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Track ever-shrinking sets of types for variables, not a single type. (#381) r=nalexander

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This commit is contained in:
Richard Newman 2017-03-20 14:11:32 +00:00
parent 97749833d0
commit 7024978517
4 changed files with 237 additions and 26 deletions
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248
query-algebrizer/src/cc.rs
View file

@ -19,8 +19,11 @@ use std::fmt::{
use std::collections::{
BTreeMap,
BTreeSet,
HashSet,
};
use std::collections::btree_map::Entry;
use self::mentat_core::{
Attribute,
Entid,
@ -36,6 +39,7 @@ use self::mentat_query::{
Pattern,
PatternNonValuePlace,
PatternValuePlace,
PlainSymbol,
Predicate,
SrcVar,
Variable,
@ -83,6 +87,12 @@ impl<T> OptionEffect<T> for Option<T> {
}
}
fn unit_type_set(t: ValueType) -> HashSet<ValueType> {
let mut s = HashSet::with_capacity(1);
s.insert(t);
s
}
/// A `ConjoiningClauses` (CC) is a collection of clauses that are combined with `JOIN`.
/// The topmost form in a query is a `ConjoiningClauses`.
///
@ -143,7 +153,7 @@ pub struct ConjoiningClauses {
/// A map from var to type. Whenever a var maps unambiguously to two different types, it cannot
/// yield results, so we don't represent that case here. If a var isn't present in the map, it
/// means that its type is not known in advance.
pub known_types: BTreeMap<Variable, ValueType>,
pub known_types: BTreeMap<Variable, HashSet<ValueType>>,
/// A mapping, similar to `column_bindings`, but used to pull type tags out of the store at runtime.
/// If a var isn't present in `known_types`, it should be present here.
@ -153,7 +163,8 @@ pub struct ConjoiningClauses {
#[derive(PartialEq)]
pub enum EmptyBecause {
// Var, existing, desired.
TypeMismatch(Variable, ValueType, ValueType),
TypeMismatch(Variable, HashSet<ValueType>, ValueType),
NonNumericArgument,
UnresolvedIdent(NamespacedKeyword),
InvalidAttributeIdent(NamespacedKeyword),
InvalidAttributeEntid(Entid),
@ -170,6 +181,9 @@ impl Debug for EmptyBecause {
write!(f, "Type mismatch: {:?} can't be {:?}, because it's already {:?}",
var, desired, existing)
},
&NonNumericArgument => {
write!(f, "Non-numeric argument in numeric place")
},
&UnresolvedIdent(ref kw) => {
write!(f, "Couldn't resolve keyword {}", kw)
},
@ -237,7 +251,7 @@ impl ConjoiningClauses {
// Pre-fill our type mappings with the types of the input bindings.
cc.known_types
.extend(cc.value_bindings.iter()
.map(|(k, v)| (k.clone(), v.value_type())));
.map(|(k, v)| (k.clone(), unit_type_set(v.value_type()))));
cc
}
}
@ -247,6 +261,17 @@ impl ConjoiningClauses {
self.value_bindings.get(var).cloned()
}
/// Return a single `ValueType` if the given variable is known to have a precise type.
/// Returns `None` if the type of the variable is unknown.
/// Returns `None` if the type of the variable is known but not precise -- "double
/// or integer" isn't good enough.
pub fn known_type(&self, var: &Variable) -> Option<ValueType> {
match self.known_types.get(var) {
Some(types) if types.len() == 1 => types.iter().next().cloned(),
_ => None,
}
}
pub fn bind_column_to_var(&mut self, schema: &Schema, table: TableAlias, column: DatomsColumn, var: Variable) {
// Do we have an external binding for this?
if let Some(bound_val) = self.bound_value(&var) {
@ -291,7 +316,7 @@ impl ConjoiningClauses {
let needs_type_extraction =
!late_binding && // Never need to extract for bound vars.
column == DatomsColumn::Value && // Never need to extract types for refs.
!self.known_types.contains_key(&var) && // We know the type!
self.known_type(&var).is_none() && // Don't need to extract if we know a single type.
!self.extracted_types.contains_key(&var); // We're already extracting the type.
let alias = QualifiedAlias(table, column);
@ -322,6 +347,36 @@ impl ConjoiningClauses {
QueryValue::PrimitiveLong(value)))
}
/// Mark the given value as one of the set of numeric types.
fn constrain_var_to_numeric(&mut self, variable: Variable) {
let mut numeric_types = HashSet::with_capacity(2);
numeric_types.insert(ValueType::Double);
numeric_types.insert(ValueType::Long);
let entry = self.known_types.entry(variable);
match entry {
Entry::Vacant(vacant) => {
vacant.insert(numeric_types);
},
Entry::Occupied(mut occupied) => {
let narrowed: HashSet<ValueType> = numeric_types.intersection(occupied.get()).cloned().collect();
match narrowed.len() {
0 => {
// TODO: can't borrow as mutable more than once!
//self.mark_known_empty(EmptyBecause::TypeMismatch(occupied.key().clone(), occupied.get().clone(), ValueType::Double)); // I know…
},
1 => {
// Hooray!
self.extracted_types.remove(occupied.key());
