diff --git a/pages/blog/2024-07-05-release_3_2.md b/pages/blog/2024-07-05-release_3_2.md new file mode 100644 index 00000000..31eed8ab --- /dev/null +++ b/pages/blog/2024-07-05-release_3_2.md @@ -0,0 +1,109 @@ +--- +title: 'Release 3.2: 🔎 Knowing what to optimize' +--- + +For this release, we mainly focused on improving tooling to more easily track down performance issues. +Concretely, we improved our query explain output, +started running multiple benchmarks in our CI to avoid performance regressions, +and applied several performance improvements that were identified following these changes. + + + +## 🔎 Query explain improvements + +Comunica has had several [query explain functionalities](/docs/query/advanced/explain/) for a while now, +to show how a query is parsed, optimized (logical), and executed (physical). +However, the physical plan output tended to be very verbose, which made it difficult to draw conclusions from. + +In this update, the physical plan output has undergone three main changes: + +1. The output from joins (especially Bind Joins) are _compacted_, so that recurring patterns in sub-plans are not repeated. Instead, a counter is added showing how many times a certain sub-plan was executed. +2. The default output is a compact text representation instead of the previous JSON output. (The old JSON representation is still available when passing the `physical-json` explain value) +3. Additional metadata is emitted, such as cardinalities and execution times. + +For example, outputs such as the following can now be obtained: + +```bash +$ node bin/query.js https://fragments.dbpedia.org/2016-04/en \ + -q 'SELECT ?movie ?title ?name +WHERE { + ?movie dbpedia-owl:starring [ rdfs:label "Brad Pitt"@en ]; + rdfs:label ?title; + dbpedia-owl:director [ rdfs:label ?name ]. + FILTER LANGMATCHES(LANG(?title), "EN") + FILTER LANGMATCHES(LANG(?name), "EN") +}' --explain physical +``` +```text +project (movie,title,name) + join + join-inner(bind) bindOperation:(?g_0 http://www.w3.org/2000/01/rdf-schema#label "Brad Pitt"@en) bindCardEst:~2 cardReal:43 timeSelf:2.567ms timeLife:667.726ms + join compacted-occurrences:1 + join-inner(bind) bindOperation:(?movie http://dbpedia.org/ontology/starring http://dbpedia.org/resource/Brad_Pitt) bindCardEst:~40 cardReal:43 timeSelf:6.011ms timeLife:641.139ms + join compacted-occurrences:38 + join-inner(bind) bindOperation:(http://dbpedia.org/resource/12_Monkeys http://dbpedia.org/ontology/director ?g_1) bindCardEst:~1 cardReal:1 timeSelf:0.647ms timeLife:34.827ms + filter compacted-occurrences:1 + join + join-inner(nested-loop) cardReal:1 timeSelf:0.432ms timeLife:4.024ms + pattern (http://dbpedia.org/resource/12_Monkeys http://www.w3.org/2000/01/rdf-schema#label ?title) cardEst:~1 src:0 + pattern (http://dbpedia.org/resource/Terry_Gilliam http://www.w3.org/2000/01/rdf-schema#label ?name) cardEst:~1 src:0 + join compacted-occurrences:2 + join-inner(multi-empty) timeSelf:0.004ms timeLife:0.053ms + pattern (http://dbpedia.org/resource/Contact_(1992_film) http://dbpedia.org/ontology/director ?g_1) cardEst:~0 src:0 + filter cardEst:~5,188,789.667 + join + join-inner(nested-loop) timeLife:0.6ms + pattern (http://dbpedia.org/resource/Contact_(1992_film) http://www.w3.org/2000/01/rdf-schema#label ?title) cardEst:~1 src:0 + pattern (?g_1 http://www.w3.org/2000/01/rdf-schema#label ?name) cardEst:~20,013,903 src:0 + join compacted-occurrences:1 + join-inner(multi-empty) timeSelf:0.053ms timeLife:0.323ms + pattern (?movie http://dbpedia.org/ontology/director ?g_1) cardEst:~118,505 src:0 + pattern (?movie http://dbpedia.org/ontology/starring http://wikidata.dbpedia.org/resource/Q35332) cardEst:~0 src:0 + filter cardEst:~242,311,843,844,161 + join + join-inner(symmetric-hash) timeLife:36.548ms + pattern (?movie http://www.w3.org/2000/01/rdf-schema#label ?title) cardEst:~20,013,903 src:0 + pattern (?g_1 http://www.w3.org/2000/01/rdf-schema#label ?name) cardEst:~20,013,903 src:0 + +sources: + 0: QuerySourceHypermedia(https://fragments.dbpedia.org/2016-04/en)(SkolemID:0) +``` + +## ⚙️ Continuous performance tracking + +In order to keep better track of the evolution of Comunica's performance, +we