TODO

1 files changed, 28 insertions, 2646 deletions

diff --git a/cursor.go b/cursor.go
index d61ce80..d1990dc 100644
--- a/cursor.go
+++ b/cursor.go
@@ -1,1593 +1,14 @@
 package bolt
 
-// TODO: #define CURSOR_STACK		 32
-
-const (
-	c_initialized = 0x01 /**< cursor has been initialized and is valid */
-	c_eof         = 0x02 /**< No more data */
-	c_del         = 0x08 /**< last op was a cursor_del */
-	c_splitting   = 0x20 /**< Cursor is in page_split */
-	c_untrack     = 0x40 /**< Un-track cursor when closing */
-)
-
 type Cursor struct {
-	flags       int
-	next        *Cursor
-	backup      *Cursor
 	transaction *Transaction
 	bucket      *Bucket
-	top         int
-	pages       []*page
-	indices     []int /* the index of the node for the page at the same level */
-}
-
-// , data []byte, op int
-func (c *Cursor) Get(key []byte) ([]byte, error) {
-	/*
-			int		 rc;
-			int		 exact = 0;
-			int		 (*mfunc)(MDB_cursor *mc, MDB_val *key, MDB_val *data);
-
-			switch (op) {
-			case MDB_GET_CURRENT:
-				if (!(mc->mc_flags & C_INITIALIZED)) {
-					rc = EINVAL;
-				} else {
-					MDB_page *mp = mc->mc_pg[mc->mc_top];
-					int nkeys = NUMKEYS(mp);
-					if (!nkeys || mc->mc_ki[mc->mc_top] >= nkeys) {
-						mc->mc_ki[mc->mc_top] = nkeys;
-						rc = MDB_NOTFOUND;
-						break;
-					}
-					rc = MDB_SUCCESS;
-					if (IS_LEAF2(mp)) {
-						key->mv_size = mc->mc_db->md_pad;
-						key->mv_data = LEAF2KEY(mp, mc->mc_ki[mc->mc_top], key->mv_size);
-					} else {
-						MDB_node *leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-						MDB_GET_KEY(leaf, key);
-						if (data) {
-							if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-								if (mc->mc_flags & C_DEL)
-									mdb_xcursor_init1(mc, leaf);
-								rc = mdb_cursor_get(&mc->mc_xcursor->mx_cursor, data, NULL, MDB_GET_CURRENT);
-							} else {
-								rc = mdb_node_read(mc->mc_txn, leaf, data);
-							}
-						}
-					}
-				}
-				break;
-			case MDB_GET_BOTH:
-			case MDB_GET_BOTH_RANGE:
-				if (data == NULL) {
-					rc = EINVAL;
-					break;
-				}
-				if (mc->mc_xcursor == NULL) {
-					rc = MDB_INCOMPATIBLE;
-					break;
-				}
-				// FALLTHRU
-			case MDB_SET:
-			case MDB_SET_KEY:
-			case MDB_SET_RANGE:
-				if (key == NULL) {
-					rc = EINVAL;
-				} else {
-					rc = mdb_cursor_set(mc, key, data, op,
-						op == MDB_SET_RANGE ? NULL : &exact);
-				}
-				break;
-			case MDB_GET_MULTIPLE:
-				if (data == NULL || !(mc->mc_flags & C_INITIALIZED)) {
-					rc = EINVAL;
-					break;
-				}
-				if (!(mc->mc_db->md_flags & MDB_DUPFIXED)) {
-					rc = MDB_INCOMPATIBLE;
-					break;
-				}
-				rc = MDB_SUCCESS;
-				if (!(mc->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED) ||
-					(mc->mc_xcursor->mx_cursor.mc_flags & C_EOF))
-					break;
-				goto fetchm;
-			case MDB_NEXT_MULTIPLE:
-				if (data == NULL) {
-					rc = EINVAL;
-					break;
-				}
-				if (!(mc->mc_db->md_flags & MDB_DUPFIXED)) {
-					rc = MDB_INCOMPATIBLE;
-					break;
-				}
-				if (!(mc->mc_flags & C_INITIALIZED))
-					rc = mdb_cursor_first(mc, key, data);
-				else
-					rc = mdb_cursor_next(mc, key, data, MDB_NEXT_DUP);
-				if (rc == MDB_SUCCESS) {
-					if (mc->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED) {
-						MDB_cursor *mx;
-		fetchm:
-						mx = &mc->mc_xcursor->mx_cursor;
-						data->mv_size = NUMKEYS(mx->mc_pg[mx->mc_top]) *
-							mx->mc_db->md_pad;
-						data->mv_data = METADATA(mx->mc_pg[mx->mc_top]);
-						mx->mc_ki[mx->mc_top] = NUMKEYS(mx->mc_pg[mx->mc_top])-1;
-					} else {
-						rc = MDB_NOTFOUND;
-					}
-				}
-				break;
-			case MDB_NEXT:
-			case MDB_NEXT_DUP:
-			case MDB_NEXT_NODUP:
-				if (!(mc->mc_flags & C_INITIALIZED))
-					rc = mdb_cursor_first(mc, key, data);
-				else
-					rc = mdb_cursor_next(mc, key, data, op);
-				break;
-			case MDB_PREV:
-			case MDB_PREV_DUP:
-			case MDB_PREV_NODUP:
-				if (!(mc->mc_flags & C_INITIALIZED)) {
-					rc = mdb_cursor_last(mc, key, data);
-					if (rc)
-						break;
-					mc->mc_flags |= C_INITIALIZED;
-					mc->mc_ki[mc->mc_top]++;
-				}
-				rc = mdb_cursor_prev(mc, key, data, op);
-				break;
-			case MDB_FIRST:
-				rc = mdb_cursor_first(mc, key, data);
-				break;
-			case MDB_FIRST_DUP:
-				mfunc = mdb_cursor_first;
-			mmove:
-				if (data == NULL || !(mc->mc_flags & C_INITIALIZED)) {
-					rc = EINVAL;
-					break;
-				}
-				if (mc->mc_xcursor == NULL) {
-					rc = MDB_INCOMPATIBLE;
-					break;
-				}
-				if (!(mc->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED)) {
-					rc = EINVAL;
-					break;
-				}
-				rc = mfunc(&mc->mc_xcursor->mx_cursor, data, NULL);
-				break;
-			case MDB_LAST:
-				rc = mdb_cursor_last(mc, key, data);
-				break;
-			case MDB_LAST_DUP:
-				mfunc = mdb_cursor_last;
-				goto mmove;
-			default:
-				DPRINTF(("unhandled/unimplemented cursor operation %u", op));
-				rc = EINVAL;
-				break;
-			}
-
-			if (mc->mc_flags & C_DEL)
-				mc->mc_flags ^= C_DEL;
-
-			return rc;
-	*/
-	return nil, nil
-}
-
-// page retrieves a page with a given key.
-func (c *Cursor) page(key []byte, flags int) (*page, error) {
-	p := c.pages[c.top]
-
-	for {
-		// Find the page index.
-		var index indx
-		if (flags & ps_first) != 0 {
-			index = 0
-		} else if (flags & ps_last) != 0 {
-			index = indx(p.numkeys()) - 1
-		} else {
-			node, i, exact := p.find(key, c.transaction.db.pageSize)
-			if exact {
-				c.indices[c.top] = i
-			}
-			if node == nil {
-				index = indx(p.numkeys()) - 1
-			} else {
-				index = indx(c.indices[c.top])
-				if !exact {
-					index -= 1
-				}
-			}
-		}
-
-		// Find the node index.
-		node := p.node(index)
-
-		// Traverse to next page.
-		p = c.transaction.db.page(c.transaction.db.data, int(node.pgno()))
-		c.indices[c.top] = int(index)
-		c.push(p)
-
-		// TODO:
-		// if (flags & MDB_PS_MODIFY) {
-		// if ((rc = mdb_page_touch(mc)) != 0)
-		//   return rc;
-		// mp = mc->mc_pg[mc->mc_top];
-		// }
-	}
-
-	// If we ended up with a non-leaf page by the end then something is wrong.
-	if p.flags&p_leaf == 0 {
-		return nil, CorruptedError
-	}
-
-	// TODO: mc->mc_flags |= C_INITIALIZED;
-	// TODO: mc->mc_flags &= ~C_EOF;
-
-	return p, nil
-}
-
-// pop moves the last page off the cursor's page stack.
-func (c *Cursor) pop() {
-	top := len(c.pages) - 1
-	c.pages = c.pages[0:c.top]
-	c.indices = c.indices[0:c.top]
-}
-
-// push moves a page onto the top of the cursor's page stack.
-func (c *Cursor) push(p *page) {
-	c.pages = append(c.pages, p)
-	c.indices = append(c.indices, 0)
-	c.top = len(c.pages) - 1
-}
-
-// currentPage retrieves the last page on the page stack.
-func (c *Cursor) currentPage() *page {
-	top := len(c.pages)
-	if top > 0 {
-		return c.pages[top]
-	}
-	return nil
-}
-
-// branchNode retrieves the branch node pointed to on the current page.
-func (c *Cursor) currentBranchNode() *page {
-	top := len(c.pages)
-	if top > 0 {
-		return c.pages[top].branchNode(c.indices[top])
-	}
-	return nil
-}
-
-// lnode retrieves the leaf node pointed to on the current page.
-func (c *Cursor) currentLeafNode() *node {
-	top := len(c.pages)
-	if top > 0 {
-		return c.pages[top].leaf(c.indices[top])
-	}
-	return nil
-}
-
-//                                                                            //
-//                                                                            //
-//                                                                            //
-//                                                                            //
-//                                                                            //
-// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONVERTED ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ //
-//                                                                            //
-//                                                                            //
-//                                                                            //
-//                                                                            //
-//                                                                            //
-
-// Set or clear P_KEEP in dirty, non-overflow, non-sub pages watched by txn.
-// @param[in] mc A cursor handle for the current operation.
-// @param[in] pflags Flags of the pages to update:
-// P_DIRTY to set P_KEEP, P_DIRTY|P_KEEP to clear it.
-// @param[in] all No shortcuts. Needed except after a full #mdb_page_flush().
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) xkeep(pflags int, all int) error {
-	/*
-		enum { Mask = P_SUBP|P_DIRTY|P_KEEP };
-		MDB_txn *txn = mc->mc_txn;
-		MDB_cursor *m3;
-		MDB_xcursor *mx;
-		MDB_page *dp, *mp;
-		MDB_node *leaf;
-		unsigned i, j;
-		int rc = MDB_SUCCESS, level;
-
-		// Mark pages seen by cursors
-		if (mc->mc_flags & C_UNTRACK)
-			mc = NULL;				// will find mc in mt_cursors
-		for (i = txn->mt_numdbs;; mc = txn->mt_cursors[--i]) {
-			for (; mc; mc=mc->mc_next) {
-				if (!(mc->mc_flags & C_INITIALIZED))
-					continue;
-				for (m3 = mc;; m3 = &mx->mx_cursor) {
-					mp = NULL;
-					for (j=0; j<m3->mc_snum; j++) {
-						mp = m3->mc_pg[j];
-						if ((mp->mp_flags & Mask) == pflags)
-							mp->mp_flags ^= P_KEEP;
-					}
-					mx = m3->mc_xcursor;
-					// Proceed to mx if it is at a sub-database
-					if (! (mx && (mx->mx_cursor.mc_flags & C_INITIALIZED)))
-						break;
-					if (! (mp && (mp->mp_flags & P_LEAF)))
-						break;
-					leaf = NODEPTR(mp, m3->mc_ki[j-1]);
-					if (!(leaf->mn_flags & F_SUBDATA))
-						break;
-				}
-			}
-			if (i == 0)
-				break;
-		}
-
-		if (all) {
-			// Mark dirty root pages
-			for (i=0; i<txn->mt_numdbs; i++) {
-				if (txn->mt_dbflags[i] & DB_DIRTY) {
-					pgno_t pgno = txn->mt_dbs[i].md_root;
-					if (pgno == P_INVALID)
-						continue;
-					if ((rc = mdb_page_get(txn, pgno, &dp, &level)) != MDB_SUCCESS)
-						break;
-					if ((dp->mp_flags & Mask) == pflags && level <= 1)
-						dp->mp_flags ^= P_KEEP;
-				}
-			}
-		}
-
-		return rc;
-	*/
-	return nil
-}
-
-//	Spill pages from the dirty list back to disk.
-// This is intended to prevent running into #MDB_TXN_FULL situations,
-// but note that they may still occur in a few cases:
-//	1) our estimate of the txn size could be too small. Currently this
-//	 seems unlikely, except with a large number of #MDB_MULTIPLE items.
-//	2) child txns may run out of space if their parents dirtied a
-//	 lot of pages and never spilled them. TODO: we probably should do
-//	 a preemptive spill during #mdb_txn_begin() of a child txn, if
-//	 the parent's dirty_room is below a given threshold.
-//
-// Otherwise, if not using nested txns, it is expected that apps will
-// not run into #MDB_TXN_FULL any more. The pages are flushed to disk
-// the same way as for a txn commit, e.g. their P_DIRTY flag is cleared.
-// If the txn never references them again, they can be left alone.
-// If the txn only reads them, they can be used without any fuss.
-// If the txn writes them again, they can be dirtied immediately without
-// going thru all of the work of #mdb_page_touch(). Such references are
-// handled by #mdb_page_unspill().
