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package datomic.samples;
import datomic.Connection;
import datomic.Database;
import datomic.Peer;
import datomic.Util;
import java.util.Scanner;
import java.util.Collection;
import static datomic.Util.read;
import static datomic.samples.Fns.scratchConnection;
import static datomic.samples.Schema.CARDINALITY_MANY;
import static datomic.samples.Schema.CARDINALITY_ONE;
import static datomic.samples.Schema.cardinality;
public class Query {
public static void main(String[] args) {
// Your connection information for local mbrainz 1968-1973 subset goes here.
String uri = "datomic:free://localhost:4334/mbrainz-1968-1973";
// Connect to transactor, get latest database value from storage.
Connection conn = Peer.connect(uri);
Database db = conn.db();
System.out.println("All releases in the database with release names.");
Collection results = Peer.query("[:find ?release-name :where [_ :release/name ?release-name]]", db);
System.out.println(results);
pause();
System.out.println("Same as previous query, but with explicit db-var ($).");
results = Peer.query("[:find ?release-name :in $ :where [$ _ :release/name ?release-name]]", db);
System.out.println(results);
pause();
System.out.println("Query that finds releases by artist. Parameterized to accept artist name as an argument.");
results = Peer.query("[:find ?release-name " +
":in $ ?artist-name " +
":where [?artist :artist/name ?artist-name] " +
"[?release :release/artists ?artist] " +
"[?release :release/name ?release-name]]",
db, "John Lennon");
System.out.println(results);
pause();
System.out.println("This query accepts a relation argument as a vector and destructures it within the :in.");
results = Peer.query("[:find ?release " +
" :in $ [?artist-name ?release-name] " +
" :where [?artist :artist/name ?artist-name] " +
" [?release :release/artists ?artist] " +
" [?release :release/name ?release-name]]",
db, Util.list("John Lennon", "Mind Games"));
System.out.println(results);
pause();
System.out.println("This query accepts a list of artist arguments and uses destructuring to satisfy the " +
"query for each of them (union of results).");
results = Peer.query("[:find ?release-name " +
":in $ [?artist-name ...] " +
":where [?artist :artist/name ?artist-name] " +
" [?release :release/artists ?artist] " +
" [?release :release/name ?release-name]]",
db, Util.list("Paul McCartney", "George Harrison"));
pause();
System.out.println("This query accepts a list of relations, also a list, and destructures the arguments in " +
"the :in clause.");
results = Peer.query("[:find ?release " +
":in $ [[?artist-name ?release-name]] " +
":where [?artist :artist/name ?artist-name] " +
" [?release :release/artists ?artist] " +
" [?release :release/name ?release-name]]",
db, Util.list(Util.list("John Lennon", "Mind Games"),
Util.list("Paul McCartney", "Ram")));
System.out.println(results);
pause();
System.out.println("This query returns a collection of relations, all artists and their releases.");
results = Peer.query("[:find ?artist-name ?release-name " +
":where [?release :release/name ?release-name] " +
" [?release :release/artists ?artist] " +
" [?artist :artist/name ?artist-name]]",
db);
System.out.println(results);
pause();
System.out.println("This query returns a list of releases by using a find specification.");
results = Peer.query("[:find [?release-name ...]" +
" :in $ ?artist-name " +
" :where [?artist :artist/name ?artist-name] " +
" [?release :release/artists ?artist] " +
" [?release :release/name ?release-name]]",
db, "John Lennon");
System.out.println(results);
pause();
System.out.println("This query returns values from multiple attributes to provide artist's start date.");
results = Peer.query("[:find [?year ?month ?day] " +
" :in $ ?name " +
" :where [?artist :artist/name ?name] " +
" [?artist :artist/startDay ?day] " +
" [?artist :artist/startMonth ?month] " +
" [?artist :artist/startYear ?year]]",
db, "John Lennon");
System.out.println(results);
pause();
System.out.println("Return just the year of start date using a scalar find specification.");
Long year = Peer.query("[:find ?year . " +
" :in $ ?name " +
" :where [?artist :artist/name ?name] " +
" [?artist :artist/startYear ?year]]",
db, "John Lennon");
System.out.println(year);
pause();
System.out.println("Total number of artists who aren't Canadian.");
Integer res = Peer.query("[:find (count ?eid) . " +
":where [?eid :artist/name] " +
"(not [?eid :artist/country :country/CA])]",
db);
System.out.println(res);
pause();
System.out.println("Use not-join to bind variable in subquery. Artists w/o releases in 1970.");
res = Peer.query("[:find (count ?artist) . " +
