[Planner Dev] Database schemas, versions and upgrading paths

[Alvaro del Castillo <acs barrapunto com>]

Hi guys!

I am working in coding the database schema from a file. We will do it
when the SQL module storage is loaded and I imagine the steps like:

1. Check if we have any planner SQL schemas:

	1.1 If we don't have any schemas we try to load the schemas from 	the
file database-VERSION.sql. If we can't find the file, we 	have to report
an error to the user. If we find the file, we'll 	load it in the
database and continue execution. 

	1.2 If we have them, then go 2.


2. If 1.2 then check if we have the correct tables in the database:

We need to check that the actual schemas in the database are the good
ones for our planner version. For example, when you upgrade from 0.13 to
0.14, maybe we have created a upgrade SQL file with the needed commands
to upgrade the SQL schemas stuff.

If we detect that the database schemas are from and older planner
version (we need to put the planner version in someplace in schemas), we
try to find the file "upgrade-OLD_VERSION-NEW_VERSION.sql". If we don't
find any, then no upgrades are needed.

If we find the file, we'll load it in the database.


If we follow this way, we need to call the SQL files in a very strict
way in order we don't break the code in storage sql module.

I attach a patch with some ideas about the code.

Cheers

-- Alvaro

Index: libplanner/mrp-storage-sql.c
===================================================================
RCS file: /cvs/gnome/planner/libplanner/mrp-storage-sql.c,v
retrieving revision 1.2
diff -u -b -B -p -r1.2 mrp-storage-sql.c
--- libplanner/mrp-storage-sql.c	15 Jan 2004 19:51:15 -0000	1.2
+++ libplanner/mrp-storage-sql.c	1 Jul 2004 05:03:01 -0000
@@ -102,6 +102,26 @@ module_init (GTypeModule *module)
 G_MODULE_EXPORT MrpStorageModule *
 module_new (void *project)
 {
+	GDir*           dir;
+	const gchar    *name;
+	const gchar    *version_old_test="0.11";
+
+	/* Check for tables */
+	dir = g_dir_open (SQL_DIR, 0, NULL);
+	g_message ("Loading scheme data for tables from "SQL_DIR);
+	while ((name = g_dir_read_name (dir)) != NULL) {
+		if (strncmp (name + strlen (name) - 4, ".sql", 4) == 0) {
+			gchar *schema = g_build_path (G_DIR_SEPARATOR_S,
+						      SQL_DIR,
+						      name,
+						      NULL);
+			g_message ("Schemas found in %s", schema);
+			g_message ("Looking for schema: database-%s.sql", VERSION);
+			g_message ("Looking from upgrade: upgrade-%s-%s.sql", version_old_test, VERSION);
+			g_free (schema);				
+		}
+	}
+	
 	return MRP_STORAGE_MODULE (g_object_new (MRP_TYPE_STORAGE_SQL, NULL));
 }

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