Part 2: implement complex 'or' translation. Fixes #57. r=nalexander
We implement sql-projection-for-simple-variable-list to allow us to add a projection to subqueries.
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Richard Newman
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@ -6,6 +6,7 @@
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(:require
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[datomish.query.cc :as cc]
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[datomish.query.functions :as functions]
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[datomish.query.projection :refer [sql-projection-for-simple-variable-list]]
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[datomish.query.source
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:refer [pattern->schema-value-type
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attribute-in-source
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@ -18,6 +19,7 @@
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#?@(:cljs
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[:refer
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[
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And
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Constant
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DefaultSrc
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Function
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@ -35,6 +37,7 @@
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#?(:clj
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(:import
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[datascript.parser
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And
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Constant
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DefaultSrc
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Function
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@ -50,6 +53,8 @@
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;; Pattern building is recursive, so we need forward declarations.
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(declare
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Not->NotJoinClause not-join->where-fragment
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expand-pattern-clauses
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complex-or->cc
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simple-or? simple-or->cc)
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(defn- check-or-apply-value-type [cc value-type pattern-part]
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@ -202,19 +207,19 @@
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;; This can be converted into a single join and an `or` :where expression.
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;;
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;; Otherwise -- perhaps each leg of the `or` binds different variables, which
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;; is acceptable for an `or-join` form -- we need to turn this into a joined
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;; subquery.
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;; is acceptable for an `or-join` form -- we call this a complex `or`. To
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;; execute those, we need to turn them into a joined subquery composed of
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;; `UNION`ed queries.
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(let [f (if (simple-or? orc) simple-or->cc complex-or->cc)]
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(cc/merge-ccs
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cc
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(f (:source cc)
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(:known-types cc)
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(merge-with concat
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(:external-bindings cc)
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(:bindings cc))
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orc))))
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(if (simple-or? orc)
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(cc/merge-ccs cc (simple-or->cc (:source cc)
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(:known-types cc)
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(merge-with concat
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(:external-bindings cc)
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(:bindings cc))
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orc))
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;; TODO: handle And within the Or patterns.
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(raise "Non-simple `or` clauses not yet supported." {:clause orc})))
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(defn apply-function-clause [cc function]
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(or (functions/apply-sql-function cc function)
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@ -226,6 +231,9 @@
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Or
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(apply-or-clause cc it)
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And
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(expand-pattern-clauses cc (:clauses it))
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Not
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(apply-not-clause cc it)
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@ -354,14 +362,7 @@
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;; We 'fork' a CC for each pattern, then union them together.
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;; We need to build the first in order that the others use the same
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;; column names and known types.
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(let [cc (cc/map->ConjoiningClauses
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{:source source
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:from []
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:known-types (or known-types {})
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:extracted-types {}
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:external-bindings (or external-bindings {})
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:bindings {}
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:wheres []})
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(let [cc (make-cc source known-types external-bindings)
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primary (apply-pattern-clause cc (first (:clauses orc)))
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remainder (rest (:clauses orc))]
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@ -392,3 +393,90 @@
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(conj acc (cons :and w)))))
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[]
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(cons primary ccs)))])))))
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(defn complex-or->cc
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[source known-types external-bindings orc]
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(validate-or-clause orc)
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;; Step one: any clauses that are standalone patterns might differ only in
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;; attribute. In that case, we can treat them as a 'simple or' -- a single
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;; pattern with a WHERE clause that alternates on the attribute.
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;; Pull those out first.
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;;
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;; Step two: for each cluster of patterns, and for each `and`, recursively
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;; build a CC and simple projection. The projection must be the same for each
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;; CC, because we will concatenate these with a `UNION`.
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;;
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;; Finally, we alias this entire UNION block as a FROM; it can be stitched into
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;; the outer query by looking at the projection.
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;;
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;; For example,
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;;
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;; [:find ?page :in $ ?string :where
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;; (or [?page :page/title ?string]
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;; [?page :page/excerpt ?string]
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;; (and [?save :save/string ?string]
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;; [?page :page/save ?save]))]
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;;
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;; would expand to
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;;
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;; SELECT or123.page AS page FROM
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;; (SELECT datoms124.e AS page FROM datoms AS datoms124
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;; WHERE datoms124.v = ? AND
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;; (datoms124.a = :page/title OR
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;; datoms124.a = :page/excerpt)
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;; UNION
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;; SELECT datoms126.e AS page FROM datoms AS datoms125, datoms AS datoms126
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;; WHERE datoms125.a = :save/string AND
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;; datoms125.v = ? AND
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;; datoms126.v = datoms125.e AND
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;; datoms126.a = :page/save)
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;; AS or123
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;;
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;; Note that a top-level standalone `or` doesn't really need to be aliased, but
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;; it shouldn't do any harm.
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(if (= 1 (count (:clauses orc)))
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;; Well, this is silly.
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(pattern->cc source (first (:clauses orc)) known-types external-bindings)
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;; TODO: pull out simple patterns. Issue #62.
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(let [
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;; First: turn each arm of the `or` into a CC. We can easily turn this
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;; into SQL.
