// This function takes a column value and if necessary adjusts it based on rules defined in the requirements.
// The values are adjusted so that one can be subtracted from another to find a range, compare, etc.
uint64_t RowEstimator::adjustValue(const execplan::CalpontSystemCatalog::ColType& ct,
const uint64_t& value)
{
switch(ct.colDataType)
{
// Use day precision for dates. We'll use day relative to the year 0 without worrying about leap
// years. This is for row count estimation and we are close enough for hand grenades.
case CalpontSystemCatalog::DATE:
{
dataconvert::Date dt(value);
return dt.year * 365 + daysThroughMonth(dt.month - 1) + dt.day;
}
// Use second precision for datetime estimates. We'll use number of seconds since the year 0
// without worrying about leap years.
case CalpontSystemCatalog::DATETIME:
{
dataconvert::DateTime dtm(value);
// 86,400 seconds in a day.
return (dtm.year * 365 + daysThroughMonth(dtm.month - 1) + dtm.day - 1) * 86400 +
dtm.hour * 3600 + dtm.minute * 60 + dtm.second;
}
// Use the first character only for estimating chars and varchar ranges.
// TODO: Use dictionary column HWM for dictionary columns.
case CalpontSystemCatalog::CHAR:
case CalpontSystemCatalog::VARCHAR:
// Last byte is the first character in the string.
return (0xFF & value);
default:
return value;
}
}
void find_bridges(const Graph &g, UnaryFunction output_bridge) {
const size_t num_v = g.num_vertices();
size_t time = 0;
std::vector<size_t> pred(num_v, SIZE_MAX);
std::vector<size_t> dtm(num_v);
std::vector<size_t> low(num_v);
std::function<void(size_t)> dfs_visit;
dfs_visit = [&](const size_t src) {
low[src] = dtm[src] = ++time;
for (const auto e : g.out_edges(src)) {
const size_t tgt = (src == g.source(e)) ? g.target(e) : g.source(e);
if (!dtm[tgt]) {
pred[tgt] = src;
dfs_visit(tgt);
low[src] = std::min(low[src], low[tgt]);
if (low[tgt] > dtm[src])
output_bridge(e);
} else if (tgt != pred[src])
low[src] = std::min(low[src], dtm[tgt]);
}
};
for (size_t v = 0; v != num_v; ++v)
if (!dtm[v])
dfs_visit(v);
}