-//
-// Also note, we never spill DB root pages, nor pages of active cursors,
-// because we'll need these back again soon anyway. And in nested txns,
-// we can't spill a page in a child txn if it was already spilled in a
-// parent txn. That would alter the parent txns' data even though
-// the child hasn't committed yet, and we'd have no way to undo it if
-// the child aborted.
-//
-// @param[in] m0 cursor A cursor handle identifying the transaction and
-//	database for which we are checking space.
-// @param[in] key For a put operation, the key being stored.
-// @param[in] data For a put operation, the data being stored.
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) spill(key []byte, data []byte) error {
-	/*
-			MDB_txn *txn = m0->mc_txn;
-			MDB_page *dp;
-			MDB_ID2L dl = txn->mt_u.dirty_list;
-			unsigned int i, j, need;
-			int rc;
-
-			if (m0->mc_flags & C_SUB)
-				return MDB_SUCCESS;
-
-			// Estimate how much space this op will take
-			i = m0->mc_db->md_depth;
-			// Named DBs also dirty the main DB
-			if (m0->mc_dbi > MAIN_DBI)
-				i += txn->mt_dbs[MAIN_DBI].md_depth;
-			// For puts, roughly factor in the key+data size
-			if (key)
-				i += (LEAFSIZE(key, data) + txn->mt_env->me_psize) / txn->mt_env->me_psize;
-			i += i;	// double it for good measure
-			need = i;
-
-			if (txn->mt_dirty_room > i)
-				return MDB_SUCCESS;
-
-			if (!txn->mt_spill_pgs) {
-				txn->mt_spill_pgs = mdb_midl_alloc(MDB_IDL_UM_MAX);
-				if (!txn->mt_spill_pgs)
-					return ENOMEM;
-			} else {
-				// purge deleted slots
-				MDB_IDL sl = txn->mt_spill_pgs;
-				unsigned int num = sl[0];
-				j=0;
-				for (i=1; i<=num; i++) {
-					if (!(sl[i] & 1))
-						sl[++j] = sl[i];
-				}
-				sl[0] = j;
-			}
-
-			// Preserve pages which may soon be dirtied again
-			if ((rc = mdb_pages_xkeep(m0, P_DIRTY, 1)) != MDB_SUCCESS)
-				goto done;
-
-			// Less aggressive spill - we originally spilled the entire dirty list,
-			// with a few exceptions for cursor pages and DB root pages. But this
-			// turns out to be a lot of wasted effort because in a large txn many
-			// of those pages will need to be used again. So now we spill only 1/8th
-			// of the dirty pages. Testing revealed this to be a good tradeoff,
-			// better than 1/2, 1/4, or 1/10.
-			if (need < MDB_IDL_UM_MAX / 8)
-				need = MDB_IDL_UM_MAX / 8;
-
-			// Save the page IDs of all the pages we're flushing
-			// flush from the tail forward, this saves a lot of shifting later on.
-			for (i=dl[0].mid; i && need; i--) {
-				MDB_ID pn = dl[i].mid << 1;
-				dp = dl[i].mptr;
-				if (dp->mp_flags & P_KEEP)
-					continue;
-				// Can't spill twice, make sure it's not already in a parent's
-				// spill list.
-				if (txn->mt_parent) {
-					MDB_txn *tx2;
-					for (tx2 = txn->mt_parent; tx2; tx2 = tx2->mt_parent) {
-						if (tx2->mt_spill_pgs) {
-							j = mdb_midl_search(tx2->mt_spill_pgs, pn);
-							if (j <= tx2->mt_spill_pgs[0] && tx2->mt_spill_pgs[j] == pn) {
-								dp->mp_flags |= P_KEEP;
-								break;
-							}
-						}
-					}
-					if (tx2)
-						continue;
-				}
-				if ((rc = mdb_midl_append(&txn->mt_spill_pgs, pn)))
-					goto done;
-				need--;
-			}
-			mdb_midl_sort(txn->mt_spill_pgs);
-
-			// Flush the spilled part of dirty list
-			if ((rc = mdb_page_flush(txn, i)) != MDB_SUCCESS)
-				goto done;
-
-			// Reset any dirty pages we kept that page_flush didn't see
-			rc = mdb_pages_xkeep(m0, P_DIRTY|P_KEEP, i);
-
-		done:
-			txn->mt_flags |= rc ? MDB_TXN_ERROR : MDB_TXN_SPILLS;
-			return rc;
-			return 0
-		}
-	*/
-	return nil
-}
-
-// Copy the used portions of a non-overflow page.
-// @param[in] dst page to copy into
-// @param[in] src page to copy from
-// @param[in] psize size of a page
-func (p *page) copyTo(dst *page, size int) {
-	/*
-		enum { Align = sizeof(pgno_t) };
-		indx_t upper = src->mp_upper, lower = src->mp_lower, unused = upper-lower;
-
-		// If page isn't full, just copy the used portion. Adjust
-		// alignment so memcpy may copy words instead of bytes.
-		if ((unused &= -Align) && !IS_LEAF2(src)) {
-			upper &= -Align;
-			memcpy(dst, src, (lower + (Align-1)) & -Align);
-			memcpy((pgno_t *)((char *)dst+upper), (pgno_t *)((char *)src+upper),
-				psize - upper);
-		} else {
-			memcpy(dst, src, psize - unused);
-		}
-	*/
-}
-
-// Touch a page: make it dirty and re-insert into tree with updated pgno.
-// @param[in] mc cursor pointing to the page to be touched
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) page_touch() int {
-	/*
-			MDB_page *mp = mc->mc_pg[mc->mc_top], *np;
-			MDB_txn *txn = mc->mc_txn;
-			MDB_cursor *m2, *m3;
-			pgno_t	pgno;
-			int rc;
-
-			if (!F_ISSET(mp->mp_flags, P_DIRTY)) {
-				if (txn->mt_flags & MDB_TXN_SPILLS) {
-					np = NULL;
-					rc = mdb_page_unspill(txn, mp, &np);
-					if (rc)
-						goto fail;
-					if (np)
-						goto done;
-				}
-				if ((rc = mdb_midl_need(&txn->mt_free_pgs, 1)) ||
-					(rc = mdb_page_alloc(mc, 1, &np)))
-					goto fail;
-				pgno = np->mp_pgno;
-				DPRINTF(("touched db %d page %"Z"u -> %"Z"u", DDBI(mc),
-					mp->mp_pgno, pgno));
-				mdb_cassert(mc, mp->mp_pgno != pgno);
-				mdb_midl_xappend(txn->mt_free_pgs, mp->mp_pgno);
-				// Update the parent page, if any, to point to the new page
-				if (mc->mc_top) {
-					MDB_page *parent = mc->mc_pg[mc->mc_top-1];
-					MDB_node *node = NODEPTR(parent, mc->mc_ki[mc->mc_top-1]);
-					SETPGNO(node, pgno);
-				} else {
-					mc->mc_db->md_root = pgno;
-				}
-			} else if (txn->mt_parent && !IS_SUBP(mp)) {
-				MDB_ID2 mid, *dl = txn->mt_u.dirty_list;
-				pgno = mp->mp_pgno;
-				// If txn has a parent, make sure the page is in our
-				// dirty list.
-				if (dl[0].mid) {
-					unsigned x = mdb_mid2l_search(dl, pgno);
-					if (x <= dl[0].mid && dl[x].mid == pgno) {
-						if (mp != dl[x].mptr) { // bad cursor?
-							mc->mc_flags &= ~(C_INITIALIZED|C_EOF);
-							txn->mt_flags |= MDB_TXN_ERROR;
-							return MDB_CORRUPTED;
-						}
-						return 0;
-					}
-				}
-				mdb_cassert(mc, dl[0].mid < MDB_IDL_UM_MAX);
-				// No - copy it
-				np = mdb_page_malloc(txn, 1);
-				if (!np)
-					return ENOMEM;
-				mid.mid = pgno;
-				mid.mptr = np;
-				rc = mdb_mid2l_insert(dl, &mid);
-				mdb_cassert(mc, rc == 0);
-			} else {
-				return 0;
-			}
-
-			mdb_page_copy(np, mp, txn->mt_env->me_psize);
-			np->mp_pgno = pgno;
-			np->mp_flags |= P_DIRTY;
-
-		done:
-			// Adjust cursors pointing to mp
-			mc->mc_pg[mc->mc_top] = np;
-			m2 = txn->mt_cursors[mc->mc_dbi];
-			if (mc->mc_flags & C_SUB) {
-				for (; m2; m2=m2->mc_next) {
-					m3 = &m2->mc_xcursor->mx_cursor;
-					if (m3->mc_snum < mc->mc_snum) continue;
-					if (m3->mc_pg[mc->mc_top] == mp)
-						m3->mc_pg[mc->mc_top] = np;
-				}
-			} else {
-				for (; m2; m2=m2->mc_next) {
-					if (m2->mc_snum < mc->mc_snum) continue;
-					if (m2->mc_pg[mc->mc_top] == mp) {
-						m2->mc_pg[mc->mc_top] = np;
-						if ((mc->mc_db->md_flags & MDB_DUPSORT) &&
-							m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top])
-						{
-							MDB_node *leaf = NODEPTR(np, mc->mc_ki[mc->mc_top]);
-							if (!(leaf->mn_flags & F_SUBDATA))
-								m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-						}
-					}
-				}
-			}
-			return 0;
-
-		fail:
-			txn->mt_flags |= MDB_TXN_ERROR;
-			return rc;
-	*/
-
-	return 0
-}
-
-// Search for the lowest key under the current branch page.
-// This just bypasses a NUMKEYS check in the current page
-// before calling mdb_page_search_root(), because the callers
-// are all in situations where the current page is known to
-// be underfilled.
-func (c *Cursor) searchLowest() error {
-	/*
-		MDB_page	*mp = mc->mc_pg[mc->mc_top];
-		MDB_node	*node = NODEPTR(mp, 0);
-		int rc;
-
-		if ((rc = mdb_page_get(mc->mc_txn, NODEPGNO(node), &mp, NULL)) != 0)
-			return rc;
-
-		mc->mc_ki[mc->mc_top] = 0;
-		if ((rc = mdb_cursor_push(mc, mp)))
-			return rc;
-		return mdb_page_search_root(mc, NULL, MDB_PS_FIRST);
-	*/
-	return nil
-}
-
-func (c *Cursor) freeOverflowPage(p *page) error {
-	/*
-			MDB_txn *txn = mc->mc_txn;
-			pgno_t pg = mp->mp_pgno;
-			unsigned x = 0, ovpages = mp->mp_pages;
-			MDB_env *env = txn->mt_env;
-			MDB_IDL sl = txn->mt_spill_pgs;
-			MDB_ID pn = pg << 1;
-			int rc;
-
-			DPRINTF(("free ov page %"Z"u (%d)", pg, ovpages));
-			// If the page is dirty or on the spill list we just acquired it,
-			// so we should give it back to our current free list, if any.
-			// Otherwise put it onto the list of pages we freed in this txn.
-			//
-			// Won't create me_pghead: me_pglast must be inited along with it.
-			// Unsupported in nested txns: They would need to hide the page
-			// range in ancestor txns' dirty and spilled lists.
-			if (env->me_pghead &&
-				!txn->mt_parent &&
-				((mp->mp_flags & P_DIRTY) ||
-				 (sl && (x = mdb_midl_search(sl, pn)) <= sl[0] && sl[x] == pn)))
-			{
-				unsigned i, j;
-				pgno_t *mop;
-				MDB_ID2 *dl, ix, iy;
-				rc = mdb_midl_need(&env->me_pghead, ovpages);
-				if (rc)
-					return rc;
-				if (!(mp->mp_flags & P_DIRTY)) {
-					// This page is no longer spilled
-					if (x == sl[0])
-						sl[0]--;
-					else
-						sl[x] |= 1;
-					goto release;
-				}
-				// Remove from dirty list
-				dl = txn->mt_u.dirty_list;
-				x = dl[0].mid--;
-				for (ix = dl[x]; ix.mptr != mp; ix = iy) {
-					if (x > 1) {
-						x--;
-						iy = dl[x];
-						dl[x] = ix;
-					} else {
-						mdb_cassert(mc, x > 1);
-						j = ++(dl[0].mid);
-						dl[j] = ix;		// Unsorted. OK when MDB_TXN_ERROR.
-						txn->mt_flags |= MDB_TXN_ERROR;
-						return MDB_CORRUPTED;
-					}
-				}
-				if (!(env->me_flags & MDB_WRITEMAP))
-					mdb_dpage_free(env, mp);
-		release:
-				// Insert in me_pghead
-				mop = env->me_pghead;
-				j = mop[0] + ovpages;
-				for (i = mop[0]; i && mop[i] < pg; i--)
-					mop[j--] = mop[i];
-				while (j>i)
-					mop[j--] = pg++;
-				mop[0] += ovpages;
-			} else {
-				rc = mdb_midl_append_range(&txn->mt_free_pgs, pg, ovpages);
-				if (rc)
-					return rc;
-			}
-			mc->mc_db->md_overflow_pages -= ovpages;
-			return 0;
-	*/
-	return nil
-}
-
-// Find a sibling for a page.
-// Replaces the page at the top of the cursor's stack with the
-// specified sibling, if one exists.
-// @param[in] mc The cursor for this operation.
-// @param[in] move_right Non-zero if the right sibling is requested,
-// otherwise the left sibling.