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ccs (map (fn [p] (pattern->cc source p known-types external-bindings))
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(:clauses orc))
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free-vars (:free (:rule-vars orc))
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;; Second: wrap an equivalent projection around each. The Or knows which
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;; variables to use.
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projection-list-fn
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(partial sql-projection-for-simple-variable-list
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free-vars)
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;; Third: turn each CC and projection into an arm of a UNION.
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subqueries {:union (map (fn [cc]
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(cc->partial-subquery (projection-list-fn cc)
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cc))
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ccs)}
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;; Fourth: map this query to an alias in `:from`, and establish bindings
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;; so that the enclosing query and projection know which names to use.
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;; Finally, return a CC that can be merged.
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alias ((:table-alias source) :orjoin)
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bindings (into {} (map (fn [var]
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(let [sym (:symbol var)]
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[sym [(sql/qualify alias (util/var->sql-var sym))]]))
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free-vars))]
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(cc/map->ConjoiningClauses
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{:source source
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:from [[subqueries alias]]
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:known-types (apply merge (map :known-types ccs))
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:extracted-types (apply merge (map :extracted-types ccs))
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:external-bindings {} ; No need: caller will merge.
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:bindings bindings
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:ctes {}
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:wheres []}))))
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@ -170,6 +170,25 @@
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(symbol->projection var lookup-fn known-types type-proj-fn))
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full-var-list))))
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;; Like sql-projection-for-relation, but exposed for simpler
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;; use (e.g., in handling complex `or` patterns).
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(defn sql-projection-for-simple-variable-list [elements cc]
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{:pre [(every? (partial instance? Variable) elements)]}
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(let [{:keys [known-types extracted-types]} cc
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projected-vars
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(map variable->var elements)
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type-proj-fn
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(partial type-projection extracted-types)
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lookup-fn
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(partial lookup-variable cc)]
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(mapcat (fn [var]
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(symbol->projection var lookup-fn known-types type-proj-fn))
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projected-vars)))
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(defn sql-projection-for-aggregation
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"Project an element list that contains aggregates. This expects a subquery
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aliased to `inner-table` which itself will project each var with the
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@ -85,6 +85,12 @@
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:db/ident :page/title
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:db/valueType :db.type/string
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:db/cardinality :db.cardinality/one}
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{:db/id (d/id-literal :db.part/user)
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:db.install/_attribute :db.part/db
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:db/ident :page/save
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:db/valueType :db.type/ref
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:db/unique :db.unique/identity ; A save uniquely identifies a page.
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:db/cardinality :db.cardinality/many}
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{:db/id (d/id-literal :db.part/user)
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:db.install/_attribute :db.part/db
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:db/ident :page/starred
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@ -438,6 +444,60 @@
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[?entity :page/loves ?page])]
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conn)))))
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(deftest-db test-complex-or conn
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(let [attrs (<? (<initialize-with-schema
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conn
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(concat save-schema schema-with-page)))]
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(is (= {:select '([:datoms0.e :page] [:datoms0.v :starred]),
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:modifiers [:distinct],
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:where (list :and
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[:= :datoms0.a (:page/starred attrs)]
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[:= :datoms0.e :orjoin1.page])
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:from
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[[:datoms 'datoms0]
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[{:union
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(list
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;; These first two will be merged together when
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;; we implement simple pattern alternation within
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;; complex `or`.
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{:from '([:datoms datoms2]),
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:select '([:datoms2.e :page]),
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:where (list :and
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[:= :datoms2.a (:page/url attrs)]
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[:= :datoms0.e :datoms2.e]
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[:= (sql/param :s) :datoms2.v])}
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{:from '([:datoms datoms3]),
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:select '([:datoms3.e :page]),
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:where (list :and
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[:= :datoms3.a (:page/title attrs)]
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[:= :datoms0.e :datoms3.e]
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[:= (sql/param :s) :datoms3.v])}
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{:from '([:datoms datoms4]
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[:fulltext_datoms fulltext_datoms5]
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[:fulltext_datoms fulltext_datoms6]),
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:select '([:datoms4.e :page]),
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:where (list :and
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[:= :datoms4.a (:page/save attrs)]
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[:= :fulltext_datoms5.a (:save/excerpt attrs)]
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[:= :fulltext_datoms6.a (:save/content attrs)]
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[:= :datoms4.v :fulltext_datoms5.e]
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[:= :datoms4.v :fulltext_datoms6.e]
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[:= :fulltext_datoms5.v :fulltext_datoms6.v]
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[:= :datoms0.e :datoms4.e]
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[:= (sql/param :s) :fulltext_datoms5.v])})}
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'orjoin1]]}
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(expand
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'[:find ?page ?starred :in $ ?s :where
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[?page :page/starred ?starred]
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(or-join [?page]
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[?page :page/url ?s]
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[?page :page/title ?s]
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(and [?page :page/save ?saved]
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[?saved :save/excerpt ?s]
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[?saved :save/content ?s]))]
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conn)))))
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(defn tag-clauses [column input]
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(let [codes (cc/->tag-codes input)]
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(if (= 1 (count codes))
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