src/test/modules/injection_points/specs/inplace.spec

   1 # Test race conditions involving:
   2 # - s1: VACUUM inplace-updating a pg_class row
   3 # - s2: GRANT/REVOKE making pg_class rows dead
   4 # - s3: "VACUUM pg_class" making dead rows LP_UNUSED; DDL reusing them
   5
   6 # Need GRANT to make a non-HOT update.  Otherwise, "VACUUM pg_class" would
   7 # leave an LP_REDIRECT that persists.  To get non-HOT, make rels so the
   8 # pg_class row for vactest.orig50 is on a filled page (assuming BLCKSZ=8192).
   9 # Just to save on filesystem syscalls, use relkind=c for every other rel.
  10 setup
  11 {
  12         CREATE EXTENSION injection_points;
  13         CREATE SCHEMA vactest;
  14         CREATE FUNCTION vactest.mkrels(text, int, int) RETURNS void
  15                 LANGUAGE plpgsql SET search_path = vactest AS $$
  16         DECLARE
  17                 tname text;
  18         BEGIN
  19                 FOR i in $2 .. $3 LOOP
  20                         tname := $1 || i;
  21                         EXECUTE FORMAT('CREATE TYPE ' || tname || ' AS ()');
  22                         RAISE DEBUG '% at %', tname, ctid
  23                                 FROM pg_class WHERE oid = tname::regclass;
  24                 END LOOP;
  25         END
  26         $$;
  27 }
  28 setup   { VACUUM FULL pg_class;  -- reduce free space }
  29 setup
  30 {
  31         SELECT vactest.mkrels('orig', 1, 49);
  32         CREATE TABLE vactest.orig50 ();
  33         SELECT vactest.mkrels('orig', 51, 100);
  34 }
  35 teardown
  36 {
  37         DROP SCHEMA vactest CASCADE;
  38         DROP EXTENSION injection_points;
  39 }
  40
  41 # Wait during inplace update, in a VACUUM of vactest.orig50.
  42 session s1
  43 setup   {
  44         SELECT injection_points_set_local();
  45         SELECT injection_points_attach('inplace-before-pin', 'wait');
  46 }
  47 step vac1       { VACUUM vactest.orig50;  -- wait during inplace update }
  48 # One bug scenario leaves two live pg_class tuples for vactest.orig50 and zero
  49 # live tuples for one of the "intruder" rels.  REINDEX observes the duplicate.
  50 step read1      {
  51         REINDEX TABLE pg_class;  -- look for duplicates
  52         SELECT reltuples = -1 AS reltuples_unknown
  53         FROM pg_class WHERE oid = 'vactest.orig50'::regclass;
  54 }
  55
  56 # Transactional updates of the tuple vac1 is waiting to inplace-update.
  57 session s2
  58 step grant2             { GRANT SELECT ON TABLE vactest.orig50 TO PUBLIC; }
  59 step revoke2    { REVOKE SELECT ON TABLE vactest.orig50 FROM PUBLIC; }
  60 step begin2             { BEGIN; }
  61 step c2                 { COMMIT; }
  62 step r2                 { ROLLBACK; }
  63
  64 # Non-blocking actions.
  65 session s3
  66 step vac3               { VACUUM pg_class; }
  67 # Reuse the lp that vac1 is waiting to change.  I've observed reuse at the 1st
  68 # or 18th CREATE, so create excess.
  69 step mkrels3    {
  70         SELECT vactest.mkrels('intruder', 1, 100);  -- repopulate LP_UNUSED
  71         SELECT injection_points_detach('inplace-before-pin');
  72         SELECT injection_points_wakeup('inplace-before-pin');
  73 }
  74
  75
  76 # target gains a successor at the last moment
  77 permutation
  78         vac1(mkrels3)   # reads pg_class tuple T0 for vactest.orig50, xmax invalid
  79         grant2                  # T0 becomes eligible for pruning, T1 is successor
  80         vac3                    # T0 becomes LP_UNUSED
  81         mkrels3                 # vac1 wakes, scans to T1
  82         read1
  83
  84 # target already has a successor, which commits
  85 permutation
  86         begin2
  87         grant2                  # T0.t_ctid = T1
  88         vac1(mkrels3)   # reads T0 for vactest.orig50
  89         c2                              # T0 becomes eligible for pruning
  90         vac3                    # T0 becomes LP_UNUSED
  91         mkrels3                 # vac1 wakes, scans to T1
  92         read1
  93
  94 # target already has a successor, which becomes LP_UNUSED at the last moment
  95 permutation
  96         begin2
  97         grant2                  # T0.t_ctid = T1
  98         vac1(mkrels3)   # reads T0 for vactest.orig50
  99         r2                              # T1 becomes eligible for pruning
 100         vac3                    # T1 becomes LP_UNUSED
 101         mkrels3                 # reuse T1; vac1 scans to T0
 102         read1
 103
 104 # target already has a successor, which becomes LP_REDIRECT at the last moment
 105 permutation
 106         begin2
 107         grant2                  # T0.t_ctid = T1, non-HOT due to filled page
 108         vac1(mkrels3)   # reads T0
 109         c2
 110         revoke2                 # HOT update to T2
 111         grant2                  # HOT update to T3
 112         vac3                    # T1 becomes LP_REDIRECT
 113         mkrels3                 # reuse T2; vac1 scans to T3
 114         read1
 115
 116 # waiting for updater to end
 117 permutation
 118         vac1(c2)                # reads pg_class tuple T0 for vactest.orig50, xmax invalid
 119         begin2
 120         grant2                  # T0.t_ctid = T1, non-HOT due to filled page
 121         revoke2                 # HOT update to T2
 122         mkrels3                 # vac1 awakes briefly, then waits for s2
 123         c2
 124         read1
 125
 126 # Another LP_UNUSED.  This time, do change the live tuple.  Final live tuple
 127 # body is identical to original, at a different TID.
 128 permutation
 129         begin2
 130         grant2                  # T0.t_ctid = T1, non-HOT due to filled page
 131         vac1(mkrels3)   # reads T0
 132         r2                              # T1 becomes eligible for pruning
 133         grant2                  # T0.t_ctid = T2; T0 becomes eligible for pruning
 134         revoke2                 # T2.t_ctid = T3; T2 becomes eligible for pruning
 135         vac3                    # T0, T1 & T2 become LP_UNUSED
 136         mkrels3                 # reuse T0, T1 & T2; vac1 scans to T3
 137         read1
 138
 139 # Another LP_REDIRECT.  Compared to the earlier test, omit the last grant2.
 140 # Hence, final live tuple body is identical to original, at a different TID.
 141 permutation begin2 grant2 vac1(mkrels3) c2 revoke2 vac3 mkrels3 read1