Add pages deleted from pending list to FSM

Add pages deleted from GIN's pending list during cleanup to free space map
immediately. Clean up process could be initiated by ordinary insert but adding
page to FSM might occur only at vacuum. On some workload like never-vacuumed
insert-only tables it could cause a huge bloat.

Jeff Janes <jeff.janes@gmail.com>

diff --git a/src/backend/access/gin/ginfast.c b/src/backend/access/gin/ginfast.c
index ae446653a956a3b830d18013dd5e812c13448759..fa8d8a756ebc901850504ddb7b78a97db0e3dd3e 100644 (file)
--- a/src/backend/access/gin/ginfast.c
+++ b/src/backend/access/gin/ginfast.c
@@ -24,6 +24,7 @@
 #include "miscadmin.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
+#include "storage/indexfsm.h"
 
 /* GUC parameter */
 int            gin_pending_list_limit = 0;
@@ -521,10 +522,12 @@ shiftList(Relation index, Buffer metabuffer, BlockNumber newHead,
        int64       nDeletedHeapTuples = 0;
        ginxlogDeleteListPages data;
        Buffer      buffers[GIN_NDELETE_AT_ONCE];
+       BlockNumber freespace[GIN_NDELETE_AT_ONCE];
 
        data.ndeleted = 0;
        while (data.ndeleted < GIN_NDELETE_AT_ONCE && blknoToDelete != newHead)
        {
+           freespace[data.ndeleted] = blknoToDelete;
            buffers[data.ndeleted] = ReadBuffer(index, blknoToDelete);
            LockBuffer(buffers[data.ndeleted], GIN_EXCLUSIVE);
            page = BufferGetPage(buffers[data.ndeleted]);
@@ -609,6 +612,10 @@ shiftList(Relation index, Buffer metabuffer, BlockNumber newHead,
            UnlockReleaseBuffer(buffers[i]);
 
        END_CRIT_SECTION();
+
+       for (i = 0; i < data.ndeleted; i++)
+           RecordFreeIndexPage(index, freespace[i]);
+
    } while (blknoToDelete != newHead);
 
    return false;
@@ -744,6 +751,7 @@ ginInsertCleanup(GinState *ginstate,
    BuildAccumulator accum;
    KeyArray    datums;
    BlockNumber blkno;
+   bool        fsm_vac = false;
 
    metabuffer = ReadBuffer(index, GIN_METAPAGE_BLKNO);
    LockBuffer(metabuffer, GIN_SHARE);
@@ -793,6 +801,7 @@ ginInsertCleanup(GinState *ginstate,
        {
            /* another cleanup process is running concurrently */
            UnlockReleaseBuffer(buffer);
+           fsm_vac = false;
            break;
        }
 
@@ -857,6 +866,7 @@ ginInsertCleanup(GinState *ginstate,
                /* another cleanup process is running concurrently */
                UnlockReleaseBuffer(buffer);
                LockBuffer(metabuffer, GIN_UNLOCK);
+               fsm_vac = false;
                break;
            }
 
@@ -895,9 +905,13 @@ ginInsertCleanup(GinState *ginstate,
            {
                /* another cleanup process is running concurrently */
                LockBuffer(metabuffer, GIN_UNLOCK);
+               fsm_vac = false;
                break;
            }
 
+           /* At this point, some pending pages have been freed up */
+           fsm_vac = true;
+
            Assert(blkno == metadata->head);
            LockBuffer(metabuffer, GIN_UNLOCK);
 
@@ -931,6 +945,15 @@ ginInsertCleanup(GinState *ginstate,
 
    ReleaseBuffer(metabuffer);
 
+   /*
+    * As pending list pages can have a high churn rate, it is
+    * desirable to recycle them immediately to the FreeSpace Map when
+    * ordinary backends clean the list.
+    */
+   if (fsm_vac && !vac_delay)
+       IndexFreeSpaceMapVacuum(index);
+
+
    /* Clean up temporary space */
    MemoryContextSwitchTo(oldCtx);
    MemoryContextDelete(opCtx);