Handle failure cases of report gc

documentation/release_notes_7.markdown

@@ -15,6 +15,21 @@ canonical: "/puppetdb/latest/release_notes.html"
 
 # PuppetDB: Release notes
 
+## PuppetDB 7.20.1
+
+Released TBD.
+
+### Bug fixes
+
+* Fixed an issue with report garbage collection where a partition would become
+  partially detached and block future garbage collection progress. Garbage
+  collection will now finalize the partition detach operation and remove the
+  table. ([GitHub #4013](https://github.com/puppetlabs/puppetdb/issues/4013))
+* Fixed an issue with report garbage collection where a partition would be
+  detached, but the table was never deleted. Garbage collection will now
+  identify and clean-up these tables.
+  ([GitHub #4013](https://github.com/puppetlabs/puppetdb/issues/4013))
+
 ## PuppetDB 7.20.0
 
 Released October 22 2024

src/puppetlabs/puppetdb/jdbc.clj

@@ -24,6 +24,7 @@
   (or ({:admin-shutdown "57P01"
         :invalid-regular-expression "2201B"
         :program-limit-exceeded "54000"
+        :not-in-prerequisite-state "55000"
         :lock-not-available "55P03"
         :query-canceled "57014"}
        kw-name)

src/puppetlabs/puppetdb/scf/partitioning.clj

@@ -1,6 +1,7 @@
 (ns puppetlabs.puppetdb.scf.partitioning
   "Handles all work related to database table partitioning"
   (:require
+   [clojure.string :refer [lower-case]]
    [puppetlabs.i18n.core :refer [trs]]
    [puppetlabs.puppetdb.jdbc :as jdbc]
    [schema.core :as s])
@@ -32,8 +33,8 @@
 
 (defn date-suffix
   [date]
-  (let [formatter (.withZone (DateTimeFormatter/BASIC_ISO_DATE) (ZoneId/of "UTC"))]
-    (.format date formatter)))
+  (let [formatter (.withZone DateTimeFormatter/BASIC_ISO_DATE (ZoneId/of "UTC"))]
+    (lower-case (.format date formatter))))
 
 (defn to-zoned-date-time
   [date]

src/puppetlabs/puppetdb/scf/storage.clj

@@ -1673,6 +1673,39 @@
   (let [{current-db-version :version} (sutils/db-metadata)]
     (not (neg? (compare current-db-version pg14-db)))))
 