have added continuous performance tracking into our continuous integration. +For various benchmarks, we can now see the evolution of execution times across our commit history. +This allows us to easily identify which changes have a positive or negative impact on performance. + +For considering the performance for different aspects, we have included the following benchmarks: + +- WatDiv (in-memory) +- WatDiv (TPF) +- Berlin SPARQL Benchmark (in-memory) +- Berlin SPARQL Benchmark (TPF) +- Custom web queries: manually crafted queries to test for specific edge cases over the live Web + +This allows us to inspect performance as follows: + +
+ Continuous performance +
+ +These results can be inspected in [more close detail](https://github.com/comunica/comunica-performance-results) together with execution times per query separately. + +## 🏎️ Performance improvements + +Thanks to the improvements to our physical query plan output and the continuous performance tracking, +we identified several low-hanging efforts for improving performance: + +- [Addition of a hash-based optional join actor](https://github.com/comunica/comunica/commit/de90db0140cd10e2bfdf23c26f9eeff5e94f3ef2) +- [Tweaking constants of our internal join cost model](https://github.com/comunica/comunica/commit/50333c92ed1cf5410f172f608a213424e510986e) +- [Making optional hash and bind join only work with common variables](https://github.com/comunica/comunica/commit/df40c20e001121cd0ae9a9adf67ed221dc2966ba) + +Besides these changes, we have many more performance-impacting changes in the pipeline for upcoming releases! + +## Full changelog + +Besides this, several fixes were applied, as well as various changes and additions. +If you want to learn more about all changes, check out the [full changelog](https://github.com/comunica/comunica/blob/master/CHANGELOG.md#v320---2024-07-05). diff --git a/pages/docs/1_query/advanced/explain.md b/pages/docs/1_query/advanced/explain.md index a8a5dade..0c81eba8 100644 --- a/pages/docs/1_query/advanced/explain.md +++ b/pages/docs/1_query/advanced/explain.md @@ -147,9 +147,54 @@ $ comunica-sparql https://fragments.dbpedia.org/2016-04/en \ ### Explain physical on the command line +```bash +$ node bin/query.js https://fragments.dbpedia.org/2016-04/en \ + -q 'SELECT ?movie ?title ?name +WHERE { + ?movie dbpedia-owl:starring [ rdfs:label "Brad Pitt"@en ]; + rdfs:label ?title; + dbpedia-owl:director [ rdfs:label ?name ]. + FILTER LANGMATCHES(LANG(?title), "EN") + FILTER LANGMATCHES(LANG(?name), "EN") +}' --explain physical + +project (movie,title,name) + join + join-inner(bind) bindOperation:(?g_0 http://www.w3.org/2000/01/rdf-schema#label "Brad Pitt"@en) bindCardEst:~2 cardReal:43 timeSelf:2.567ms timeLife:667.726ms + join compacted-occurrences:1 + join-inner(bind) bindOperation:(?movie http://dbpedia.org/ontology/starring http://dbpedia.org/resource/Brad_Pitt) bindCardEst:~40 cardReal:43 timeSelf:6.011ms timeLife:641.139ms + join compacted-occurrences:38 + join-inner(bind) bindOperation:(http://dbpedia.org/resource/12_Monkeys http://dbpedia.org/ontology/director ?g_1) bindCardEst:~1 cardReal:1 timeSelf:0.647ms timeLife:34.827ms + filter compacted-occurrences:1 + join + join-inner(nested-loop) cardReal:1 timeSelf:0.432ms timeLife:4.024ms + pattern (http://dbpedia.org/resource/12_Monkeys http://www.w3.org/2000/01/rdf-schema#label ?title) cardEst:~1 src:0 + pattern (http://dbpedia.org/resource/Terry_Gilliam http://www.w3.org/2000/01/rdf-schema#label ?name) cardEst:~1 src:0 + join compacted-occurrences:2 + join-inner(multi-empty) timeSelf:0.004ms timeLife:0.053ms + pattern (http://dbpedia.org/resource/Contact_(1992_film) http://dbpedia.org/ontology/director ?g_1) cardEst:~0 src:0 + filter cardEst:~5,188,789.667 + join + join-inner(nested-loop) timeLife:0.6ms + pattern (http://dbpedia.org/resource/Contact_(1992_film) http://www.w3.org/2000/01/rdf-schema#label ?title) cardEst:~1 src:0 + pattern (?g_1 http://www.w3.org/2000/01/rdf-schema#label ?name) cardEst:~20,013,903 src:0 + join compacted-occurrences:1 + join-inner(multi-empty) timeSelf:0.053ms timeLife:0.323ms + pattern (?movie http://dbpedia.org/ontology/director ?g_1) cardEst:~118,505 