mariadb/mysql-test/r/maria-recovery.result

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* WL#4137 Maria- Framework for testing recovery in mysql-test-run See test maria-recovery.test for a model; all include scripts have an "API" section at start if they do take parameters from outside. * Fixing bug reported by Jani and Monty (when two REDOs about the same page in one group, see ma_blockrec.c). * Fixing small bugs in recovery mysql-test/include/wait_until_connected_again.inc: be sure to enter the loop (the previous query by the caller may not have failed: it could be query; mysqladmin shutdown; call this script). mysql-test/lib/mtr_process.pl: * Through the "expect" file a test can tell mtr that a server crash is expected. What the file contains is irrelevant. Now if its last line starts with "wait", mtr will wait before restarting (it will wait for the last line to not start with "wait"). This is for tests which need to mangle files under the feet of a dead mysqld. * Remove "expect" file before restarting; otherwise there could be a race condition: tests sees server restarted, does something, writes an "expect" file, and then mtr removes that file, then test kills mysqld, and then mtr will never restart it. storage/maria/ma_blockrec.c: - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - fixing bug in applying of REDO_PURGE_BLOCKS in recovery: page_range sometimes has TAIL_BIT set, need to turn it down to know the real page range. - Both bugs are covered in maria-recovery.test storage/maria/ma_checkpoint.c: Capability to, in debug builds only, do some special operations (flush all bitmap and data pages, flush state, flush log) and crash mysqld, to later test recovery. Driven by some --debug=d, symbols. storage/maria/ma_open.c: debugging info storage/maria/ma_pagecache.c: Now that we can _ma_unpin_all_pages() during the REDO phase to set page's LSN, the assertion needs to be relaxed. storage/maria/ma_recovery.c: - open trace file in append mode (useful when a test triggers several recoveries, we see them all). - fixing wrong error detection, it's possible that during recovery we want to open an already open table. - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - we verify that all log records of a group are about the same table, for debugging. mysql-test/r/maria-recovery.result: result mysql-test/t/maria-recovery-master.opt: crash is expected, core file would take room, stack trace would wake pushbuild up. mysql-test/t/maria-recovery.test: Test of recovery from mysql-test (it is already tested as unit tests in ma_test_recovery) (WL#4137) - test that, if recovery is made to start on an empty table it can replay the effects of committed and uncommitted statements (having only the committed ones in the end result). This should be the first test for someone writing code of new REDOs. - test that, if mysqld is crashed and recovery runs we have only committed statements in the end result. Crashes are done in different ways: flush nothing (so, uncommitted statement is often missing from the log => no rollback to do); flush pagecache (implicitely flushes log (WAL)) and flush log, both causes rollbacks; flush log can also flush state (state.records etc) to test recovery of the state (not tested well now as we repair the index anyway). - test of bug found by Jani and Monty in recovery (two REDO about the same page in one group). mysql-test/include/maria_empty_logs.inc: removes logs, to have a clean sheet for testing recovery. mysql-test/include/maria_make_snapshot.inc: copies a table to another directory, or back, or compares both (comparison is not implemented as physical comparison is impossible if an UNDO phase happened). mysql-test/include/maria_make_snapshot_for_comparison.inc: copies tables to another directory so that they can later serve as a comparison reference (they are the good tables, recovery should produce similar ones). mysql-test/include/maria_make_snapshot_for_feeding_recovery.inc: When we want to force recovery to start on old tables, we prepare old tables with this script: we put them in a spare directory. They are later copied back over mysqltest tables while mysqld is dead. We also need to copy back the control file, otherwise mysqld, in recovery, would start from the latest checkpoint: latest checkpoint plus old tables is not a recovery-possible scenario of course. mysql-test/include/maria_verify_recovery.inc: causes mysqld to crash, restores old tables if requested, lets recovery run, compares resulting tables with reference tables by using CHECKSUM TABLE. We don't do any sanity checks on page's LSN in resulting tables, yet.