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) sibling(moveRight bool) error {
-	/*
-		int		 rc;
-		MDB_node	*indx;
-		MDB_page	*mp;
-
-		if (mc->mc_snum < 2) {
-			return MDB_NOTFOUND;		// root has no siblings
-		}
-
-		mdb_cursor_pop(mc);
-		DPRINTF(("parent page is page %"Z"u, index %u",
-			mc->mc_pg[mc->mc_top]->mp_pgno, mc->mc_ki[mc->mc_top]));
-
-		if (move_right ? (mc->mc_ki[mc->mc_top] + 1u >= NUMKEYS(mc->mc_pg[mc->mc_top]))
-			       : (mc->mc_ki[mc->mc_top] == 0)) {
-			DPRINTF(("no more keys left, moving to %s sibling",
-			    move_right ? "right" : "left"));
-			if ((rc = mdb_cursor_sibling(mc, move_right)) != MDB_SUCCESS) {
-				// undo cursor_pop before returning
-				mc->mc_top++;
-				mc->mc_snum++;
-				return rc;
-			}
-		} else {
-			if (move_right)
-				mc->mc_ki[mc->mc_top]++;
-			else
-				mc->mc_ki[mc->mc_top]--;
-			DPRINTF(("just moving to %s index key %u",
-			    move_right ? "right" : "left", mc->mc_ki[mc->mc_top]));
-		}
-		mdb_cassert(mc, IS_BRANCH(mc->mc_pg[mc->mc_top]));
-
-		indx = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
-		if ((rc = mdb_page_get(mc->mc_txn, NODEPGNO(indx), &mp, NULL)) != 0) {
-			// mc will be inconsistent if caller does mc_snum++ as above
-			mc->mc_flags &= ~(C_INITIALIZED|C_EOF);
-			return rc;
-		}
-
-		mdb_cursor_push(mc, mp);
-		if (!move_right)
-			mc->mc_ki[mc->mc_top] = NUMKEYS(mp)-1;
-
-		return MDB_SUCCESS;
-	*/
-	return nil
-}
-
-// Move the cursor to the next data item.
-func (c *Cursor) Next(key []byte, data []byte, op int) error {
-	/*
-			MDB_page	*mp;
-			MDB_node	*leaf;
-			int rc;
-
-			if (mc->mc_flags & C_EOF) {
-				return MDB_NOTFOUND;
-			}
-
-			mdb_cassert(mc, mc->mc_flags & C_INITIALIZED);
-
-			mp = mc->mc_pg[mc->mc_top];
-
-			if (mc->mc_db->md_flags & MDB_DUPSORT) {
-				leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-				if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-					if (op == MDB_NEXT || op == MDB_NEXT_DUP) {
-						rc = mdb_cursor_next(&mc->mc_xcursor->mx_cursor, data, NULL, MDB_NEXT);
-						if (op != MDB_NEXT || rc != MDB_NOTFOUND) {
-							if (rc == MDB_SUCCESS)
-								MDB_GET_KEY(leaf, key);
-							return rc;
-						}
-					}
-				} else {
-					mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
-					if (op == MDB_NEXT_DUP)
-						return MDB_NOTFOUND;
-				}
-			}
-
-			DPRINTF(("cursor_next: top page is %"Z"u in cursor %p",
-				mdb_dbg_pgno(mp), (void *) mc));
-			if (mc->mc_flags & C_DEL)
-				goto skip;
-
-			if (mc->mc_ki[mc->mc_top] + 1u >= NUMKEYS(mp)) {
-				DPUTS("=====> move to next sibling page");
-				if ((rc = mdb_cursor_sibling(mc, 1)) != MDB_SUCCESS) {
-					mc->mc_flags |= C_EOF;
-					return rc;
-				}
-				mp = mc->mc_pg[mc->mc_top];
-				DPRINTF(("next page is %"Z"u, key index %u", mp->mp_pgno, mc->mc_ki[mc->mc_top]));
-			} else
-				mc->mc_ki[mc->mc_top]++;
-
-		skip:
-			DPRINTF(("==> cursor points to page %"Z"u with %u keys, key index %u",
-			    mdb_dbg_pgno(mp), NUMKEYS(mp), mc->mc_ki[mc->mc_top]));
-
-			if (IS_LEAF2(mp)) {
-				key->mv_size = mc->mc_db->md_pad;
-				key->mv_data = LEAF2KEY(mp, mc->mc_ki[mc->mc_top], key->mv_size);
-				return MDB_SUCCESS;
-			}
-
-			mdb_cassert(mc, IS_LEAF(mp));
-			leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-
-			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				mdb_xcursor_init1(mc, leaf);
-			}
-			if (data) {
-				if ((rc = mdb_node_read(mc->mc_txn, leaf, data)) != MDB_SUCCESS)
-					return rc;
-
-				if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-					rc = mdb_cursor_first(&mc->mc_xcursor->mx_cursor, data, NULL);
-					if (rc != MDB_SUCCESS)
-						return rc;
-				}
-			}
-
-			MDB_GET_KEY(leaf, key);
-			return MDB_SUCCESS;
-	*/
-	return nil
-}
-
-// Move the cursor to the previous data item.
-func (c *Cursor) prev(key []byte, data []byte, op int) error {
-	/*
-		MDB_page	*mp;
-		MDB_node	*leaf;
-		int rc;
-
-		mdb_cassert(mc, mc->mc_flags & C_INITIALIZED);
-
-		mp = mc->mc_pg[mc->mc_top];
-
-		if (mc->mc_db->md_flags & MDB_DUPSORT) {
-			leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				if (op == MDB_PREV || op == MDB_PREV_DUP) {
-					rc = mdb_cursor_prev(&mc->mc_xcursor->mx_cursor, data, NULL, MDB_PREV);
-					if (op != MDB_PREV || rc != MDB_NOTFOUND) {
-						if (rc == MDB_SUCCESS)
-							MDB_GET_KEY(leaf, key);
-						return rc;
-					}
-				} else {
-					mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
-					if (op == MDB_PREV_DUP)
-						return MDB_NOTFOUND;
-				}
-			}
-		}
-
-		DPRINTF(("cursor_prev: top page is %"Z"u in cursor %p",
-			mdb_dbg_pgno(mp), (void *) mc));
-
-		if (mc->mc_ki[mc->mc_top] == 0)  {
-			DPUTS("=====> move to prev sibling page");
-			if ((rc = mdb_cursor_sibling(mc, 0)) != MDB_SUCCESS) {
-				return rc;
-			}
-			mp = mc->mc_pg[mc->mc_top];
-			mc->mc_ki[mc->mc_top] = NUMKEYS(mp) - 1;
-			DPRINTF(("prev page is %"Z"u, key index %u", mp->mp_pgno, mc->mc_ki[mc->mc_top]));
-		} else
-			mc->mc_ki[mc->mc_top]--;
-
-		mc->mc_flags &= ~C_EOF;
-
-		DPRINTF(("==> cursor points to page %"Z"u with %u keys, key index %u",
-		    mdb_dbg_pgno(mp), NUMKEYS(mp), mc->mc_ki[mc->mc_top]));
-
-		if (IS_LEAF2(mp)) {
-			key->mv_size = mc->mc_db->md_pad;
-			key->mv_data = LEAF2KEY(mp, mc->mc_ki[mc->mc_top], key->mv_size);
-			return MDB_SUCCESS;
-		}
-
-		mdb_cassert(mc, IS_LEAF(mp));
-		leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-
-		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-			mdb_xcursor_init1(mc, leaf);
-		}
-		if (data) {
-			if ((rc = mdb_node_read(mc->mc_txn, leaf, data)) != MDB_SUCCESS)
-				return rc;
-
-			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				rc = mdb_cursor_last(&mc->mc_xcursor->mx_cursor, data, NULL);
-				if (rc != MDB_SUCCESS)
-					return rc;
-			}
-		}
-
-		MDB_GET_KEY(leaf, key);
-		return MDB_SUCCESS;
-	*/
-	return nil
-}
-
-// Set the cursor on a specific data item.
-// (bool return is whether it is exact).
-func (c *Cursor) set(key []byte, data []byte, op int) (error, bool) {
-	/*
-			int		 rc;
-			MDB_page	*mp;
-			MDB_node	*leaf = NULL;
-			DKBUF;
-
-			if (key->mv_size == 0)
-				return MDB_BAD_VALSIZE;
-
-			if (mc->mc_xcursor)
-				mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
-
-			// See if we're already on the right page
-			if (mc->mc_flags & C_INITIALIZED) {
-				MDB_val nodekey;
-
-				mp = mc->mc_pg[mc->mc_top];
-				if (!NUMKEYS(mp)) {
-					mc->mc_ki[mc->mc_top] = 0;
-					return MDB_NOTFOUND;
-				}
-				if (mp->mp_flags & P_LEAF2) {
-					nodekey.mv_size = mc->mc_db->md_pad;
-					nodekey.mv_data = LEAF2KEY(mp, 0, nodekey.mv_size);
-				} else {
-					leaf = NODEPTR(mp, 0);
-					MDB_GET_KEY2(leaf, nodekey);
-				}
-				rc = mc->mc_dbx->md_cmp(key, &nodekey);
-				if (rc == 0) {
-					// Probably happens rarely, but first node on the page
-					// was the one we wanted.
-					mc->mc_ki[mc->mc_top] = 0;
-					if (exactp)
-						*exactp = 1;
-					goto set1;
-				}
-				if (rc > 0) {
-					unsigned int i;
-					unsigned int nkeys = NUMKEYS(mp);
-					if (nkeys > 1) {
-						if (mp->mp_flags & P_LEAF2) {
-							nodekey.mv_data = LEAF2KEY(mp,
-								 nkeys-1, nodekey.mv_size);
-						} else {
-							leaf = NODEPTR(mp, nkeys-1);
-							MDB_GET_KEY2(leaf, nodekey);
-						}
-						rc = mc->mc_dbx->md_cmp(key, &nodekey);
-						if (rc == 0) {
-							// last node was the one we wanted
-							mc->mc_ki[mc->mc_top] = nkeys-1;
-							if (exactp)
-								*exactp = 1;
-							goto set1;
-						}
-						if (rc < 0) {
-							if (mc->mc_ki[mc->mc_top] < NUMKEYS(mp)) {
-								// This is definitely the right page, skip search_page 
-								if (mp->mp_flags & P_LEAF2) {
-									nodekey.mv_data = LEAF2KEY(mp,
-										 mc->mc_ki[mc->mc_top], nodekey.mv_size);
-								} else {
-									leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-									MDB_GET_KEY2(leaf, nodekey);
-								}
-								rc = mc->mc_dbx->md_cmp(key, &nodekey);
-								if (rc == 0) {
-									// current node was the one we wanted
-									if (exactp)
-										*exactp = 1;
-									goto set1;
-								}
-							}
-							rc = 0;
-							goto set2;
-						}
-					}
-					// If any parents have right-sibs, search.
-					// Otherwise, there's nothing further.
-					for (i=0; i<mc->mc_top; i++)
-						if (mc->mc_ki[i] <
-							NUMKEYS(mc->mc_pg[i])-1)
-							break;
-					if (i == mc->mc_top) {
-						// There are no other pages
-						mc->mc_ki[mc->mc_top] = nkeys;
-						return MDB_NOTFOUND;
-					}
-				}
-				if (!mc->mc_top) {
-					// There are no other pages
-					mc->mc_ki[mc->mc_top] = 0;
-					if (op == MDB_SET_RANGE) {
-						rc = 0;
-						goto set1;
-					} else
-						return MDB_NOTFOUND;
-				}
-			}
-
-			rc = mdb_page_search(mc, key, 0);
-			if (rc != MDB_SUCCESS)
-				return rc;
-
-			mp = mc->mc_pg[mc->mc_top];
-			mdb_cassert(mc, IS_LEAF(mp));
-
-		set2:
-			leaf = mdb_node_search(mc, key, exactp);
-			if (exactp != NULL && !*exactp) {
-				// MDB_SET specified and not an exact match.
-				return MDB_NOTFOUND;
-			}
-
-			if (leaf == NULL) {
-				DPUTS("===> inexact leaf not found, goto sibling");
-				if ((rc = mdb_cursor_sibling(mc, 1)) != MDB_SUCCESS)
-					return rc;		// no entries matched
-				mp = mc->mc_pg[mc->mc_top];
-				mdb_cassert(mc, IS_LEAF(mp));
-				leaf = NODEPTR(mp, 0);
-			}
-
-		set1:
-			mc->mc_flags |= C_INITIALIZED;
-			mc->mc_flags &= ~C_EOF;
-
-			if (IS_LEAF2(mp)) {
-				key->mv_size = mc->mc_db->md_pad;
-				key->mv_data = LEAF2KEY(mp, mc->mc_ki[mc->mc_top], key->mv_size);
-				return MDB_SUCCESS;
-			}
-
-			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				mdb_xcursor_init1(mc, leaf);
-			}
-			if (data) {
-				if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-					if (op == MDB_SET || op == MDB_SET_KEY || op == MDB_SET_RANGE) {
-						rc = mdb_cursor_first(&mc->mc_xcursor->mx_cursor, data, NULL);
-					} else {
-						int ex2, *ex2p;
-						if (op == MDB_GET_BOTH) {
-							ex2p = &ex2;
-							ex2 = 0;
-						} else {
-							ex2p = NULL;
-						}
-						rc = mdb_cursor_set(&mc->mc_xcursor->mx_cursor, data, NULL, MDB_SET_RANGE, ex2p);
-						if (rc != MDB_SUCCESS)
-							return rc;
-					}
-				} else if (op == MDB_GET_BOTH || op == MDB_GET_BOTH_RANGE) {
-					MDB_val d2;
-					if ((rc = mdb_node_read(mc->mc_txn, leaf, &d2)) != MDB_SUCCESS)
-						return rc;
-					rc = mc->mc_dbx->md_dcmp(data, &d2);
-					if (rc) {
-						if (op == MDB_GET_BOTH || rc > 0)
-							return MDB_NOTFOUND;
-						rc = 0;
-						*data = d2;
-					}
-
-				} else {
-					if (mc->mc_xcursor)
-						mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
-					if ((rc = mdb_node_read(mc->mc_txn, leaf, data)) != MDB_SUCCESS)
-						return rc;
-				}
-			}
-
-			// The key already matches in all other cases
-			if (op == MDB_SET_RANGE || op == MDB_SET_KEY)
-				MDB_GET_KEY(leaf, key);
-			DPRINTF(("==> cursor placed on key [%s]", DKEY(key)));
-
-			return rc;
-	*/
-
-	return nil, false
-}
-
-// Move the cursor to the first item in the database.
