A spider_conn may outlive its associated ha_spider (in the field
queued_ping_spider) used for connecting to and pinging the data
node (a call to spider_db_ping(), guarded by the boolean field
queued_ping). In a call to ha_spider::close() (which is often preceded
with the deletion of the ha_spider itself), many cleanups happen,
including freeing the associated spider_share, which is used by the
spider_conn in spider_db_ping. Therefore it is necessary to reset both
the queued_ping_spider and queued_ping fields, so that any further
spider interaction with the data node will not trigger the call using
the ha_spider including its freed spider_share.
Also out of caution added an assert and internal error in case a
connection has not been established (the db_conn field of type
MYSQL * is NULL), and attempt to connect is skipped because both
queued_connect and queued_ping are false. Note that this unlikely (if
not impossible) scenario would not be a regression caused by this
change, as it strictly falls under the scenario of this bug.
The conn_kind, which stands for "connection kind", is no longer useful
because the HandlerSocket support is deleted and Spider now has only
one connection kind, SPIDER_CONN_KIND_MYSQL. Remove conn_kind and
related code.
Signed-off-by: Yuchen Pei <yuchen.pei@mariadb.com>
Reviewed-by: Nayuta Yanagisawa <nayuta.yanagisawa@mariadb.com>
This is a fixup of MDEV-26345 commit
77ed235d50.
In MDEV-26345 the spider group by handler was updated so that it uses
the item_ptr fields of Query::group_by and Query::order_by, instead of
item. This was and is because the call to
join->set_items_ref_array(join->items1) during the execution stage,
just before the execution replaces the order-by / group-by item arrays
with Item_temptable_field.
Spider traverses the item tree during the group by handler (gbh)
creation at the end of the optimization stage, and decides a gbh could
handle the execution of the query. Basically spider gbh can handle the
execution if it can construct a well-formed query, executes on the
data node, and store the results in the correct places. If so, it will
create one, otherwise it will return NULL and the execution will use
the usual handler (ha_spider instead of spider_group_by_handler). To
that end, the general principle is the items checked for creation
should be the same items later used for query construciton. Since in
MDEV-26345 we changed to use the item_ptr field instead of item field
of order-by and group-by in query construction, in this patch we do
the same for the gbh creation.
The item_ptr field could be the uninitialised NULL value during the
gbh creation. This is because the optimizer may replace a DISTINCT
with a GROUP BY, which only happens if the original GROUP BY is empty.
It creates the artificial GROUP BY by calling create_distinct_group(),
which creates the corresponding ORDER object with item field aligning
with somewhere in ref_pointer_array, but leaving item_ptr to be NULL.
When spider finds out that item_ptr is NULL, it knows there's some
optimizer skullduggery and it is passed a query different from the
original. Without a clear contract between the server layer and the
gbh, it is better to be safe than sorry and not create the gbh in this
case.
Also add a check and error reporting for the unlikely case of item_ptr
changing from non-NULL at gbh construction to NULL at execution to
prevent server crash.
Also, we remove a check added in MDEV-29480 of order by items being
aggregate functions. That check was added with the premise that spider
was including auxiliary SELECT items which is referenced by ORDER BY
items. This premise was no longer true since MDEV-26345, and caused
problems such as MDEV-29546, which was fixed by MDEV-26345.
The existing default value 1000 is too big and could result in
"hanging" when failing to connect a remote server. Three tries in
total is a more sensible default.
Partial commit of the greater MDEV-34348 scope.
MDEV-34348: MariaDB is violating clang-16 -Wcast-function-type-strict
Change the type of my_hash_get_key to:
1) Return const
2) Change the context parameter to be const void*
Also fix casting in hash adjacent areas.
Reviewed By:
============
Marko Mäkelä <marko.makela@mariadb.com>
Stop skipping const items when selecting but skip them when storing
their results to spider row to avoid storing in mismatching temporary
table fields.
Skip auxiliary fields in SELECTing, and do not store
the (non-existing) results to the corresponding temporary table
accordingly.
When there are BOTH auxiliary fields AND const items in the auxiliary
field items, do not use the spider GBH. This is a rare occasion if it
happens at all and not worth the added complexity to cover it.
Use the original item (item_ptr) in constructing GROUP BY and ORDER
BY, which also means using item->name instead of field->field_name as
aliases in constructing SELECT items. This fixes spurious regressions
caused by the above changes in some tests using ORDER BY, such as
mdev_24517.test. As a by-product, this also fixes MDEV-29546.
Therefore we update mdev_29008.test to include the MDEV-29546 case.
During spider query construction of certain cast functions, it
locates the last occurrence of a keyword in the output of the
Item::print() function and append from there to the constructed query
so far. For example, consider the following query
SELECT * FROM t2 ORDER BY CAST(c AS INET6);
It constructs the following query and executes it at the data
node (assuming the data node table is called t0).
select cast(t0.`c` as inet6) ``,t0.`c` `c` from `test`.`t1` t0 order by ``
When the construction has completed the initial part
select cast(t0.`c`
It then attempts to construct the " as inet6" part. To that end, it
calls print() on the Item_typecast_fbt corresponding to the cast item,
and obtains
cast(`test`.`t2`.`c` as inet6)
It then looks for " as ", and places cursor there for appending:
cast(`test`.`t2`.`c` as inet6)
^
In this patch, if the search fails, i.e. there's no " as ...", we
make sure that the cursor is not placed before the beginning of the
string (out of bound).
We also relax the search from " as char" to " as " in the case of
CHAR_TYPECAST_FUNC, since there is more than one Item type with this
func type. For example, "AS INET6" is an Item_typecast_fbt which has
this func type.
