reddb_server/storage/query/planner/
rewriter.rs

1//! Query Rewriter
2//!
3//! Multi-pass AST transformation system inspired by Neo4j's query rewriting.
4//!
5//! # Rewrite Passes
6//!
7//! 1. **Normalize**: Standardize AST structure
8//! 2. **InjectCachedProperties**: Cache property lookups at compile time
9//! 3. **SimplifyFilters**: Combine and simplify filter expressions
10//! 4. **PushdownPredicates**: Move filters closer to data source
11//! 5. **ValidateFunctions**: Check function calls against schema
12
13use crate::storage::query::ast::{
14    CompareOp, FieldRef, Filter as AstFilter, JoinQuery, Projection, QueryExpr,
15};
16use crate::storage::query::sql_lowering::{
17    effective_graph_filter, effective_join_filter, effective_table_filter, effective_vector_filter,
18};
19use crate::storage::schema::Value;
20
21/// Context for rewrite operations
22#[derive(Debug, Clone, Default)]
23pub struct RewriteContext {
24    /// Property cache for compile-time lookups
25    pub property_cache: Vec<CachedProperty>,
26    /// Validation errors encountered
27    pub errors: Vec<String>,
28    /// Warnings generated
29    pub warnings: Vec<String>,
30    /// Statistics about rewrites
31    pub stats: RewriteStats,
32}
33
34/// A cached property lookup
35#[derive(Debug, Clone)]
36pub struct CachedProperty {
37    /// Source alias (table or node)
38    pub source: String,
39    /// Property name
40    pub property: String,
41    /// Cached value if known at compile time
42    pub cached_value: Option<String>,
43}
44
45/// Statistics about rewrite passes
46#[derive(Debug, Clone, Default)]
47pub struct RewriteStats {
48    /// Number of filters simplified
49    pub filters_simplified: u32,
50    /// Number of predicates pushed down
51    pub predicates_pushed: u32,
52    /// Number of properties cached
53    pub properties_cached: u32,
54    /// Number of expressions normalized
55    pub expressions_normalized: u32,
56}
57
58/// A rewrite rule that transforms query expressions
59pub trait RewriteRule: Send + Sync {
60    /// Rule name for debugging
61    fn name(&self) -> &str;
62
63    /// Apply the rule to a query expression
64    fn apply(&self, query: QueryExpr, ctx: &mut RewriteContext) -> QueryExpr;
65
66    /// Check if this rule is applicable to the query
67    fn is_applicable(&self, query: &QueryExpr) -> bool;
68}
69
70/// Query rewriter with pluggable rules
71pub struct QueryRewriter {
72    /// Ordered list of rewrite rules
73    rules: Vec<Box<dyn RewriteRule>>,
74    /// Maximum number of rewrite iterations
75    max_iterations: usize,
76}
77
78impl QueryRewriter {
79    /// Create a new rewriter with default rules
80    pub fn new() -> Self {
81        let rules: Vec<Box<dyn RewriteRule>> = vec![
82            Box::new(NormalizeRule),
83            Box::new(SimplifyFiltersRule),
84            Box::new(PushdownPredicatesRule),
85            Box::new(EliminateDeadCodeRule),
86            Box::new(FoldConstantsRule),
87        ];
88
89        Self {
90            rules,
91            max_iterations: 10,
92        }
93    }
94
95    /// Add a custom rewrite rule
96    pub fn add_rule(&mut self, rule: Box<dyn RewriteRule>) {
97        self.rules.push(rule);
98    }
99
100    /// Rewrite a query expression
101    pub fn rewrite(&self, query: QueryExpr) -> QueryExpr {
102        let mut ctx = RewriteContext::default();
103        self.rewrite_with_context(query, &mut ctx)
104    }
105
106    /// Rewrite with access to context
107    pub fn rewrite_with_context(
108        &self,
109        mut query: QueryExpr,
110        ctx: &mut RewriteContext,
111    ) -> QueryExpr {
112        // Apply rules iteratively until fixed point
113        for _iteration in 0..self.max_iterations {
114            let original = format!("{:?}", query);
115
116            for rule in &self.rules {
117                if rule.is_applicable(&query) {
118                    query = rule.apply(query, ctx);
119                }
120            }
121
122            // Check for fixed point