-func (c *Cursor) first(key []byte, data []byte) error {
-	/*
-		int		 rc;
-		MDB_node	*leaf;
-
-		if (mc->mc_xcursor)
-			mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
-
-		if (!(mc->mc_flags & C_INITIALIZED) || mc->mc_top) {
-			rc = mdb_page_search(mc, NULL, MDB_PS_FIRST);
-			if (rc != MDB_SUCCESS)
-				return rc;
-		}
-		mdb_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top]));
-
-		leaf = NODEPTR(mc->mc_pg[mc->mc_top], 0);
-		mc->mc_flags |= C_INITIALIZED;
-		mc->mc_flags &= ~C_EOF;
-
-		mc->mc_ki[mc->mc_top] = 0;
-
-		if (IS_LEAF2(mc->mc_pg[mc->mc_top])) {
-			key->mv_size = mc->mc_db->md_pad;
-			key->mv_data = LEAF2KEY(mc->mc_pg[mc->mc_top], 0, key->mv_size);
-			return MDB_SUCCESS;
-		}
-
-		if (data) {
-			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				mdb_xcursor_init1(mc, leaf);
-				rc = mdb_cursor_first(&mc->mc_xcursor->mx_cursor, data, NULL);
-				if (rc)
-					return rc;
-			} else {
-				if ((rc = mdb_node_read(mc->mc_txn, leaf, data)) != MDB_SUCCESS)
-					return rc;
-			}
-		}
-		MDB_GET_KEY(leaf, key);
-		return MDB_SUCCESS;
-	*/
-	return nil
-}
-
-// Move the cursor to the last item in the database.
-func (c *Cursor) last() ([]byte, []byte) {
-	/*
-		int		 rc;
-		MDB_node	*leaf;
-
-		if (mc->mc_xcursor)
-			mc->mc_xcursor->mx_cursor.mc_flags &= ~(C_INITIALIZED|C_EOF);
-
-		if (!(mc->mc_flags & C_EOF)) {
-
-			if (!(mc->mc_flags & C_INITIALIZED) || mc->mc_top) {
-				rc = mdb_page_search(mc, NULL, MDB_PS_LAST);
-				if (rc != MDB_SUCCESS)
-					return rc;
-			}
-			mdb_cassert(mc, IS_LEAF(mc->mc_pg[mc->mc_top]));
-
-		}
-		mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]) - 1;
-		mc->mc_flags |= C_INITIALIZED|C_EOF;
-		leaf = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
-
-		if (IS_LEAF2(mc->mc_pg[mc->mc_top])) {
-			key->mv_size = mc->mc_db->md_pad;
-			key->mv_data = LEAF2KEY(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top], key->mv_size);
-			return MDB_SUCCESS;
-		}
-
-		if (data) {
-			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-				mdb_xcursor_init1(mc, leaf);
-				rc = mdb_cursor_last(&mc->mc_xcursor->mx_cursor, data, NULL);
-				if (rc)
-					return rc;
-			} else {
-				if ((rc = mdb_node_read(mc->mc_txn, leaf, data)) != MDB_SUCCESS)
-					return rc;
-			}
-		}
-
-		MDB_GET_KEY(leaf, key);
-		return MDB_SUCCESS;
-	*/
-	return nil, nil
+	stack       []stackelem
 }
 
-// Touch all the pages in the cursor stack. Set mc_top.
-//	Makes sure all the pages are writable, before attempting a write operation.
-// @param[in] mc The cursor to operate on.
-func (c *Cursor) touch() error {
-	/*
-			int rc = MDB_SUCCESS;
-
-			if (mc->mc_dbi > MAIN_DBI && !(*mc->mc_dbflag & DB_DIRTY)) {
-				MDB_cursor mc2;
-				MDB_xcursor mcx;
-				mdb_cursor_init(&mc2, mc->mc_txn, MAIN_DBI, &mcx);
-				rc = mdb_page_search(&mc2, &mc->mc_dbx->md_name, MDB_PS_MODIFY);
-				if (rc)
-					 return rc;
-				*mc->mc_dbflag |= DB_DIRTY;
-			}
-			mc->mc_top = 0;
-			if (mc->mc_snum) {
-				do {
-					rc = mdb_page_touch(mc);
-				} while (!rc && ++(mc->mc_top) < mc->mc_snum);
-				mc->mc_top = mc->mc_snum-1;
-			}
-			return rc;
-		}
-	*/
-	return nil
-}
-
-func (c *Cursor) Del(flags int) error {
-	/*
-		MDB_node	*leaf;
-		MDB_page	*mp;
-		int rc;
-
-		if (mc->mc_txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR))
-			return (mc->mc_txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
-
-		if (!(mc->mc_flags & C_INITIALIZED))
-			return EINVAL;
-
-		if (mc->mc_ki[mc->mc_top] >= NUMKEYS(mc->mc_pg[mc->mc_top]))
-			return MDB_NOTFOUND;
-
-		if (!(flags & MDB_NOSPILL) && (rc = mdb_page_spill(mc, NULL, NULL)))
-			return rc;
-
-		rc = mdb_cursor_touch(mc);
-		if (rc)
-			return rc;
-
-		mp = mc->mc_pg[mc->mc_top];
-		leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-
-		if (!IS_LEAF2(mp) && F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-			if (!(flags & MDB_NODUPDATA)) {
-				if (!F_ISSET(leaf->mn_flags, F_SUBDATA)) {
-					mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-				}
-				rc = mdb_cursor_del(&mc->mc_xcursor->mx_cursor, MDB_NOSPILL);
-				// If sub-DB still has entries, we're done
-				if (mc->mc_xcursor->mx_db.md_entries) {
-					if (leaf->mn_flags & F_SUBDATA) {
-						// update subDB info
-						void *db = NODEDATA(leaf);
-						memcpy(db, &mc->mc_xcursor->mx_db, sizeof(MDB_db));
-					} else {
-						MDB_cursor *m2;
-						// shrink fake page
-						mdb_node_shrink(mp, mc->mc_ki[mc->mc_top]);
-						leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-						mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-						// fix other sub-DB cursors pointed at this fake page
-						for (m2 = mc->mc_txn->mt_cursors[mc->mc_dbi]; m2; m2=m2->mc_next) {
-							if (m2 == mc || m2->mc_snum < mc->mc_snum) continue;
-							if (m2->mc_pg[mc->mc_top] == mp &&
-								m2->mc_ki[mc->mc_top] == mc->mc_ki[mc->mc_top])
-								m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
-						}
-					}
-					mc->mc_db->md_entries--;
-					mc->mc_flags |= C_DEL;
-					return rc;
-				}
-				// otherwise fall thru and delete the sub-DB
-			}
-
-			if (leaf->mn_flags & F_SUBDATA) {
-				// add all the child DB's pages to the free list
-				rc = mdb_drop0(&mc->mc_xcursor->mx_cursor, 0);
-				if (rc == MDB_SUCCESS) {
-					mc->mc_db->md_entries -=
-						mc->mc_xcursor->mx_db.md_entries;
-				}
-			}
-		}
-
-		return mdb_cursor_del0(mc, leaf);
-	*/
-	return nil
-}
-
-// Add a node to the page pointed to by the cursor.
-// @param[in] mc The cursor for this operation.
-// @param[in] indx The index on the page where the new node should be added.
-// @param[in] key The key for the new node.
-// @param[in] data The data for the new node, if any.
-// @param[in] pgno The page number, if adding a branch node.
-// @param[in] flags Flags for the node.
-// @return 0 on success, non-zero on failure. Possible errors are:
-// <ul>
-//	<li>ENOMEM - failed to allocate overflow pages for the node.
-//	<li>MDB_PAGE_FULL - there is insufficient room in the page. This error
-//	should never happen since all callers already calculate the
-//	page's free space before calling this function.
-// </ul>
-func (c *Cursor) addNode(index int, key []byte, data []byte, pgno int, flags int) error {
-	/*
-			unsigned int	 i;
-			size_t		 node_size = NODESIZE;
-			ssize_t		 room;
-			indx_t		 ofs;
-			MDB_node	*node;
-			MDB_page	*mp = mc->mc_pg[mc->mc_top];
-			MDB_page	*ofp = NULL;		// overflow page
-			DKBUF;
-
-			mdb_cassert(mc, mp->mp_upper >= mp->mp_lower);
-
-			DPRINTF(("add to %s %spage %"Z"u index %i, data size %"Z"u key size %"Z"u [%s]",
-			    IS_LEAF(mp) ? "leaf" : "branch",
-				IS_SUBP(mp) ? "sub-" : "",
-				mdb_dbg_pgno(mp), indx, data ? data->mv_size : 0,
-				key ? key->mv_size : 0, key ? DKEY(key) : "null"));
-
-			if (IS_LEAF2(mp)) {
-				// Move higher keys up one slot.
-				int ksize = mc->mc_db->md_pad, dif;
-				char *ptr = LEAF2KEY(mp, indx, ksize);
-				dif = NUMKEYS(mp) - indx;
-				if (dif > 0)
-					memmove(ptr+ksize, ptr, dif*ksize);
-				// insert new key
-				memcpy(ptr, key->mv_data, ksize);
-
-				// Just using these for counting
-				mp->mp_lower += sizeof(indx_t);
-				mp->mp_upper -= ksize - sizeof(indx_t);
-				return MDB_SUCCESS;
-			}
-
-			room = (ssize_t)SIZELEFT(mp) - (ssize_t)sizeof(indx_t);
-			if (key != NULL)
-				node_size += key->mv_size;
-			if (IS_LEAF(mp)) {
-				mdb_cassert(mc, data);
-				if (F_ISSET(flags, F_BIGDATA)) {
-					// Data already on overflow page.
-					node_size += sizeof(pgno_t);
-				} else if (node_size + data->mv_size > mc->mc_txn->mt_env->me_nodemax) {
-					int ovpages = OVPAGES(data->mv_size, mc->mc_txn->mt_env->me_psize);
-					int rc;
-					// Put data on overflow page.
-					DPRINTF(("data size is %"Z"u, node would be %"Z"u, put data on overflow page",
-					    data->mv_size, node_size+data->mv_size));
-					node_size = EVEN(node_size + sizeof(pgno_t));
-					if ((ssize_t)node_size > room)
-						goto full;
-					if ((rc = mdb_page_new(mc, P_OVERFLOW, ovpages, &ofp)))
-						return rc;
-					DPRINTF(("allocated overflow page %"Z"u", ofp->mp_pgno));
-					flags |= F_BIGDATA;
-					goto update;
-				} else {
-					node_size += data->mv_size;
-				}
-			}
-			node_size = EVEN(node_size);
-			if ((ssize_t)node_size > room)
-				goto full;
-
-		update:
-			// Move higher pointers up one slot.
-			for (i = NUMKEYS(mp); i > indx; i--)
-				mp->mp_ptrs[i] = mp->mp_ptrs[i - 1];
-
-			// Adjust free space offsets.
-			ofs = mp->mp_upper - node_size;
-			mdb_cassert(mc, ofs >= mp->mp_lower + sizeof(indx_t));
-			mp->mp_ptrs[indx] = ofs;
-			mp->mp_upper = ofs;
-			mp->mp_lower += sizeof(indx_t);
-
-			// Write the node data.
-			node = NODEPTR(mp, indx);
-			node->mn_ksize = (key == NULL) ? 0 : key->mv_size;
-			node->mn_flags = flags;
-			if (IS_LEAF(mp))
-				SETDSZ(node,data->mv_size);
-			else
-				SETPGNO(node,pgno);
-
-			if (key)
-				memcpy(NODEKEY(node), key->mv_data, key->mv_size);
-
-			if (IS_LEAF(mp)) {
-				mdb_cassert(mc, key);
-				if (ofp == NULL) {
-					if (F_ISSET(flags, F_BIGDATA))
-						memcpy(node->mn_data + key->mv_size, data->mv_data,
-						    sizeof(pgno_t));
-					else if (F_ISSET(flags, MDB_RESERVE))
-						data->mv_data = node->mn_data + key->mv_size;
-					else
-						memcpy(node->mn_data + key->mv_size, data->mv_data,
-						    data->mv_size);
-				} else {
-					memcpy(node->mn_data + key->mv_size, &ofp->mp_pgno,
-					    sizeof(pgno_t));
-					if (F_ISSET(flags, MDB_RESERVE))
-						data->mv_data = METADATA(ofp);
-					else
-						memcpy(METADATA(ofp), data->mv_data, data->mv_size);
-				}
-			}
-
-			return MDB_SUCCESS;
-
-		full:
-			DPRINTF(("not enough room in page %"Z"u, got %u ptrs",
-				mdb_dbg_pgno(mp), NUMKEYS(mp)));
-			DPRINTF(("upper-lower = %u - %u = %"Z"d", mp->mp_upper,mp->mp_lower,room));
-			DPRINTF(("node size = %"Z"u", node_size));
-			mc->mc_txn->mt_flags |= MDB_TXN_ERROR;
-			return MDB_PAGE_FULL;
-	*/
-
-	return nil
-}
-
-// Delete the specified node from a page.
