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help / color / mirror / Atom feedFrom: Melanie Plageman <[email protected]>
Subject: [PATCH v7 6/7] Vacuum first pass uses Streaming Read interface
Date: Sun, 31 Dec 2023 11:29:02 -0500
Now vacuum's first pass, which HOT prunes and records the TIDs of
non-removable dead tuples, uses the streaming read API by implementing a
streaming read callback which invokes heap_vac_scan_next_block().
---
src/backend/access/heap/vacuumlazy.c | 131 +++++++++++++++++++--------
1 file changed, 92 insertions(+), 39 deletions(-)
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index d2c8f27fc57..d07a2a58b15 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -54,6 +54,7 @@
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/lmgr.h"
+#include "storage/streaming_read.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/pg_rusage.h"
@@ -168,7 +169,12 @@ typedef struct LVRelState
char *relnamespace;
char *relname;
char *indname; /* Current index name */
- BlockNumber blkno; /* used only for heap operations */
+
+ /*
+ * The current block being processed by vacuum. Used only for heap
+ * operations. Primarily for error reporting and logging.
+ */
+ BlockNumber blkno;
OffsetNumber offnum; /* used only for heap operations */
VacErrPhase phase;
bool verbose; /* VACUUM VERBOSE? */
@@ -220,6 +226,12 @@ typedef struct LVRelState
BlockNumber next_unskippable_block;
/* Next unskippable block's visibility status */
bool next_unskippable_allvis;
+
+ /*
+ * Buffer containing block of VM with visibility information for
+ * next_unskippable_block.
+ */
+ Buffer next_unskippable_vmbuffer;
} next_block_state;
} LVRelState;
@@ -233,8 +245,7 @@ typedef struct LVSavedErrInfo
/* non-export function prototypes */
static void lazy_scan_heap(LVRelState *vacrel);
-static bool heap_vac_scan_next_block(LVRelState *vacrel, Buffer *vmbuffer,
- BlockNumber *blkno,
+static void heap_vac_scan_next_block(LVRelState *vacrel,
bool *all_visible_according_to_vm);
static bool lazy_scan_new_or_empty(LVRelState *vacrel, Buffer buf,
BlockNumber blkno, Page page,
@@ -777,6 +788,47 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
}
}
+static BlockNumber
+vacuum_scan_pgsr_next(PgStreamingRead *pgsr,
+ void *pgsr_private, void *per_buffer_data)
+{
+ LVRelState *vacrel = pgsr_private;
+ bool *all_visible_according_to_vm = per_buffer_data;
+
+ heap_vac_scan_next_block(vacrel,
+ all_visible_according_to_vm);
+
+ /*
+ * If there are no further blocks to vacuum in the relation, release the
+ * vmbuffer.
+ */
+ if (!BlockNumberIsValid(vacrel->next_block_state.current_block) &&
+ BufferIsValid(vacrel->next_block_state.next_unskippable_vmbuffer))
+ {
+ ReleaseBuffer(vacrel->next_block_state.next_unskippable_vmbuffer);
+ vacrel->next_block_state.next_unskippable_vmbuffer = InvalidBuffer;
+ }
+
+ return vacrel->next_block_state.current_block;
+}
+
+static inline PgStreamingRead *
+vac_scan_pgsr_alloc(LVRelState *vacrel, PgStreamingReadBufferCB next_block_cb)
+{
+ PgStreamingRead *result = pg_streaming_read_buffer_alloc(PGSR_FLAG_MAINTENANCE, vacrel,
+ sizeof(bool), vacrel->bstrategy, BMR_REL(vacrel->rel),
+ MAIN_FORKNUM, next_block_cb);
+
+ /*
+ * Initialize for first heap_vac_scan_next_block() call. These rely on
+ * InvalidBlockNumber + 1 = 0
+ */
+ vacrel->next_block_state.current_block = InvalidBlockNumber;
+ vacrel->next_block_state.next_unskippable_block = InvalidBlockNumber;
+
+ return result;
+}
+
/*
* lazy_scan_heap() -- workhorse function for VACUUM
*
@@ -816,10 +868,10 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
static void
lazy_scan_heap(LVRelState *vacrel)