2007-11-13 17:12:29 +01:00
drop database if exists mysqltest;
create database mysqltest;
use mysqltest;
* shut down mysqld, removed logs, restarted it
use mysqltest;
create table t1 (a varchar(1000)) engine=maria;
* TEST of REDO: see if recovery can reconstruct if we give it an old table
* WL#4137 Maria- Framework for testing recovery in mysql-test-run See test maria-recovery.test for a model; all include scripts have an "API" section at start if they do take parameters from outside. * Fixing bug reported by Jani and Monty (when two REDOs about the same page in one group, see ma_blockrec.c). * Fixing small bugs in recovery mysql-test/include/wait_until_connected_again.inc: be sure to enter the loop (the previous query by the caller may not have failed: it could be query; mysqladmin shutdown; call this script). mysql-test/lib/mtr_process.pl: * Through the "expect" file a test can tell mtr that a server crash is expected. What the file contains is irrelevant. Now if its last line starts with "wait", mtr will wait before restarting (it will wait for the last line to not start with "wait"). This is for tests which need to mangle files under the feet of a dead mysqld. * Remove "expect" file before restarting; otherwise there could be a race condition: tests sees server restarted, does something, writes an "expect" file, and then mtr removes that file, then test kills mysqld, and then mtr will never restart it. storage/maria/ma_blockrec.c: - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - fixing bug in applying of REDO_PURGE_BLOCKS in recovery: page_range sometimes has TAIL_BIT set, need to turn it down to know the real page range. - Both bugs are covered in maria-recovery.test storage/maria/ma_checkpoint.c: Capability to, in debug builds only, do some special operations (flush all bitmap and data pages, flush state, flush log) and crash mysqld, to later test recovery. Driven by some --debug=d, symbols. storage/maria/ma_open.c: debugging info storage/maria/ma_pagecache.c: Now that we can _ma_unpin_all_pages() during the REDO phase to set page's LSN, the assertion needs to be relaxed. storage/maria/ma_recovery.c: - open trace file in append mode (useful when a test triggers several recoveries, we see them all). - fixing wrong error detection, it's possible that during recovery we want to open an already open table. - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - we verify that all log records of a group are about the same table, for debugging. mysql-test/r/maria-recovery.result: result mysql-test/t/maria-recovery-master.opt: crash is expected, core file would take room, stack trace would wake pushbuild up. mysql-test/t/maria-recovery.test: Test of recovery from mysql-test (it is already tested as unit tests in ma_test_recovery) (WL#4137) - test that, if recovery is made to start on an empty table it can replay the effects of committed and uncommitted statements (having only the committed ones in the end result). This should be the first test for someone writing code of new REDOs. - test that, if mysqld is crashed and recovery runs we have only committed statements in the end result. Crashes are done in different ways: flush nothing (so, uncommitted statement is often missing from the log => no rollback to do); flush pagecache (implicitely flushes log (WAL)) and flush log, both causes rollbacks; flush log can also flush state (state.records etc) to test recovery of the state (not tested well now as we repair the index anyway). - test of bug found by Jani and Monty in recovery (two REDO about the same page in one group). mysql-test/include/maria_empty_logs.inc: removes logs, to have a clean sheet for testing recovery. mysql-test/include/maria_make_snapshot.inc: copies a table to another directory, or back, or compares both (comparison is not implemented as physical comparison is impossible if an UNDO phase happened). mysql-test/include/maria_make_snapshot_for_comparison.inc: copies tables to another directory so that they can later serve as a comparison reference (they are the good tables, recovery should produce similar ones). mysql-test/include/maria_make_snapshot_for_feeding_recovery.inc: When we want to force recovery to start on old tables, we prepare old tables with this script: we put them in a spare directory. They are later copied back over mysqltest tables while mysqld is dead. We also need to copy back the control file, otherwise mysqld, in recovery, would start from the latest checkpoint: latest checkpoint plus old tables is not a recovery-possible scenario of course. mysql-test/include/maria_verify_recovery.inc: causes mysqld to crash, restores old tables if requested, lets recovery run, compares resulting tables with reference tables by using CHECKSUM TABLE. We don't do any sanity checks on page's LSN in resulting tables, yet.