":where [?artist :artist/name] " +
"(not-join [?artist] " +
" [?release :release/artists ?artist] " +
" [?release :release/year 1970])]",
db);
System.out.println(res);
pause();
System.out.println("Number of 'Live at Carnegie Hall' releases not by Bill Withers");
res = Peer.query("[:find (count ?r) . " +
":where [?r :release/name \"Live at Carnegie Hall\"] " +
"(not-join [?r] " +
"[?r :release/artists ?a] " +
"[?a :artist/name \"Bill Withers\"])]",
db);
System.out.println(res);
pause();
System.out.println("Total of artists who are a group or female by use of 'or'.");
res = Peer.query("[:find (count ?artist) . " +
" :where (or [?artist :artist/type :artist.type/group] " +
" (and [?artist :artist/type :artist.type/person] " +
" [?artist :artist/gender :artist.gender/female]))]",
db);
System.out.println(res);
pause();
System.out.println("Count of releases from Canadian artists or the year 1970 using 'or-join'");
res = Peer.query("[:find (count ?release) . " +
" :where [?release :release/name] " +
" (or-join [?release] " +
" (and [?release :release/artists ?artist] " +
" [?artist :artist/country :country/CA]) " +
" [?release :release/year 1970])]",
db);
System.out.println(res);
pause();
System.out.println("Track name and duration in minutes using function call in query.");
results = Peer.query("[:find ?track-name ?minutes " +
":in $ ?artist-name " +
":where [?artist :artist/name ?artist-name] " +
" [?track :track/artists ?artist] " +
" [?track :track/duration ?millis] " +
" [(quot ?millis 60000) ?minutes] " +
" [?track :track/name ?track-name]]",
db, "John Lennon");
System.out.println(results);
pause();
// Can't nest expression clauses
String QueryFail = "[:find ?celsius . " +
" :in ?fahrenheit " +
" :where [(/ (- ?fahrenheit 32) 1.8) ?celsius]]";
Integer QueryFailInput = 212;
System.out.println("Function calls without nesting:");
Double celsius = Peer.query("[:find ?celsius . " +
" :in ?fahrenheit " +
" :where [(- ?fahrenheit 32) ?f-32] " +
" [(/ ?f-32 1.8) ?celsius]]",
212);
System.out.println(celsius);
pause();
System.out.println("get-else example:");
results = Peer.query("[:find ?artist-name ?year " +
" :in $ [?artist-name ...] " +
" :where [?artist :artist/name ?artist-name] " +
" [(get-else $ ?artist :artist/startYear \"N/A\") ?year]]",
db, Util.list("Crosby, Stills & Nash", "Crosby & Nash"));
System.out.println(results);
pause();
System.out.println("get-some example:");
results = Peer.query("[:find [?e ?attr ?name] " +
":in $ ?e " +
":where [(get-some $ ?e :country/name :artist/name) [?attr ?name]]]",
db, Util.read(":country/US"));
System.out.println(results);
pause();
System.out.println("fulltext example returns info for songs with 'Jane' in the title.");
results = Peer.query("[:find ?entity ?name ?tx ?score " +
" :in $ ?search " +
" :where [(fulltext $ :artist/name ?search) [[?entity ?name ?tx ?score]]]]",
db, "Jane");
System.out.println(results);
pause();
System.out.println("'missing' query finds artists without start year.");
results = Peer.query("[:find ?name " +
" :where [?artist :artist/name ?name] " +
" [(missing? $ ?artist :artist/startYear)]]",
db);
System.out.println(results);
pause();
System.out.println("This query finds transactions using the Log API.");
results = Peer.query("[:find [?tx ...] " +
" :in ?log " +
" :where [(tx-ids ?log 1000 1050) [?tx ...]]]",
conn.log());
System.out.println(results);
pause();
System.out.println("This query finds information about a transaction using the Log API.");
results = Peer.query("[:find [?e ...] " +
" :in ?log ?tx " +
" :where [(tx-data ?log ?tx) [[?e]]]]",
conn.log(), 13194139534312L);
System.out.println(results);
pause();
System.out.println("Calling a Java static method in a query.");
results = Peer.query("[:find ?k ?v " +
" :where [(System/getProperties) [[?k ?v]]]]");
System.out.println(results);
pause();
System.out.println("Calling a Java instance method in a query.");
results = Peer.query("[:find ?k ?v " +
" :where [(System/getProperties) [[?k ?v]]]]");
System.out.println(results);
pause();
System.out.println("Calling Clojure functions");
results = Peer.query("[:find [?prefix ...] " +
" :in [?word ...] " +
" :where [(subs ?word 0 5) ?prefix]]",
Util.list("hello", "antidisestablishmentarianism"));
System.out.println(results);
pause();
System.out.println("Attr bound by entity ID, query for ident.");
results = Peer.query("[:find [?aname ...] " +
" :where [?attr 42 _] " +
" [?attr :db/ident ?aname]]",
db);
System.out.println(results);
pause();
System.out.println("Avoid dynamic attr. specs unless you really need them.");
// results = Peer.query("[:find [?aname ...] " +
// " :in $ [?property ...] " +
// " :where [?attr ?property _] " +
