Changeset: f097e1fd8aff for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=f097e1fd8aff
Modified Files:
monetdb5/modules/mal/mosaic.c
Branch: mosaic
Log Message:
Optimize attempts to compress chunks
Several compression schemes have an inherent limitation.
diffs (123 lines):
diff --git a/monetdb5/modules/mal/mosaic.c b/monetdb5/modules/mal/mosaic.c
--- a/monetdb5/modules/mal/mosaic.c
+++ b/monetdb5/modules/mal/mosaic.c
@@ -289,7 +289,7 @@ inheritCOL( BAT *bn, COLrec *cn, BAT *b,
* sequence is found with high compression factor.
*/
static int
-MOSoptimizer(Client cntxt, MOStask task)
+MOSoptimizer(Client cntxt, MOStask task, int typewidth)
{
int cand = MOSAIC_NONE;
float ratio = 1.0, fac = 1.0;
@@ -302,20 +302,6 @@ MOSoptimizer(Client cntxt, MOStask task)
ratio = fac;
}
}
- if ( task->filter[MOSAIC_DICT]){
- fac = MOSestimate_dictionary(cntxt,task);
- if (fac > ratio){
- cand = MOSAIC_DICT;
- ratio = fac;
- }
- }
- if ( task->filter[MOSAIC_DELTA]){
- fac = MOSestimate_delta(cntxt,task);
- if ( fac > ratio ){
- cand = MOSAIC_DELTA;
- ratio = fac;
- }
- }
if ( task->filter[MOSAIC_LINEAR]){
fac = MOSestimate_linear(cntxt,task);
if ( fac >ratio){
@@ -323,14 +309,8 @@ MOSoptimizer(Client cntxt, MOStask task)
ratio = fac;
}
}
- if ( task->filter[MOSAIC_FRAME]){
- fac = MOSestimate_frame(cntxt,task);
- if (fac > ratio){
- cand = MOSAIC_FRAME;
- ratio = fac;
- }
- }
- if ( task->filter[MOSAIC_PREFIX]){
+ // max achievable compression factor is 64x
+ if (ratio < typewidth && task->filter[MOSAIC_PREFIX]){
fac = MOSestimate_prefix(cntxt,task);
if ( fac > ratio ){
cand = MOSAIC_PREFIX;
@@ -339,6 +319,30 @@ MOSoptimizer(Client cntxt, MOStask task)
if ( fac < 0.0)
task->filter[MOSAIC_PREFIX] = 0;
}
+ // max achievable compression factor is 8x
+ if (ratio < 8 && task->filter[MOSAIC_DICT]){
+ fac = MOSestimate_dictionary(cntxt,task);
+ if (fac > ratio){
+ cand = MOSAIC_DICT;
+ ratio = fac;
+ }
+ }
+ // max achievable compression factor is 8x
+ if (ratio < 8 && task->filter[MOSAIC_FRAME]){
+ fac = MOSestimate_frame(cntxt,task);
+ if (fac > ratio){
+ cand = MOSAIC_FRAME;
+ ratio = fac;
+ }
+ }
+ // max achievable compression factor is 8x
+ if (ratio < 8 && task->filter[MOSAIC_DELTA]){
+ fac = MOSestimate_delta(cntxt,task);
+ if ( fac > ratio ){
+ cand = MOSAIC_DELTA;
+ ratio = fac;
+ }
+ }
//mnstr_printf(cntxt->fdout,"#cand %d factor %f\n",cand,ratio);
return cand;
}
@@ -350,13 +354,14 @@ MOScompressInternal(Client cntxt, bat *r
BAT *bcompress; // the BAT that will contain the compressed version
str msg = MAL_SUCCEED;
int cand;
+ int tpe, typewidth;
*ret = 0;
if ((bcompress = BATdescriptor(*bid)) == NULL)
throw(MAL, "mosaic.compress", INTERNAL_BAT_ACCESS);
- switch(ATOMbasetype(bcompress->ttype)){
+ switch( tpe =ATOMbasetype(bcompress->ttype)){
case TYPE_bit:
case TYPE_bte:
case TYPE_sht:
@@ -370,6 +375,7 @@ MOScompressInternal(Client cntxt, bat *r
case TYPE_flt:
case TYPE_dbl:
case TYPE_str:
+ typewidth = ATOMsize(tpe) * 8;
break;
default:
// don't compress them
@@ -391,7 +397,7 @@ MOScompressInternal(Client cntxt, bat *r
#ifdef _DEBUG_MOSAIC_
mnstr_printf(cntxt->fdout,"#compress bat %d \n",*bid);
#endif
- bsrc = BATcopy(bcompress, bcompress->htype, bcompress->ttype,
TRUE,TRANSIENT);
+ bsrc = BATcopy(bcompress, TYPE_void, bcompress->ttype, TRUE,TRANSIENT);
if (bsrc == NULL) {
BBPunfix(bcompress->batCacheid);
@@ -459,7 +465,7 @@ MOScompressInternal(Client cntxt, bat *r
while(task->start < task->stop ){
// default is to extend the non-compressed block
- cand = MOSoptimizer(cntxt,task);
+ cand = MOSoptimizer(cntxt, task, typewidth);
// wrapup previous block
switch(cand){
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