- "Using MRR" is no longer shown with range access.
- Instead, both range and BKA accesses will show one of the following:
= "Rowid-ordered scan"
= "Key-ordered scan"
= "Key-ordered Rowid-ordered scan"
depending on whether DS-MRR implementation will do scan keys in order, rowids in order,
or both.
- The patch also introduces a way for other storage engines/MRR implementations to
pass information to EXPLAIN output about the properties of employed MRR scans.
- The problem was that Mrr_ordered_index_reader's interrupt_read() and resume_read() would
save and restore 1) index tuple 2) the rowid (as bytes returned by handler->position()). Clustered
primary key columns were not saved/restored.
They are not explicitly present in the index tuple (i.e. table->key_info[secondary_key].key_parts
doesn't list them), but they are actually there, in particular
table->field[clustered_primary_key_member].part_of_key(secondary_key) == 1. Index condition pushdown
code [correctly] uses the latter as inidication that pushed index condition can refer to clustered PK
members.
The fix was to make interrupt_read()/resume_read() to save/restore clustered primary key members as well,
so that we get correct values for them when evaluating pushed index condition.
[3rd attempt: remove the debugging aids, fix comments in testcase]
- Make DsMrr_impl::dsmrr_init() handle the case of
1. 1st MRR scan using DS-MRR strategy (i.e. doing key sorting and rowid sorting)
2. 2nd MRR scan getting a buffer that's too small to fit one key element
and one rowid element, and so falling back to default MRR implementation
In this case, dsmrr_init() is invoked with {primary_handler, secondary_handler}
initialized for DS-MRR scan and have to reset them to be initialized for the
default MRR scan.
(attempt 2, with simplified testcase)
sql/multi_range_read.cc:
Added printing of error if something goes wrong in get_next()
(Not critical for this bug fix, but this was something that I noticed while testing and found missing)
storage/myisam/mi_rkey.c:
Fixed wrong error number in mi_yield_and_check_if_killed()
- In Maria/MyISAM: Release/re-acquire locks to give queries that wait on them a chance to make progress
- In Maria/MyISAM: Change from numeric constants to ICP_RES values.
- In Maria: Do check index condition in maria_rprev() (was lost in the merge/backport?)
- In Maria/MyISAM/XtraDB: Check if the query was killed, and return immediately if it was.
Added new storage engine error: HA_ERR_ABORTED_BY_USER, for handler to signal that it detected a kill of the query and aborted
Authors: Sergey Petrunia & Monty
include/my_base.h:
Added HA_ERR_ABORTED_BY_USER, for handler to signal that it detected a kill of the query and aborted
include/my_handler.h:
Added comment
mysql-test/r/myisam_icp.result:
Updated test
mysql-test/t/myisam_icp.test:
Drop used tables at start of test
Added test case that can help with manual testing of killing index condition pushdown query.
mysys/my_handler_errors.h:
Text for new storage engine error
sql/handler.cc:
If engine got HA_ERR_ABORTED_BY_USER, send kill message.
sql/multi_range_read.cc:
Return error code
storage/maria/ha_maria.cc:
Added ma_killed_in_mariadb() to detect kill.
Ensure that file->external_ref points to TABLE object.
storage/maria/ma_extra.c:
Dummy test-if-killed for standalone
storage/maria/ma_key.c:
If ma_check_index_cond() fails, set my_errno and info->cur_row.lastpos
storage/maria/ma_rkey.c:
Release/re-acquire locks to give queries that wait on them a chance to make progress
Check if the query was killed, and return immediately if it was
storage/maria/ma_rnext.c:
Check if the query was killed, and return immediately if it was
Added missing fast_ma_writeinfo(info)
storage/maria/ma_rnext_same.c:
Check if the query was killed, and return immediately if it was
Added missing fast_ma_writeinfo(info)
storage/maria/ma_rprev.c:
Check if the query was killed, and return immediately if it was
Added missing fast_ma_writeinfo(info) and ma_check_index_cond()
storage/maria/ma_search.c:
Give error message if we find a wrong key
storage/maria/ma_static.c:
Added pointer to test-if-killed function
storage/maria/maria_def.h:
New prototypes
storage/myisam/ha_myisam.cc:
Added mi_killed_in_mariadb()
Ensure that file->external_ref points to TABLE object.
storage/myisam/mi_extra.c:
Dummy test-if-killed for standalone
storage/myisam/mi_key.c:
If ma_check_index_cond() fails, set my_errno and info->lastpos
storage/myisam/mi_rkey.c:
Ensure that info->lastpos= HA_OFFSET_ERROR in case of error
Release/re-acquire locks to give queries that wait on them a chance to make progress
Check if the query was killed, and return immediately if it was
Reorder code to do less things in case of error.
