diff options
Diffstat (limited to 'sql/ha_partition.cc')
| -rw-r--r-- | sql/ha_partition.cc | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/sql/ha_partition.cc b/sql/ha_partition.cc index 852f437b213..47d2d36ac8d 100644 --- a/sql/ha_partition.cc +++ b/sql/ha_partition.cc @@ -2818,6 +2818,36 @@ void ha_partition::unlock_row() DBUG_VOID_RETURN; } +/** + Check if semi consistent read was used + + SYNOPSIS + was_semi_consistent_read() + + RETURN VALUE + TRUE Previous read was a semi consistent read + FALSE Previous read was not a semi consistent read + + DESCRIPTION + See handler.h: + In an UPDATE or DELETE, if the row under the cursor was locked by another + transaction, and the engine used an optimistic read of the last + committed row value under the cursor, then the engine returns 1 from this + function. MySQL must NOT try to update this optimistic value. If the + optimistic value does not match the WHERE condition, MySQL can decide to + skip over this row. Currently only works for InnoDB. This can be used to + avoid unnecessary lock waits. + + If this method returns nonzero, it will also signal the storage + engine that the next read will be a locking re-read of the row. +*/ +bool ha_partition::was_semi_consistent_read() +{ + DBUG_ENTER("ha_partition::was_semi_consistent_read"); + DBUG_ASSERT(m_last_part < m_tot_parts && + bitmap_is_set(&(m_part_info->used_partitions), m_last_part)); + DBUG_RETURN(m_file[m_last_part]->was_semi_consistent_read()); +} /** Use semi consistent read if possible |