Bug#12845774 OPTIMISTIC INSERT/UPDATE USES WRONG HEURISTICS FOR

COMPRESSED PAGE SIZE

This was submitted as MySQL Bug 61456 and a patch provided by
Facebook. This patch follows the same idea, but instead of adding a
parameter to btr_cur_pessimistic_insert(), we simply remove the
btr_cur_optimistic_insert() call there and add it to the only caller
that needs it.

btr_cur_pessimistic_insert(): Do not try btr_cur_optimistic_insert().

btr_insert_on_non_leaf_level_func(): Invoke btr_cur_optimistic_insert()
before invoking btr_cur_pessimistic_insert().

btr_cur_pessimistic_update(): Clarify in a comment why it is not
necessary to invoke btr_cur_optimistic_insert().

btr_root_raise_and_insert(): Assert that the root page is not empty.
This could happen if a pessimistic insert (involving a split or merge)
is performed without first attempting an optimistic (intra-page) insert.

rb:1219 approved by Sunny Bains

storage/innodb_plugin/ChangeLog

+2012-08-16	The InnoDB Team
+
+	* btr/btr0btr.c, btr/btr0cur.c:
+	Fix Bug#12845774 OPTIMISTIC INSERT/UPDATE USES WRONG HEURISTICS FOR
+	COMPRESSED PAGE SIZE
+
 2012-08-16	The InnoDB Team
 
 	* btr/btr0cur.c, page/page0page.c:

storage/innodb_plugin/btr/btr0btr.c

@@ -1822,6 +1822,7 @@ btr_root_raise_and_insert(
 	root = btr_cur_get_page(cursor);
 	root_block = btr_cur_get_block(cursor);
 	root_page_zip = buf_block_get_page_zip(root_block);
+	ut_ad(page_get_n_recs(root) > 0);
 #ifdef UNIV_ZIP_DEBUG
 	ut_a(!root_page_zip || page_zip_validate(root_page_zip, root));
 #endif /* UNIV_ZIP_DEBUG */
@@ -2302,12 +2303,20 @@ btr_insert_on_non_leaf_level_func(
 				    BTR_CONT_MODIFY_TREE,
 				    &cursor, 0, file, line, mtr);
 
-	err = btr_cur_pessimistic_insert(BTR_NO_LOCKING_FLAG
-					 | BTR_KEEP_SYS_FLAG
-					 | BTR_NO_UNDO_LOG_FLAG,
-					 &cursor, tuple, &rec,
-					 &dummy_big_rec, 0, NULL, mtr);
-	ut_a(err == DB_SUCCESS);
+	ut_ad(cursor.flag == BTR_CUR_BINARY);
+
+	err = btr_cur_optimistic_insert(
+		BTR_NO_LOCKING_FLAG | BTR_KEEP_SYS_FLAG
+		| BTR_NO_UNDO_LOG_FLAG, &cursor, tuple, &rec,
+		&dummy_big_rec, 0, NULL, mtr);
+
+	if (err == DB_FAIL) {
+		err = btr_cur_pessimistic_insert(
+			BTR_NO_LOCKING_FLAG | BTR_KEEP_SYS_FLAG
+			| BTR_NO_UNDO_LOG_FLAG,
+			&cursor, tuple, &rec, &dummy_big_rec, 0, NULL, mtr);
+		ut_a(err == DB_SUCCESS);
+	}
 }
 
 /**************************************************************//**

storage/innodb_plugin/btr/btr0cur.c

@@ -1361,20 +1361,9 @@ btr_cur_pessimistic_insert(
 	ut_ad(mtr_memo_contains(mtr, btr_cur_get_block(cursor),
 				MTR_MEMO_PAGE_X_FIX));
 
-	/* Try first an optimistic insert; reset the cursor flag: we do not
-	assume anything of how it was positioned */
-
 	cursor->flag = BTR_CUR_BINARY;
 
-	err = btr_cur_optimistic_insert(flags, cursor, entry, rec,
-					big_rec, n_ext, thr, mtr);
-	if (err != DB_FAIL) {
-
-		return(err);
-	}
-
-	/* Retry with a pessimistic insert. Check locks and write to undo log,
-	if specified */
+	/* Check locks and write to undo log, if specified */
 
 	err = btr_cur_ins_lock_and_undo(flags, cursor, entry,
 					thr, mtr, &dummy_inh);
@@ -2365,8 +2354,10 @@ btr_cur_pessimistic_update(
 	record on its page? */
 	was_first = page_cur_is_before_first(page_cursor);
 
-	/* The first parameter means that no lock checking and undo logging
-	is made in the insert */
+	/* Lock checks and undo logging were already performed by
+	btr_cur_upd_lock_and_undo(). We do not try
+	btr_cur_optimistic_insert() because
+	btr_cur_insert_if_possible() already failed above. */
 
 	err = btr_cur_pessimistic_insert(BTR_NO_UNDO_LOG_FLAG
 					 | BTR_NO_LOCKING_FLAG