Added missing fast_mi_writeinfo()
storage/myisam/mi_rnext.c:
Check if the query was killed, and return immediately if it was
Simplify old ICP code
Added missing fast_ma_writeinfo(info)
storage/myisam/mi_rnext_same.c:
Check if the query was killed, and return immediately if it was
Added missing fast_mi_writeinfo(info)
storage/myisam/mi_rprev.c:
Check if the query was killed, and return immediately if it was
Simplify error handling of ICP
Added missing fast_mi_writeinfo(info)
storage/myisam/mi_search.c:
Give error message if we find a wrong key
storage/myisam/mi_static.c:
Added pointer to test-if-killed function
storage/myisam/myisamdef.h:
New prototypes
storage/xtradb/handler/ha_innodb.cc:
Added DB_SEARCH_ABORTED_BY_USER and ha_innobase::is_thd_killed()
Check if the query was killed, and return immediately if it was
storage/xtradb/handler/ha_innodb.h:
Added prototype
storage/xtradb/include/db0err.h:
Added DB_SEARCH_ABORTED_BY_USER
storage/xtradb/include/row0mysql.h:
Added possible ICP errors
storage/xtradb/row/row0sel.c:
Use ICP errors instead of constants.
Detect if killed and return B_SEARCH_ABORTED_BY_USER
Switch from "Disable identical key handling optimization when
IndexConditionPushdown is used" approach
To
an approach where we save/restore index tuple and so can use index condition pushdown.
- Make Mrr_ordered_index_reader() save the rowid across scan interruptions
Also
- Fix compiler warning for setup_buffer_sizes()
- Add commented key_copy/key_restore for better handling of a similar issue
with index record being destroyed by scan interruption (which causes
incorrect evaluation of pushed index condition later on).
Changed rows_read and rows_sent status variables to be longlong (to avoid compiler warnings)
sql/item_func.cc:
Fixed wrong usage of alias
sql/item_subselect.cc:
Changed buffer size to ulonglong to be able detect buffers bigger than size_t
sql/item_subselect.h:
Changed buffer size to ulonglong to be able detect buffers bigger than size_t
sql/multi_range_read.cc:
Fixed compiler warning by using correct type for function argument
sql/mysqld.cc:
Changed rows_read and rows_sent status variables to be longlong
sql/opt_subselect.h:
Fixed compiler warning by using correct type for function argument
sql/sql_class.cc:
Changed rows_read and rows_sent status variables to be longlong
sql/sql_class.h:
Changed rows_read and rows_sent status variables to be longlong
Changed max_nulls_in_row to uint as this is number of columns in row.
This fixed some compiler warnings.
sql/sql_select.cc:
Added casts to avoid compiler warnings
storage/heap/ha_heap.cc:
Initilize different types separate
storage/oqgraph/ha_oqgraph.cc:
Fixed argument to store(longlong) to avoid compiler warnings
Employed the same kind of optimization as in the fix for the cases
when join buffer is used.
The optimization performs early evaluation of the conditions from
on expression with table references to only outer tables of
an outer join.
- Lots of TODO comments
- add mrr_sort_keys flag to @@optimizer_switch
- [from Igor] SQL layer part passes HA_MRR_MATERIALIZED_KEYS flag
- Don't call rnd_pos() many times in a row if sorted rowid buffer
has the same rowid value for multiple consequive (rowid, range_id) pairs.
- Make index condition pushdown be controlled by an @@optimizer_switch flag,
not by @@engine_condition_pushdown
- Make MRR buffer size be controlled by @@mrr_buffer_size, not
by @@read_rnd_buffer_size
- Move parts of code to separate files
- Code cleanup
- Add --sorted_result to some SELECTs in tests.
