diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/nbtree/nbtinsert.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c index bb19c3d2637..2c3656c1cd3 100644 --- a/src/backend/access/nbtree/nbtinsert.c +++ b/src/backend/access/nbtree/nbtinsert.c @@ -1249,7 +1249,8 @@ _bt_insertonpg(Relation rel, if (postingoff != 0) memcpy(oposting, nposting, MAXALIGN(IndexTupleSize(nposting))); - if (!_bt_pgaddtup(page, itemsz, itup, newitemoff)) + if (PageAddItem(page, (Item) itup, itemsz, newitemoff, false, + false) == InvalidOffsetNumber) elog(PANIC, "failed to add new item to block %u in index \"%s\"", BufferGetBlockNumber(buf), RelationGetRelationName(rel)); @@ -2528,19 +2529,30 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf) } /* - * _bt_pgaddtup() -- add a tuple to a particular page in the index. + * _bt_pgaddtup() -- add a data item to a particular page during split. * * This routine adds the tuple to the page as requested. It does * not affect pin/lock status, but you'd better have a write lock * and pin on the target buffer! Don't forget to write and release * the buffer afterwards, either. * - * The main difference between this routine and a bare PageAddItem call - * is that this code knows that the leftmost index tuple on a non-leaf + * The difference between this routine and a bare PageAddItem call is + * that this code knows that the leftmost data item on an internal * btree page has a key that must be treated as minus infinity. - * Therefore, it truncates away all attributes. CAUTION: this works - * ONLY if we insert the tuples in order, so that the given itup_off - * does represent the final position of the tuple! + * Therefore, it truncates away all attributes. This extra step is + * only needed during internal page splits. + * + * Truncation of an internal page data item can be thought of as one + * of the steps used to "move" a boundary separator key during an + * internal page split. Conceptually, _bt_split() caller splits + * internal pages "inside" the firstright data item: firstright's + * separator key is used as the high key for the left page, while its + * downlink is used within the first data item (also the negative + * infinity item) for the right page. Each distinct separator key + * should appear no more than once per level of the tree. + * + * CAUTION: this works ONLY if we insert the tuples in order, so that + * the given itup_off does represent the final position of the tuple! */ static bool _bt_pgaddtup(Page page, |