When the Item_ref points to another Item_ref, delegate the
propagate_equal_fields to the latter.
This fixes the inconsitency in equal_field of the underlying
Item_field, when an Item_ref points to a Item_direct_view_ref, as the
latter has its own propagate_equal_fields() that may "move" the
equal_field of the Item_field to itself.
in (select inner_col' from inner_table where inner_col = outer_col)
to
, outer_col in (select inner_col', inner_col from inner_table)
Achieved by implementing Item_in_subselect::exists2in_processor(),
accompanied with comprehensive test coverage. Factored out common code
between the two transformations.
Caveat:
- Cannot recognise bad item mismatch in equalities that causes
materialization to not materialize down the road
MDEV-29502 Fix some issues with spider direct aggregate
The direct aggregate mechanism sems to be only intended to work when
otherwise a full table scan query will be executed from the spider
node and the aggregation done at the spider node too. Typically this
happens in sub_select(). In the test spider.direct_aggregate_part
direct aggregate allows to send COUNT statements directly to the data
nodes and adds up the results at the spider node, instead of iterating
over the rows one by one at the spider node.
By contrast, the group by handler (GBH) typically sends aggregated
queries directly to data nodes, in which case DA does not improve the
situation here.
That is why we should fix it by disabling DA when GBH is used.
There are other reasons supporting this change. First, the creation of
GBH results in a call to change_to_use_tmp_fields() (as opposed to
setup_copy_fields()) which causes the spider DA function
spider_db_fetch_for_item_sum_funcs() to work on wrong items. Second,
the spider DA function only calls direct_add() on the items, and the
follow-up add() needs to be called by the sql layer code. In
do_select(), after executing the query with the GBH, it seems that the
required add() would not necessarily be called.
Disabling DA when GBH is used does fix the bug. There are a few
other things included in this commit to improve the situation with
spider DA:
1. Add a session variable that allows user to disable DA completely,
this will help as a temporary measure if/when further bugs with DA
emerge.
2. Move the increment of direct_aggregate_count to the spider DA
function. Currently this is done in rather bizarre and random
locations.
3. Fix the spider_db_mbase_row creation so that the last of its row
field (sentinel) is NULL. The code is already doing a null check, but
somehow the sentinel field is on an invalid address, causing the
segfaults. With a correct implementation of the row creation, we can
avoid such segfaults.
MDEV-31117 clean up spider connection info parsing
Spider connection string is a comma-separated parameter definitions,
where each definition is of the form "<param_title> <param_value>",
where <param_value> is quote delimited on both ends, with backslashes
acting as an escaping prefix.
The code however treated param title the same way as param value when
assigning, and have nonsensical fields like delim_title_len and
delim_title. We remove these.
We also clean up the spider comment connection string parsing,
including:
- Factoring out some code from the parsing function
- Rewriting the struct `st_spider_param_string_parse`, including
replacing its messy methods with cleaner ones
- And any necessary changes caused by the above changes
Fix spider init bugs (MDEV-22979, MDEV-27233, MDEV-28218) while
preventing regression on old ones (MDEV-30370, MDEV-29904)
Two things are changed:
First, Spider initialisation is made fully synchronous, i.e. it no
longer happens in a background thread. Adapted from the original fix
by nayuta for MDEV-27233. This change itself would cause failure when
spider is initialised early, by plugin-load-add, due to dependency on
Aria and udf function creation, which are fixed in the second and
third parts below. Requires SQL Service, thus porting earlier versions
requires MDEV-27595
Second, if spider is initialised before udf_init(), create udf by
inserting into `mysql.func`, otherwise do it by `CREATE FUNCTION` as
usual. This change may be generalised in MDEV-31401.
Also factor out some clean-up queries from deinit_spider.inc for use
of spider init tests.
A minor caveat is that early spider initialisation will fail if the
server is bootstrapped for the first time, due to missing `mysql`
database which needs to be created by the bootstrap script.
Removing procedures that were created and dropped during init.
This also fixes a race condition where mtr test with
plugin-load-add=ha_spider.so causes post test check to fail as it
expects the procedures to still be there.
