InnoDB: Implement fast TRUNCATE TABLE (Bug #7150)

innobase/dict/dict0boot.c:
  Added DICT_SYS_INDEXES_TYPE_FIELD
innobase/dict/dict0crea.c:
  Added dict_truncate_index_tree()
innobase/include/dict0boot.h:
  Added DICT_SYS_INDEXES_TYPE_FIELD
innobase/include/dict0crea.h:
  Added dict_truncate_index_tree()
innobase/include/row0mysql.h:
  Added row_truncate_table_for_mysql()
innobase/row/row0mysql.c:
  Added row_truncate_table_for_mysql()
sql/ha_innodb.cc:
  Added ha_innobase::delete_all_rows() in order to
  implement fast TRUNCATE TABLE
sql/ha_innodb.h:
  Added ha_innobase::delete_all_rows() in order to
  implement fast TRUNCATE TABLE

2 files changed, 98 insertions, 0 deletions

diff --git a/innobase/dict/dict0boot.c b/innobase/dict/dict0boot.c
index e500b92252f..883c5464319 100644
--- a/innobase/dict/dict0boot.c
+++ b/innobase/dict/dict0boot.c
@@ -333,6 +333,9 @@ dict_boot(void)
 #if DICT_SYS_INDEXES_SPACE_NO_FIELD != 5 + 2
 #error "DICT_SYS_INDEXES_SPACE_NO_FIELD != 5 + 2"
 #endif
+#if DICT_SYS_INDEXES_TYPE_FIELD != 4 + 2
+#error "DICT_SYS_INDEXES_TYPE_FIELD != 4 + 2"
+#endif
 
 	table->id = DICT_INDEXES_ID;
 	dict_table_add_to_cache(table);
diff --git a/innobase/dict/dict0crea.c b/innobase/dict/dict0crea.c
index 747a99ebdc9..e744ffda7a6 100644
--- a/innobase/dict/dict0crea.c
+++ b/innobase/dict/dict0crea.c
@@ -706,6 +706,101 @@ dict_drop_index_tree(
 				DICT_SYS_INDEXES_PAGE_NO_FIELD, FIL_NULL, mtr);
 }
 
+/***********************************************************************
+Truncates the index tree associated with a row in SYS_INDEXES table. */
+
+void
+dict_truncate_index_tree(
+/*=====================*/
+	dict_table_t*	table,	/* in: the table the index belongs to */
+	rec_t*		rec,	/* in: record in the clustered index of
+				SYS_INDEXES table */
+	mtr_t*		mtr)	/* in: mtr having the latch
+				on the record page */
+{
+	ulint		root_page_no;
+	ulint		space;
+	ulint		type;
+	dulint		index_id;
+	byte*		ptr;
+	ulint		len;
+	ibool		comp;
+	dict_index_t*	index;
+
+#ifdef UNIV_SYNC_DEBUG
+	ut_ad(mutex_own(&(dict_sys->mutex)));
+#endif /* UNIV_SYNC_DEBUG */
+
+	ut_a(!dict_sys->sys_indexes->comp);
+	ptr = rec_get_nth_field_old(rec, DICT_SYS_INDEXES_PAGE_NO_FIELD, &len);
+
+	ut_ad(len == 4);
+
+	root_page_no = mtr_read_ulint(ptr, MLOG_4BYTES, mtr);
+
+	if (root_page_no == FIL_NULL) {
+		/* The tree has been freed. */
+
+		return;
+	}
+
+	ptr = rec_get_nth_field_old(rec,
+				DICT_SYS_INDEXES_SPACE_NO_FIELD, &len);
+
+	ut_ad(len == 4);
+
+	space = mtr_read_ulint(ptr, MLOG_4BYTES, mtr);
+
+	if (!fil_tablespace_exists_in_mem(space)) {
+		/* It is a single table tablespace and the .ibd file is
+		missing: do nothing */
+
+		return;
+	}
+
+	ptr = rec_get_nth_field_old(rec,
+				DICT_SYS_INDEXES_TYPE_FIELD, &len);
+	ut_ad(len == 4);
+	type = mach_read_from_4(ptr);
+
+	ptr = rec_get_nth_field_old(rec, 1, &len);
+	ut_ad(len == 8);
+	index_id = mach_read_from_8(ptr);
+
+	/* We free all the pages but the root page first; this operation
+	may span several mini-transactions */
+
+	btr_free_but_not_root(space, root_page_no);
+
+	/* Then we free the root page in the same mini-transaction where
+	we create the b-tree and write its new root page number to the
+	appropriate field in the SYS_INDEXES record: this mini-transaction
+	marks the B-tree totally truncated */
+
+	comp = page_is_comp(btr_page_get(
+				space, root_page_no, RW_X_LATCH, mtr));
+
+	btr_free_root(space, root_page_no, mtr);
+
+	/* Find the index corresponding to this SYS_INDEXES record. */
+	for (index = UT_LIST_GET_FIRST(table->indexes);
+			index;
+			index = UT_LIST_GET_NEXT(indexes, index)) {
+		if (!ut_dulint_cmp(index->id, index_id)) {
+			break;
+		}
+	}
+
+	root_page_no = btr_create(type, space, index_id, comp, mtr);
+	if (index) {
+		index->page_no = root_page_no;
+	}
+
+	page_rec_write_index_page_no(rec,
+				DICT_SYS_INDEXES_PAGE_NO_FIELD,
+				root_page_no, mtr);
+}
+
 /*************************************************************************
 Creates a table create graph. */