Roger Binns, I ran some tests today and found that sqlite3_blob_reopen is
significantly faster than sqlite3_blob_open. Attached is the Very Sleepy Full
Profiler report. The modified C++ code is shown below. Thank you.
unsigned long *cIntersectingDedupe::GetSubGraphBlob(sSUBGRAPHINFO
*SubGraph_,int *Size_) {
int Size;
unsigned long *RetVal;
// Grab a BLOB and put it into a unsigned long buffer. As the BLOB contains
record numbers,
// we will never see a value of zero. Thus, we use 0 to mark the end of the
array.
//
// Note that we can have BLOBs of size 0, though. If we used DistillSubGraph to
// dedupe the subgraph, some records will be consolidated into others. The
// donor record's BLOB gets zapped because all of it's BLOB was rolled into
the
// donee (All your BLOB are belong to us!)
if (SubGraph_->hBlob == 0){
sqlite3_blob_open(SubGraph_->Database,"main","AggregatedData","Rows",SubGraph_->IteratorPos+1,0,&(SubGraph_->hBlob));
}
else{
sqlite3_blob_reopen(SubGraph_->hBlob,SubGraph_->IteratorPos+1);
}
Size=sqlite3_blob_bytes(SubGraph_->hBlob)/sizeof(unsigned long);
RetVal=new unsigned long[(Size+1)*sizeof(unsigned long)];
sqlite3_blob_read(SubGraph_->hBlob,RetVal,Size*sizeof(unsigned long),0);
RetVal[Size]=0;
if (Size_!=0)
*Size_=Size;
return RetVal;
}
Frank has a file to share with you on SkyDrive. To view it, click the link
below.
sqlite3_blob_reopen.ppt
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