When we need to add/remove or change LIMIT, INTERVAL, AUTO we have to
recreate partitioning from scratch (via data copy). Such operations
should be done fast. To remove options like LIMIT or INTERVAL one
should write:
alter table t1 partition by system_time;
The command checks whether it is new or existing SYSTEM_TIME
partitioning. And in the case of new it behaves as CREATE would do:
adds default number of partitions (2). If SYSTEM_TIME partitioning
already existed it just changes its options: removes unspecified ones
and adds/changes those specified explicitly. In case when partitions
list was supplied it behaves as usual: does full repartitioning.
Examples:
create or replace table t1 (x int) with system versioning
partition by system_time limit 100 partitions 4;
# Change LIMIT
alter table t1 partition by system_time limit 33;
# Remove LIMIT
alter table t1 partition by system_time;
# This does full repartitioning
alter table t1 partition by system_time limit 33 partitions 4;
# This does data copy as pruning will require records in correct partitions
alter table t1 partition by system_time interval 1 hour
starts '2000-01-01 00:00:00';
# But this works fast, LIMIT will apply to DML commands
alter table t1 partition by system_time limit 33;
To sum up, ALTER for SYSTEM_TIME partitioning does full repartitioning
when:
- INTERVAL was added or changed;
- partition list or partition number was specified;
Otherwise it does fast alter table.
Cleaned up dead condition in set_up_default_partitions().
Reviewed by:
Oleksandr Byelkin <sanja@mariadb.com>
Nikita Malyavin <nikitamalyavin@gmail.com>
LIMIT history switching requires the number of history partitions to
be marked for read: from first to last non-empty plus one empty. The
least we can do is to fail with error message if the needed partition
was not marked for read. As this is handler interface we require new
handler error code to display user-friendly error message.
Switching by INTERVAL works out-of-the-box with
ER_ROW_DOES_NOT_MATCH_GIVEN_PARTITION_SET error.
Dead code cleanup:
part_info->num_parts usage was wrong and working incorrectly in
mysql_drop_partitions() because num_parts is already updated in
prep_alter_part_table(). We don't have to update part_info->partitions
because part_info is destroyed at alter_partition_lock_handling().
Cleanups:
- DBUG_EVALUATE_IF() macro replaced by shorter form DBUG_IF();
- Typo in ER_KEY_COLUMN_DOES_NOT_EXITS.
Refactorings:
- Splitted write_log_replace_delete_frm() into write_log_delete_frm()
and write_log_replace_frm();
- partition_info via DDL_LOG_STATE;
- set_part_info_exec_log_entry() removed.
DBUG_EVALUATE removed
DBUG_EVALUTATE was only added for consistency together with
DBUG_EVALUATE_IF. It is not used anywhere in the code.
DBUG_SUICIDE() fix on release build
On release DBUG_SUICIDE() was statement. It was wrong as
DBUG_SUICIDE() is used in expression context.
When there are E empty partitions left, auto-create N new empty
partitions for SYSTEM_TIME partitioning rotated by INTERVAL/LIMIT and
marked by AUTO_INCREMENT keyword. Syntax change: AUTO_INCREMENT
keyword (or shorter AUTO may be used instead) after LIMIT/INTERVAL
clause.
CREATE OR REPLACE TABLE t (x INT) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME LIMIT 100000 AUTO_INCREMENT;
CREATE OR REPLACE TABLE t (x INT) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME INTERVAL 1 WEEK AUTO_INCREMENT;
The current revision implements hard-coded values of 1 for E and N. As
well as auto-creation threshold MinInterval = 1 hour, MinLimit = 1000.
The name for newly added partition will be first chosen as "pX", where
X is partition number and "p" is hard-coded name prefix. If this name
is already occupied, the X will be incremented until the resulting
name will be free to use.
ALTER TABLE ADD PARTITION is now always fast. If there some history
partition overflow occurs manual ALTER TABLE REBUILD PARTITION is
needed.
* Explicit STARTS syntax
* SHOW CREATE
* Default STARTS rounding depending on INTERVAL type
* Warn when STARTS timestamp is later than query time
* Fix uninitialized Lex->create_last_non_select_table under
mysql_unpack_partition()
Default STARTS rounding depending on INTERVAL type
If STARTS clause is omitted, default one is assigned with value
derived from query timestamp. The rounding is done on STARTS value
depending on INTERVAL type:
SECOND: no rounding is done;
MINUTE: timestamp seconds is set to 0;
HOUR: timestamp seconds and minutes are set to 0;
DAY, WEEK, MONTH and YEAR: timestamp seconds, minutes and hours are
set to 0 (the date of rotation is kept as current date).
SYSTEM_TYPE partitioning: COLUMN properties removed. Partitioning is
now pure RANGE based on UNIX_TIMESTAMP(row_end).
DECIMAL type is now allowed as RANGE partitioning, we can partition by
UNIX_TIMESTAMP() (but not for DATETIME which depends on local timezone
of course).
The problem here is EITS statistics does not calculate statistics for the partitions of the table.
So a temporary solution would be to not read EITS statistics for partitioned tables.
Also disabling reading of EITS for columns that participate in the partition list of a table.
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
partition_info had a bunch of function pointers to avoid if()'s
when invoking part_type specific functionality (like get_part_id, etc).
But check_range_constants() and check_list_constants() were still
invoked conditionally, with if()'s.
Create partition_info::check_constants function pointer, get rid
of if()'s
Also remove alloc argument of check_range_constants(), added
in 26a3ff0a22. Broken system versioning will be fixed in
following commits.
Handle string length as size_t, consistently (almost always:))
Change function prototypes to accept size_t, where in the past
ulong or uint were used. change local/member variables to size_t
when appropriate.
This fix excludes rocksdb, spider,spider, sphinx and connect for now.
Now we don't open partitions if it was explicitly cpecified.
ha_partition::m_opened_partition bitmap added to track
partitions that were actually opened.
