(OUT success bool,
+                                        OUT value text
+) 
+RETURNS record 
+AS 'MODULE_PATHNAME' 
 LANGUAGE C STRICT;

src/pgmoneta_ext/lib.c

@@ -52,6 +52,7 @@ PG_MODULE_MAGIC;
 
 PG_FUNCTION_INFO_V1(pgmoneta_ext_version);
 PG_FUNCTION_INFO_V1(pgmoneta_ext_switch_wal);
+PG_FUNCTION_INFO_V1(pgmoneta_ext_checkpoint);
 
 Datum
 pgmoneta_ext_version(PG_FUNCTION_ARGS)
@@ -114,5 +115,57 @@ pgmoneta_ext_switch_wal(PG_FUNCTION_ARGS)
    tuple = heap_form_tuple(tupdesc, values, nulls);
    result = HeapTupleGetDatum(tuple);
 
+   PG_RETURN_DATUM(result);
+}
+
+#ifndef RequestCheckpoint
+extern void RequestCheckpoint(int flags);
+#endif
+
+Datum
+pgmoneta_ext_checkpoint(PG_FUNCTION_ARGS)
+{
+   Datum values[2];
+   Datum result;
+   HeapTuple tuple;
+   Oid roleid;
+   TupleDesc tupdesc;
+   bool nulls[2];
+   int is_superuser;
+   char cp[1024];
+
+   memset(nulls, 0, sizeof(nulls));
+   memset(&cp, 0, sizeof(cp));
+
+   roleid = GetUserId();
+   is_superuser = pgmoneta_ext_check_privilege(roleid);
+
+   if (!is_superuser)
+   {
+      // Perform the checkpoint
+      RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT | CHECKPOINT_FORCE);
+
+      values[0] = BoolGetDatum(true);
+      snprintf(&cp[0], sizeof(cp), "%s", "CHECKPOINT");
+      values[1] = CStringGetTextDatum(cp);
+   }
+   else
+   {
+      ereport(LOG, errmsg_internal("pgmoneta_ext_checkpoint: Current role is not a superuser"));
+
+      values[0] = BoolGetDatum(false);
+      nulls[1] = true;
+   }
+
+   // Create a tuple descriptor for our result type
+   if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+   {
+      ereport(ERROR, errmsg_internal("pgmoneta_ext_checkpoint: Return type must be a row type"));
+   }
+
+   // Build the result tuple
+   tuple = heap_form_tuple(tupdesc, values, nulls);
+   result = HeapTupleGetDatum(tuple);
+
    PG_RETURN_DATUM(result);
 }