{
+ Buffer buf;
BlockNumber rel_pages = vacrel->rel_pages,
- blkno,
next_fsm_block_to_vacuum = 0;
- bool all_visible_according_to_vm;
+ bool *all_visible_according_to_vm;
VacDeadItems *dead_items = vacrel->dead_items;
Buffer vmbuffer = InvalidBuffer;
@@ -830,23 +882,27 @@ lazy_scan_heap(LVRelState *vacrel)
};
int64 initprog_val[3];
+ PgStreamingRead *pgsr = vac_scan_pgsr_alloc(vacrel, vacuum_scan_pgsr_next);
+
/* Report that we're scanning the heap, advertising total # of blocks */
initprog_val[0] = PROGRESS_VACUUM_PHASE_SCAN_HEAP;
initprog_val[1] = rel_pages;
initprog_val[2] = dead_items->max_items;
pgstat_progress_update_multi_param(3, initprog_index, initprog_val);
- /* Initialize for first heap_vac_scan_next_block() call */
- vacrel->next_block_state.current_block = InvalidBlockNumber;
- vacrel->next_block_state.next_unskippable_block = InvalidBlockNumber;
-
- while (heap_vac_scan_next_block(vacrel, &vmbuffer,
- &blkno, &all_visible_according_to_vm))
+ while (BufferIsValid(buf = pg_streaming_read_buffer_get_next(pgsr,
+ (void **) &all_visible_according_to_vm)))
{
- Buffer buf;
Page page;
bool has_lpdead_items;
bool got_cleanup_lock = false;
+ BlockNumber blkno;
+
+ vacrel->blkno = blkno = BufferGetBlockNumber(buf);
+
+ CheckBufferIsPinnedOnce(buf);
+
+ page = BufferGetPage(buf);
vacrel->scanned_pages++;
@@ -914,9 +970,6 @@ lazy_scan_heap(LVRelState *vacrel)
*/
visibilitymap_pin(vacrel->rel, blkno, &vmbuffer);
- buf = ReadBufferExtended(vacrel->rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
- vacrel->bstrategy);
- page = BufferGetPage(buf);
/*
* We need a buffer cleanup lock to prune HOT chains and defragment
@@ -973,7 +1026,7 @@ lazy_scan_heap(LVRelState *vacrel)
*/
if (got_cleanup_lock)
lazy_scan_prune(vacrel, buf, blkno, page,
- vmbuffer, all_visible_according_to_vm,
+ vmbuffer, *all_visible_according_to_vm,
&has_lpdead_items);
/*
@@ -1030,7 +1083,7 @@ lazy_scan_heap(LVRelState *vacrel)
}
/* report that everything is now scanned */
- pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
+ pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, vacrel->rel_pages);
/* now we can compute the new value for pg_class.reltuples */
vacrel->new_live_tuples = vac_estimate_reltuples(vacrel->rel, rel_pages,
@@ -1045,6 +1098,8 @@ lazy_scan_heap(LVRelState *vacrel)
Max(vacrel->new_live_tuples, 0) + vacrel->recently_dead_tuples +
vacrel->missed_dead_tuples;
+ pg_streaming_read_free(pgsr);
+
/*
* Do index vacuuming (call each index's ambulkdelete routine), then do
* related heap vacuuming
@@ -1056,11 +1111,11 @@ lazy_scan_heap(LVRelState *vacrel)
* Vacuum the remainder of the Free Space Map. We must do this whether or
* not there were indexes, and whether or not we bypassed index vacuuming.
*/
- if (blkno > next_fsm_block_to_vacuum)
- FreeSpaceMapVacuumRange(vacrel->rel, next_fsm_block_to_vacuum, blkno);
+ if (vacrel->rel_pages > next_fsm_block_to_vacuum)
+ FreeSpaceMapVacuumRange(vacrel->rel, next_fsm_block_to_vacuum, vacrel->rel_pages);
/* report all blocks vacuumed */
- pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
+ pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, vacrel->rel_pages);
/* Do final index cleanup (call each index's amvacuumcleanup routine) */
if (vacrel->nindexes > 0 && vacrel->do_index_cleanup)
@@ -1072,12 +1127,13 @@ lazy_scan_heap(LVRelState *vacrel)
*
* lazy_scan_heap() calls here every time it needs to get the next block to
* prune and vacuum, using the visibility map, vacuum options, and various
- * thresholds to skip blocks which do not need to be processed and set blkno to
- * the next block that actually needs to be processed.