src:0 + pattern (?movie http://dbpedia.org/ontology/starring http://wikidata.dbpedia.org/resource/Q35332) cardEst:~0 src:0 + filter cardEst:~242,311,843,844,161 + join + join-inner(symmetric-hash) timeLife:36.548ms + pattern (?movie http://www.w3.org/2000/01/rdf-schema#label ?title) cardEst:~20,013,903 src:0 + pattern (?g_1 http://www.w3.org/2000/01/rdf-schema#label ?name) cardEst:~20,013,903 src:0 + +sources: + 0: QuerySourceHypermedia(https://fragments.dbpedia.org/2016-04/en)(SkolemID:0) +``` + ```bash $ comunica-sparql https://fragments.dbpedia.org/2016-04/en \ - -q 'SELECT * { ?s ?p ?o. ?s a ?o } LIMIT 100' --explain physical + -q 'SELECT * { ?s ?p ?o. ?s a ?o } LIMIT 100' --explain physical-json { "logical": "slice", @@ -157,56 +202,54 @@ $ comunica-sparql https://fragments.dbpedia.org/2016-04/en \ { "logical": "project", "variables": [ - "s", + "o", "p", - "o" + "s" ], "children": [ { "logical": "join", "children": [ - { - "logical": "pattern", - "pattern": "?s ?p ?o" - }, - { - "logical": "pattern", - "pattern": "?s http://www.w3.org/1999/02/22-rdf-syntax-ns#type ?o" - }, { "logical": "join-inner", "physical": "bind", "bindIndex": 1, + "bindOperation": { + "source": "QuerySourceHypermedia(https://fragments.dbpedia.org/2016-04/en)(SkolemID:0)", + "pattern": "?s http://www.w3.org/1999/02/22-rdf-syntax-ns#type ?o" + }, + "bindOperationCardinality": { + "type": "estimate", + "value": 100022186, + "dataset": "https://fragments.dbpedia.org/2016-04/en?predicate=http%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23type" + }, "bindOrder": "depth-first", "cardinalities": [ { "type": "estimate", - "value": 1040358853 + "value": 1040358853, + "dataset": "https://fragments.dbpedia.org/2016-04/en" }, { "type": "estimate", - "value": 100022186 + "value": 100022186, + "dataset": "https://fragments.dbpedia.org/2016-04/en?predicate=http%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23type" } ], "joinCoefficients": { "iterations": 6404592831613.728, "persistedItems": 0, "blockingItems": 0, - "requestTime": 556926378.1422498 + "requestTime": 8902477556686.99 }, - "children": [ - { - "logical": "pattern", - "pattern": "http://commons.wikimedia.org/wiki/Special:FilePath/!!!善福寺.JPG ?p http://dbpedia.org/ontology/Image" - }, + "childrenCompact": [ { - "logical": "pattern", - "pattern": "http://commons.wikimedia.org/wiki/Special:FilePath/!!!善福寺.JPG ?p http://wikidata.dbpedia.org/ontology/Image" - }, - ... - { - "logical": "pattern", - "pattern": "http://commons.wikimedia.org/wiki/Special:FilePath/%22..._WAAC_cooks_prepare_dinner_for_the_first_time_in_new_kitchen_at_Fort_Huachuca,_Arizona.%22,_12-05-1942_-_NARA_-_531152.jpg ?p http://wikidata.dbpedia.org/ontology/Image" + "occurrences": 100, + "firstOccurrence": { + "logical": "pattern", + "source": "QuerySourceHypermedia(https://fragments.dbpedia.org/2016-04/en)(SkolemID:0)", + "pattern": "http://commons.wikimedia.org/wiki/Special:FilePath/!!!善福寺.JPG ?p http://dbpedia.org/ontology/Image" + } } ] } @@ -318,21 +361,15 @@ Will print: { explain: true, type: 'physical', - data: { - logical: 'project', - variables: [ 's', 'p', 'o' ], - children: [ - { - logical: 'join', - children: [ - { - logical: 'pattern', - pattern: '?s ?p ?o', - }, - ], - }, - ], - }, + data: `slice + project (o,p,s) + join + join-inner(bind) bindOperation:(?s http://www.w3.org/1999/02/22-rdf-syntax-ns#type ?o) bindCardEst:~100,022,186 + pattern (http://commons.wikimedia.org/wiki/Special:FilePath/!!!善福寺.JPG ?p http://dbpedia.org/ontology/Image) src:0 compacted-occurrences:100 + +sources: + 0: QuerySourceHypermedia(https://fragments.dbpedia.org/2016-04/en)(SkolemID:0) +`, } */ ``` diff --git a/pages/docs/2_modify/advanced/buses.md b/pages/docs/2_modify/advanced/buses.md index 9d01412e..687f5dce 100644 --- a/pages/docs/2_modify/advanced/buses.md +++ b/pages/docs/2_modify/advanced/buses.md @@ -236,12 +236,13 @@ Subscribed actors need to implement [`ActorQueryProcess`](https://comunica.githu ### Actors -| Name | Package | Description | -|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------| -| Explain Logical | [`@comunica/actor-query-process-explain-logical`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-explain-logical) | Explains