Add a new table to store package versions by revision ranges

This isn't new information, but derived from information already in the
database. It's collected here to make querying faster.

The table is updated when each new revision is entered.

guix-data-service/jobs/load-new-guix-revision.scm

@@ -864,13 +864,78 @@ WHERE job_id = $1"
                     git-repository-id))
               (commit commit)))))
 
+(define (update-package-versions-table conn git-repository-id commit)
+  ;; Lock the table to wait for other transactions to commit before updating
+  ;; the table
+  (exec-query
+   conn
+   "
+LOCK TABLE ONLY package_versions_by_guix_revision_range
+  IN SHARE ROW EXCLUSIVE MODE")
+
+  (for-each
+   (match-lambda
+     ((branch-name)
+      (log-time
+       (simple-format #f "deleting package version entries for ~A" branch-name)
+       (lambda ()
+         (exec-query
+          conn
+          "
+DELETE FROM package_versions_by_guix_revision_range
+WHERE git_repository_id = $1 AND branch_name = $2"
+          (list git-repository-id
+                branch-name))))
+      (log-time
+       (simple-format #f "inserting package version entries for ~A" branch-name)
+       (lambda ()
+         (exec-query
+          conn
+          "
+INSERT INTO package_versions_by_guix_revision_range
+SELECT DISTINCT
+       $1::integer AS git_repository_id,
+       $2 AS branch_name,
+       packages.name AS package_name,
+       packages.version AS package_version,
+       first_value(guix_revisions.id)
+         OVER package_version AS first_guix_revision_id,
+       last_value(guix_revisions.id)
+         OVER package_version AS last_guix_revision_id
+FROM packages
+INNER JOIN (
+  SELECT DISTINCT package_derivations.package_id,
+                  guix_revision_package_derivations.revision_id
+  FROM package_derivations
+  INNER JOIN guix_revision_package_derivations
+    ON package_derivations.id = guix_revision_package_derivations.package_derivation_id
+) AS revision_packages ON packages.id = revision_packages.package_id
+INNER JOIN guix_revisions ON revision_packages.revision_id = guix_revisions.id
+INNER JOIN git_branches ON guix_revisions.commit = git_branches.commit
+WHERE git_branches.name = $2
+WINDOW package_version AS (
+  PARTITION BY packages.name, packages.version
+  ORDER BY git_branches.datetime
+  RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+)
+ORDER BY packages.name, packages.version"
+          (list git-repository-id branch-name))))))
+   (exec-query
+    conn
+    "SELECT name FROM git_branches WHERE commit = $1 AND git_repository_id = $2"
+    (list commit git-repository-id)))
+
+  #t)
+
 (define (load-new-guix-revision conn git-repository-id commit)
   (let ((store-item
          (store-item-for-git-repository-id-and-commit
           conn git-repository-id commit)))
     (if store-item
-        (extract-information-from conn git-repository-id
-                                  commit store-item)
+        (and
+         (extract-information-from conn git-repository-id
+                                   commit store-item)
+         (update-package-versions-table conn git-repository-id commit))
         (begin
           (simple-format #t "Failed to generate store item for ~A\n"
                          commit)