public RewritingPass(T_Tile toFill, T_Tile toAvoid, List <T_Tile> views, RewritingProcessor <T_Tile> qp)
{
m_toFill = toFill;
m_toAvoid = toAvoid;
m_views = views;
m_qp = qp;
}
// used for union simplification
private RewritingSimplifier(T_Tile rewriting, T_Tile toFill, T_Tile toAvoid, RewritingProcessor <T_Tile> qp)
{
m_originalRewriting = toFill;
m_toAvoid = toAvoid;
m_qp = qp;
m_usedViews = new Dictionary <T_Tile, TileOpKind>();
GatherUnionedSubqueriesInUsedViews(rewriting);
}
// used for join/antisemijoin simplification
private RewritingSimplifier(T_Tile originalRewriting, T_Tile toAvoid, Dictionary <T_Tile, TileOpKind> usedViews,
RewritingProcessor <T_Tile> qp)
{
m_originalRewriting = originalRewriting;
m_toAvoid = toAvoid;
m_qp = qp;
m_usedViews = usedViews;
}
// modifies usedViews - removes all redundant views from it
internal static bool TrySimplifyJoinRewriting(ref T_Tile rewriting, T_Tile toAvoid, Dictionary <T_Tile, TileOpKind> usedViews, RewritingProcessor <T_Tile> qp)
{
RewritingSimplifier <T_Tile> simplifier = new RewritingSimplifier <T_Tile>(rewriting, toAvoid, usedViews, qp);
T_Tile simplifiedRewriting;
if (simplifier.SimplifyRewriting(out simplifiedRewriting))
{
rewriting = simplifiedRewriting;
return(true);
}
return(false);
}
// called for top query only
internal static bool TrySimplifyUnionRewriting(ref T_Tile rewriting, T_Tile toFill, T_Tile toAvoid, RewritingProcessor <T_Tile> qp)
{
RewritingSimplifier <T_Tile> simplifier = new RewritingSimplifier <T_Tile>(rewriting, toFill, toAvoid, qp);
// gather all unioned subqueries
T_Tile simplifiedRewriting;
if (simplifier.SimplifyRewriting(out simplifiedRewriting))
{
rewriting = simplifiedRewriting;
return(true);
}
return(false);
}
private static bool RewriteQueryInternal(T_Tile toFill, T_Tile toAvoid, out T_Tile rewriting, List <T_Tile> views, HashSet <T_Tile> recentlyUsedViews, RewritingProcessor <T_Tile> qp)
{
if (qp.REORDER_VIEWS && recentlyUsedViews.Count > 0)
{
// move recently used views toward the end
List <T_Tile> reorderedViews = new List <T_Tile>();
foreach (T_Tile view in views)
{
if (false == recentlyUsedViews.Contains(view))
{
reorderedViews.Add(view);
}
}
reorderedViews.AddRange(recentlyUsedViews);
views = reorderedViews;
}
RewritingPass <T_Tile> rewritingPass = new RewritingPass <T_Tile>(toFill, toAvoid, views, qp);
return(rewritingPass.RewriteQuery(out rewriting));
}
public static bool RewriteQuery(T_Tile toFill, T_Tile toAvoid, out T_Tile rewriting, List <T_Tile> views, RewritingProcessor <T_Tile> qp)
{
RewritingPass <T_Tile> rewritingPass = new RewritingPass <T_Tile>(toFill, toAvoid, views, qp);
if (rewritingPass.RewriteQuery(out rewriting))
{
RewritingSimplifier <T_Tile> .TrySimplifyUnionRewriting(ref rewriting, toFill, toAvoid, qp);
return(true);
}
return(false);
}
