no compression for database server: let PostgreSQL/TOAST do the job;

--- a/src/Pure/General/sql.scala	Sat Oct 22 19:51:08 2022 +0200
+++ b/src/Pure/General/sql.scala	Sat Oct 22 20:06:55 2022 +0200
@@ -287,6 +287,8 @@
   trait Database extends AutoCloseable {
     db =>
 
+    def is_server: Boolean
+
 
     /* types */
 
@@ -387,6 +389,7 @@
 
   class Database private[SQLite](name: String, val connection: Connection) extends SQL.Database {
     override def toString: String = name
+    override def is_server: Boolean = false
 
     def sql_type(T: SQL.Type.Value): SQL.Source = SQL.sql_type_sqlite(T)
 
@@ -461,6 +464,7 @@
     port_forwarding: Option[SSH.Port_Forwarding]
   ) extends SQL.Database {
     override def toString: String = name
+    override def is_server: Boolean = true
 
     def sql_type(T: SQL.Type.Value): SQL.Source = SQL.sql_type_postgresql(T)
 

--- a/src/Pure/Thy/export.scala	Sat Oct 22 19:51:08 2022 +0200
+++ b/src/Pure/Thy/export.scala	Sat Oct 22 20:06:55 2022 +0200
@@ -224,8 +224,9 @@
             (results, true)
           })
 
-    def make_entry(session_name: String, args: Protocol.Export.Args, body: Bytes): Unit = {
+    def make_entry(session_name: String, args0: Protocol.Export.Args, body: Bytes): Unit = {
       if (!progress.stopped && !body.is_empty) {
+        val args = if (db.is_server) args0.copy(compress = false) else args0
         consumer.send(Export.make_entry(session_name, args, body, cache) -> args.strict)
       }
     }