the logical query plan after parsing and optimizing. | -| Explain Parsed | [`@comunica/actor-query-process-explain-parsed`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-explain-parsed) | Explains the parsed query. | -| Explain Physical | [`@comunica/actor-query-process-explain-physical`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-explain-physical) | Explains the physical query plan after parsing, optimizing, and evaluating. | -| Sequential | [`@comunica/actor-query-process-sequential`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-sequential) | Processes a query in a sequential manner. It first parses the query, optimizes it, and then evaluates it. | +| Name | Package | Description | +|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------| +| Annotate Source Binding | [`@comunica/actor-query-process-annotate-source-binding`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-annotate-source-binding) | Annotates bindings with their sources. | +| Explain Logical | [`@comunica/actor-query-process-explain-logical`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-explain-logical) | Explains the logical query plan after parsing and optimizing. | +| Explain Parsed | [`@comunica/actor-query-process-explain-parsed`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-explain-parsed) | Explains the parsed query. | +| Explain Physical | [`@comunica/actor-query-process-explain-physical`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-explain-physical) | Explains the physical query plan after parsing, optimizing, and evaluating. | +| Sequential | [`@comunica/actor-query-process-sequential`](https://github.com/comunica/comunica/tree/master/packages/actor-query-process-sequential) | Processes a query in a sequential manner. It first parses the query, optimizes it, and then evaluates it. | ## Query Result Serialize @@ -295,11 +296,12 @@ Subscribed actors need to implement [`ActorQuerySourceIdentifyHypermedia`](https ### Actors -| Name | Package | Description | -| ---- | ------- | ----------- | -| None | [`@comunica/actor-query-source-identify-hypermedia-none`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-none) | The source is considered a raw RDF file, for which all data quads matching the quad pattern are returned. | -| QPF | [`@comunica/actor-query-source-identify-hypermedia-qpf`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-qpf) | The source is considered a [Triple/Quad Pattern Fragments](https://linkeddatafragments.org/) interface. | -| SPARQL | [`@comunica/actor-query-source-identify-hypermedia-sparql`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-sparql) | The source is considered a SPARQL endpoint if it has a service description, for which we use the SPARQL protocol. | +| Name | Package | Description | +| ---- |-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------| +| Annotate Source | [`@comunica/actor-query-source-identify-hypermedia-annotate-source`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-annotate-source) | This actor wraps around other hypermedia sources and adds the URL from which the bindings are derived to the binding's context. | +| None | [`@comunica/actor-query-source-identify-hypermedia-none`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-none) | The source is considered a raw RDF file, for which all data quads matching the quad pattern are returned. | +| QPF | [`@comunica/actor-query-source-identify-hypermedia-qpf`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-qpf) | The source is considered a [Triple/Quad Pattern Fragments](https://linkeddatafragments.org/) interface. | +| SPARQL | [`@comunica/actor-query-source-identify-hypermedia-sparql`](https://github.com/comunica/comunica/tree/master/packages/actor-query-source-identify-hypermedia-sparql) | The source is considered a SPARQL endpoint if it has a service description, for which we use the SPARQL protocol. | ## RDF Join @@ -314,23 +316,25 @@ Subscribed actors need to implement [`ActorRdfJoin`](https://comunica.github.io/ ### Actors -| Name | Package | Description | -|--------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| -| Inner