possibly_not_on_disk_segno -> possibly_not_on_disk_blkno

already had this in one place, but let's expand the practice, as
it seems cleaner

diff --git a/src/backend/access/conveyor/conveyor.c b/src/backend/access/conveyor/conveyor.c
index 2c932d0f22f8a85a6a83d4e97aa050ba6524dcb7..dfffea7a2c7f36c6d9ce44a28c153e2adcc84e96 100644 (file)
--- a/src/backend/access/conveyor/conveyor.c
+++ b/src/backend/access/conveyor/conveyor.c
@@ -157,6 +157,7 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
        BlockNumber indexblock = InvalidBlockNumber;
        BlockNumber prevblock = InvalidBlockNumber;
        BlockNumber fsmblock = InvalidBlockNumber;
+       BlockNumber     possibly_not_on_disk_blkno = CONVEYOR_METAPAGE + 1;
        Buffer          metabuffer;
        Buffer          indexbuffer = InvalidBuffer;
        Buffer          prevbuffer = InvalidBuffer;
@@ -165,7 +166,6 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
        CBPageNo        next_pageno;
        CBPageNo        previous_next_pageno = 0;
        CBSegNo         free_segno = CB_INVALID_SEGMENT;
-       CBSegNo         possibly_not_on_disk_segno = 0;
        bool            needs_xlog;
        int                     mode = BUFFER_LOCK_SHARE;
        int                     iterations_without_next_pageno_change = 0;
@@ -283,12 +283,19 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
                                 next_pageno, (int) insert_state);
 
                /*
-                * All existing segments must be on disk.
-                *
-                * (The last one might be partial, but that's OK.)
+                * next_segno need not exist on disk, but at least the first block
+                * of the previous segment should be there.
                 */
-               if (next_segno > possibly_not_on_disk_segno)
-                       possibly_not_on_disk_segno = next_segno;
+               if (next_segno > 0)
+               {
+                       BlockNumber last_segno_first_blkno;
+
+                       last_segno_first_blkno =
+                               cb_segment_to_block(cb->cb_pages_per_segment,
+                                                                       next_segno - 1, 0);
+                       if (last_segno_first_blkno > possibly_not_on_disk_blkno)
+                               possibly_not_on_disk_blkno = last_segno_first_blkno + 1;
+               }
 
                /*
                 * If we need to allocate a payload or index segment, and we don't
@@ -313,12 +320,20 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
                 * previously, but otherwise it's only true if we've verified that the
                 * size of the relation on disk is large enough.
                 */
-               can_allocate_segment =
-                       (insert_state == CBM_INSERT_NEEDS_PAYLOAD_SEGMENT
-                        || insert_state == CBM_INSERT_NEEDS_INDEX_SEGMENT) &&
-                       mode == BUFFER_LOCK_EXCLUSIVE &&
-                       free_segno != CB_INVALID_SEGMENT &&
-                       free_segno < possibly_not_on_disk_segno;
+               if (mode != BUFFER_LOCK_EXCLUSIVE ||
+                       free_segno == CB_INVALID_SEGMENT ||
+                       (insert_state != CBM_INSERT_NEEDS_PAYLOAD_SEGMENT
+                        && insert_state != CBM_INSERT_NEEDS_INDEX_SEGMENT))
+                       can_allocate_segment = false;
+               else
+               {
+                       BlockNumber     free_segno_first_blkno;
+
+                       free_segno_first_blkno =
+                               cb_segment_to_block(cb->cb_pages_per_segment, free_segno, 0);
+                       can_allocate_segment =
+                               (free_segno_first_blkno < possibly_not_on_disk_blkno);
+               }
 
                /*
                 * If it still looks like we can allocate, check for the case where we
@@ -460,21 +475,6 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
                }
                else
                {
-                       BlockNumber possibly_not_on_disk_blkno;
-
-                       /*
-                        * The current payload segment is not full, but if it's the last
-                        * segment in the conveyor belt, the page we need may not yet
-                        * exist on disk.
-                        *
-                        * The previous segment's first page must exist on disk, but the
-                        * later pages may not.
-                        */
-                       possibly_not_on_disk_blkno =
-                               cb_segment_to_block(cb->cb_pages_per_segment,
-                                                                       possibly_not_on_disk_segno, 0)
-                               - cb->cb_pages_per_segment + 1;
-
                        /* Extend the relation if needed. */
                        buffer = InvalidBuffer;
                        if (next_blkno >= possibly_not_on_disk_blkno)
@@ -501,6 +501,7 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
                                else
                                {
                                        /* we don't need to extend */
+                                       possibly_not_on_disk_blkno = nblocks;
                                        UnlockRelationForExtension(cb->cb_rel, ExclusiveLock);
                                }
                        }
@@ -642,12 +643,8 @@ ConveyorBeltGetNewPage(ConveyorBelt *cb, CBPageNo *pageno)
                                }
                                UnlockRelationForExtension(cb->cb_rel, ExclusiveLock);
 
-                               /*
-                                * The first page of this segment, at least, is now known to
-                                * be on disk, either because we verified the length of the
-                                * relation fork, or because we extended it.
-                                */
-                               possibly_not_on_disk_segno = free_segno + 1;
+                               /* Update our notion of what blocks exist on disk. */
+                               possibly_not_on_disk_blkno = nblocks;
                        }
                }