},
_ => {
},
};
occupied.insert(narrowed);
},
}
}
/// Constrains the var if there's no existing type.
/// Marks as known-empty if it's impossible for this type to apply because there's a conflicting
/// type already known.
@ -343,13 +398,17 @@ impl ConjoiningClauses {
// spot it here.
if let Some(existing) = self.known_types.get(&variable).cloned() {
// If so, the types must match.
if existing != this_type {
if !existing.contains(&this_type) {
self.mark_known_empty(EmptyBecause::TypeMismatch(variable, existing, this_type));
} else {
if existing.len() > 1 {
// Narrow.
self.known_types.insert(variable, unit_type_set(this_type));
}
}
} else {
// If not, record the one we just determined.
self.known_types.insert(variable, this_type);
self.known_types.insert(variable, unit_type_set(this_type));
}
}
@ -424,8 +483,14 @@ impl ConjoiningClauses {
match value {
// TODO: see if the variable is projected, aggregated, or compared elsewhere in
// the query. If it's not, we don't need to use all_datoms here.
&PatternValuePlace::Variable(_) =>
DatomsTable::AllDatoms, // TODO: check types.
&PatternValuePlace::Variable(ref v) => {
// Do we know that this variable can't be a string? If so, we don't need
// AllDatoms. None or String means it could be or definitely is.
match self.known_types.get(v).map(|types| types.contains(&ValueType::String)) {
Some(false) => DatomsTable::Datoms,
_ => DatomsTable::AllDatoms,
}
}
&PatternValuePlace::Constant(NonIntegerConstant::Text(_)) =>
DatomsTable::AllDatoms,
_ =>
@ -792,6 +857,38 @@ impl ConjoiningClauses {
/// Take a function argument and turn it into a `QueryValue` suitable for use in a concrete
/// constraint.
/// Additionally, do two things:
/// - Mark the pattern as known-empty if any argument is known non-numeric.
/// - Mark any variables encountered as numeric.
fn resolve_numeric_argument(&mut self, function: &PlainSymbol, position: usize, arg: FnArg) -> Result<QueryValue> {
use self::FnArg::*;
match arg {
FnArg::Variable(var) => {
self.constrain_var_to_numeric(var.clone());
self.column_bindings
.get(&var)
.and_then(|cols| cols.first().map(|col| QueryValue::Column(col.clone())))
.ok_or_else(|| Error::from_kind(ErrorKind::UnboundVariable(var)))
},
// Can't be an entid.
EntidOrInteger(i) => Ok(QueryValue::TypedValue(TypedValue::Long(i))),
Ident(_) |
SrcVar(_) |
Constant(NonIntegerConstant::Boolean(_)) |
Constant(NonIntegerConstant::Text(_)) |
Constant(NonIntegerConstant::BigInteger(_)) => {
self.mark_known_empty(EmptyBecause::NonNumericArgument);
// We use Double because… well, we only have one slot!
bail!(ErrorKind::NonNumericArgument(function.clone(), position));
},
Constant(NonIntegerConstant::Float(f)) => Ok(QueryValue::TypedValue(TypedValue::Double(f))),
}
}
/// Take a function argument and turn it into a `QueryValue` suitable for use in a concrete
/// constraint.
#[allow(dead_code)]
fn resolve_argument(&self, arg: FnArg) -> Result<QueryValue> {
use self::FnArg::*;
match arg {
@ -843,8 +940,8 @@ impl ConjoiningClauses {
// Any variables that aren't bound by this point in the linear processing of clauses will
// cause the application of the predicate to fail.
let mut args = predicate.args.into_iter();
let left = self.resolve_argument(args.next().unwrap())?;
let right = self.resolve_argument(args.next().unwrap())?;
let left = self.resolve_numeric_argument(&predicate.operator, 0, args.next().unwrap())?;
let right = self.resolve_numeric_argument(&predicate.operator, 1, args.next().unwrap())?;
// These arguments must be variables or numeric constants.
// TODO: generalize argument resolution and validation for different kinds of predicates:
@ -944,7 +1041,7 @@ mod testing {
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::Datoms, "datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_types.get(&x).unwrap(), &ValueType::Ref);
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
@ -982,7 +1079,7 @@ mod testing {
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::Datoms, "datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_types.get(&x).unwrap(), &ValueType::Ref);
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
@ -1031,7 +1128,7 @@ mod testing {
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::Datoms, "datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_types.get(&x).unwrap(), &ValueType::Ref);
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
@ -1091,7 +1188,7 @@ mod testing {
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::AllDatoms, "all_datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_types.get(&x).unwrap(), &ValueType::Ref);
