Re: [Monetdb-developers] [Monetdb-pf-checkins] pathfinder/runtime xrpc_client.mx, xquery-decomposition, 1.41.2.8, 1.41.2.9

10 Mar 2008

Hi Stefan,

Thanks again for the comments and pointing out the mistakes!
...
...
Index: xrpc_client.mx
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/runtime/xrpc_client.mx,v
retrieving revision 1.41.2.8
retrieving revision 1.41.2.9
diff -u -d -r1.41.2.8 -r1.41.2.9

--- xrpc_client.mx	8 Mar 2008 21:17:27 -0000	1.41.2.8
+++ xrpc_client.mx	10 Mar 2008 02:01:13 -0000	1.41.2.9
@@ -94,94 +94,40 @@
        BAT[void, dbl] dbl_values,
        BAT[void, dbl] dec_values,
        BAT[void, str] str_values) : oid {
-
    var maxnconts := ws.fetch(0).count();
    # split used_ into multiple BATs according to their  
container IDs
          vvvvvvvvv
    var uitems := bat(oid, bat, maxnconts); # container ID in head
    var ukinds := bat(oid, bat, maxnconts);
          ^^^^^^^^^
These two BATs are IMHO overwritten below (see  
"vvvvvvvvv"/"^^^^^^^^^");
hence, no (more) need to make them, here!??
This is because I might insert more BUNs ("align uitems|kinds and  
ritems|kinds") after the leftfetchjoin below, so I though I can  
initialize these BATs with large enough spaces to avoid that insert()  
first has to extend the BATs.  From you comments, it seems that such  
initialization does not make sense?
...
...
+    var conts := get_container([int](used_kind)); # [oid,int]:  
container IDs in tail
+    var unq_conts := tunique(conts).hmark(0@0);
+    var nconts := count(unq_conts);
+    var rs := rangesplit(conts,  
nconts).tmark(0@0).reverse().join(unq_conts).reverse();
This will do want you want (have rs's head contain the conts from  
the BATs
in its tail) ONLY if tunique(conts) & rangesplit(conts, nconts)  
happen to
produce the same order!
To be sure, you'd need to sort the unq_conts before marking them  
(result of
rangesplit shoiuld hopefully be sorted):
  var unq_conts := tunique(conts).sort().hmark(0@0);
Was there something wrong with my proposal:
  var rs := rangesplit(conts, nconts);
      rs := rs.reverse().mirror().[fetch](0).reverse();
?
No, there is nothing wrong with it.  I saw you e-mail much later, and  
since my solution seemed working (by accident), I didn't adopt your  
code.  Sorry.


Jennie
...
vvvvvvvvv
...
+    uitems := rs.[mirror]().[leftfetchjoin](const used_item);
+    uitems := [tmark](uitems, const 0@0);
+    ukinds := rs.[mirror]().[leftfetchjoin](const used_kind);
+    ukinds := [tmark](ukinds, const 0@0);
      ^^^^^^^^^
(see "vvvvvvvvv"/^^^^^^^^^" above)
Plus: It might be more efficient to get rid of the head before the  
join,
since you "overwrite" them afterwards, anyway; i.e.:
  uitems := rs.[tmark](oid(nil)).[leftfetchjoin](const used_item). 
[tmark](uitems, const 0@0);
...
# split returned_ into multiple BATs according to  
their container IDs
vvvvvvvvv
...
var ritems := bat(oid, bat, maxnconts); # container ID in head
    var rkinds := bat(oid, bat, maxnconts);
^^^^^^^^^
Same as with uitems/ukinds above.
...
-    conts := returned_kind.[int]().[>>](6).tsort(); # [oid,int]:  
container IDs in tail
-    nconts := conts.tunique().count();
-    if(nconts = 1){ # all items are from the same container
-        ritems.insert(conts.fetch(0).oid(), returned_item);
-        rkinds.insert(conts.fetch(0).oid(), returned_kind);
-    } else {
-        # sort used_ on container ID
-        var itemcont :=  
returned_item.reverse().join(conts).reverse().tmark(0@0);
-        var kindcont :=  
returned_kind.reverse().join(conts).reverse().tmark(0@0);
-
-        var curcont := conts.fetch(0);
-        var tmpitem := bat(void, oid).seqbase(0@0);
-        var tmpkind := bat(void, int).seqbase(0@0);
-
-        conts := conts.tmark(0@0); # conts[void,int]
-        conts@batloop(){
-            # start of next container, save items|kinds of  
previous container
-            if($t != curcont) {
-                curcont := $t;
-                ritems.insert(curcont, tmpitem);
-                rkinds.insert(curcont, tmpkind);
-                tmpitem := bat(void, oid).seqbase(0@0);
-                tmpkind := bat(void, int).seqbase(0@0);
-            }
-
-            tmpitem.append(itemcont.fetch($h));
-            tmpkind.append(kindcont.fetch($h));
-        }
-        ritems.insert(curcont, tmpitem);
-        rkinds.insert(curcont, tmpkind);
-    }
+    conts := get_container([int](returned_kind)); # [oid,int]:  
container IDs in tail
+    unq_conts := tunique(conts).hmark(0@0);
+    nconts := count(unq_conts);
+    rs := rangesplit(conts,  
nconts).tmark(0@0).reverse().join(unq_conts).reverse();
(see above)
vvvvvvvvv
...
+    ritems := rs.[mirror]().[leftfetchjoin](const returned_item);
+    ritems := [tmark](ritems, const 0@0);
+    rkinds := rs.[mirror]().[leftfetchjoin](const returned_kind);
+    rkinds := [tmark](rkinds, const 0@0);
      ^^^^^^^^^
(see above)
...
# align uitems|kinds and ritems|kinds,
    # fill missing container with emtpybat
    var emptybat := bat(void,void,0);
-    uitems@batloop(){
-        var err := CATCH({ritems.find($h);});
-        if(err.search("not found") >= 0){
-            ritems.insert($h, emptybat);
-        }
-    }
-    ritems@batloop(){
-        var err := CATCH({uitems.find($h);});
-        if(err.search("not found") >= 0){
-            uitems.insert($h, emptybat);
-        }
-    }
-
+    var usedonly := kdiff(uitems,ritems).project(emptybat);
+    ritems.access(BAT_WRITE).insert(usedonly);
+    rkinds.access(BAT_WRITE).insert(usedonly);
+    var returnedonly := kdiff(ritems,uitems).project(emptybat);
+    uitems.access(BAT_WRITE).insert(returnedonly);
+    ukinds.access(BAT_WRITE).insert(returnedonly);
a) Do you need to modify these BATs later on?
  If not, you might want the set them read-only, again, after the  
insert:
  ritems.access(BAT_WRITE).insert(usedonly).access(BAT_READ);
b) To be sure that your variables till point to the correct BATs
  (access(BAT_WRITE) *might* return a copy!), you should asign the  
result:
  ritems := ritems.access(BAT_WRITE).insert(usedonly) 
[.access(BAT_READ)];
Stefan
-- 
| Dr. Stefan Manegold | mailto:Stefan.Manegold@cwi.nl |
| CWI,  P.O.Box 94079 | http://www.cwi.nl/~manegold/  |
| 1090 GB Amsterdam   | Tel.: +31 (20) 592-4212       |
| The Netherlands     | Fax : +31 (20) 592-4312       |
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Re: [Monetdb-developers] [Monetdb-pf-checkins] pathfinder/runtime xrpc_client.mx, xquery-decomposition, 1.41.2.8, 1.41.2.9

Ying Zhang