SQL: Add packages.c_hasman cache to speed up package listings

Going from average ~100ms to ~10ms or so. The previous query had a
tendency to be much slower sometimes, let's see if this cache also takes
care of those outliers.

Migration script:

  ALTER TABLE packages ADD COLUMN c_hasman boolean NOT NULL DEFAULT FALSE;

  DROP INDEX packages_system_name_key;
  CREATE UNIQUE INDEX packages_system_name_key ON packages (system, name) INCLUDE (id, c_hasman, dead);

  UPDATE packages SET c_hasman = NOT c_hasman
   WHERE c_hasman <> EXISTS(SELECT 1 FROM package_versions pv WHERE pv.package = packages.id AND EXISTS(SELECT 1 FROM files f WHERE f.pkgver = pv.id));

indexer/src/pkg.rs

@@ -47,7 +47,7 @@ pub struct PkgOpt<'a> {
 }
 
 
-fn insert_pkg(tr: &mut postgres::Transaction, opt: &PkgOpt) -> Option<i32> {
+fn insert_pkg(tr: &mut postgres::Transaction, opt: &PkgOpt) -> Option<(i32,i32)> {
     let pkginfo = format!("sys {} / {} - {} @ {:?} @ {}", opt.sys, opt.pkg, opt.ver, opt.date, opt.file.path);
 
     // Use a custom CTE-based insert-or-update. Using an INSERT with an ON CONFLICT clause would be
@@ -80,14 +80,14 @@ fn insert_pkg(tr: &mut postgres::Transaction, opt: &PkgOpt) -> Option<i32> {
         let q = "INSERT INTO package_versions (package, version, released, arch) VALUES($1, $2, $3::text::date, $4) RETURNING id";
         verid = tr.query_one(q, &[&pkgid, &opt.ver, &date, &opt.arch]).unwrap().get(0);
         info!("New package pkgid {} verid {}, {}", pkgid, verid, pkginfo);
-        Some(verid)
+        Some((pkgid,verid))
 
     } else if opt.force {
         // XXX: Should we update released & arch here?
         verid = res?.get(0);
         info!("Overwriting package pkgid {} verid {}, {}", pkgid, verid, pkginfo);
         tr.query("DELETE FROM files WHERE pkgver = $1", &[&verid]).unwrap();
-        Some(verid)
+        Some((pkgid,verid))
 
     } else {
         debug!("Package already in database, pkgid {} verid {}, {}", pkgid, res?.get::<usize,i32>(0), pkginfo);
@@ -187,10 +187,12 @@ fn with_pkg<F,T>(opt: &mut PkgOpt, cb: F) -> std::io::Result<T>
 }
 
 
-fn index_pkg<T: postgres::GenericClient>(tr: &mut T, mut opt: PkgOpt, verid: i32) -> std::io::Result<()> {
+fn index_pkg<T: postgres::GenericClient>(tr: &mut T, mut opt: PkgOpt, pkgid: i32, verid: i32) -> std::io::Result<()> {
+    let mut hasman = false;
     let missed = with_pkg(&mut opt, |e, opt| {
             archread::FileList::read(e, man::ismanpath, |ent| opt.date.update(ent), |paths, ent| {
                 insert_man(tr, verid, paths, ent);
+                hasman = true;
                 Ok(())
             })
         })?.links(|src, dest| { insert_link(tr, verid, src, dest) });
@@ -199,10 +201,15 @@ fn index_pkg<T: postgres::GenericClient>(tr: &mut T, mut opt: PkgOpt, verid: i32
         warn!("Some links were missed, reading package again");
         with_pkg(&mut opt, |e, _| { missed.read(e, |paths, ent| {
             insert_man(tr, verid, paths, ent);
+            hasman = true;
             Ok(())
         }) })?
     }
 
+    if hasman {
+        tr.execute("UPDATE packages SET c_hasman = true WHERE NOT c_hasman AND id = $1", &[&pkgid]).unwrap();
+    }
+
     match opt.date {
         Date::Known(_) => Ok(()),
         Date::Found(t) | Date::MaxVal(t) => {
@@ -219,12 +226,12 @@ fn index_pkg<T: postgres::GenericClient>(tr: &mut T, mut opt: PkgOpt, verid: i32
 pub fn pkg<T>(conn: &mut T, opt: PkgOpt) where T: postgres::GenericClient {
     let mut tr = conn.transaction().unwrap();
 