-// @param[in] mp The page to operate on.
-// @param[in] indx The index of the node to delete.
-// @param[in] ksize The size of a node. Only used if the page is
-// part of a #MDB_DUPFIXED database.
-func (c *Cursor) deleteNode(ksize int) {
-	/*
-		MDB_page *mp = mc->mc_pg[mc->mc_top];
-		indx_t	indx = mc->mc_ki[mc->mc_top];
-		unsigned int	 sz;
-		indx_t		 i, j, numkeys, ptr;
-		MDB_node	*node;
-		char		*base;
-
-		DPRINTF(("delete node %u on %s page %"Z"u", indx,
-		    IS_LEAF(mp) ? "leaf" : "branch", mdb_dbg_pgno(mp)));
-		numkeys = NUMKEYS(mp);
-		mdb_cassert(mc, indx < numkeys);
-
-		if (IS_LEAF2(mp)) {
-			int x = numkeys - 1 - indx;
-			base = LEAF2KEY(mp, indx, ksize);
-			if (x)
-				memmove(base, base + ksize, x * ksize);
-			mp->mp_lower -= sizeof(indx_t);
-			mp->mp_upper += ksize - sizeof(indx_t);
-			return;
-		}
-
-		node = NODEPTR(mp, indx);
-		sz = NODESIZE + node->mn_ksize;
-		if (IS_LEAF(mp)) {
-			if (F_ISSET(node->mn_flags, F_BIGDATA))
-				sz += sizeof(pgno_t);
-			else
-				sz += NODEDSZ(node);
-		}
-		sz = EVEN(sz);
-
-		ptr = mp->mp_ptrs[indx];
-		for (i = j = 0; i < numkeys; i++) {
-			if (i != indx) {
-				mp->mp_ptrs[j] = mp->mp_ptrs[i];
-				if (mp->mp_ptrs[i] < ptr)
-					mp->mp_ptrs[j] += sz;
-				j++;
-			}
-		}
-
-		base = (char *)mp + mp->mp_upper;
-		memmove(base + sz, base, ptr - mp->mp_upper);
-
-		mp->mp_lower -= sizeof(indx_t);
-		mp->mp_upper += sz;
-	*/
-}
-
-// Final setup of a sorted-dups cursor.
-//	Sets up the fields that depend on the data from the main cursor.
-// @param[in] mc The main cursor whose sorted-dups cursor is to be initialized.
-// @param[in] node The data containing the #MDB_db record for the
-// sorted-dup database.
-func (c *Cursor) xcursor_init1(n *node) {
-	/*
-			MDB_xcursor *mx = mc->mc_xcursor;
-
-			if (node->mn_flags & F_SUBDATA) {
-				memcpy(&mx->mx_db, NODEDATA(node), sizeof(MDB_db));
-				mx->mx_cursor.mc_pg[0] = 0;
-				mx->mx_cursor.mc_snum = 0;
-				mx->mx_cursor.mc_top = 0;
-				mx->mx_cursor.mc_flags = C_SUB;
-			} else {
-				MDB_page *fp = NODEDATA(node);
-				mx->mx_db.md_pad = mc->mc_pg[mc->mc_top]->mp_pad;
-				mx->mx_db.md_flags = 0;
-				mx->mx_db.md_depth = 1;
-				mx->mx_db.md_branch_pages = 0;
-				mx->mx_db.md_leaf_pages = 1;
-				mx->mx_db.md_overflow_pages = 0;
-				mx->mx_db.md_entries = NUMKEYS(fp);
-				COPY_PGNO(mx->mx_db.md_root, fp->mp_pgno);
-				mx->mx_cursor.mc_snum = 1;
-				mx->mx_cursor.mc_top = 0;
-				mx->mx_cursor.mc_flags = C_INITIALIZED|C_SUB;
-				mx->mx_cursor.mc_pg[0] = fp;
-				mx->mx_cursor.mc_ki[0] = 0;
-				if (mc->mc_db->md_flags & MDB_DUPFIXED) {
-					mx->mx_db.md_flags = MDB_DUPFIXED;
-					mx->mx_db.md_pad = fp->mp_pad;
-					if (mc->mc_db->md_flags & MDB_INTEGERDUP)
-						mx->mx_db.md_flags |= MDB_INTEGERKEY;
-				}
-			}
-			DPRINTF(("Sub-db -%u root page %"Z"u", mx->mx_cursor.mc_dbi,
-				mx->mx_db.md_root));
-			mx->mx_dbflag = DB_VALID|DB_DIRTY; // DB_DIRTY guides mdb_cursor_touch
-		#if UINT_MAX < SIZE_MAX
-			if (mx->mx_dbx.md_cmp == mdb_cmp_int && mx->mx_db.md_pad == sizeof(size_t))
-		#ifdef MISALIGNED_OK
-				mx->mx_dbx.md_cmp = mdb_cmp_long;
-		#else
-				mx->mx_dbx.md_cmp = mdb_cmp_cint;
-		#endif
-		#endif
-	*/
-}
-
-// Return the count of duplicate data items for the current key.
-func (c *Cursor) count() (int, error) {
-	/*
-		MDB_node	*leaf;
-
-		if (mc == NULL || countp == NULL)
-			return EINVAL;
-
-		if (mc->mc_xcursor == NULL)
-			return MDB_INCOMPATIBLE;
-
-		leaf = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
-		if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-			*countp = 1;
-		} else {
-			if (!(mc->mc_xcursor->mx_cursor.mc_flags & C_INITIALIZED))
-				return EINVAL;
-
-			*countp = mc->mc_xcursor->mx_db.md_entries;
-		}
-		return MDB_SUCCESS;
-	*/
-	return 0, nil
-}
-
-func (c *Cursor) Close() {
-	/*
-		if (mc && !mc->mc_backup) {
-			// remove from txn, if tracked
-			if ((mc->mc_flags & C_UNTRACK) && mc->mc_txn->mt_cursors) {
-				MDB_cursor **prev = &mc->mc_txn->mt_cursors[mc->mc_dbi];
-				while (*prev && *prev != mc) prev = &(*prev)->mc_next;
-				if (*prev == mc)
-					*prev = mc->mc_next;
-			}
-			free(mc);
-		}
-	*/
+type stackelem struct {
+	page  *page
+	index int
 }
 
 func (c *Cursor) Transaction() *Transaction {
@@ -1598,1078 +19,39 @@ func (c *Cursor) Bucket() *Bucket {
 	return c.bucket
 }
 
-// Replace the key for a branch node with a new key.
-// @param[in] mc Cursor pointing to the node to operate on.
-// @param[in] key The new key to use.
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) updateKey(key []byte) error {
-	/*
-			MDB_page		*mp;
-			MDB_node		*node;
-			char			*base;
-			size_t			 len;
-			int				 delta, ksize, oksize;
-			indx_t			 ptr, i, numkeys, indx;
-			DKBUF;
-
-			indx = mc->mc_ki[mc->mc_top];
-			mp = mc->mc_pg[mc->mc_top];
-			node = NODEPTR(mp, indx);
-			ptr = mp->mp_ptrs[indx];
-		#if MDB_DEBUG
-			{
-				MDB_val	k2;
-				char kbuf2[DKBUF_MAXKEYSIZE*2+1];
-				k2.mv_data = NODEKEY(node);
-				k2.mv_size = node->mn_ksize;
-				DPRINTF(("update key %u (ofs %u) [%s] to [%s] on page %"Z"u",
-					indx, ptr,
-					mdb_dkey(&k2, kbuf2),
-					DKEY(key),
-					mp->mp_pgno));
-			}
-		#endif
-
-			// Sizes must be 2-byte aligned.
-			ksize = EVEN(key->mv_size);
-			oksize = EVEN(node->mn_ksize);
-			delta = ksize - oksize;
-
-			// Shift node contents if EVEN(key length) changed.
-			if (delta) {
-				if (delta > 0 && SIZELEFT(mp) < delta) {
-					pgno_t pgno;
-					// not enough space left, do a delete and split
-					DPRINTF(("Not enough room, delta = %d, splitting...", delta));
-					pgno = NODEPGNO(node);
-					mdb_node_del(mc, 0);
-					return mdb_page_split(mc, key, NULL, pgno, MDB_SPLIT_REPLACE);
-				}
-
-				numkeys = NUMKEYS(mp);
-				for (i = 0; i < numkeys; i++) {
-					if (mp->mp_ptrs[i] <= ptr)
-						mp->mp_ptrs[i] -= delta;
-				}
-
-				base = (char *)mp + mp->mp_upper;
-				len = ptr - mp->mp_upper + NODESIZE;
-				memmove(base - delta, base, len);
-				mp->mp_upper -= delta;
-
-				node = NODEPTR(mp, indx);
-			}
-
-			// But even if no shift was needed, update ksize
-			if (node->mn_ksize != key->mv_size)
-				node->mn_ksize = key->mv_size;
-
-			if (key->mv_size)
-				memcpy(NODEKEY(node), key->mv_data, key->mv_size);
-
-			return MDB_SUCCESS;
-	*/
-	return nil
-}
-
-// Move a node from csrc to cdst.
-func (c *Cursor) moveNodeTo(dst *Cursor) error {
-	/*
-		MDB_node		*srcnode;
-		MDB_val		 key, data;
-		pgno_t	srcpg;
-		MDB_cursor mn;
-		int			 rc;
-		unsigned short flags;
-
-		DKBUF;
-
-		// Mark src and dst as dirty.
-		if ((rc = mdb_page_touch(csrc)) ||
-		    (rc = mdb_page_touch(cdst)))
-			return rc;
-
-		if (IS_LEAF2(csrc->mc_pg[csrc->mc_top])) {
-			key.mv_size = csrc->mc_db->md_pad;
-			key.mv_data = LEAF2KEY(csrc->mc_pg[csrc->mc_top], csrc->mc_ki[csrc->mc_top], key.mv_size);
-			data.mv_size = 0;
-			data.mv_data = NULL;
-			srcpg = 0;
-			flags = 0;
-		} else {
-			srcnode = NODEPTR(csrc->mc_pg[csrc->mc_top], csrc->mc_ki[csrc->mc_top]);
-			mdb_cassert(csrc, !((size_t)srcnode & 1));
-			srcpg = NODEPGNO(srcnode);
-			flags = srcnode->mn_flags;
-			if (csrc->mc_ki[csrc->mc_top] == 0 && IS_BRANCH(csrc->mc_pg[csrc->mc_top])) {
-				unsigned int snum = csrc->mc_snum;
-				MDB_node *s2;
-				// must find the lowest key below src
-				mdb_page_search_lowest(csrc);
-				if (IS_LEAF2(csrc->mc_pg[csrc->mc_top])) {
-					key.mv_size = csrc->mc_db->md_pad;
-					key.mv_data = LEAF2KEY(csrc->mc_pg[csrc->mc_top], 0, key.mv_size);
-				} else {
-					s2 = NODEPTR(csrc->mc_pg[csrc->mc_top], 0);
-					key.mv_size = NODEKSZ(s2);
-					key.mv_data = NODEKEY(s2);
-				}
-				csrc->mc_snum = snum--;
-				csrc->mc_top = snum;
-			} else {
-				key.mv_size = NODEKSZ(srcnode);
-				key.mv_data = NODEKEY(srcnode);
-			}
-			data.mv_size = NODEDSZ(srcnode);
-			data.mv_data = NODEDATA(srcnode);
-		}
-		if (IS_BRANCH(cdst->mc_pg[cdst->mc_top]) && cdst->mc_ki[cdst->mc_top] == 0) {
-			unsigned int snum = cdst->mc_snum;
-			MDB_node *s2;
-			MDB_val bkey;
-			// must find the lowest key below dst
-			mdb_page_search_lowest(cdst);
-			if (IS_LEAF2(cdst->mc_pg[cdst->mc_top])) {
-				bkey.mv_size = cdst->mc_db->md_pad;
-				bkey.mv_data = LEAF2KEY(cdst->mc_pg[cdst->mc_top], 0, bkey.mv_size);
-			} else {
-				s2 = NODEPTR(cdst->mc_pg[cdst->mc_top], 0);
-				bkey.mv_size = NODEKSZ(s2);
-				bkey.mv_data = NODEKEY(s2);
-			}
-			cdst->mc_snum = snum--;
-			cdst->mc_top = snum;
-			mdb_cursor_copy(cdst, &mn);
-			mn.mc_ki[snum] = 0;
-			rc = mdb_update_key(&mn, &bkey);
-			if (rc)
-				return rc;
-		}
-
-		DPRINTF(("moving %s node %u [%s] on page %"Z"u to node %u on page %"Z"u",
-		    IS_LEAF(csrc->mc_pg[csrc->mc_top]) ? "leaf" : "branch",
-		    csrc->mc_ki[csrc->mc_top],
-			DKEY(&key),
-		    csrc->mc_pg[csrc->mc_top]->mp_pgno,
-		    cdst->mc_ki[cdst->mc_top], cdst->mc_pg[cdst->mc_top]->mp_pgno));
-
-		// Add the node to the destination page.
