/// <summary>
/// Finds common substrings for each position in the texts of the specified column.
/// It uses a batch approach to query for several positions (specified using SubstringQueryColumnCount)
/// using a single query.
/// </summary>
private static async Task <SubstringsData> ExploreSubstrings(
DConnection conn,
ExplorerContext ctx,
int substringQueryColumnCount,
params int[] substringLengths)
{
var substrings = new SubstringsData();
foreach (var length in substringLengths)
{
var hasRows = true;
for (var pos = 0; hasRows; pos += substringQueryColumnCount)
{
var query = new TextColumnSubstring(ctx.Table, ctx.Column, pos, length, substringQueryColumnCount);
var sstrResult = await conn.Exec(query);
hasRows = false;
foreach (var row in sstrResult.Rows)
{
if (row.HasValue)
{
hasRows = true;
substrings.Add(pos + row.Index, row.Value, row.Count);
}
}
}
}
return(substrings);
}
