diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 700271fd40..8945959f9d 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -11239,19 +11239,29 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx Possible values are: - normal means that the claimed files + reserved means that the claimed files are within max_wal_size. - reserved means + extended means that max_wal_size is exceeded but the files are - still held, either by some replication slot or - by wal_keep_segments. + still retained, either by the replication slot or + by wal_keep_segments. + - lost means that some WAL files are - definitely lost and this slot cannot be used to resume replication - anymore. + + unreserved means that the slot no longer + retains the required WAL files and some of them are to be removed at + the next checkpoint. This state can return + to reserved or extended. + + + + + lost means that some required WAL files have + been removed and this slot is no longer usable. + The last two states are seen only when diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index aca4fdd2a6..d5dfd5764e 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -9488,15 +9488,20 @@ CreateRestartPoint(int flags) * (typically a slot's restart_lsn) * * Returns one of the following enum values: - * * WALAVAIL_NORMAL means targetLSN is available because it is in the range - * of max_wal_size. * - * * WALAVAIL_PRESERVED means it is still available by preserving extra + * * WALAVAIL_RESERVED means targetLSN is available and it is in the range of + * max_wal_size. + * + * * WALAVAIL_EXTENDED means it is still available by preserving extra * segments beyond max_wal_size. If max_slot_wal_keep_size is smaller * than max_wal_size, this state is not returned. * - * * WALAVAIL_REMOVED means it is definitely lost. A replication stream on - * a slot with this LSN cannot continue. + * * WALAVAIL_UNRESERVED means it is being lost and the next checkpoint will + * remove reserved segments. The walsender using this slot may return to the + * above. + * + * * WALAVAIL_REMOVED means it has been removed. A replication stream on + * a slot with this LSN cannot continue after a restart. * * * WALAVAIL_INVALID_LSN means the slot hasn't been set to reserve WAL. */ @@ -9512,13 +9517,18 @@ GetWALAvailability(XLogRecPtr targetLSN) * slot */ uint64 keepSegs; - /* slot does not reserve WAL. Either deactivated, or has never been active */ + /* + * slot does not reserve WAL. Either deactivated, or has never been active + */ if (XLogRecPtrIsInvalid(targetLSN)) return WALAVAIL_INVALID_LSN; currpos = GetXLogWriteRecPtr(); - /* calculate oldest segment currently needed by slots */ + /* + * calculate the oldest segment currently reserved by all slots, + * considering wal_keep_segments and max_slot_wal_keep_size + */ XLByteToSeg(targetLSN, targetSeg, wal_segment_size); KeepLogSeg(currpos, &oldestSlotSeg); @@ -9529,10 +9539,9 @@ GetWALAvailability(XLogRecPtr targetLSN) */ oldestSeg = XLogGetLastRemovedSegno() + 1; - /* calculate oldest segment by max_wal_size and wal_keep_segments */ + /* calculate oldest segment by max_wal_size */ XLByteToSeg(currpos, currSeg, wal_segment_size); - keepSegs = ConvertToXSegs(Max(max_wal_size_mb, wal_keep_segments), - wal_segment_size) + 1; + keepSegs = ConvertToXSegs(max_wal_size_mb, wal_segment_size) + 1; if (currSeg > keepSegs) oldestSegMaxWalSize = currSeg - keepSegs; @@ -9540,27 +9549,23 @@ GetWALAvailability(XLogRecPtr targetLSN) oldestSegMaxWalSize = 1; /* - * If max_slot_wal_keep_size has changed after the last call, the segment - * that would been kept by the current setting might have been lost by the - * previous setting. No point in showing normal or keeping status values - * if the targetSeg