-		rc = mdb_node_add(cdst, cdst->mc_ki[cdst->mc_top], &key, &data, srcpg, flags);
-		if (rc != MDB_SUCCESS)
-			return rc;
-
-		// Delete the node from the source page.
-		mdb_node_del(csrc, key.mv_size);
-
-		{
-			// Adjust other cursors pointing to mp
-			MDB_cursor *m2, *m3;
-			MDB_dbi dbi = csrc->mc_dbi;
-			MDB_page *mp = csrc->mc_pg[csrc->mc_top];
-
-			for (m2 = csrc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-				if (csrc->mc_flags & C_SUB)
-					m3 = &m2->mc_xcursor->mx_cursor;
-				else
-					m3 = m2;
-				if (m3 == csrc) continue;
-				if (m3->mc_pg[csrc->mc_top] == mp && m3->mc_ki[csrc->mc_top] ==
-					csrc->mc_ki[csrc->mc_top]) {
-					m3->mc_pg[csrc->mc_top] = cdst->mc_pg[cdst->mc_top];
-					m3->mc_ki[csrc->mc_top] = cdst->mc_ki[cdst->mc_top];
-				}
-			}
-		}
-
-		// Update the parent separators.
-		if (csrc->mc_ki[csrc->mc_top] == 0) {
-			if (csrc->mc_ki[csrc->mc_top-1] != 0) {
-				if (IS_LEAF2(csrc->mc_pg[csrc->mc_top])) {
-					key.mv_data = LEAF2KEY(csrc->mc_pg[csrc->mc_top], 0, key.mv_size);
-				} else {
-					srcnode = NODEPTR(csrc->mc_pg[csrc->mc_top], 0);
-					key.mv_size = NODEKSZ(srcnode);
-					key.mv_data = NODEKEY(srcnode);
-				}
-				DPRINTF(("update separator for source page %"Z"u to [%s]",
-					csrc->mc_pg[csrc->mc_top]->mp_pgno, DKEY(&key)));
-				mdb_cursor_copy(csrc, &mn);
-				mn.mc_snum--;
-				mn.mc_top--;
-				if ((rc = mdb_update_key(&mn, &key)) != MDB_SUCCESS)
-					return rc;
-			}
-			if (IS_BRANCH(csrc->mc_pg[csrc->mc_top])) {
-				MDB_val	 nullkey;
-				indx_t	ix = csrc->mc_ki[csrc->mc_top];
-				nullkey.mv_size = 0;
-				csrc->mc_ki[csrc->mc_top] = 0;
-				rc = mdb_update_key(csrc, &nullkey);
-				csrc->mc_ki[csrc->mc_top] = ix;
-				mdb_cassert(csrc, rc == MDB_SUCCESS);
-			}
-		}
-
-		if (cdst->mc_ki[cdst->mc_top] == 0) {
-			if (cdst->mc_ki[cdst->mc_top-1] != 0) {
-				if (IS_LEAF2(csrc->mc_pg[csrc->mc_top])) {
-					key.mv_data = LEAF2KEY(cdst->mc_pg[cdst->mc_top], 0, key.mv_size);
-				} else {
-					srcnode = NODEPTR(cdst->mc_pg[cdst->mc_top], 0);
-					key.mv_size = NODEKSZ(srcnode);
-					key.mv_data = NODEKEY(srcnode);
-				}
-				DPRINTF(("update separator for destination page %"Z"u to [%s]",
-					cdst->mc_pg[cdst->mc_top]->mp_pgno, DKEY(&key)));
-				mdb_cursor_copy(cdst, &mn);
-				mn.mc_snum--;
-				mn.mc_top--;
-				if ((rc = mdb_update_key(&mn, &key)) != MDB_SUCCESS)
-					return rc;
-			}
-			if (IS_BRANCH(cdst->mc_pg[cdst->mc_top])) {
-				MDB_val	 nullkey;
-				indx_t	ix = cdst->mc_ki[cdst->mc_top];
-				nullkey.mv_size = 0;
-				cdst->mc_ki[cdst->mc_top] = 0;
-				rc = mdb_update_key(cdst, &nullkey);
-				cdst->mc_ki[cdst->mc_top] = ix;
-				mdb_cassert(csrc, rc == MDB_SUCCESS);
-			}
-		}
-
-		return MDB_SUCCESS;
-	*/
-
-	return nil
-}
-
-// Merge one page into another.
-//  The nodes from the page pointed to by \b csrc will
-//	be copied to the page pointed to by \b cdst and then
-//	the \b csrc page will be freed.
-// @param[in] csrc Cursor pointing to the source page.
-// @param[in] cdst Cursor pointing to the destination page.
-func (c *Cursor) mergePage(dst *Cursor) error {
-	/*
-		int			 rc;
-		indx_t			 i, j;
-		MDB_node		*srcnode;
-		MDB_val		 key, data;
-		unsigned	nkeys;
-
-		DPRINTF(("merging page %"Z"u into %"Z"u", csrc->mc_pg[csrc->mc_top]->mp_pgno,
-			cdst->mc_pg[cdst->mc_top]->mp_pgno));
-
-		mdb_cassert(csrc, csrc->mc_snum > 1);	// can't merge root page
-		mdb_cassert(csrc, cdst->mc_snum > 1);
-
-		// Mark dst as dirty.
-		if ((rc = mdb_page_touch(cdst)))
-			return rc;
-
-		// Move all nodes from src to dst.
-		j = nkeys = NUMKEYS(cdst->mc_pg[cdst->mc_top]);
-		if (IS_LEAF2(csrc->mc_pg[csrc->mc_top])) {
-			key.mv_size = csrc->mc_db->md_pad;
-			key.mv_data = METADATA(csrc->mc_pg[csrc->mc_top]);
-			for (i = 0; i < NUMKEYS(csrc->mc_pg[csrc->mc_top]); i++, j++) {
-				rc = mdb_node_add(cdst, j, &key, NULL, 0, 0);
-				if (rc != MDB_SUCCESS)
-					return rc;
-				key.mv_data = (char *)key.mv_data + key.mv_size;
-			}
-		} else {
-			for (i = 0; i < NUMKEYS(csrc->mc_pg[csrc->mc_top]); i++, j++) {
-				srcnode = NODEPTR(csrc->mc_pg[csrc->mc_top], i);
-				if (i == 0 && IS_BRANCH(csrc->mc_pg[csrc->mc_top])) {
-					unsigned int snum = csrc->mc_snum;
-					MDB_node *s2;
-					// must find the lowest key below src
-					mdb_page_search_lowest(csrc);
-					if (IS_LEAF2(csrc->mc_pg[csrc->mc_top])) {
-						key.mv_size = csrc->mc_db->md_pad;
-						key.mv_data = LEAF2KEY(csrc->mc_pg[csrc->mc_top], 0, key.mv_size);
-					} else {
-						s2 = NODEPTR(csrc->mc_pg[csrc->mc_top], 0);
-						key.mv_size = NODEKSZ(s2);
-						key.mv_data = NODEKEY(s2);
-					}
-					csrc->mc_snum = snum--;
-					csrc->mc_top = snum;
-				} else {
-					key.mv_size = srcnode->mn_ksize;
-					key.mv_data = NODEKEY(srcnode);
-				}
-
-				data.mv_size = NODEDSZ(srcnode);
-				data.mv_data = NODEDATA(srcnode);
-				rc = mdb_node_add(cdst, j, &key, &data, NODEPGNO(srcnode), srcnode->mn_flags);
-				if (rc != MDB_SUCCESS)
-					return rc;
-			}
-		}
-
-		DPRINTF(("dst page %"Z"u now has %u keys (%.1f%% filled)",
-		    cdst->mc_pg[cdst->mc_top]->mp_pgno, NUMKEYS(cdst->mc_pg[cdst->mc_top]),
-			(float)PAGEFILL(cdst->mc_txn->mt_env, cdst->mc_pg[cdst->mc_top]) / 10));
-
-		// Unlink the src page from parent and add to free list.
-		csrc->mc_top--;
-		mdb_node_del(csrc, 0);
-		if (csrc->mc_ki[csrc->mc_top] == 0) {
-			key.mv_size = 0;
-			rc = mdb_update_key(csrc, &key);
-			if (rc) {
-				csrc->mc_top++;
-				return rc;
-			}
-		}
-		csrc->mc_top++;
-
-		rc = mdb_midl_append(&csrc->mc_txn->mt_free_pgs,
-			csrc->mc_pg[csrc->mc_top]->mp_pgno);
-		if (rc)
-			return rc;
-		if (IS_LEAF(csrc->mc_pg[csrc->mc_top]))
-			csrc->mc_db->md_leaf_pages--;
-		else
-			csrc->mc_db->md_branch_pages--;
-		{
-			// Adjust other cursors pointing to mp 
-			MDB_cursor *m2, *m3;
-			MDB_dbi dbi = csrc->mc_dbi;
-			MDB_page *mp = cdst->mc_pg[cdst->mc_top];
-
-			for (m2 = csrc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-				if (csrc->mc_flags & C_SUB)
-					m3 = &m2->mc_xcursor->mx_cursor;
-				else
-					m3 = m2;
-				if (m3 == csrc) continue;
-				if (m3->mc_snum < csrc->mc_snum) continue;
-				if (m3->mc_pg[csrc->mc_top] == csrc->mc_pg[csrc->mc_top]) {
-					m3->mc_pg[csrc->mc_top] = mp;
-					m3->mc_ki[csrc->mc_top] += nkeys;
-				}
-			}
-		}
-		mdb_cursor_pop(csrc);
-
-		return mdb_rebalance(csrc);
-	*/
-
-	return nil
-}
-
-// Copy the contents of a cursor.
-// @param[in] csrc The cursor to copy from.
-// @param[out] cdst The cursor to copy to.
-func (c *Cursor) copyTo(dst *Cursor) {
-	/*
-		unsigned int i;
-
-		cdst->mc_txn = csrc->mc_txn;
-		cdst->mc_dbi = csrc->mc_dbi;
-		cdst->mc_db  = csrc->mc_db;
-		cdst->mc_dbx = csrc->mc_dbx;
-		cdst->mc_snum = csrc->mc_snum;
-		cdst->mc_top = csrc->mc_top;
-		cdst->mc_flags = csrc->mc_flags;
-
-		for (i=0; i<csrc->mc_snum; i++) {
-			cdst->mc_pg[i] = csrc->mc_pg[i];
-			cdst->mc_ki[i] = csrc->mc_ki[i];
-		}
-	*/
+func (c *Cursor) Get(key []byte) ([]byte, error) {
+	// TODO: Move to key
+	// TODO: If it doesn't exist, return nil, nil
+	// TODO: Otherwise return node key+data.
+	return nil, nil
 }
 
-// Rebalance the tree after a delete operation.
-// @param[in] mc Cursor pointing to the page where rebalancing
-// should begin.
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) rebalance() error {
-	/*
-		MDB_node	*node;
-		int rc;
-		unsigned int ptop, minkeys;
-		MDB_cursor	mn;
-
-		minkeys = 1 + (IS_BRANCH(mc->mc_pg[mc->mc_top]));
-		DPRINTF(("rebalancing %s page %"Z"u (has %u keys, %.1f%% full)",
-		    IS_LEAF(mc->mc_pg[mc->mc_top]) ? "leaf" : "branch",
-		    mdb_dbg_pgno(mc->mc_pg[mc->mc_top]), NUMKEYS(mc->mc_pg[mc->mc_top]),
-			(float)PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) / 10));
-
-		if (PAGEFILL(mc->mc_txn->mt_env, mc->mc_pg[mc->mc_top]) >= FILL_THRESHOLD &&
-			NUMKEYS(mc->mc_pg[mc->mc_top]) >= minkeys) {
-			DPRINTF(("no need to rebalance page %"Z"u, above fill threshold",
-			    mdb_dbg_pgno(mc->mc_pg[mc->mc_top])));
-			return MDB_SUCCESS;
-		}
-
-		if (mc->mc_snum < 2) {
-			MDB_page *mp = mc->mc_pg[0];
-			if (IS_SUBP(mp)) {
-				DPUTS("Can't rebalance a subpage, ignoring");
-				return MDB_SUCCESS;
-			}
-			if (NUMKEYS(mp) == 0) {
-				DPUTS("tree is completely empty");
-				mc->mc_db->md_root = P_INVALID;
-				mc->mc_db->md_depth = 0;
-				mc->mc_db->md_leaf_pages = 0;
-				rc = mdb_midl_append(&mc->mc_txn->mt_free_pgs, mp->mp_pgno);
-				if (rc)
-					return rc;
-				// Adjust cursors pointing to mp
-				mc->mc_snum = 0;
-				mc->mc_top = 0;
-				mc->mc_flags &= ~C_INITIALIZED;
-				{
-					MDB_cursor *m2, *m3;
-					MDB_dbi dbi = mc->mc_dbi;
-
-					for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-						if (mc->mc_flags & C_SUB)
-							m3 = &m2->mc_xcursor->mx_cursor;
-						else
-							m3 = m2;
-						if (m3->mc_snum < mc->mc_snum) continue;
-						if (m3->mc_pg[0] == mp) {
-							m3->mc_snum = 0;
-							m3->mc_top = 0;
-							m3->mc_flags &= ~C_INITIALIZED;
-						}
-					}
-				}
-			} else if (IS_BRANCH(mp) && NUMKEYS(mp) == 1) {
-				DPUTS("collapsing root page!");
-				rc = mdb_midl_append(&mc->mc_txn->mt_free_pgs, mp->mp_pgno);
-				if (rc)
-					return rc;
-				mc->mc_db->md_root = NODEPGNO(NODEPTR(mp, 0));
-				rc = mdb_page_get(mc->mc_txn,mc->mc_db->md_root,&mc->mc_pg[0],NULL);
-				if (rc)
-					return rc;
-				mc->mc_db->md_depth--;
-				mc->mc_db->md_branch_pages--;
-				mc->mc_ki[0] = mc->mc_ki[1];
-				{
-					// Adjust other cursors pointing to mp
-					MDB_cursor *m2, *m3;
-					MDB_dbi dbi = mc->mc_dbi;
-
-					for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-						if (mc->mc_flags & C_SUB)
-							m3 = &m2->mc_xcursor->mx_cursor;
-						else
-							m3 = m2;
-						if (m3 == mc || m3->mc_snum < mc->mc_snum) continue;
-						if (m3->mc_pg[0] == mp) {
-							int i;
-							m3->mc_snum--;
-							m3->mc_top--;
-							for (i=0; i<m3->mc_snum; i++) {
-								m3->mc_pg[i] = m3->mc_pg[i+1];
-								m3->mc_ki[i] = m3->mc_ki[i+1];
-							}
-						}
-					}
-				}
-			} else
-				DPUTS("root page doesn't need rebalancing");
-			return MDB_SUCCESS;
-		}
-
-		// The parent (branch page) must have at least 2 pointers,
-		// otherwise the tree is invalid.