123            if format!("{:?}", query) == original {
124                break;
125            }
126        }
127
128        query
129    }
130}
131
132impl Default for QueryRewriter {
133    fn default() -> Self {
134        Self::new()
135    }
136}
137
138// =============================================================================
139// Built-in Rewrite Rules
140// =============================================================================
141
142/// Normalize AST structure
143struct NormalizeRule;
144
145impl RewriteRule for NormalizeRule {
146    fn name(&self) -> &str {
147        "Normalize"
148    }
149
150    fn apply(&self, query: QueryExpr, ctx: &mut RewriteContext) -> QueryExpr {
151        match query {
152            QueryExpr::Table(mut tq) => {
153                // Normalize column order
154                tq.columns.sort_by(|a, b| {
155                    let a_name = projection_name(a);
156                    let b_name = projection_name(b);
157                    a_name.cmp(&b_name)
158                });
159                ctx.stats.expressions_normalized += 1;
160                QueryExpr::Table(tq)
161            }
162            QueryExpr::Graph(gq) => {
163                // Graph queries don't need normalization currently
164                QueryExpr::Graph(gq)
165            }
166            QueryExpr::Join(jq) => {
167                // Recursively normalize children
168                let left = self.apply(*jq.left, ctx);
169                let right = self.apply(*jq.right, ctx);
170                QueryExpr::Join(JoinQuery {
171                    left: Box::new(left),
172                    right: Box::new(right),
173                    ..jq
174                })
175            }
176            QueryExpr::Path(pq) => QueryExpr::Path(pq),
177            QueryExpr::Vector(vq) => {
178                // Vector queries don't need normalization currently
179                QueryExpr::Vector(vq)
180            }
181            QueryExpr::Hybrid(mut hq) => {
182                // Normalize the structured part
183                hq.structured = Box::new(self.apply(*hq.structured, ctx));
184                QueryExpr::Hybrid(hq)
185            }
186            // DML/DDL/Command statements pass through without normalization
187            other @ (QueryExpr::Insert(_)
188            | QueryExpr::Update(_)
189            | QueryExpr::Delete(_)
190            | QueryExpr::CreateTable(_)
191            | QueryExpr::CreateCollection(_)
192            | QueryExpr::CreateVector(_)
193            | QueryExpr::DropTable(_)
194            | QueryExpr::DropGraph(_)
195            | QueryExpr::DropVector(_)
196            | QueryExpr::DropDocument(_)
197            | QueryExpr::DropKv(_)
198            | QueryExpr::DropCollection(_)
199            | QueryExpr::Truncate(_)
200            | QueryExpr::AlterTable(_)
201            | QueryExpr::GraphCommand(_)
202            | QueryExpr::SearchCommand(_)
203            | QueryExpr::CreateIndex(_)
204            | QueryExpr::DropIndex(_)
205            | QueryExpr::ProbabilisticCommand(_)
206            | QueryExpr::Ask(_)
207            | QueryExpr::SetConfig { .. }
208            | QueryExpr::ShowConfig { .. }
209            | QueryExpr::SetSecret { .. }
210            | QueryExpr::DeleteSecret { .. }
211            | QueryExpr::ShowSecrets { .. }
212            | QueryExpr::SetTenant(_)
213            | QueryExpr::ShowTenant
214            | QueryExpr::CreateTimeSeries(_)
215            | QueryExpr::CreateMetric(_)
216            | QueryExpr::AlterMetric(_)
217            | QueryExpr::CreateSlo(_)
218            | QueryExpr::DropTimeSeries(_)
219            | QueryExpr::CreateQueue(_)
220            | QueryExpr::AlterQueue(_)
221            | QueryExpr::DropQueue(_)
222            | QueryExpr::QueueSelect(_)
223            | QueryExpr::QueueCommand(_)
224            | QueryExpr::KvCommand(_)
225            | QueryExpr::ConfigCommand(_)
226            | QueryExpr::CreateTree(_)
227            | QueryExpr::DropTree(_)
