When the variable, spider_semi_table_lock, is 1, Spider sends
LOCK TABLES before each SQL execution. The feature is for
non-transactional remote tables and adds some overhead to query
executions.
We change the default value of the plugin variable to 0 and then
deprecate the variable because it is rare to use non-transactional
engines these days and the variable complicates the code.
The variable, spider_semi_table_lock_connection, should be too
deprecated because it is for tweaking the semi-table locking.
Delete the deprecated variable, spider_use_handler and related code.
Spider now does not supports accessing data nodes via handler
statements. Thus, the notion of SQL kinds are no longer useful.
We too discard it.
Deprecate the server variable spider_internal_offset and the corresponding
table parameters "ios" and "internal_offset".
We believe this variable is not much use to users, therefore decided to
deprecate it.
Reviewed-by: Nayuta Yanagisawa <nayuta.yanagisawa@hey.com>
The variables, spider_crd_mode and spider_sts_mode, specify the
ways to fetch statistics from data nodes.
Using the SHOW command seems to work for any cases. Thus, we deprecate
the variables.
We deprecate the variable spider_xa_register_mode because there is
no need to perform a two phase commit for a read-only transaction.
Note that the variable only affects Spider's internal XA transactions.
The variable spider_internal_limit is for specifying the number of
records acquired by Spider from each remote server.
There seems not to be much use of the variable. Thus, we deprecate it
and the corresponding table options.
Reviewed-by: Nayuta Yanagisawa <nayuta.yanagisawa@hey.com>
Configuring UDFs via plugin variables looks not a good idea.
The more variables Spider has, the more complex it becomes.
Further, I expect that only a few users use Spider UDFs.
Deprecate the following plugin variables regarding Spider UDFs:
* spider_udf_ds_bulk_insert_rows
* spider_udf_ds_table_loop_mode
* spider_udf_ds_use_real_table
* spider_udf_ct_bulk_insert_interval
* spider_udf_ct_bulk_insert_rows
spider_udf_table_lock_mutex_count and spider_udf_table_mon_mutex_count
are also for tweaking UDFs but they are already read-only. So,
there is no need to deprecate them.
"#ifdef WITH_PARTITION_STORAGE_ENGINE ... #endif" appears frequently
in the Spider code base. However, there is no need to maintain such
ifdefs because Spider is disabled if the partitioning engine is disabled.
Some Spider table options introduces an unnecessary complication to
Spider settings. For example, the default value of the plugin variable
spider_auto_increment_mode is -1 (use table value) and the default
table option value is 0 (normal mode). Thus, the virtual default value
of the variable is 0. This kind of indirection is confusing.
In order to delete such confusing table options in a future release,
we first change the default values of some Spider plugin variables
from -1 (use table value) to the corresponding default table values.
The default table values are defined in spider_set_connect_info_default().
At the same time, we also deprecate the option value -1 (use table value).
Deprecate the plugin variable spider_use_handler and the corresponding
table parameters "uhd" and "use_handler".
Passing a Handler statement to data nodes, without converting it to
SQL sometimes, might improve the performance, while this introduces
some complication to the implementation.
In the first place, only a few people use Handler statements and the
performance gain seems not to be very significant. Further, setting
spider_use_handler > 0 disables the GROUP BY handler. So, we decided
to deprecate the variable.
Remove the dead-code, in Spider, which is related to the Spider's
HandlerSocket support. The code has been disabled for a long time
and it is unlikely that the code will be enabled.
- Handle stored function conditions correctly, with the same logic as with UDFs.
- When running queries on Spider SE, by default, we do not push down WHERE conditions containing usage of UDFs/stored functions to remote data nodes, unless the user demands (by setting spider_use_pushdown_udf).
- Disable direct update/delete when a udf condition is skipped.