-		ptop = mc->mc_top-1;
-		mdb_cassert(mc, NUMKEYS(mc->mc_pg[ptop]) > 1);
-
-		// Leaf page fill factor is below the threshold.
-		// Try to move keys from left or right neighbor, or
-		// merge with a neighbor page.
-
-		// Find neighbors.
-		mdb_cursor_copy(mc, &mn);
-		mn.mc_xcursor = NULL;
-
-		if (mc->mc_ki[ptop] == 0) {
-			// We're the leftmost leaf in our parent.
-			DPUTS("reading right neighbor");
-			mn.mc_ki[ptop]++;
-			node = NODEPTR(mc->mc_pg[ptop], mn.mc_ki[ptop]);
-			rc = mdb_page_get(mc->mc_txn,NODEPGNO(node),&mn.mc_pg[mn.mc_top],NULL);
-			if (rc)
-				return rc;
-			mn.mc_ki[mn.mc_top] = 0;
-			mc->mc_ki[mc->mc_top] = NUMKEYS(mc->mc_pg[mc->mc_top]);
-		} else {
-			// There is at least one neighbor to the left.
-			DPUTS("reading left neighbor");
-			mn.mc_ki[ptop]--;
-			node = NODEPTR(mc->mc_pg[ptop], mn.mc_ki[ptop]);
-			rc = mdb_page_get(mc->mc_txn,NODEPGNO(node),&mn.mc_pg[mn.mc_top],NULL);
-			if (rc)
-				return rc;
-			mn.mc_ki[mn.mc_top] = NUMKEYS(mn.mc_pg[mn.mc_top]) - 1;
-			mc->mc_ki[mc->mc_top] = 0;
-		}
-
-		DPRINTF(("found neighbor page %"Z"u (%u keys, %.1f%% full)",
-		    mn.mc_pg[mn.mc_top]->mp_pgno, NUMKEYS(mn.mc_pg[mn.mc_top]),
-			(float)PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) / 10));
-
-		// If the neighbor page is above threshold and has enough keys,
-		// move one key from it. Otherwise we should try to merge them.
-		// (A branch page must never have less than 2 keys.)
-		minkeys = 1 + (IS_BRANCH(mn.mc_pg[mn.mc_top]));
-		if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= FILL_THRESHOLD && NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys)
-			return mdb_node_move(&mn, mc);
-		else {
-			if (mc->mc_ki[ptop] == 0)
-				rc = mdb_page_merge(&mn, mc);
-			else {
-				mn.mc_ki[mn.mc_top] += mc->mc_ki[mn.mc_top] + 1;
-				rc = mdb_page_merge(mc, &mn);
-				mdb_cursor_copy(&mn, mc);
-			}
-			mc->mc_flags &= ~(C_INITIALIZED|C_EOF);
-		}
-		return rc;
-	*/
-	return nil
+// Move the cursor to the next key/value.
+func (c *Cursor) Next() ([]byte, []byte, error) {
+	return nil, nil, nil
 }
 
-// Complete a delete operation started by #mdb_cursor_del().
-func (c *Cursor) del0(leaf *node) error {
-	/*
-		int rc;
-		MDB_page *mp;
-		indx_t ki;
-		unsigned int nkeys;
-
-		mp = mc->mc_pg[mc->mc_top];
-		ki = mc->mc_ki[mc->mc_top];
-
-		// add overflow pages to free list
-		if (!IS_LEAF2(mp) && F_ISSET(leaf->mn_flags, F_BIGDATA)) {
-			MDB_page *omp;
-			pgno_t pg;
-
-			memcpy(&pg, NODEDATA(leaf), sizeof(pg));
-			if ((rc = mdb_page_get(mc->mc_txn, pg, &omp, NULL)) ||
-				(rc = mdb_ovpage_free(mc, omp)))
-				return rc;
-		}
-		mdb_node_del(mc, mc->mc_db->md_pad);
-		mc->mc_db->md_entries--;
-		rc = mdb_rebalance(mc);
-		if (rc != MDB_SUCCESS)
-			mc->mc_txn->mt_flags |= MDB_TXN_ERROR;
-		else {
-			MDB_cursor *m2, *m3;
-			MDB_dbi dbi = mc->mc_dbi;
-
-			mp = mc->mc_pg[mc->mc_top];
-			nkeys = NUMKEYS(mp);
-
-			// if mc points past last node in page, find next sibling
-			if (mc->mc_ki[mc->mc_top] >= nkeys)
-				mdb_cursor_sibling(mc, 1);
-
-			// Adjust other cursors pointing to mp
-			for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-				m3 = (mc->mc_flags & C_SUB) ? &m2->mc_xcursor->mx_cursor : m2;
-				if (! (m2->mc_flags & m3->mc_flags & C_INITIALIZED))
-					continue;
-				if (m3 == mc || m3->mc_snum < mc->mc_snum)
-					continue;
-				if (m3->mc_pg[mc->mc_top] == mp) {
-					if (m3->mc_ki[mc->mc_top] >= ki) {
-						m3->mc_flags |= C_DEL;
-						if (m3->mc_ki[mc->mc_top] > ki)
-							m3->mc_ki[mc->mc_top]--;
-					}
-					if (m3->mc_ki[mc->mc_top] >= nkeys)
-						mdb_cursor_sibling(m3, 1);
-				}
-			}
-			mc->mc_flags |= C_DEL;
-		}
-
-		return rc;
-	*/
-	return nil
+// First moves the cursor to the first item in the bucket and returns its key and data.
+func (c *Cursor) First() ([]byte, []byte, error) {
+	// TODO: Traverse to the first key.
+	return nil, nil, nil
 }
 
-// Split a page and insert a new node.
-// @param[in,out] mc Cursor pointing to the page and desired insertion index.
-// The cursor will be updated to point to the actual page and index where
-// the node got inserted after the split.
-// @param[in] newkey The key for the newly inserted node.
-// @param[in] newdata The data for the newly inserted node.
-// @param[in] newpgno The page number, if the new node is a branch node.
-// @param[in] nflags The #NODE_ADD_FLAGS for the new node.
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) splitPage(newKey []byte, newData []byte, newpgno int, nflags int) error {
-	/*
-		unsigned int flags;
-		int		 rc = MDB_SUCCESS, new_root = 0, did_split = 0;
-		indx_t		 newindx;
-		pgno_t		 pgno = 0;
-		int	 i, j, split_indx, nkeys, pmax;
-		MDB_env 	*env = mc->mc_txn->mt_env;
-		MDB_node	*node;
-		MDB_val	 sepkey, rkey, xdata, *rdata = &xdata;
-		MDB_page	*copy = NULL;
-		MDB_page	*mp, *rp, *pp;
-		int ptop;
-		MDB_cursor	mn;
-		DKBUF;
-
-		mp = mc->mc_pg[mc->mc_top];
-		newindx = mc->mc_ki[mc->mc_top];
-		nkeys = NUMKEYS(mp);
-
-		DPRINTF(("-----> splitting %s page %"Z"u and adding [%s] at index %i/%i",
-		    IS_LEAF(mp) ? "leaf" : "branch", mp->mp_pgno,
-		    DKEY(newkey), mc->mc_ki[mc->mc_top], nkeys));
-
-		// Create a right sibling.
-		if ((rc = mdb_page_new(mc, mp->mp_flags, 1, &rp)))
-			return rc;
-		DPRINTF(("new right sibling: page %"Z"u", rp->mp_pgno));
-
-		if (mc->mc_snum < 2) {
-			if ((rc = mdb_page_new(mc, P_BRANCH, 1, &pp)))
-				return rc;
-			// shift current top to make room for new parent
-			mc->mc_pg[1] = mc->mc_pg[0];
-			mc->mc_ki[1] = mc->mc_ki[0];
-			mc->mc_pg[0] = pp;
-			mc->mc_ki[0] = 0;
-			mc->mc_db->md_root = pp->mp_pgno;
-			DPRINTF(("root split! new root = %"Z"u", pp->mp_pgno));
-			mc->mc_db->md_depth++;
-			new_root = 1;
-
-			// Add left (implicit) pointer.
-			if ((rc = mdb_node_add(mc, 0, NULL, NULL, mp->mp_pgno, 0)) != MDB_SUCCESS) {
-				// undo the pre-push
-				mc->mc_pg[0] = mc->mc_pg[1];
-				mc->mc_ki[0] = mc->mc_ki[1];
-				mc->mc_db->md_root = mp->mp_pgno;
-				mc->mc_db->md_depth--;
-				return rc;
-			}
-			mc->mc_snum = 2;
-			mc->mc_top = 1;
-			ptop = 0;
-		} else {
-			ptop = mc->mc_top-1;
-			DPRINTF(("parent branch page is %"Z"u", mc->mc_pg[ptop]->mp_pgno));
-		}
-
-		mc->mc_flags |= C_SPLITTING;
-		mdb_cursor_copy(mc, &mn);
-		mn.mc_pg[mn.mc_top] = rp;
-		mn.mc_ki[ptop] = mc->mc_ki[ptop]+1;
-
-		if (nflags & MDB_APPEND) {
-			mn.mc_ki[mn.mc_top] = 0;
-			sepkey = *newkey;
-			split_indx = newindx;
-			nkeys = 0;
-		} else {
-
-			split_indx = (nkeys+1) / 2;
-
-			if (IS_LEAF2(rp)) {
-				char *split, *ins;
-				int x;
-				unsigned int lsize, rsize, ksize;
-				// Move half of the keys to the right sibling
-				copy = NULL;
-				x = mc->mc_ki[mc->mc_top] - split_indx;
-				ksize = mc->mc_db->md_pad;
-				split = LEAF2KEY(mp, split_indx, ksize);
-				rsize = (nkeys - split_indx) * ksize;
-				lsize = (nkeys - split_indx) * sizeof(indx_t);
-				mp->mp_lower -= lsize;
-				rp->mp_lower += lsize;
-				mp->mp_upper += rsize - lsize;
-				rp->mp_upper -= rsize - lsize;
-				sepkey.mv_size = ksize;
-				if (newindx == split_indx) {
-					sepkey.mv_data = newkey->mv_data;
-				} else {
-					sepkey.mv_data = split;
-				}
-				if (x<0) {
-					ins = LEAF2KEY(mp, mc->mc_ki[mc->mc_top], ksize);
-					memcpy(rp->mp_ptrs, split, rsize);
-					sepkey.mv_data = rp->mp_ptrs;
-					memmove(ins+ksize, ins, (split_indx - mc->mc_ki[mc->mc_top]) * ksize);
-					memcpy(ins, newkey->mv_data, ksize);
-					mp->mp_lower += sizeof(indx_t);
-					mp->mp_upper -= ksize - sizeof(indx_t);
-				} else {
-					if (x)
-						memcpy(rp->mp_ptrs, split, x * ksize);
-					ins = LEAF2KEY(rp, x, ksize);
-					memcpy(ins, newkey->mv_data, ksize);
-					memcpy(ins+ksize, split + x * ksize, rsize - x * ksize);
-					rp->mp_lower += sizeof(indx_t);
-					rp->mp_upper -= ksize - sizeof(indx_t);
-					mc->mc_ki[mc->mc_top] = x;
-					mc->mc_pg[mc->mc_top] = rp;
-				}
-			} else {
-				int psize, nsize, k;
-				// Maximum free space in an empty page
-				pmax = env->me_psize - PAGEHDRSZ;
-				if (IS_LEAF(mp))
-					nsize = mdb_leaf_size(env, newkey, newdata);
-				else
-					nsize = mdb_branch_size(env, newkey);
-				nsize = EVEN(nsize);
-
-				// grab a page to hold a temporary copy
-				copy = mdb_page_malloc(mc->mc_txn, 1);
-				if (copy == NULL)
-					return ENOMEM;
-				copy->mp_pgno  = mp->mp_pgno;
-				copy->mp_flags = mp->mp_flags;
-				copy->mp_lower = PAGEHDRSZ;
-				copy->mp_upper = env->me_psize;
-
-				// prepare to insert
-				for (i=0, j=0; i<nkeys; i++) {
-					if (i == newindx) {
-						copy->mp_ptrs[j++] = 0;
-					}
-					copy->mp_ptrs[j++] = mp->mp_ptrs[i];
-				}
-
-				// When items are relatively large the split point needs
-				// to be checked, because being off-by-one will make the
-				// difference between success or failure in mdb_node_add.