228            | QueryExpr::TreeCommand(_)
229            | QueryExpr::ExplainAlter(_)
230            | QueryExpr::TransactionControl(_)
231            | QueryExpr::MaintenanceCommand(_)
232            | QueryExpr::CreateSchema(_)
233            | QueryExpr::DropSchema(_)
234            | QueryExpr::CreateSequence(_)
235            | QueryExpr::DropSequence(_)
236            | QueryExpr::CopyFrom(_)
237            | QueryExpr::CreateView(_)
238            | QueryExpr::DropView(_)
239            | QueryExpr::RefreshMaterializedView(_)
240            | QueryExpr::CreatePolicy(_)
241            | QueryExpr::DropPolicy(_)
242            | QueryExpr::CreateServer(_)
243            | QueryExpr::DropServer(_)
244            | QueryExpr::CreateForeignTable(_)
245            | QueryExpr::DropForeignTable(_)
246            | QueryExpr::Grant(_)
247            | QueryExpr::Revoke(_)
248            | QueryExpr::AlterUser(_)
249            | QueryExpr::CreateIamPolicy { .. }
250            | QueryExpr::DropIamPolicy { .. }
251            | QueryExpr::AttachPolicy { .. }
252            | QueryExpr::DetachPolicy { .. }
253            | QueryExpr::ShowPolicies { .. }
254            | QueryExpr::ShowEffectivePermissions { .. }
255            | QueryExpr::SimulatePolicy { .. }
256            | QueryExpr::LintPolicy { .. }
257            | QueryExpr::MigratePolicyMode { .. }
258            | QueryExpr::CreateMigration(_)
259            | QueryExpr::ApplyMigration(_)
260            | QueryExpr::RollbackMigration(_)
261            | QueryExpr::ExplainMigration(_)
262            | QueryExpr::EventsBackfill(_)
263            | QueryExpr::EventsBackfillStatus { .. }) => other,
264        }
265    }
266
267    fn is_applicable(&self, _query: &QueryExpr) -> bool {
268        true
269    }
270}
271
272/// Simplify filter expressions
273struct SimplifyFiltersRule;
274
275impl RewriteRule for SimplifyFiltersRule {
276    fn name(&self) -> &str {
277        "SimplifyFilters"
278    }
279
280    fn apply(&self, query: QueryExpr, ctx: &mut RewriteContext) -> QueryExpr {
281        match query {
282            QueryExpr::Table(mut tq) => {
283                if let Some(filter) = effective_table_filter(&tq) {
284                    tq.filter = Some(simplify_filter(filter, ctx));
285                }
286                QueryExpr::Table(tq)
287            }
288            QueryExpr::Graph(mut gq) => {
289                if let Some(filter) = effective_graph_filter(&gq) {
290                    gq.filter = Some(simplify_filter(filter, ctx));
291                }
292                QueryExpr::Graph(gq)
293            }
294            QueryExpr::Join(mut jq) => {
295                let join_filter = effective_join_filter(&jq);
296                let left = self.apply(*jq.left, ctx);
297                let right = self.apply(*jq.right, ctx);
298                if let Some(filter) = join_filter {
299                    jq.filter = Some(simplify_filter(filter, ctx));
300                }
301                jq.left = Box::new(left);
302                jq.right = Box::new(right);
303                QueryExpr::Join(jq)
304            }
305            QueryExpr::Path(pq) => QueryExpr::Path(pq),
306            QueryExpr::Vector(vq) => {
307                // Vector queries have MetadataFilter, not AstFilter
308                // Pass through for now
309                QueryExpr::Vector(vq)
310            }
311            QueryExpr::Hybrid(mut hq) => {
312                // Simplify filters in the structured part
313                hq.structured = Box::new(self.apply(*hq.structured, ctx));
314                QueryExpr::Hybrid(hq)
315            }
316            // DML/DDL/Command statements pass through without filter simplification
317            other @ (QueryExpr::Insert(_)
318            | QueryExpr::Update(_)
319            | QueryExpr::Delete(_)
320            | QueryExpr::CreateTable(_)
321            | QueryExpr::CreateCollection(_)
322            | QueryExpr::CreateVector(_)
323            | QueryExpr::DropTable(_)