is known to be lost. + * No point in returning reserved or extended status values if the + * targetSeg is known to be lost. */ - if (targetSeg >= oldestSeg) + if (targetSeg >= oldestSlotSeg) { - /* - * show "normal" when targetSeg is within max_wal_size, even if - * max_slot_wal_keep_size is smaller than max_wal_size. - */ - if ((max_slot_wal_keep_size_mb <= 0 || - max_slot_wal_keep_size_mb >= max_wal_size_mb) && - oldestSegMaxWalSize <= targetSeg) - return WALAVAIL_NORMAL; - - /* being retained by slots */ - if (oldestSlotSeg <= targetSeg) + /* show "reserved" when targetSeg is within max_wal_size */ + if (targetSeg >= oldestSegMaxWalSize) return WALAVAIL_RESERVED; + + /* being retained by slots exceeding max_wal_size */ + return WALAVAIL_EXTENDED; } + /* WAL segments are no longer retained but haven't been removed yet */ + if (targetSeg >= oldestSeg) + return WALAVAIL_UNRESERVED; + /* Definitely lost */ return WALAVAIL_REMOVED; } diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c index 3fc54cb9ba..df854bc6e3 100644 --- a/src/backend/replication/slotfuncs.c +++ b/src/backend/replication/slotfuncs.c @@ -359,24 +359,47 @@ pg_get_replication_slots(PG_FUNCTION_ARGS) nulls[i++] = true; break; - case WALAVAIL_NORMAL: - values[i++] = CStringGetTextDatum("normal"); - break; - case WALAVAIL_RESERVED: values[i++] = CStringGetTextDatum("reserved"); break; - case WALAVAIL_REMOVED: - values[i++] = CStringGetTextDatum("lost"); + case WALAVAIL_EXTENDED: + values[i++] = CStringGetTextDatum("extended"); break; - default: - elog(ERROR, "invalid walstate: %d", (int) walstate); + case WALAVAIL_UNRESERVED: + values[i++] = CStringGetTextDatum("unreserved"); + break; + + case WALAVAIL_REMOVED: + + /* + * If we read the restart_lsn long enough ago, maybe that file + * has been removed by now. However, the walsender could have + * moved forward enough that it jumped to another file after + * we looked. If checkpointer signalled the process to + * termination, then it's definitely lost; but if a process is + * still alive, then "unreserved" seems more appropriate. + */ + if (!XLogRecPtrIsInvalid(slot_contents.data.restart_lsn)) + { + int pid; + + SpinLockAcquire(&slot->mutex); + pid = slot->active_pid; + SpinLockRelease(&slot->mutex); + if (pid != 0) + { + values[i++] = CStringGetTextDatum("unreserved"); + break; + } + } + values[i++] = CStringGetTextDatum("lost"); + break; } if (max_slot_wal_keep_size_mb >= 0 && - (walstate == WALAVAIL_NORMAL || walstate == WALAVAIL_RESERVED) && + (walstate == WALAVAIL_RESERVED || walstate == WALAVAIL_EXTENDED) && ((last_removed_seg = XLogGetLastRemovedSegno()) != 0)) { XLogRecPtr min_safe_lsn; diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 12d7b89e7a..f51d933e8e 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -270,8 +270,10 @@ extern CheckpointStatsData CheckpointStats; typedef enum WALAvailability { WALAVAIL_INVALID_LSN, /* parameter error */ - WALAVAIL_NORMAL, /* WAL segment is within max_wal_size */ - WALAVAIL_RESERVED, /* WAL segment is reserved by a slot */ + WALAVAIL_RESERVED, /* WAL segment is within max_wal_size */ + WALAVAIL_EXTENDED, /* WAL segment is reserved by a slot or + * wal_keep_segments */ + WALAVAIL_UNRESERVED, /* no longer reserved, but not removed yet */ WALAVAIL_REMOVED /* WAL segment has been removed */ } WALAvailability; diff --git a/src/test/recovery/t/019_replslot_limit.pl b/src/test/recovery/t/019_replslot_limit.pl index f1be984cc9..7d22ae5720 100644 --- a/src/test/recovery/t/019_replslot_limit.pl +++ b/src/test/recovery/t/019_replslot_limit.pl @@ -56,7 +56,7 @@ $node_standby->stop; $result = $node_master->safe_psql('postgres', "SELECT wal_status, min_safe_lsn is NULL FROM pg_replication_slots WHERE slot_name = 'rep1'" ); -is($result, "normal|t", 'check the catching-up state'); +is($result, "reserved|t", 'check the catching-up state'); # Advance WAL by five segments (= 5MB) on master advance_wal($node_master, 1); @@ -66,7 +66,8 @@ $node_master->safe_psql('postgres', "CHECKPOINT;"); $result = $node_master->safe_psql('postgres', "SELECT wal_status, min_safe_lsn is NULL FROM pg_replication_slots WHERE slot_name = 'rep1'" ); -is($result, "normal|t", 'check that it is safe if WAL fits in max_wal_size'); +is($result, "reserved|t", + 'check that it is safe if WAL fits in max_wal_size'); advance_wal($node_master, 4); $node_master->safe_psql('postgres', "CHECKPOINT;"); @@ -75,7 +76,7 @@ $node_master->safe_psql('postgres', "CHECKPOINT;"); $result = $node_master->safe_psql('postgres', "SELECT wal_status, min_safe_lsn is NULL FROM pg_replication_slots WHERE slot_name = 'rep1'" ); -is($result, "normal|t", 'check that slot is working'); +is($result, "reserved|t", 'check that slot is working'); # The standby can reconnect to master $node_standby->start; @@ -99,7 +100,7 @@ $node_master->reload; $result = $node_master->safe_psql('postgres', "SELECT wal_status FROM pg_replication_slots WHERE slot_name = 'rep1'"); -is($result, "normal", 'check that max_slot_wal_keep_size is working'); +is($result, "reserved", 'check that max_slot_wal_keep_size is working'); # Advance WAL again then checkpoint, reducing remain by 2 MB. advance_wal($node_master, 2); @@ -108,7 +109,7 @@ $node_master->safe_psql('postgres', "CHECKPOINT;"); # The slot is still working $result = $node_master->safe_psql('postgres', "SELECT wal_status FROM pg_replication_slots WHERE slot_name = 'rep1'"); -is($result, "normal", +is($result, "reserved", 'check that min_safe_lsn gets close to the current LSN'); # The standby can reconnect to master @@ -125,7 +126,7 @@ advance_wal($node_master, 6); $result = $node_master->safe_psql('postgres', "SELECT wal_status as remain FROM pg_replication_slots WHERE slot_name = 'rep1'" ); -is($result, "normal", +is($result, "extended", 'check that wal_keep_segments overrides max_slot_wal_keep_size'); # restore wal_keep_segments $result = $node_master->safe_psql('postgres', @@ -143,7 +144,7 @@ advance_wal($node_master, 6); # Slot gets into 'reserved' state $result = $node_master->safe_psql('postgres', "SELECT wal_status FROM pg_replication_slots WHERE slot_name = 'rep1'"); -is($result, "reserved", 'check that the slot state changes to "reserved"'); +is($result, "extended", 'check that the slot state changes to "extended"'); # do checkpoint so that the next checkpoint runs too early $node_master->safe_psql('postgres', "CHECKPOINT;"); @@ -151,11 +152,12 @@ $node_master->safe_psql('postgres', "CHECKPOINT;"); # Advance WAL again without checkpoint; remain goes to 0. advance_wal($node_master, 1); -# Slot gets into 'lost' state +# Slot gets into 'unreserved' state $result = $node_master->safe_psql('postgres', "SELECT wal_status, min_safe_lsn is NULL FROM pg_replication_slots WHERE slot_name = 'rep1'" ); -is($result, "lost|t", 'check that the slot state changes to "lost"'); +is($result, "unreserved|t", + 'check that the slot state changes to "unreserved"'); # The standby still can connect to master before a checkpoint $node_standby->start; @@ -186,7 +188,8 @@ ok( find_in_log( $result = $node_master->safe_psql('postgres', "SELECT slot_name, active, restart_lsn IS NULL, wal_status, min_safe_lsn FROM pg_replication_slots WHERE slot_name = 'rep1'" ); -is($result, "rep1|f|t|lost|", 'check that the slot became inactive'); +is($result, "rep1|f|t|lost|", + 'check that the slot became inactive and the state "lost" persists'); # The standby no longer can connect to the master $logstart = get_log_size($node_standby);