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Adjust _bt_insertonpg() comments

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Remove an obsolete reference to the 'afteritem' argument, which was
removed by commit bc292937.  Add a comment that clarifies how
_bt_insertonpg() indirectly handles the insertion of high key items.

Author: Peter Geoghegan
This commit is contained in:
Teodor Sigaev
2018-04-19 11:08:45 +03:00
parent 3d927961ae
commit f97f0c921a
1 changed files with 6 additions and 6 deletions
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12
src/backend/access/nbtree/nbtinsert.c
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@ -817,18 +817,18 @@ _bt_findinsertloc(Relation rel,
* insertion, and the buffer must be pinned and write-locked. On return, * insertion, and the buffer must be pinned and write-locked. On return,
* we will have dropped both the pin and the lock on the buffer. * we will have dropped both the pin and the lock on the buffer.
* *
* When inserting to a non-leaf page, 'cbuf' is the left-sibling of the * This routine only performs retail tuple insertions. 'itup' should
* page we're inserting the downlink for. This function will clear the * always be either a non-highkey leaf item, or a downlink (new high
* key items are created indirectly, when a page is split). When
* inserting to a non-leaf page, 'cbuf' is the left-sibling of the page
* we're inserting the downlink for. This function will clear the
* INCOMPLETE_SPLIT flag on it, and release the buffer. * INCOMPLETE_SPLIT flag on it, and release the buffer.
* *
* The locking interactions in this code are critical. You should * The locking interactions in this code are critical. You should
* grok Lehman and Yao's paper before making any changes. In addition, * grok Lehman and Yao's paper before making any changes. In addition,
* you need to understand how we disambiguate duplicate keys in this * you need to understand how we disambiguate duplicate keys in this
* implementation, in order to be able to find our location using * implementation, in order to be able to find our location using
* L&Y "move right" operations. Since we may insert duplicate user * L&Y "move right" operations.
* keys, and since these dups may propagate up the tree, we use the
* 'afteritem' parameter to position ourselves correctly for the
* insertion on internal pages.
*---------- *----------
*/ */
static void static void