+ * thresholds to skip blocks which do not need to be processed and set
+ * current_block to the next block that actually needs to be processed.
*
- * The block number and visibility status of the next block to process are set
- * in blkno and all_visible_according_to_vm. heap_vac_scan_next_block()
- * returns false if there are no further blocks to process.
+ * The number and visibility status of the next block to process are set in
+ * vacrel->next_block_state->current_block and all_visible_according_to_vm.
+ * vacrel->next_block_state->current_block is set to InvalidBlockNumber if
+ * there are no further blocks to process.
*
* vacrel is an in/out parameter here; vacuum options and information about the
* relation are read, members of vacrel->next_block_state are read and set as
@@ -1085,12 +1141,10 @@ lazy_scan_heap(LVRelState *vacrel)
* don't advance relfrozenxid when we have skipped vacuuming all-visible
* blocks.
*
- * vmbuffer is an output parameter which, upon return, will contain the block
- * from the VM containing visibility information for the next unskippable heap
- * block. If we decide not to skip this heap block, the caller is responsible
- * for fetching the correct VM block into vmbuffer before using it. This is
- * okay as providing it as an output parameter is an optimization, not a
- * requirement.
+ * vacrel->next_block_state->vmbuffer will contain visibility information for
+ * the next unskippable heap block. If we decide not to skip this heap block,
+ * the caller is responsible for fetching the correct VM block into the
+ * vmbuffer before using it.
*
* Note: our opinion of which blocks can be skipped can go stale immediately.
* It's okay if caller "misses" a page whose all-visible or all-frozen marking
@@ -1100,9 +1154,9 @@ lazy_scan_heap(LVRelState *vacrel)
* older XIDs/MXIDs. The vacrel->skippedallvis flag will be set here when the
* choice to skip such a range is actually made, making everything safe.)
*/
-static bool
-heap_vac_scan_next_block(LVRelState *vacrel, Buffer *vmbuffer,
- BlockNumber *blkno, bool *all_visible_according_to_vm)
+static void
+heap_vac_scan_next_block(LVRelState *vacrel,
+ bool *all_visible_according_to_vm)
{
/* Relies on InvalidBlockNumber + 1 == 0 */
BlockNumber next_block = vacrel->next_block_state.current_block + 1;
@@ -1129,8 +1183,8 @@ heap_vac_scan_next_block(LVRelState *vacrel, Buffer *vmbuffer,
*/
if (next_block >= vacrel->rel_pages)
{
- vacrel->next_block_state.current_block = *blkno = InvalidBlockNumber;
- return false;
+ vacrel->next_block_state.current_block = InvalidBlockNumber;
+ return;
}
if (vacrel->next_block_state.next_unskippable_block == InvalidBlockNumber ||
@@ -1144,7 +1198,7 @@ heap_vac_scan_next_block(LVRelState *vacrel, Buffer *vmbuffer,
{
uint8 mapbits = visibilitymap_get_status(vacrel->rel,
next_unskippable_block,
- vmbuffer);
+ &vacrel->next_block_state.next_unskippable_vmbuffer);
vacrel->next_block_state.next_unskippable_allvis = mapbits & VISIBILITYMAP_ALL_VISIBLE;
@@ -1224,8 +1278,7 @@ heap_vac_scan_next_block(LVRelState *vacrel, Buffer *vmbuffer,
else
*all_visible_according_to_vm = true;
- vacrel->next_block_state.current_block = *blkno = next_block;
- return true;
+ vacrel->next_block_state.current_block = next_block;
}
/*
--
2.40.1
--3uc3jkcn3zcvmfik
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v7-0007-Vacuum-second-pass-uses-Streaming-Read-interface.patch"
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