Shard-Query examines INFORMATION_SCHEMA.PARTITIONS to determine
if a table is partitioned. When a table is partitioned,
Shard-Query creates multiple background queries, each limited to
a single partition. Unfortunately, it seems that examining
INFORMATION_SCHEMA.PARTITIONS causes query plans to change after
the view is accessed.
I have reported bug
69179 to MySQL AB Oracle Corporation(old
habits die hard).
Be careful: If you have automated tools (like schema management
GUI tools) then make sure they don’t examine
INFORMATION_SCHEMA.PARTITIONS or you may get bad plans until you
analyze your tables or restart the database, even if using
I can only get the bug to happen when a WHERE clause is issued
that limits access to a single partition. It may be that
the per partition statistics …[Read more]