-				//
-				// It's also relevant if a page happens to be laid out
-				// such that one half of its nodes are all "small" and
-				// the other half of its nodes are "large." If the new
-				// item is also "large" and falls on the half with
-				// "large" nodes, it also may not fit.
-				//
-				// As a final tweak, if the new item goes on the last
-				// spot on the page (and thus, onto the new page), bias
-				// the split so the new page is emptier than the old page.
-				// This yields better packing during sequential inserts.
-				if (nkeys < 20 || nsize > pmax/16 || newindx >= nkeys) {
-					// Find split point
-					psize = 0;
-					if (newindx <= split_indx || newindx >= nkeys) {
-						i = 0; j = 1;
-						k = newindx >= nkeys ? nkeys : split_indx+2;
-					} else {
-						i = nkeys; j = -1;
-						k = split_indx-1;
-					}
-					for (; i!=k; i+=j) {
-						if (i == newindx) {
-							psize += nsize;
-							node = NULL;
-						} else {
-							node = (MDB_node *)((char *)mp + copy->mp_ptrs[i]);
-							psize += NODESIZE + NODEKSZ(node) + sizeof(indx_t);
-							if (IS_LEAF(mp)) {
-								if (F_ISSET(node->mn_flags, F_BIGDATA))
-									psize += sizeof(pgno_t);
-								else
-									psize += NODEDSZ(node);
-							}
-							psize = EVEN(psize);
-						}
-						if (psize > pmax || i == k-j) {
-							split_indx = i + (j<0);
-							break;
-						}
-					}
-				}
-				if (split_indx == newindx) {
-					sepkey.mv_size = newkey->mv_size;
-					sepkey.mv_data = newkey->mv_data;
-				} else {
-					node = (MDB_node *)((char *)mp + copy->mp_ptrs[split_indx]);
-					sepkey.mv_size = node->mn_ksize;
-					sepkey.mv_data = NODEKEY(node);
-				}
-			}
-		}
-
-		DPRINTF(("separator is %d [%s]", split_indx, DKEY(&sepkey)));
-
-		// Copy separator key to the parent.
-		if (SIZELEFT(mn.mc_pg[ptop]) < mdb_branch_size(env, &sepkey)) {
-			mn.mc_snum--;
-			mn.mc_top--;
-			did_split = 1;
-			rc = mdb_page_split(&mn, &sepkey, NULL, rp->mp_pgno, 0);
-
-			// root split?
-			if (mn.mc_snum == mc->mc_snum) {
-				mc->mc_pg[mc->mc_snum] = mc->mc_pg[mc->mc_top];
-				mc->mc_ki[mc->mc_snum] = mc->mc_ki[mc->mc_top];
-				mc->mc_pg[mc->mc_top] = mc->mc_pg[ptop];
-				mc->mc_ki[mc->mc_top] = mc->mc_ki[ptop];
-				mc->mc_snum++;
-				mc->mc_top++;
-				ptop++;
-			}
-			// Right page might now have changed parent.
-			// Check if left page also changed parent.
-			if (mn.mc_pg[ptop] != mc->mc_pg[ptop] &&
-			    mc->mc_ki[ptop] >= NUMKEYS(mc->mc_pg[ptop])) {
-				for (i=0; i<ptop; i++) {
-					mc->mc_pg[i] = mn.mc_pg[i];
-					mc->mc_ki[i] = mn.mc_ki[i];
-				}
-				mc->mc_pg[ptop] = mn.mc_pg[ptop];
-				mc->mc_ki[ptop] = mn.mc_ki[ptop] - 1;
-			}
-		} else {
-			mn.mc_top--;
-			rc = mdb_node_add(&mn, mn.mc_ki[ptop], &sepkey, NULL, rp->mp_pgno, 0);
-			mn.mc_top++;
-		}
-		mc->mc_flags ^= C_SPLITTING;
-		if (rc != MDB_SUCCESS) {
-			return rc;
-		}
-		if (nflags & MDB_APPEND) {
-			mc->mc_pg[mc->mc_top] = rp;
-			mc->mc_ki[mc->mc_top] = 0;
-			rc = mdb_node_add(mc, 0, newkey, newdata, newpgno, nflags);
-			if (rc)
-				return rc;
-			for (i=0; i<mc->mc_top; i++)
-				mc->mc_ki[i] = mn.mc_ki[i];
-		} else if (!IS_LEAF2(mp)) {
-			// Move nodes
-			mc->mc_pg[mc->mc_top] = rp;
-			i = split_indx;
-			j = 0;
-			do {
-				if (i == newindx) {
-					rkey.mv_data = newkey->mv_data;
-					rkey.mv_size = newkey->mv_size;
-					if (IS_LEAF(mp)) {
-						rdata = newdata;
-					} else
-						pgno = newpgno;
-					flags = nflags;
-					// Update index for the new key.
-					mc->mc_ki[mc->mc_top] = j;
-				} else {
-					node = (MDB_node *)((char *)mp + copy->mp_ptrs[i]);
-					rkey.mv_data = NODEKEY(node);
-					rkey.mv_size = node->mn_ksize;
-					if (IS_LEAF(mp)) {
-						xdata.mv_data = NODEDATA(node);
-						xdata.mv_size = NODEDSZ(node);
-						rdata = &xdata;
-					} else
-						pgno = NODEPGNO(node);
-					flags = node->mn_flags;
-				}
-
-				if (!IS_LEAF(mp) && j == 0) {
-					// First branch index doesn't need key data.
-					rkey.mv_size = 0;
-				}
-
-				rc = mdb_node_add(mc, j, &rkey, rdata, pgno, flags);
-				if (rc) {
-					// return tmp page to freelist
-					mdb_page_free(env, copy);
-					return rc;
-				}
-				if (i == nkeys) {
-					i = 0;
-					j = 0;
-					mc->mc_pg[mc->mc_top] = copy;
-				} else {
-					i++;
-					j++;
-				}
-			} while (i != split_indx);
-
-			nkeys = NUMKEYS(copy);
-			for (i=0; i<nkeys; i++)
-				mp->mp_ptrs[i] = copy->mp_ptrs[i];
-			mp->mp_lower = copy->mp_lower;
-			mp->mp_upper = copy->mp_upper;
-			memcpy(NODEPTR(mp, nkeys-1), NODEPTR(copy, nkeys-1),
-				env->me_psize - copy->mp_upper);
-
-			// reset back to original page
-			if (newindx < split_indx) {
-				mc->mc_pg[mc->mc_top] = mp;
-				if (nflags & MDB_RESERVE) {
-					node = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
-					if (!(node->mn_flags & F_BIGDATA))
-						newdata->mv_data = NODEDATA(node);
-				}
-			} else {
-				mc->mc_pg[mc->mc_top] = rp;
-				mc->mc_ki[ptop]++;
-				// Make sure mc_ki is still valid.
-				if (mn.mc_pg[ptop] != mc->mc_pg[ptop] &&
-					mc->mc_ki[ptop] >= NUMKEYS(mc->mc_pg[ptop])) {
-					for (i=0; i<ptop; i++) {
-						mc->mc_pg[i] = mn.mc_pg[i];
-						mc->mc_ki[i] = mn.mc_ki[i];
-					}
-					mc->mc_pg[ptop] = mn.mc_pg[ptop];
-					mc->mc_ki[ptop] = mn.mc_ki[ptop] - 1;
-				}
-			}
-			// return tmp page to freelist
-			mdb_page_free(env, copy);
-		}
+// Set the cursor on a specific data item.
+// (bool return is whether it is exact).
+func (c *Cursor) set(key []byte, data []byte, op int) (error, bool) {
+	// TODO(benbjohnson): Optimize for specific use cases.
 
-		{
-			// Adjust other cursors pointing to mp
-			MDB_cursor *m2, *m3;
-			MDB_dbi dbi = mc->mc_dbi;
-			int fixup = NUMKEYS(mp);
+	// TODO: Check if len(key) > 0.
+	// TODO: Start from root page and traverse to correct page.
 
-			for (m2 = mc->mc_txn->mt_cursors[dbi]; m2; m2=m2->mc_next) {
-				if (mc->mc_flags & C_SUB)
-					m3 = &m2->mc_xcursor->mx_cursor;
-				else
-					m3 = m2;
-				if (m3 == mc)
-					continue;
-				if (!(m2->mc_flags & m3->mc_flags & C_INITIALIZED))
-					continue;
-				if (m3->mc_flags & C_SPLITTING)
-					continue;
-				if (new_root) {
-					int k;
-					// root split
-					for (k=m3->mc_top; k>=0; k--) {
-						m3->mc_ki[k+1] = m3->mc_ki[k];
-						m3->mc_pg[k+1] = m3->mc_pg[k];
-					}
-					if (m3->mc_ki[0] >= split_indx) {
-						m3->mc_ki[0] = 1;
-					} else {
-						m3->mc_ki[0] = 0;
-					}
-					m3->mc_pg[0] = mc->mc_pg[0];
-					m3->mc_snum++;
-					m3->mc_top++;
-				}
-				if (m3->mc_top >= mc->mc_top && m3->mc_pg[mc->mc_top] == mp) {
-					if (m3->mc_ki[mc->mc_top] >= newindx && !(nflags & MDB_SPLIT_REPLACE))
-						m3->mc_ki[mc->mc_top]++;
-					if (m3->mc_ki[mc->mc_top] >= fixup) {
-						m3->mc_pg[mc->mc_top] = rp;
-						m3->mc_ki[mc->mc_top] -= fixup;
-						m3->mc_ki[ptop] = mn.mc_ki[ptop];
-					}
-				} else if (!did_split && m3->mc_top >= ptop && m3->mc_pg[ptop] == mc->mc_pg[ptop] &&
-					m3->mc_ki[ptop] >= mc->mc_ki[ptop]) {
-					m3->mc_ki[ptop]++;
-				}
-			}
-		}
-		DPRINTF(("mp left: %d, rp left: %d", SIZELEFT(mp), SIZELEFT(rp)));
-		return rc;
-	*/
-	return nil
+	return nil, false
 }
 
-// Add all the DB's pages to the free list.
-// @param[in] mc Cursor on the DB to free.
-// @param[in] subs non-Zero to check for sub-DBs in this DB.
-// @return 0 on success, non-zero on failure.
-func (c *Cursor) drop0(subs int) error {
-	/*
-		int rc;
-
-		rc = mdb_page_search(mc, NULL, MDB_PS_FIRST);
-		if (rc == MDB_SUCCESS) {
-			MDB_txn *txn = mc->mc_txn;
-			MDB_node *ni;
-			MDB_cursor mx;
-			unsigned int i;
-
-			// LEAF2 pages have no nodes, cannot have sub-DBs
-			if (IS_LEAF2(mc->mc_pg[mc->mc_top]))
-				mdb_cursor_pop(mc);
-
-			mdb_cursor_copy(mc, &mx);
-			while (mc->mc_snum > 0) {
-				MDB_page *mp = mc->mc_pg[mc->mc_top];
-				unsigned n = NUMKEYS(mp);
-				if (IS_LEAF(mp)) {
-					for (i=0; i<n; i++) {
-						ni = NODEPTR(mp, i);
-						if (ni->mn_flags & F_BIGDATA) {
-							MDB_page *omp;
-							pgno_t pg;
-							memcpy(&pg, NODEDATA(ni), sizeof(pg));
-							rc = mdb_page_get(txn, pg, &omp, NULL);
-							if (rc != 0)
-								return rc;
-							mdb_cassert(mc, IS_OVERFLOW(omp));
-							rc = mdb_midl_append_range(&txn->mt_free_pgs,
-								pg, omp->mp_pages);
-							if (rc)
-								return rc;
-						} else if (subs && (ni->mn_flags & F_SUBDATA)) {
-							mdb_xcursor_init1(mc, ni);
-							rc = mdb_drop0(&mc->mc_xcursor->mx_cursor, 0);
-							if (rc)
-								return rc;
-						}
-					}
-				} else {
-					if ((rc = mdb_midl_need(&txn->mt_free_pgs, n)) != 0)
-						return rc;
-					for (i=0; i<n; i++) {
-						pgno_t pg;
-						ni = NODEPTR(mp, i);
-						pg = NODEPGNO(ni);
-						// free it
-						mdb_midl_xappend(txn->mt_free_pgs, pg);
-					}
-				}
-				if (!mc->mc_top)
-					break;
-				mc->mc_ki[mc->mc_top] = i;
-				rc = mdb_cursor_sibling(mc, 1);
-				if (rc) {
-					// no more siblings, go back to beginning
-					// of previous level.
-					mdb_cursor_pop(mc);
-					mc->mc_ki[0] = 0;
-					for (i=1; i<mc->mc_snum; i++) {
-						mc->mc_ki[i] = 0;
-						mc->mc_pg[i] = mx.mc_pg[i];
-					}
-				}
-			}
-			// free it
-			rc = mdb_midl_append(&txn->mt_free_pgs, mc->mc_db->md_root);
-		} else if (rc == MDB_NOTFOUND) {
-			rc = MDB_SUCCESS;
-		}
-		return rc;
-	*/
+func (c *Cursor) insert(key []byte, data []byte) error {
+	// TODO: If there is not enough space on page for key+data then split.
+	// TODO: Move remaining data on page forward.
+	// TODO: Write leaf node to current location.	
+	// TODO: Adjust available page size.
 	return nil
 }