324            | QueryExpr::DropGraph(_)
325            | QueryExpr::DropVector(_)
326            | QueryExpr::DropDocument(_)
327            | QueryExpr::DropKv(_)
328            | QueryExpr::DropCollection(_)
329            | QueryExpr::Truncate(_)
330            | QueryExpr::AlterTable(_)
331            | QueryExpr::GraphCommand(_)
332            | QueryExpr::SearchCommand(_)
333            | QueryExpr::CreateIndex(_)
334            | QueryExpr::DropIndex(_)
335            | QueryExpr::ProbabilisticCommand(_)
336            | QueryExpr::Ask(_)
337            | QueryExpr::SetConfig { .. }
338            | QueryExpr::ShowConfig { .. }
339            | QueryExpr::SetSecret { .. }
340            | QueryExpr::DeleteSecret { .. }
341            | QueryExpr::ShowSecrets { .. }
342            | QueryExpr::SetTenant(_)
343            | QueryExpr::ShowTenant
344            | QueryExpr::CreateTimeSeries(_)
345            | QueryExpr::CreateMetric(_)
346            | QueryExpr::AlterMetric(_)
347            | QueryExpr::CreateSlo(_)
348            | QueryExpr::DropTimeSeries(_)
349            | QueryExpr::CreateQueue(_)
350            | QueryExpr::AlterQueue(_)
351            | QueryExpr::DropQueue(_)
352            | QueryExpr::QueueSelect(_)
353            | QueryExpr::QueueCommand(_)
354            | QueryExpr::KvCommand(_)
355            | QueryExpr::ConfigCommand(_)
356            | QueryExpr::CreateTree(_)
357            | QueryExpr::DropTree(_)
358            | QueryExpr::TreeCommand(_)
359            | QueryExpr::ExplainAlter(_)
360            | QueryExpr::TransactionControl(_)
361            | QueryExpr::MaintenanceCommand(_)
362            | QueryExpr::CreateSchema(_)
363            | QueryExpr::DropSchema(_)
364            | QueryExpr::CreateSequence(_)
365            | QueryExpr::DropSequence(_)
366            | QueryExpr::CopyFrom(_)
367            | QueryExpr::CreateView(_)
368            | QueryExpr::DropView(_)
369            | QueryExpr::RefreshMaterializedView(_)
370            | QueryExpr::CreatePolicy(_)
371            | QueryExpr::DropPolicy(_)
372            | QueryExpr::CreateServer(_)
373            | QueryExpr::DropServer(_)
374            | QueryExpr::CreateForeignTable(_)
375            | QueryExpr::DropForeignTable(_)
376            | QueryExpr::Grant(_)
377            | QueryExpr::Revoke(_)
378            | QueryExpr::AlterUser(_)
379            | QueryExpr::CreateIamPolicy { .. }
380            | QueryExpr::DropIamPolicy { .. }
381            | QueryExpr::AttachPolicy { .. }
382            | QueryExpr::DetachPolicy { .. }
383            | QueryExpr::ShowPolicies { .. }
384            | QueryExpr::ShowEffectivePermissions { .. }
385            | QueryExpr::SimulatePolicy { .. }
386            | QueryExpr::LintPolicy { .. }
387            | QueryExpr::MigratePolicyMode { .. }
388            | QueryExpr::CreateMigration(_)
389            | QueryExpr::ApplyMigration(_)
390            | QueryExpr::RollbackMigration(_)
391            | QueryExpr::ExplainMigration(_)
392            | QueryExpr::EventsBackfill(_)
393            | QueryExpr::EventsBackfillStatus { .. }) => other,
394        }
395    }
396
397    fn is_applicable(&self, query: &QueryExpr) -> bool {
398        match query {
399            QueryExpr::Table(tq) => effective_table_filter(tq).is_some(),
400            QueryExpr::Graph(gq) => effective_graph_filter(gq).is_some(),
401            QueryExpr::Join(_) => true,
402            QueryExpr::Path(_) => false,
403            QueryExpr::Vector(vq) => effective_vector_filter(vq).is_some(),
404            QueryExpr::Hybrid(_) => true, // May have filters in structured part
405            // DML/DDL/Command statements are not applicable for filter simplification
406            QueryExpr::Insert(_)
407            | QueryExpr::Update(_)
408            | QueryExpr::Delete(_)
409            | QueryExpr::CreateTable(_)
410            | QueryExpr::CreateCollection(_)
411            | QueryExpr::CreateVector(_)
412            | QueryExpr::DropTable(_)
