Fix partitioning for trx_id-versioned tables.
`partition by hash`, `range` and others now work.
`partition by system_time` is forbidden.
Currently we cannot use row_start and row_end in `partition by`, because
insertion of versioned field is done by engine's handler, as well as
row_start/row_end's value set up, which is a transaction id -- so it's
also forbidden.
The drawback is that it's now impossible to use `partition by key()`
without parameters for such tables, because it references row_start and
row_end implicitly.
* add handler::vers_can_native()
* drop Table_scope_and_contents_source_st::vers_native()
* drop partition_element::find_engine_flag as unused
* forbid versioning partitioning for trx_id as not supported
* adopt vers tests for trx_id partitioning
* forbid any row_end referencing in `partition by` clauses,
including implicit `by key()`
In a test case Update occurs between Search and Delete/Update. This corrupts rowid
which Search saves for Delete/Update. Patch prevents this by using of
HA_EXTRA_REMEMBER_POS and HA_EXTRA_RESTORE_POS in a partition code.
This situation possibly occurs only with system versioning table and partition.
MyISAM and Aria engines are affected.
fix by midenok
Closes#705
MDEV-14823 Wrong error message upon selecting from a system_time partition
MDEV-15956 Strange ER_UNSUPPORTED_ACTION_ON_GENERATED_COLUMN upon ALTER on versioning column
Lots of changes:
* calculate the current history partition in ::external_lock(),
not in ::write_row() or ::update_row()
* remove dynamically collected per-partition row_end stats
* no full table scan in open_table_from_share to calculate these
stats, no manual MDL/thr_locks in open_table_from_share
* no shared stats in TABLE_SHARE = no mutexes or condition waits when
calculating current history partition
* always compare timestamps, don't convert them to MYSQL_TIME
(avoid DST ambiguity, and it's faster too)
* correct interval handling, 1 month = 1 month, not 30 * 24 * 3600 seconds
* save/restore first partition start time, and count intervals from there
* only allow to drop first partitions if INTERVAL
* when adding new history partitions, split the data in the last history
parition, if it was overflowed
* show partition boundaries in INFORMATION_SCHEMA.PARTITIONS
use include/have_xxx.inc when some feature needs to be present
(because --xxx in the opt file will fail if the xxx is not compiled in)
set variables in the test, not on the command line, to avoid unnecessary
server restarts (they're must slower than SET).
* again, as in 10.2, NOW is a keyword only if followed by parentheses
* use AS OF CURRENT_TIMESTAMP or AS OF NOW()
* AS OF CURRENT_TIMESTAMP and AS OF NOW() mean AS OF NOW(6),
not AS OF NOW(0), (same behavior as in a DEFAULT clause)
* based on RANGE pruning by COLUMNS (sys_trx_end) condition
* removed DEFAULT; AS OF NOW is always last; current VERSIONING as last non-empty (or first empty)
* Min/Max stats in TABLE_SHARE
* ALTER TABLE ADD PARTITION adds before AS OF NOW partition
* one `AS OF NOW`, multiple `VERSIONING` partitions;
* rotation of `VERSIONING` partitions by record count, time period;
* rotation is multi-threaded;
* conventional subpartitions as bottom level for versioned partitions;
* `DEFAULT` keyword selects first `VERSIONING` partition;
* ALTER TABLE ADD/DROP partition;
* REBUILD PARTITION basic operation.
