create full view on build_log data, but avoid bombing sqlitebrowser;

--- a/src/Pure/Admin/build_log.scala	Mon May 01 17:28:25 2017 +0200
+++ b/src/Pure/Admin/build_log.scala	Mon May 01 20:14:50 2017 +0200
@@ -865,4 +865,26 @@
       Build_Info(sessions)
     }
   }
+
+
+  /* full view on build_log data */
+
+  // WARNING: This may cause performance problems, e.g. with sqlitebrowser
+
+  val full_view: SQL.View =
+    SQL.View("isabelle_build_log",
+      Meta_Info.table.columns :::
+        Build_Info.sessions_table.columns.tail.map(_.copy(primary_key = false)))
+
+  def create_full_view(db: SQL.Database)
+  {
+    if (!db.tables.contains(full_view.name)) {
+      val table1 = Meta_Info.table
+      val table2 = Build_Info.sessions_table
+      db.create_view(full_view,
+        SQL.select(Meta_Info.log_name(table1) :: full_view.columns.tail) +
+        SQL.join(table1, table2,
+          Meta_Info.log_name(table1).sql + " = " + Meta_Info.log_name(table2).sql))
+    }
+  }
 }

--- a/src/Pure/Admin/isabelle_cronjob.scala	Mon May 01 17:28:25 2017 +0200
+++ b/src/Pure/Admin/isabelle_cronjob.scala	Mon May 01 20:14:50 2017 +0200
@@ -155,7 +155,15 @@
   {
     val store = Build_Log.store(options)
     val files = Build_Log.Log_File.find_files(database_dirs)
-    using(store.open_database())(db => store.write_info(db, files, ml_statistics = true))
+
+    // PostgreSQL server
+    using(store.open_database())(db =>
+      {
+        store.write_info(db, files, ml_statistics = true)
+        Build_Log.create_full_view(db)
+      })
+
+    // SQLite file
     using(SQLite.open_database(build_log_snapshot))(db =>
       {
         store.write_info(db, files)