413            | QueryExpr::DropGraph(_)
414            | QueryExpr::DropVector(_)
415            | QueryExpr::DropDocument(_)
416            | QueryExpr::DropKv(_)
417            | QueryExpr::DropCollection(_)
418            | QueryExpr::Truncate(_)
419            | QueryExpr::AlterTable(_)
420            | QueryExpr::GraphCommand(_)
421            | QueryExpr::SearchCommand(_)
422            | QueryExpr::CreateIndex(_)
423            | QueryExpr::DropIndex(_)
424            | QueryExpr::ProbabilisticCommand(_)
425            | QueryExpr::Ask(_)
426            | QueryExpr::SetConfig { .. }
427            | QueryExpr::ShowConfig { .. }
428            | QueryExpr::SetSecret { .. }
429            | QueryExpr::DeleteSecret { .. }
430            | QueryExpr::ShowSecrets { .. }
431            | QueryExpr::SetTenant(_)
432            | QueryExpr::ShowTenant
433            | QueryExpr::CreateTimeSeries(_)
434            | QueryExpr::CreateMetric(_)
435            | QueryExpr::AlterMetric(_)
436            | QueryExpr::CreateSlo(_)
437            | QueryExpr::DropTimeSeries(_)
438            | QueryExpr::CreateQueue(_)
439            | QueryExpr::AlterQueue(_)
440            | QueryExpr::DropQueue(_)
441            | QueryExpr::QueueSelect(_)
442            | QueryExpr::QueueCommand(_)
443            | QueryExpr::KvCommand(_)
444            | QueryExpr::ConfigCommand(_)
445            | QueryExpr::CreateTree(_)
446            | QueryExpr::DropTree(_)
447            | QueryExpr::TreeCommand(_)
448            | QueryExpr::ExplainAlter(_)
449            | QueryExpr::TransactionControl(_)
450            | QueryExpr::MaintenanceCommand(_)
451            | QueryExpr::CreateSchema(_)
452            | QueryExpr::DropSchema(_)
453            | QueryExpr::CreateSequence(_)
454            | QueryExpr::DropSequence(_)
455            | QueryExpr::CopyFrom(_)
456            | QueryExpr::CreateView(_)
457            | QueryExpr::DropView(_)
458            | QueryExpr::RefreshMaterializedView(_)
459            | QueryExpr::CreatePolicy(_)
460            | QueryExpr::DropPolicy(_)
461            | QueryExpr::CreateServer(_)
462            | QueryExpr::DropServer(_)
463            | QueryExpr::CreateForeignTable(_)
464            | QueryExpr::DropForeignTable(_)
465            | QueryExpr::Grant(_)
466            | QueryExpr::Revoke(_)
467            | QueryExpr::AlterUser(_)
468            | QueryExpr::CreateIamPolicy { .. }
469            | QueryExpr::DropIamPolicy { .. }
470            | QueryExpr::AttachPolicy { .. }
471            | QueryExpr::DetachPolicy { .. }
472            | QueryExpr::ShowPolicies { .. }
473            | QueryExpr::ShowEffectivePermissions { .. }
474            | QueryExpr::SimulatePolicy { .. }
475            | QueryExpr::LintPolicy { .. }
476            | QueryExpr::MigratePolicyMode { .. }
477            | QueryExpr::CreateMigration(_)
478            | QueryExpr::ApplyMigration(_)
479            | QueryExpr::RollbackMigration(_)
480            | QueryExpr::ExplainMigration(_)
481            | QueryExpr::EventsBackfill(_)
482            | QueryExpr::EventsBackfillStatus { .. } => false,
483        }
484    }
485}
486
487/// Push predicates down to data sources
488struct PushdownPredicatesRule;
489
490impl RewriteRule for PushdownPredicatesRule {
491    fn name(&self) -> &str {
492        "PushdownPredicates"
493    }
494
495    fn apply(&self, query: QueryExpr, ctx: &mut RewriteContext) -> QueryExpr {
496        match query {
497            QueryExpr::Join(mut jq) => {
498                // Try to push join predicates down to children
499                // This is a simplified version - real implementation would analyze
500                // which predicates can be pushed to which child
501
502                // For now, just recursively apply to children
503                jq.left = Box::new(self.apply(*jq.left, ctx));
504                jq.right = Box::new(self.apply(*jq.right, ctx));
505                ctx.stats.predicates_pushed += 1;