+(defn finalize-pending-detach
+  "Finalize a previously failed detach operation. A partitioned table can
+  only have one partition pending detachment at any time."
+  [parent]
+  (let [pending (->> ["SELECT inhrelid::regclass AS child
+                      FROM pg_catalog.pg_inherits
+                      WHERE inhparent = ?::regclass AND inhdetachpending = true"
+                      parent]
+                     jdbc/query-to-vec
+                     first
+                     :child)]
+    (when pending
+      (log/info (trs "Finalizing detach for partition {0}" pending))
+      (jdbc/do-commands (format "ALTER TABLE %s DETACH PARTITION %s FINALIZE" parent pending))
+      (str pending))))
+
+(defn find-stranded-partitions
+  "Identify tables that match the child format of a partitioned table (like reports_historical)
+  that are not present in the pg_inherits table. These partitions have been detached, but failed
+  to be deleted.
+
+  Tables that are not partitioned will also not be in the pg_inherits table, so you MUST
+  write a child-format that does not match any non-partitioned tables.
+
+  Returns a list of strings. Each string is a stranded partition that should be removed."
+  [child-format]
+  (->> [(str "SELECT tablename"
+             " FROM pg_tables WHERE tablename ~ ?"
+             " AND tablename NOT IN (SELECT inhrelid::regclass::text FROM pg_catalog.pg_inherits)")
+        child-format]
+       jdbc/query-to-vec
+       (map (comp str :tablename))))
+
 (defn prune-daily-partitions
   "Either detaches or drops obsolete day-oriented partitions
   older than the date. Deletes or detaches only the oldest such candidate if
@@ -1698,14 +1731,27 @@
          candidates (->> (partitioning/get-partition-names table-prefix)
                          (filter expired?)
                          sort)
-         drop-one (fn [table]
+         detach (fn detach [parent child]
+                  (jdbc/do-commands-outside-txn
+                   (format "alter table %s detach partition %s concurrently" parent child)))
+         drop-one (fn drop-one [table]
                     (update-lock-status status-key inc)
                     (try!
                       (if just-detach?
-                        (jdbc/do-commands-outside-txn
-                          (format "alter table %s detach partition %s concurrently" table-prefix table))
+                        (let [ex (try
+                                   (detach table-prefix table)
+                                   (catch SQLException ex
+                                     (if (= (jdbc/sql-state :not-in-prerequisite-state) (.getSQLState ex))
+                                       ex
+                                       (throw ex))))]
+                          (when (instance? SQLException ex)
+                            (let [finalized-table (finalize-pending-detach table-prefix)]
+                              (when-not (= finalized-table table)
+                                ;; Retry, unless the finalized partition detach was
+                                ;; for the same table
+                                (detach table-prefix table)))))
                         (jdbc/do-commands
-                          (format "drop table if exists %s cascade" table)))
+                         (format "drop table if exists %s cascade" table)))
                       (finally
                         (update-lock-status status-key dec))))
          drop #(if incremental?
@@ -1745,7 +1791,7 @@
   "Drops the given set of tables. Will throw an SQLException termination if the
   operation takes much longer than PDB_GC_DAILY_PARTITION_DROP_LOCK_TIMEOUT_MS."
   [old-partition-tables update-lock-status status-key]
-  (let [drop #(doseq [table old-partition-tables]
+  (let [drop #(doseq [table (distinct old-partition-tables)]
                  (try
                    (update-lock-status status-key inc)
                    (jdbc/do-commands
@@ -1769,9 +1815,10 @@
     ;; PG14+
     (let [detached-tables
            (detach-daily-partitions "resource_events" date incremental?
-                                    update-lock-status :write-locking-resource-events)]
+                                    update-lock-status :write-locking-resource-events)
+           stranded-tables (find-stranded-partitions "^resource_events_\\d\\d\\d\\d\\d\\d\\d\\dz$")]
       (jdbc/with-db-transaction []
-        (drop-partition-tables! detached-tables
+        (drop-partition-tables! (concat detached-tables stranded-tables)
                                 update-lock-status :write-locking-resource-events)))))
 
 (defn cleanup-dropped-report-certnames
@@ -1824,13 +1871,15 @@
       ;; PG14+
       ;; Detach partition concurrently must take place outside of a transaction.
       (let [detached-resource-event-tables
-             (detach-daily-partitions "resource_events" effective-resource-events-ttl
-                                      incremental? update-lock-status
-                                      :write-locking-resource-events)
+            (detach-daily-partitions "resource_events" effective-resource-events-ttl
+                                     incremental? update-lock-status
+                                     :write-locking-resource-events)
+            stranded-events-tables (find-stranded-partitions "^resource_events_\\d\\d\\d\\d\\d\\d\\d\\dz$")
             detached-report-tables
-             (detach-daily-partitions "reports" report-ttl
-                                    incremental? update-lock-status
-                                    :write-locking-reports)]
+            (detach-daily-partitions "reports" report-ttl
+                                     incremental? update-lock-status
+                                     :write-locking-reports)
+            stranded-reports-tables (find-stranded-partitions "^reports_\\d\\d\\d\\d\\d\\d\\d\\dz$")]
         ;; Now we can delete the partitions with less intrusive locking.
         (jdbc/with-db-transaction []
           ;; Nothing should acquire locks on the detached tables, but to be safe, acquire
@@ -1840,9 +1889,9 @@
           ;; force a resource-events GC. prior to partitioning, this would have happened
           ;; via a cascade when the report was deleted, but now we just drop whole tables
           ;; of resource events.
-          (drop-partition-tables! detached-resource-event-tables
+          (drop-partition-tables! (concat detached-resource-event-tables stranded-events-tables)
                                   update-lock-status :write-locking-resource-events)
-          (drop-partition-tables! detached-report-tables
+          (drop-partition-tables! (concat detached-report-tables stranded-reports-tables)
                                   update-lock-status :write-locking-reports)
           ;; since we cannot cascade back to the certnames table anymore, go clean up
           ;; the latest_report_id column after a GC.

