MonetDB: default - Speedup merging empty bats

[Martin Kersten]

Changeset: 1b4cc5924e53 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=1b4cc5924e53
Modified Files:
        monetdb5/modules/mal/mat.c
Branch: default
Log Message:

Speedup merging empty bats


diffs (64 lines):

diff --git a/monetdb5/modules/mal/mat.c b/monetdb5/modules/mal/mat.c
--- a/monetdb5/modules/mal/mat.c
+++ b/monetdb5/modules/mal/mat.c
@@ -114,7 +114,6 @@ MATpackInternal(MalStkPtr stk, InstrPtr 
        bn = BATnew(TYPE_void, tt, cap);
        if (bn == NULL)
                throw(MAL, "mat.pack", MAL_MALLOC_FAIL);
-       BATsettrivprop(bn);
 
        for (i = 1; i < p->argc; i++) {
                b = BATdescriptor(stk->stk[getArg(p,i)].val.ival);
@@ -441,36 +440,47 @@ MATpack(Client cntxt, MalBlkPtr mb, MalS
        return MATpackInternal(stk,p);
 }
 
-// merging multiple OID lists 
+// merging multiple OID lists, optimized for empty bats
+// Further improvement should come from multi-bat merging.
 str
 MATmergepack(Client cntxt, MalBlkPtr mb, MalStkPtr stk, InstrPtr p)
 {
        int i, *ret = (int*) getArgReference(stk,p,0);
+       int top=0, *bids;
        BAT *b, *bn, *bm;
        BUN cap = 0;
 
        (void)cntxt;
        (void)mb;
+       bids = (int*) GDKzalloc(sizeof(int) * p->argc);
+       if ( bids ==0)
+               throw(MAL,"mat.mergepack",MAL_MALLOC_FAIL);
        for (i = 1; i < p->argc; i++) {
                int bid = stk->stk[getArg(p,i)].val.ival;
                b = BBPquickdesc(ABS(bid),FALSE);
-               if (b )
+               if (b ){
                        cap += BATcount(b);
+                       if ( BATcount(b) )
+                               bids[top++] = b->batCacheid;
+               }
        }
 
        bn = BATnew(TYPE_void, TYPE_oid, cap);
        if (bn == NULL)
                throw(MAL, "mat.pack", MAL_MALLOC_FAIL);
-       BATsettrivprop(bn);
-       for (i = 1; i < p->argc; i++) {
-               b = BATdescriptor(stk->stk[getArg(p,i)].val.ival);
+       for (i = 0; i < top; i++) {
+               b = BATdescriptor(bids[i]);
                if( b ){
+            if ( i == 1)
+                BATseqbase(bn, b->hseqbase);
                        bm = BATmergecand(bn,b);
                        BBPunfix(b->batCacheid);
                        BBPunfix(bn->batCacheid);
                        bn = bm;
                }
        }
+       GDKfree(bids);
+       BATsettrivprop(bn);
        assert(!bn->H->nil || !bn->H->nonil);
        assert(!bn->T->nil || !bn->T->nonil);
        BBPkeepref(*ret = bn->batCacheid);
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