2007-11-13 17:12:29 +01:00
* copied t1 for feeding_recovery
insert into t1 values ("00000000");
flush table t1;
* copied t1 for comparison
SET SESSION debug="+d,maria_flush_whole_log,maria_crash";
* crashing mysqld intentionally
set global maria_checkpoint_interval=1;
ERROR HY000: Lost connection to MySQL server during query
* copied t1 back for feeding_recovery
* recovery happens
* rebuilding index (until we have recovery of index)
repair table t1 quick;
Table Op Msg_type Msg_text
mysqltest.t1 repair status OK
* testing that checksum after recovery is as expected
select if(substring("mysqltest.t1 488070860",instr("mysqltest.t1 488070860",".t1")) = substring("mysqltest_for_comparison.t1 488070860",instr("mysqltest_for_comparison.t1 488070860",".t1")),"ok","failure");
if(substring("mysqltest.t1 488070860",instr("mysqltest.t1 488070860",".t1")) = substring("mysqltest_for_comparison.t1 488070860",instr("mysqltest_for_comparison.t1 488070860",".t1")),"ok","failure")
ok
* compared t1 to old version
* WL#4137 Maria- Framework for testing recovery in mysql-test-run See test maria-recovery.test for a model; all include scripts have an "API" section at start if they do take parameters from outside. * Fixing bug reported by Jani and Monty (when two REDOs about the same page in one group, see ma_blockrec.c). * Fixing small bugs in recovery mysql-test/include/wait_until_connected_again.inc: be sure to enter the loop (the previous query by the caller may not have failed: it could be query; mysqladmin shutdown; call this script). mysql-test/lib/mtr_process.pl: * Through the "expect" file a test can tell mtr that a server crash is expected. What the file contains is irrelevant. Now if its last line starts with "wait", mtr will wait before restarting (it will wait for the last line to not start with "wait"). This is for tests which need to mangle files under the feet of a dead mysqld. * Remove "expect" file before restarting; otherwise there could be a race condition: tests sees server restarted, does something, writes an "expect" file, and then mtr removes that file, then test kills mysqld, and then mtr will never restart it. storage/maria/ma_blockrec.c: - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - fixing bug in applying of REDO_PURGE_BLOCKS in recovery: page_range sometimes has TAIL_BIT set, need to turn it down to know the real page range. - Both bugs are covered in maria-recovery.test storage/maria/ma_checkpoint.c: Capability to, in debug builds only, do some special operations (flush all bitmap and data pages, flush state, flush log) and crash mysqld, to later test recovery. Driven by some --debug=d, symbols. storage/maria/ma_open.c: debugging info storage/maria/ma_pagecache.c: Now that we can _ma_unpin_all_pages() during the REDO phase to set page's LSN, the assertion needs to be relaxed. storage/maria/ma_recovery.c: - open trace file in append mode (useful when a test triggers several recoveries, we see them all). - fixing wrong error detection, it's possible that during recovery we want to open an already open table. - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - we verify that all log records of a group are about the same table, for debugging. mysql-test/r/maria-recovery.result: result mysql-test/t/maria-recovery-master.opt: crash is expected, core file would take room, stack trace would wake pushbuild up. mysql-test/t/maria-recovery.test: Test of recovery from mysql-test (it is already tested as unit tests in ma_test_recovery) (WL#4137) - test that, if recovery is made to start on an empty table it can replay the effects of committed and uncommitted statements (having only the committed ones in the end result). This should be the first test for someone writing code of new REDOs. - test that, if mysqld is crashed and recovery runs we have only committed statements in the end result. Crashes are done in different ways: flush nothing (so, uncommitted statement is often missing from the log => no rollback to do); flush pagecache (implicitely flushes log (WAL)) and flush log, both causes rollbacks; flush log can also flush state (state.records etc) to test recovery of the state (not tested well now as we repair the index anyway). - test of bug found by Jani and Monty in recovery (two REDO about the same page in one group). mysql-test/include/maria_empty_logs.inc: removes logs, to have a clean sheet for testing recovery. mysql-test/include/maria_make_snapshot.inc: copies a table to another directory, or back, or compares both (comparison is not implemented as physical comparison is impossible if an UNDO phase happened). mysql-test/include/maria_make_snapshot_for_comparison.inc: copies tables to another directory so that they can later serve as a comparison reference (they are the good tables, recovery should produce similar ones). mysql-test/include/maria_make_snapshot_for_feeding_recovery.inc: When we want to force recovery to start on old tables, we prepare old tables with this script: we put them in a spare directory. They are later copied back over mysqltest tables while mysqld is dead. We also need to copy back the control file, otherwise mysqld, in recovery, would start from the latest checkpoint: latest checkpoint plus old tables is not a recovery-possible scenario of course. mysql-test/include/maria_verify_recovery.inc: causes mysqld to crash, restores old tables if requested, lets recovery run, compares resulting tables with reference tables by using CHECKSUM TABLE. We don't do any sanity checks on page's LSN in resulting tables, yet.
