_GET_IDS_SIZE_INCR
nsize = (len + _GET_IDS_SIZE_INCR) * sizeof (*t2);
_GET_IDS_SIZE_INCR * sizeof (*t2));
gh->batch.idmap_mapping_batch_len += _GET_IDS_SIZE_INCR;
nsize = (len + _GET_IDS_SIZE_INCR) * sizeof (*t1);
_GET_IDS_SIZE_INCR * sizeof (*t1));