Hash | [`@comunica/actor-rdf-join-inner-hash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-hash) | Inner hash join of two entries. | -| Inner Nested loop | [`@comunica/actor-rdf-join-inner-nestedloop`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-nestedloop) | Inner nested loop join of two entries. | -| Inner None | [`@comunica/actor-rdf-join-inner-none`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-none) | Inner join between zero entries, and returns a single binding. | -| Inner Single | [`@comunica/actor-rdf-join-inner-single`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-single) | Inner join of a single entry, and returns the entry itself. | -| Inner Symmetric hash | [`@comunica/actor-rdf-join-inner-symmetrichash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-symmetrichash) | Inner symmetric hash join of two entries. | -| Inner Multi empty | [`@comunica/actor-rdf-join-inner-multi-empty`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-empty) | Inner multi-join that accepts any number of inner-join entries of which at least one is empty and returns an empty stream. | -| Inner Multi Bind | [`@comunica/actor-rdf-join-inner-multi-bind`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-bind) | Inner multi-join that inner-joins 2 or more streams by picking the one with the lowest cardinality, binding each item with the remaining operations, and recursively resolving those operations by delegating to [`@comunica/bus-query-operation`](https://github.com/comunica/comunica/tree/master/packages/bus-query-operation). | -| Inner Multi Bind Source | [`@comunica/actor-rdf-join-inner-multi-bind-source`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-bind-source) | Inner multi-join that inner-joins 2 or more streams by picking the one with the lowest cardinality, chunking it according to a certain block size, and joining each chunk with the remaining query by pushing it into the source. | -| Inner Multi sequential | [`@comunica/actor-rdf-join-inner-multi-sequential`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-sequential) | Inner multi-join by just picking the two of them hierarchically. | -| Inner Multi smallest | [`@comunica/actor-rdf-join-inner-multi-smallest`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-smallest) | Inner multi-join by always picking the first two streams with smallest estimate cardinality. | +| Name | Package | Description | +|--------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| +| Inner Hash | [`@comunica/actor-rdf-join-inner-hash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-hash) | Inner hash join of two entries. | +| Inner Nested loop | [`@comunica/actor-rdf-join-inner-nestedloop`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-nestedloop) | Inner nested loop join of two entries. | +| Inner None | [`@comunica/actor-rdf-join-inner-none`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-none) | Inner join between zero entries, and returns a single binding. | +| Inner Single | [`@comunica/actor-rdf-join-inner-single`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-single) | Inner join of a single entry, and returns the entry itself. | +| Inner Symmetric hash | [`@comunica/actor-rdf-join-inner-symmetrichash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-symmetrichash) | Inner symmetric hash join of two entries. | +| Inner Multi empty | [`@comunica/actor-rdf-join-inner-multi-empty`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-empty) | Inner multi-join that accepts any number of inner-join entries of which at least one is empty and returns an empty stream. | +| Inner Multi Bind | [`@comunica/actor-rdf-join-inner-multi-bind`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-bind) | Inner multi-join that inner-joins 2 or more streams by picking the one with the lowest cardinality, binding each item with the remaining operations, and recursively resolving those operations by delegating to [`@comunica/bus-query-operation`](https://github.com/comunica/comunica/tree/master/packages/bus-query-operation). | +| Inner Multi Bind Source | [`@comunica/actor-rdf-join-inner-multi-bind-source`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-bind-source) | Inner multi-join that inner-joins 2 or more streams by picking the one with the lowest cardinality, chunking it according to a certain block size, and joining each chunk with the remaining query by pushing it into the source. | +| Inner Multi sequential | [`@comunica/actor-rdf-join-inner-multi-sequential`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-sequential) | Inner multi-join by just picking the two of them hierarchically. | +| Inner Multi smallest | [`@comunica/actor-rdf-join-inner-multi-smallest`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-smallest) | Inner multi-join by always picking the first two streams with smallest estimate cardinality. | | Inner Multi smallest filter bindings | [`@comunica/actor-rdf-join-inner-multi-smallest-filter-bindings`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-inner-multi-smallest-filter-bindings) | Inner multi-join that inner-joins 2 or more streams by joining the smallest two, and joining the result with the remaining streams by delegating back to the [RDF Join bus](https://github.com/comunica/comunica/tree/master/packages/bus-rdf-join). While joining the smallest two, the first stream is pushed down as filter into the second stream.. | -| Minus Hash | [`@comunica/actor-rdf-join-minus-hash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-minus-hash) | Anti-join (minus) of 2 streams using the hash join algorithm. This actor does _not_ support streams that can have undefined values. | -| Minus Hash undef | [`@comunica/actor-rdf-join-minus-hash-undef`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-minus-hash-undef) | Anti-join (minus) of 2 streams using the hash join algorithm. This actor supports streams that can have undefined values. | -| Optional Bind | [`@comunica/actor-rdf-join-optional-bind`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-optional-bind) | Left-join (optional) 2 streams using the bind join algorithm. It binds each item of the first stream with the second operation, and recursively resolving that operation by delegating to [`@comunica/bus-query-operation`](https://github.com/comunica/comunica/tree/master/packages/bus-query-operation). | -| Optional Nested loop | [`@comunica/actor-rdf-join-optional-nestedloop`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-optional-nestedloop) | Left-join (optional) 2 streams using the nested loop join algorithm. | +| Minus Hash | [`@comunica/actor-rdf-join-minus-hash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-minus-hash) | Anti-join (minus) of 2 streams using the hash join algorithm. This actor does _not_ support streams that can have undefined values. | +| Minus Hash undef | [`@comunica/actor-rdf-join-minus-hash-undef`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-minus-hash-undef) | Anti-join (minus) of 2 streams using the hash join algorithm. This actor supports streams that can have undefined values. | +| Optional Bind | [`@comunica/actor-rdf-join-optional-bind`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-optional-bind) | Left-join (optional) 2 streams using the bind join algorithm. It binds each item of the first stream with the second operation, and recursively resolving that operation by delegating to [`@comunica/bus-query-operation`](https://github.com/comunica/comunica/tree/master/packages/bus-query-operation). | +| Optional Hash | [`@comunica/actor-rdf-join-optional-hash`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-optional-hash) | Left-join (optional) 2 streams using the hash join algorithm. | +| Optional Nested loop | [`@comunica/actor-rdf-join-optional-nestedloop`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-optional-nestedloop) | Left-join (optional) 2 streams using the nested loop join algorithm. | +| Optional Opt Plus | [`@comunica/actor-rdf-join-optional-optplus`](https://github.com/comunica/comunica/tree/master/packages/actor-rdf-join-optional-optplus) | Left-join (optional) 2 streams using the [OPT+](https://www.researchgate.net/publication/333627321_OPT_A_Monotonic_Alternativeto_OPTIONAL_in_SPARQL) algorithm. | ## RDF Join Entries Sort