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
@ -1122,7 +1219,7 @@ mod testing {
assert_eq!(cc.from, vec![SourceAlias(DatomsTable::AllDatoms, "all_datoms00".to_string())]);
// ?x must be a ref.
assert_eq!(cc.known_types.get(&x).unwrap(), &ValueType::Ref);
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(), &vec![d0_e.clone()]);
@ -1188,7 +1285,7 @@ mod testing {
]);
// ?x must be a ref.
assert_eq!(cc.known_types.get(&x).unwrap(), &ValueType::Ref);
assert_eq!(cc.known_type(&x).unwrap(), ValueType::Ref);
// ?x is bound to datoms0.e and datoms1.e.
assert_eq!(cc.column_bindings.get(&x).unwrap(),
@ -1316,6 +1413,119 @@ mod testing {
assert!(cc.is_known_empty);
}
#[test]
/// Apply two patterns: a pattern and a numeric predicate.
/// Verify that after application of the predicate we know that the value
/// must be numeric.
fn test_apply_numeric_predicate() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Long,
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Placeholder,
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
assert!(!cc.is_known_empty);
let op = PlainSymbol::new("<");
let comp = NumericComparison::from_datalog_operator(op.plain_name()).unwrap();
assert!(cc.apply_numeric_predicate(&schema, comp, Predicate {
operator: op,
args: vec![
FnArg::Variable(Variable(PlainSymbol::new("?y"))), FnArg::EntidOrInteger(10),
]}).is_ok());
assert!(!cc.is_known_empty);
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
assert!(!cc.is_known_empty);
// After processing those two clauses, we know that ?y must be numeric, but not exactly
// which type it must be.
assert_eq!(None, cc.known_type(&y)); // Not just one.
let expected: HashSet<ValueType> = vec![ValueType::Double, ValueType::Long].into_iter().collect();
assert_eq!(Some(&expected), cc.known_types.get(&y));
let clauses = cc.wheres;
assert_eq!(clauses.len(), 1);
assert_eq!(clauses[0], ColumnConstraint::NumericInequality {
operator: NumericComparison::LessThan,
left: QueryValue::Column(cc.column_bindings.get(&y).unwrap()[0].clone()),
right: QueryValue::TypedValue(TypedValue::Long(10)),
});
}
#[test]
/// Apply three patterns: an unbound pattern to establish a value var,
/// a predicate to constrain the val to numeric types, and a third pattern to conflict with the
/// numeric types and cause the pattern to fail.
fn test_apply_conflict_with_numeric_range() {
let mut cc = ConjoiningClauses::default();
let mut schema = Schema::default();
associate_ident(&mut schema, NamespacedKeyword::new("foo", "bar"), 99);
associate_ident(&mut schema, NamespacedKeyword::new("foo", "roz"), 98);
add_attribute(&mut schema, 99, Attribute {
value_type: ValueType::Long,
..Default::default()
});
add_attribute(&mut schema, 98, Attribute {
value_type: ValueType::String,
unique: Some(Unique::Identity),
..Default::default()
});
let x = Variable(PlainSymbol::new("?x"));
let y = Variable(PlainSymbol::new("?y"));
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Placeholder,
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
assert!(!cc.is_known_empty);
let op = PlainSymbol::new(">=");
let comp = NumericComparison::from_datalog_operator(op.plain_name()).unwrap();
assert!(cc.apply_numeric_predicate(&schema, comp, Predicate {
operator: op,
args: vec![
FnArg::Variable(Variable(PlainSymbol::new("?y"))), FnArg::EntidOrInteger(10),
]}).is_ok());
assert!(!cc.is_known_empty);
cc.apply_pattern(&schema, Pattern {
source: None,
entity: PatternNonValuePlace::Variable(x.clone()),
attribute: PatternNonValuePlace::Ident(NamespacedKeyword::new("foo", "roz")),
value: PatternValuePlace::Variable(y.clone()),
tx: PatternNonValuePlace::Placeholder,
});
// Finally, expand column bindings to get the overlaps for ?x.
cc.expand_column_bindings();
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(),
EmptyBecause::TypeMismatch(y.clone(),
vec![ValueType::Double, ValueType::Long].into_iter()
.collect(),
ValueType::String));
}
#[test]
/// Apply two patterns with differently typed attributes, but sharing a variable in the value
/// place. No value can bind to a variable and match both types, so the CC is known to return
@ -1358,7 +1568,7 @@ mod testing {
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(),
EmptyBecause::TypeMismatch(y.clone(), ValueType::String, ValueType::Boolean));
EmptyBecause::TypeMismatch(y.clone(), unit_type_set(ValueType::String), ValueType::Boolean));
}
#[test]
@ -1396,6 +1606,6 @@ mod testing {
assert!(cc.is_known_empty);
assert_eq!(cc.empty_because.unwrap(),
EmptyBecause::TypeMismatch(x.clone(), ValueType::Ref, ValueType::Boolean));
EmptyBecause::TypeMismatch(x.clone(), unit_type_set(ValueType::Ref), ValueType::Boolean));
}
}

