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//
// Unified Query Algebra
//
// Copyright (c) 2023-2026 Cognica, Inc.
//
//! Graph-specific predicate pushdown and pattern fusion rewrites.
use std::sync::Arc;
use uqa_operators::{
EdgePatternIR, GraphPatternIR, OperatorTree, VertexPatternIR, VertexPredicate,
};
use super::{tree_map::map_operator_children, QueryOptimizer};
impl QueryOptimizer {
// ---------------------------------------------------------------
// 3. Push graph pattern filters
// ---------------------------------------------------------------
pub(super) fn push_graph_pattern_filters(&self, op: OperatorTree) -> OperatorTree {
if let OperatorTree::Filter {
field,
predicate,
source: Some(s),
} = &op
{
if let OperatorTree::PatternMatch { pattern, graph } = s.as_ref() {
let parts: Vec<&str> = field.splitn(2, '.').collect();
if parts.len() == 2 {
let target_var = parts[0];
let prop = parts[1].to_string();
let mut new_vps = Vec::with_capacity(pattern.vertex_patterns.len());
let mut pushed = false;
for vp in &pattern.vertex_patterns {
if !pushed && vp.variable == target_var {
let mut constraints = vp.constraints.clone();
let pred = predicate.clone();
let prop_clone = prop.clone();
constraints.push(Arc::new(move |v: &uqa_core::Vertex| {
v.properties
.get(&prop_clone)
.is_some_and(|val| pred.evaluate(Some(val)))
}));
new_vps.push(VertexPatternIR {
variable: vp.variable.clone(),
constraints,
label: vp.label.clone(),
});
pushed = true;
} else {
new_vps.push(vp.clone());
}
}
if pushed {
let new_pattern = GraphPatternIR {
vertex_patterns: new_vps,
edge_patterns: pattern.edge_patterns.clone(),
};
return OperatorTree::PatternMatch {
pattern: new_pattern,
graph: graph.clone(),
};
}
// Try edge variable: "src_tgt.prop". Use a two-stage
// match: first build the
// `source_target -> ep` lookup (last-write-wins so
// multi-label edges between the same vertices fall
// through to the most recently declared label),
// then push the new constraint onto *every* edge
// sharing the chosen triple `(source, target, label)`.
let mut edge_lookup: std::collections::BTreeMap<String, EdgePatternIR> =
std::collections::BTreeMap::new();
for ep in &pattern.edge_patterns {
let key = format!("{}_{}", ep.source_var, ep.target_var);
edge_lookup.insert(key, ep.clone());
}
let chosen = edge_lookup.get(target_var).cloned();
let mut new_eps = Vec::with_capacity(pattern.edge_patterns.len());
if let Some(ref chosen_ep) = chosen {
for orig_ep in &pattern.edge_patterns {
if orig_ep.source_var == chosen_ep.source_var
&& orig_ep.target_var == chosen_ep.target_var
&& orig_ep.label == chosen_ep.label
{
let mut constraints = orig_ep.constraints.clone();
let pred = predicate.clone();
let prop_clone = prop.clone();
constraints.push(Arc::new(move |e: &uqa_core::Edge| {
e.properties
.get(&prop_clone)
.is_some_and(|val| pred.evaluate(Some(val)))
}));
new_eps.push(EdgePatternIR {
source_var: orig_ep.source_var.clone(),
target_var: orig_ep.target_var.clone(),
label: orig_ep.label.clone(),
constraints,
});
pushed = true;
} else {
new_eps.push(orig_ep.clone());
}
}
}
if pushed {
let new_pattern = GraphPatternIR {
vertex_patterns: pattern.vertex_patterns.clone(),
edge_patterns: new_eps,
};
return OperatorTree::PatternMatch {
pattern: new_pattern,
graph: graph.clone(),
};
}
}
// Cannot push; keep the filter wrapped.
