Batch all INSERTS into vt_refs

[mattmundell]

What

There are about 500k vt_refs and 80k NVTs.

Previously the INSERTs into vt_refs were batched for each NVT, so there was one INSERT per NVT.

Now the INSERTs are batched across NVTs, so there's one INSERT per 50k vt_refs.

Configurable via definition VT_REFS_BATCH_SIZE:

• 5: 66s
• 50k: 54s
• 100k: 50s

Why

Saves about 10s of rebuild.

References

GEA-49

[timopollmeier]

I think for larger batch actions like this it would be good to to have a command line option do set a different batch size.

[mattmundell]

OK, I'll add one.