test/puppetlabs/puppetdb/cli/services_test.clj

@@ -5,7 +5,8 @@
             [puppetlabs.puppetdb.command.constants :as cmd-consts]
             [puppetlabs.puppetdb.lint :refer [ignore-value]]
             [puppetlabs.puppetdb.scf.partitioning
-             :refer [get-temporal-partitions]]
+             :refer [get-temporal-partitions]
+             :as part]
             [puppetlabs.trapperkeeper.testutils.logging
              :refer [with-log-output
                      logs-matching
@@ -583,7 +584,7 @@
   (with-test-db
     (let [config (-> (create-temp-config)
                      (assoc :database *db* :read-database *read-db*)
-                     (assoc-in [:database :gc-interval] "0.01"))
+                     (assoc-in [:database :gc-interval] "60"))
           store-report #(sync-command-post (svc-utils/pdb-cmd-url)
                                            example-certname
                                            "store report"
@@ -607,4 +608,73 @@
                                       :report-ttl (time/parse-period "1d")
                                       :resource-events-ttl (time/parse-period "1d")
                                       :db-lock-status db-lock-status})
-           (is (empty? (jdbc/query ["SELECT * FROM reports"])))))))))
+           (is (empty? (jdbc/query ["SELECT * FROM reports"]))))
+
+         ;; These tests are not applicable unless our Postgres version is new enough
+         ;; to support the concurrent partition detach feature.
+         (when (scf-store/detach-partitions-concurrently?)
+           (testing "a partition stuck in the pending state is finalized and removed"
+             (let [old-ts (-> 2 time/days time/ago)
+                   partition-table (format "reports_%s"
+                                           (part/date-suffix (part/to-zoned-date-time (time/to-timestamp old-ts))))
+                   lock-acquired (promise)
+                   partition-pending-detach (promise)]
+               (store-report (time/to-string old-ts))
+               (store-report (to-string (now)))
+
+               (future
+                ;; Create a query that will block the ACCESS EXCLUSIVE lock needed
+                ;; by the second transaction of the concurrent detach below
+                (jdbc/with-transacted-connection *read-db*
+                  (jdbc/with-db-transaction  []
+                    (jdbc/query [(format "select * from %s" partition-table)])
+                    (deliver lock-acquired partition-table)
+
+                    ;; wait for partition detach to fail
+                    @partition-pending-detach)))
+
+               ;; Wait until we are sure that the detach partition operation will be blocked
+               @lock-acquired
+
+               (try
+                 (jdbc/do-commands-outside-txn
+                  "SET statement_timeout = 100"
+                  (format "ALTER TABLE reports DETACH PARTITION %s CONCURRENTLY" partition-table))
+                 (catch java.sql.SQLException _)
+                 (finally
+                   (deliver partition-pending-detach partition-table)
+                   (jdbc/do-commands-outside-txn "SET statement_timeout = 0")))
+
+               (is (= [{:inhdetachpending true}]
+                      (jdbc/query ["select inhdetachpending from pg_catalog.pg_inherits where inhparent = 'reports'::regclass and inhrelid = ?::regclass" partition-table])))
+
+               (svcs/sweep-reports! *db* {:incremental? false
+                                          :report-ttl (time/parse-period "1d")
+                                          :resource-events-ttl (time/parse-period "1d")
+                                          :db-lock-status db-lock-status})
+
+               (is (empty?
+                    (jdbc/query ["SELECT tablename FROM pg_tables WHERE tablename = ?" partition-table])))
+
+               (jdbc/do-commands "DELETE FROM reports")))
+
+           (testing "a detached partition that was not removed is cleaned up by gc"
+             (let [old-ts (-> 2 time/days time/ago)
+                   partition-table (format "reports_%s"
+                                           (part/date-suffix (part/to-zoned-date-time (time/to-timestamp old-ts))))]
+               (store-report (time/to-string old-ts))
+               (store-report (to-string (now)))
+
+               ;; Strand the partition before calling GC
+               (jdbc/do-commands-outside-txn
+                (format "ALTER TABLE reports DETACH PARTITION %s CONCURRENTLY" partition-table))
+
+               (svcs/sweep-reports! *db* {:incremental? false
+                                          :report-ttl (time/parse-period "1d")
+                                          :resource-events-ttl (time/parse-period "1d")
+                                          :db-lock-status db-lock-status})
+
+               (is (empty?
+                    (jdbc/query ["SELECT tablename FROM pg_tables WHERE tablename = ?" partition-table])))
+
+               (jdbc/do-commands "DELETE FROM reports")))))))))