506                QueryExpr::Join(jq)
507            }
508            other => other,
509        }
510    }
511
512    fn is_applicable(&self, query: &QueryExpr) -> bool {
513        matches!(query, QueryExpr::Join(_))
514    }
515}
516
517/// Eliminate dead code branches
518struct EliminateDeadCodeRule;
519
520impl RewriteRule for EliminateDeadCodeRule {
521    fn name(&self) -> &str {
522        "EliminateDeadCode"
523    }
524
525    fn apply(&self, query: QueryExpr, _ctx: &mut RewriteContext) -> QueryExpr {
526        match query {
527            QueryExpr::Table(mut tq) => {
528                // Remove always-true filters
529                if let Some(filter) = effective_table_filter(&tq).as_ref() {
530                    if is_always_true(filter) {
531                        tq.filter = None;
532                    }
533                }
534                QueryExpr::Table(tq)
535            }
536            other => other,
537        }
538    }
539
540    fn is_applicable(&self, query: &QueryExpr) -> bool {
541        matches!(query, QueryExpr::Table(_))
542    }
543}
544
545/// Fold constant expressions
546struct FoldConstantsRule;
547
548impl RewriteRule for FoldConstantsRule {
549    fn name(&self) -> &str {
550        "FoldConstants"
551    }
552
553    fn apply(&self, query: QueryExpr, _ctx: &mut RewriteContext) -> QueryExpr {
554        // Constant folding is complex - for now just pass through
555        // A real implementation would evaluate constant expressions at compile time
556        query
557    }
558
559    fn is_applicable(&self, _query: &QueryExpr) -> bool {
560        true
561    }
562}
563
564// =============================================================================
565// Helper Functions
566// =============================================================================
567
568fn projection_name(proj: &Projection) -> String {
569    match proj {
570        Projection::All => "*".to_string(),
571        Projection::Column(name) => name.clone(),
572        Projection::Alias(_, alias) => alias.clone(),
573        Projection::Function(name, _) => name
574            .split_once(':')
575            .map(|(_, alias)| alias.to_string())
576            .unwrap_or_else(|| name.clone()),
577        Projection::Expression(expr, alias) => {
578            alias.clone().unwrap_or_else(|| format!("{:?}", expr))
579        }
580        Projection::Field(field, alias) => alias.clone().unwrap_or_else(|| format!("{:?}", field)),
581        Projection::Window { name, alias, .. } => alias.clone().unwrap_or_else(|| name.clone()),
582    }
583}
584
585fn simplify_filter(filter: AstFilter, ctx: &mut RewriteContext) -> AstFilter {
586    match filter {
587        AstFilter::And(left, right) => {
588            let left = simplify_filter(*left, ctx);
589            let right = simplify_filter(*right, ctx);
590
591            // AND with TRUE -> other side
592            if is_always_true(&left) {
593                ctx.stats.filters_simplified += 1;
594                return right;
595            }
596            if is_always_true(&right) {
597                ctx.stats.filters_simplified += 1;
598                return left;
599            }
600
601            // AND with FALSE -> FALSE
602            if is_always_false(&left) || is_always_false(&right) {
603                ctx.stats.filters_simplified += 1;
604                return AstFilter::Compare {
605                    field: FieldRef::TableColumn {
606                        table: String::new(),
607                        column: "1".to_string(),
608                    },
609                    op: CompareOp::Eq,
610                    value: Value::Integer(0),
611                };
612            }
613
614            AstFilter::And(Box::new(left), Box::new(right))
615        }
616        AstFilter::Or(left, right) => {
617            let left = simplify_filter(*left, ctx);
618            let right = simplify_filter(*right, ctx);
619
620            // OR with FALSE -> other side
621            if is_always_false(&left) {