-    let verid = match insert_pkg(&mut tr, &opt) { Some(x) => x, None => return };
+    let (pkgid,verid) = match insert_pkg(&mut tr, &opt) { Some(x) => x, None => return };
     if unsafe { DRY_RUN } {
         return;
     }
 
-    if let Err(e) = index_pkg(&mut tr, opt, verid) {
+    if let Err(e) = index_pkg(&mut tr, opt, pkgid, verid) {
         error!("Error reading package: {}", e);
         return;
     }

schema.sql

@@ -56,7 +56,12 @@ CREATE TABLE packages (
   -- Packages where the latest version does not have any man pages may also be
   -- marked as dead even if the package is still available in the repos.
   dead     boolean   NOT NULL DEFAULT FALSE,
-  UNIQUE(system, name)
+  -- Whether this package has at least one man page indexed in the database.
+  -- The indexer uses this table to keep track of which packages it has
+  -- already indexed, but not all packages seen by the indexer have a man page.
+  -- This cache helps the web front-end filter out irrelevant packages faster.
+  c_hasman boolean   NOT NULL DEFAULT FALSE,
+  UNIQUE(system, name) INCLUDE (id, c_hasman, dead)
 );
 
 

util/update_indices.sql

@@ -9,3 +9,13 @@ CREATE TABLE stats_cache_new AS
 DROP TABLE stats_cache;
 ALTER TABLE stats_cache_new RENAME TO stats_cache;
 COMMIT;
+
+
+-- Update c_hasman.
+-- This query is commented out because the indexer will take care to set the
+-- c_hasman column automatically. It's included here as "documentation" so it
+-- can be run manually when package versions or man pages are removed from the
+-- database.
+--
+-- UPDATE packages SET c_hasman = NOT c_hasman
+--  WHERE c_hasman <> EXISTS(SELECT 1 FROM package_versions pv WHERE pv.package = packages.id AND EXISTS(SELECT 1 FROM files f WHERE f.pkgver = pv.id));

www/index.pl

@@ -77,9 +77,6 @@ sub normalize_name { $_[0] =~ s/%5b/[/irg =~ s/%5d/]/irg =~ s/%20/ /rg }
 sub shorthash_to_hex { unpack 'H*', pack 'i', $_[0] } # int -> hex
 sub shorthash_to_int { unpack 'i', pack 'H*', $_[0] } # hex -> int
 
-# Subquery returning all packages that have a man page.
-my $packages_with_man = '(SELECT * FROM packages p WHERE EXISTS(SELECT 1 FROM package_versions pv WHERE pv.package = p.id AND EXISTS(SELECT 1 FROM files f WHERE f.pkgver = pv.id)))';
-
 sub escape_like { $_[0] =~ s/([_%\\])/\\$1/rg }
 
 sub sql_join {
@@ -111,8 +108,8 @@ sub pkg_frompath {
 
     my $pkg = tuwf->dbRowi('
         SELECT id, system, name
-          FROM', $packages_with_man, 'p
-         WHERE', $sys_where, 'AND name IN', \@names, '
+          FROM packages p
+         WHERE c_hasman AND', $sys_where, 'AND name IN', \@names, '
          ORDER BY system DESC, length(name) DESC
          LIMIT 1
     ');
@@ -928,10 +925,10 @@ TUWF::get qr{/pkg/([^/]+)} => sub {
         p => { onerror => 1, uint => 1, range => [1,200] },
     )->data;
 
-    my $where = sql 'NOT dead AND system =', \$sys->{id}, $f->{c} ne 'all' ? ('AND match_firstchar(name,', \$f->{c}, ')') : ();
-    my $count = tuwf->dbVali('SELECT count(*) FROM', $packages_with_man, 'p WHERE', $where);
+    my $where = sql 'c_hasman AND NOT dead AND system =', \$sys->{id}, $f->{c} ne 'all' ? ('AND match_firstchar(name,', \$f->{c}, ')') : ();
+    my $count = tuwf->dbVali('SELECT count(*) FROM packages p WHERE', $where);
     my $pkg = tuwf->dbPagei({ results => 200, page => $f->{p} },
-        'SELECT id, system, name FROM', $packages_with_man, 'p WHERE', $where, 'ORDER BY name'
+        'SELECT id, system, name FROM packages p WHERE', $where, 'ORDER BY name'
     );
 
     framework_ title => $sys->{full}, mainclass => 'pkglist', sub {