5
query-algebrizer/src/errors.rs
View file

@ -35,6 +35,11 @@ error_chain! {
description("unbound variable in function call")
display("unbound variable: {}", var.0)
}
NonNumericArgument(function: PlainSymbol, position: usize) {
description("invalid argument")
display("invalid argument to {}: expected numeric in position {}.", function, position)
}
}
}

2
query-projector/src/lib.rs
View file

@ -219,7 +219,7 @@ fn project_elements<'a, I: IntoIterator<Item = &'a Element>>(
let qa = columns[0].clone();
let name = column_name(var);
if let Some(t) = query.cc.known_types.get(var) {
if let Some(t) = query.cc.known_type(var) {
cols.push(ProjectedColumn(ColumnOrExpression::Column(qa), name));
let tag = t.value_type_tag();
templates.push(TypedIndex::Known(i, tag));

8
query-translator/tests/translate.rs
View file

@ -186,9 +186,8 @@ fn test_numeric_less_than_unknown_attribute() {
let input = r#"[:find ?x :where [?x _ ?y] [(< ?y 10)]]"#;
let SQLQuery { sql, args } = translate(&schema, input, None);
// TODO: we don't infer numeric types from numeric predicates, because the _SQL_ type code
// is a single value (5), but the Datalog types are a set (Double and Long).
// When we do, this will correctly use `datoms` instead of `all_datoms`.
// Although we infer numericness from numeric predicates, we've already assigned a table to the
// first pattern, and so this is _still_ `all_datoms`.
assert_eq!(sql, "SELECT `all_datoms00`.e AS `?x` FROM `all_datoms` AS `all_datoms00` WHERE `all_datoms00`.v < 10");
assert_eq!(args, vec![]);
}
@ -202,14 +201,12 @@ fn test_numeric_gte_known_attribute() {
..Default::default()
});
let input = r#"[:find ?x :where [?x :foo/bar ?y] [(>= ?y 12.9)]]"#;
let SQLQuery { sql, args } = translate(&schema, input, None);
assert_eq!(sql, "SELECT `datoms00`.e AS `?x` FROM `datoms` AS `datoms00` WHERE `datoms00`.a = 99 AND `datoms00`.v >= 12.9");
assert_eq!(args, vec![]);
}
#[test]
fn test_numeric_not_equals_known_attribute() {
let mut schema = Schema::default();
@ -219,7 +216,6 @@ fn test_numeric_not_equals_known_attribute() {
..Default::default()
});
let input = r#"[:find ?x :where [?x :foo/bar ?y] [(!= ?y 12)]]"#;
let SQLQuery { sql, args } = translate(&schema, input, None);
assert_eq!(sql, "SELECT `datoms00`.e AS `?x` FROM `datoms` AS `datoms00` WHERE `datoms00`.a = 99 AND `datoms00`.v <> 12");