622                ctx.stats.filters_simplified += 1;
623                return right;
624            }
625            if is_always_false(&right) {
626                ctx.stats.filters_simplified += 1;
627                return left;
628            }
629
630            // OR with TRUE -> TRUE
631            if is_always_true(&left) || is_always_true(&right) {
632                ctx.stats.filters_simplified += 1;
633                return AstFilter::Compare {
634                    field: FieldRef::TableColumn {
635                        table: String::new(),
636                        column: "1".to_string(),
637                    },
638                    op: CompareOp::Eq,
639                    value: Value::Integer(1),
640                };
641            }
642
643            AstFilter::Or(Box::new(left), Box::new(right))
644        }
645        AstFilter::Not(inner) => {
646            let inner = simplify_filter(*inner, ctx);
647
648            // NOT NOT x -> x
649            if let AstFilter::Not(double_inner) = inner {
650                ctx.stats.filters_simplified += 1;
651                return *double_inner;
652            }
653
654            AstFilter::Not(Box::new(inner))
655        }
656        other => other,
657    }
658}
659
660fn is_always_true(filter: &AstFilter) -> bool {
661    match filter {
662        AstFilter::Compare { field, op, value } => {
663            // 1 = 1 is always true
664            matches!(field, FieldRef::TableColumn { column, .. } if column == "1")
665                && matches!(op, CompareOp::Eq)
666                && matches!(value, Value::Integer(1))
667        }
668        _ => false,
669    }
670}
671
672fn is_always_false(filter: &AstFilter) -> bool {
673    match filter {
674        AstFilter::Compare { field, op, value } => {
675            // 1 = 0 is always false
676            matches!(field, FieldRef::TableColumn { column, .. } if column == "1")
677                && matches!(op, CompareOp::Eq)
678                && matches!(value, Value::Integer(0))
679        }
680        _ => false,
681    }
682}
683
684#[cfg(test)]
685mod tests {
686    use super::*;
687
688    fn make_field(name: &str) -> FieldRef {
689        FieldRef::TableColumn {
690            table: String::new(),
691            column: name.to_string(),
692        }
693    }
694
695    #[test]
696    fn test_simplify_and_with_true() {
697        let mut ctx = RewriteContext::default();
698
699        let filter = AstFilter::And(
700            Box::new(AstFilter::Compare {
701                field: make_field("1"),
702                op: CompareOp::Eq,
703                value: Value::Integer(1),
704            }),
705            Box::new(AstFilter::Compare {
706                field: make_field("x"),
707                op: CompareOp::Eq,
708                value: Value::Integer(5),
709            }),
710        );
711
712        let simplified = simplify_filter(filter, &mut ctx);
713
714        match simplified {
715            AstFilter::Compare { field, .. } => {
716                assert!(matches!(field, FieldRef::TableColumn { column, .. } if column == "x"));
717            }
718            _ => panic!("Expected Compare filter"),
719        }
720    }
721
722    #[test]
723    fn test_simplify_double_not() {
724        let mut ctx = RewriteContext::default();
725
726        let filter = AstFilter::Not(Box::new(AstFilter::Not(Box::new(AstFilter::Compare {
727            field: make_field("x"),
728            op: CompareOp::Eq,
729            value: Value::Integer(5),
730        }))));
731
732        let simplified = simplify_filter(filter, &mut ctx);
733
734        match simplified {
735            AstFilter::Compare { field, .. } => {
736                assert!(matches!(field, FieldRef::TableColumn { column, .. } if column == "x"));
737            }
738            _ => panic!("Expected Compare filter"),
739        }
740    }
741}
reddb_server/storage/query/planner/rewriter.rs

reddb_server/storage/query/planner/
rewriter.rs