// " [?attr :db/ident ?aname]]",
// db, Util.read(":db/unique"));
// System.out.println(results);
// pause();
System.out.println("The following three queries are equivalent...");
System.out.println("This one retrieves an entity by lookup ref.");
results = Peer.query("[:find [?artist-name ...] " +
" :in $ ?country" +
" :where [?artist :artist/name ?artist-name] " +
" [?artist :artist/country ?country]]",
db, Util.list(Util.read(":country/name"), "Belgium"));
System.out.println(results);
pause();
System.out.println("This one retrieves the same entity by ident.");
results = Peer.query("[:find [?artist-name ...] " +
" :in $ ?country" +
" :where [?artist :artist/name ?artist-name] " +
" [?artist :artist/country ?country]]",
db, Util.read(":country/BE"));
System.out.println(results);
pause();
System.out.println("This one retrieves the same entity by its entity ID (Long)");
results = Peer.query("[:find [?artist-name ...] " +
" :in $ ?country" +
" :where [?artist :artist/name ?artist-name] " +
" [?artist :artist/country ?country]]",
db, 17592186045438L);
System.out.println(results);
pause();
System.out.println("This query doesn't work as intended.");
results = Peer.query("[:find [?artist-name ...] " +
" :in $ ?country [?reference ...] " +
" :where [?artist :artist/name ?artist-name] " +
" [?artist ?reference ?country]]",
db, Util.read(":country/BE"), Util.list(Util.read(":artist/country")));
System.out.println(results);
pause();
System.out.println("We fix it by manually resolving the ident to its entity id.");
// results = Peer.query("[:find [?artist-name ...] " +
// " :in $ ?country [?reference ...] " +
// " :where [(datomic.api/entid $ ?country) ?country-id] " +
// " [?artist :artist/name ?artist-name] " +
// " [?artist ?reference ?country-id]]",
// db, Util.read(":country/BE"), Util.list(Util.read(":artist/country")));
// System.out.println(results);
// pause();
System.out.println("We have to use ':with' to get duplicate values as Datomic query returns sets by default.");
Long heads = Peer.query("[:find (sum ?heads) . " +
" :in [[_ ?heads]]]",
Util.list(Util.list("Cerberus", 3),
Util.list("Cyclops", 1),
Util.list("Medusa", 1),
Util.list("Chimera", 1)));
System.out.println("First, incorrect results: ");
System.out.println(heads);
pause();
System.out.println("This time, fixed with ':with': ");
heads = Peer.query("[:find (sum ?heads) . " +
" :with ?monster " +
" :in [[?monster ?heads]]]",
Util.list(Util.list("Cerberus", 3),
Util.list("Cyclops", 1),
Util.list("Medusa", 1),
Util.list("Chimera", 1)));
System.out.println(heads);
pause();
// Aggregate examples
System.out.println("Using 'max' and 'min' aggregates to get shortest and longest durations.");
results = Peer.query("[:find [(min ?dur) (max ?dur)] " +
" :where [_ :track/duration ?dur]]",
db);
System.out.println(results);
pause();
System.out.println("Sum of all track counts.");
Long sum = Peer.query("[:find (sum ?count) . " +
" :with ?medium " +
" :where [?medium :medium/trackCount ?count]]",
db);
System.out.println(sum);
pause();
System.out.println("Counting with and without count-distinct: ");
results = Peer.query("[:find [(count ?name) (count-distinct ?name)] " +
" :with ?artist " +
" :where [?artist :artist/name ?name]]",
db);
System.out.println(results);
pause();
System.out.println("Count of tracks.");
results = Peer.query("[:find (count ?track) " +
" :where [?track :track/name]]",
db);
System.out.println(results);
pause();
System.out.println("Some basic stats...");
results = Peer.query("[:find ?year (median ?namelen) (avg ?namelen) (stddev ?namelen) " +
" :with ?track " +
" :where [?track :track/name ?name] " +
" [(count ?name) ?namelen] " +
" [?medium :medium/tracks ?track] " +
" [?release :release/media ?medium] " +
" [?release :release/year ?year]]",
db);
System.out.println(results);
pause();
System.out.println("Set of distinct values...");
results = Peer.query("[:find (distinct ?v) . " +
" :in [?v ...]] ",
Util.list(1, 1, 2, 2, 2, 3));
System.out.println(results);
pause();
System.out.println("Five shortest and five longest track durations in milliseconds.");
results = Peer.query("[:find [(min 5 ?millis) (max 5 ?millis)] " +
" :where [?track :track/duration ?millis]]",
db);
System.out.println(results);
pause();
System.out.println("Two random names using rand (duplicates tolerated) and sample (only distinct)");
results = Peer.query("[:find [(rand 2 ?name) (sample 2 ?name)] " +
" :where [_ :artist/name ?name]]",
db);
System.out.println(results);
}
private static final Scanner scanner = new Scanner(System.in);
private static void pause() {
if (System.getProperty("NOPAUSE") == null) {
System.out.println("\nPress enter to continue...");
scanner.nextLine();
}
}
}