return OperatorTree::Filter {
field: field.clone(),
predicate: predicate.clone(),
source: Some(Box::new(s.as_ref().clone())),
};
}
}
self.recurse_graph_pattern(op)
}
pub(super) fn recurse_graph_pattern(&self, op: OperatorTree) -> OperatorTree {
map_operator_children(op, |child| self.push_graph_pattern_filters(child))
}
// ---------------------------------------------------------------
// 4. Push filter into Traverse
// ---------------------------------------------------------------
pub(super) fn push_filter_into_traverse(&self, op: OperatorTree) -> OperatorTree {
if let OperatorTree::Filter {
field,
predicate,
source: Some(s),
} = &op
{
if let OperatorTree::Traverse {
start_vertex,
graph,
label,
max_hops,
vertex_predicate,
} = s.as_ref()
{
let pred = predicate.clone();
let field_clone = field.clone();
let leaf_filter: VertexPredicate = Arc::new(move |v: &uqa_core::Vertex| {
v.properties
.get(&field_clone)
.is_some_and(|val| pred.evaluate(Some(val)))
});
let combined: VertexPredicate = match vertex_predicate {
Some(prev) => {
let prev = prev.clone();
Arc::new(move |v: &uqa_core::Vertex| prev(v) && leaf_filter(v))
}
None => leaf_filter,
};
return OperatorTree::Traverse {
start_vertex: *start_vertex,
graph: graph.clone(),
label: label.clone(),
max_hops: *max_hops,
vertex_predicate: Some(combined),
};
}
}
self.recurse_traverse_filter(op)
}
pub(super) fn recurse_traverse_filter(&self, op: OperatorTree) -> OperatorTree {
map_operator_children(op, |child| self.push_filter_into_traverse(child))
}
// ---------------------------------------------------------------
// 5. Push filter below GraphJoin
// ---------------------------------------------------------------
pub(super) fn push_filter_below_graph_join(&self, op: OperatorTree) -> OperatorTree {
if let OperatorTree::Filter {
field,
predicate,
source: Some(s),
} = op
{
if let OperatorTree::GraphJoin {
left,
right,
label,
graph,
} = *s
{
let new_left = OperatorTree::Filter {
field: field.clone(),
predicate: predicate.clone(),
source: Some(left),
};
return OperatorTree::GraphJoin {
left: Box::new(new_left),
right,
label,
graph,
};
}
return OperatorTree::Filter {
field,
predicate,
source: Some(Box::new(self.push_filter_below_graph_join(*s))),
};
}
self.recurse_graph_join(op)
}
pub(super) fn recurse_graph_join(&self, op: OperatorTree) -> OperatorTree {
map_operator_children(op, |child| self.push_filter_below_graph_join(child))
}
// ---------------------------------------------------------------
// 6. Fuse PatternMatch operators inside an Intersect
// ---------------------------------------------------------------
pub(super) fn fuse_join_pattern(op: OperatorTree) -> OperatorTree {
if let OperatorTree::Intersect(ops) = op {
let children: Vec<OperatorTree> =
ops.into_iter().map(Self::fuse_join_pattern).collect();
let mut pattern_ops: Vec<OperatorTree> = Vec::new();
let mut other_ops: Vec<OperatorTree> = Vec::new();
for child in children {
if matches!(child, OperatorTree::PatternMatch { .. }) {
pattern_ops.push(child);
} else {
other_ops.push(child);
}
}
// Pairwise fuse PatternMatch operators that share a vertex
// variable.
if pattern_ops.len() >= 2 {
let mut merged: Vec<OperatorTree> = Vec::with_capacity(pattern_ops.len());
merged.push(pattern_ops.remove(0));
for pm in pattern_ops {
let Some(last) = merged.pop() else {
merged.push(pm);
continue;
};
match Self::merge_patterns(&last, &pm) {
Some(fused) => merged.push(fused),
None => {
merged.push(last);
merged.push(pm);
}
}
}
pattern_ops = merged;
}
let mut all = other_ops;
all.extend(pattern_ops);
if all.len() == 1 {
if let Some(only) = all.pop() {
return only;
}
}
return OperatorTree::Intersect(all);
}
map_operator_children(op, Self::fuse_join_pattern)
}
pub(super) fn merge_patterns(a: &OperatorTree, b: &OperatorTree) -> Option<OperatorTree> {
let (
OperatorTree::PatternMatch {
pattern: pa,
graph: ga,
},
OperatorTree::PatternMatch {
pattern: pb,
graph: _gb,
},
) = (a, b)
else {
return None;
};
let vars_a: std::collections::BTreeSet<&String> =
pa.vertex_patterns.iter().map(|vp| &vp.variable).collect();
let vars_b: std::collections::BTreeSet<&String> =
pb.vertex_patterns.iter().map(|vp| &vp.variable).collect();
if vars_a.intersection(&vars_b).next().is_none() {
return None;
}
// The merge buffer for the merge buffer, which keeps
// insertion order. Mirror that with a parallel `Vec` (positions)
// + `BTreeMap` (lookup) so structurally-equivalent inputs give
// structurally-equivalent merged patterns regardless of name
// collation.
let mut order: Vec<String> = Vec::new();
let mut by_var: std::collections::BTreeMap<String, VertexPatternIR> =
std::collections::BTreeMap::new();
for vp in &pa.vertex_patterns {
order.push(vp.variable.clone());
by_var.insert(vp.variable.clone(), vp.clone());
}
for vp in &pb.vertex_patterns {
match by_var.get_mut(&vp.variable) {
Some(existing) => {
let mut combined = existing.constraints.clone();
combined.extend(vp.constraints.iter().cloned());
existing.constraints = combined;
}
None => {
order.push(vp.variable.clone());
by_var.insert(vp.variable.clone(), vp.clone());
}
}
}
let merged_vps: Vec<VertexPatternIR> = order
.into_iter()
.filter_map(|var| by_var.remove(&var))
.collect();
let mut edge_patterns = pa.edge_patterns.clone();
edge_patterns.extend(pb.edge_patterns.iter().cloned());
let new_pattern = GraphPatternIR {
vertex_patterns: merged_vps,
edge_patterns,
};
Some(OperatorTree::PatternMatch {
pattern: new_pattern,
graph: ga.clone(),
})
}
}