2007-11-13 17:12:29 +01:00
use mysqltest;
select * from t1;
a
00000000
* TEST of REDO+UNDO: normal recovery test (no moving tables under its feet)
* WL#4137 Maria- Framework for testing recovery in mysql-test-run See test maria-recovery.test for a model; all include scripts have an "API" section at start if they do take parameters from outside. * Fixing bug reported by Jani and Monty (when two REDOs about the same page in one group, see ma_blockrec.c). * Fixing small bugs in recovery mysql-test/include/wait_until_connected_again.inc: be sure to enter the loop (the previous query by the caller may not have failed: it could be query; mysqladmin shutdown; call this script). mysql-test/lib/mtr_process.pl: * Through the "expect" file a test can tell mtr that a server crash is expected. What the file contains is irrelevant. Now if its last line starts with "wait", mtr will wait before restarting (it will wait for the last line to not start with "wait"). This is for tests which need to mangle files under the feet of a dead mysqld. * Remove "expect" file before restarting; otherwise there could be a race condition: tests sees server restarted, does something, writes an "expect" file, and then mtr removes that file, then test kills mysqld, and then mtr will never restart it. storage/maria/ma_blockrec.c: - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - fixing bug in applying of REDO_PURGE_BLOCKS in recovery: page_range sometimes has TAIL_BIT set, need to turn it down to know the real page range. - Both bugs are covered in maria-recovery.test storage/maria/ma_checkpoint.c: Capability to, in debug builds only, do some special operations (flush all bitmap and data pages, flush state, flush log) and crash mysqld, to later test recovery. Driven by some --debug=d, symbols. storage/maria/ma_open.c: debugging info storage/maria/ma_pagecache.c: Now that we can _ma_unpin_all_pages() during the REDO phase to set page's LSN, the assertion needs to be relaxed. storage/maria/ma_recovery.c: - open trace file in append mode (useful when a test triggers several recoveries, we see them all). - fixing wrong error detection, it's possible that during recovery we want to open an already open table. - when applying a REDO in recovery, we don't anymore put UNDO's LSN on the page at once; indeed if in this REDO's group there comes another REDO for the same page it would be wrongly skipped. Instead, we keep pages pinned, don't change their LSN. When done with all REDOs of the group we unpin them and stamp them with UNDO's LSN. - we verify that all log records of a group are about the same table, for debugging. mysql-test/r/maria-recovery.result: result mysql-test/t/maria-recovery-master.opt: crash is expected, core file would take room, stack trace would wake pushbuild up. mysql-test/t/maria-recovery.test: Test of recovery from mysql-test (it is already tested as unit tests in ma_test_recovery) (WL#4137) - test that, if recovery is made to start on an empty table it can replay the effects of committed and uncommitted statements (having only the committed ones in the end result). This should be the first test for someone writing code of new REDOs. - test that, if mysqld is crashed and recovery runs we have only committed statements in the end result. Crashes are done in different ways: flush nothing (so, uncommitted statement is often missing from the log => no rollback to do); flush pagecache (implicitely flushes log (WAL)) and flush log, both causes rollbacks; flush log can also flush state (state.records etc) to test recovery of the state (not tested well now as we repair the index anyway). - test of bug found by Jani and Monty in recovery (two REDO about the same page in one group). mysql-test/include/maria_empty_logs.inc: removes logs, to have a clean sheet for testing recovery. mysql-test/include/maria_make_snapshot.inc: copies a table to another directory, or back, or compares both (comparison is not implemented as physical comparison is impossible if an UNDO phase happened). mysql-test/include/maria_make_snapshot_for_comparison.inc: copies tables to another directory so that they can later serve as a comparison reference (they are the good tables, recovery should produce similar ones). mysql-test/include/maria_make_snapshot_for_feeding_recovery.inc: When we want to force recovery to start on old tables, we prepare old tables with this script: we put them in a spare directory. They are later copied back over mysqltest tables while mysqld is dead. We also need to copy back the control file, otherwise mysqld, in recovery, would start from the latest checkpoint: latest checkpoint plus old tables is not a recovery-possible scenario of course. mysql-test/include/maria_verify_recovery.inc: causes mysqld to crash, restores old tables if requested, lets recovery run, compares resulting tables with reference tables by using CHECKSUM TABLE. We don't do any sanity checks on page's LSN in resulting tables, yet.
2007-11-13 17:12:29 +01:00
insert into t1 values ("00000000");
flush table t1;
* copied t1 for comparison
lock tables t1 write;
insert into t1 values ("aaaaaaaaa");
SET SESSION debug="+d,maria_crash";
* crashing mysqld intentionally
set global maria_checkpoint_interval=1;
ERROR HY000: Lost connection to MySQL server during query
* recovery happens
* rebuilding index (until we have recovery of index)
repair table t1 quick;
Table Op Msg_type Msg_text
mysqltest.t1 repair status OK
* testing that checksum after recovery is as expected
select if(substring("mysqltest.t1 976141720",instr("mysqltest.t1 976141720",".t1")) = substring("mysqltest_for_comparison.t1 976141720",instr("mysqltest_for_comparison.t1 976141720",".t1")),"ok","failure");
if(substring("mysqltest.t1 976141720",instr("mysqltest.t1 976141720",".t1")) = substring("mysqltest_for_comparison.t1 976141720",instr("mysqltest_for_comparison.t1 976141720",".t1")),"ok","failure")
ok
use mysqltest;
select * from t1;
a
00000000
00000000
insert into t1 values ("00000000");
flush table t1;
* copied t1 for comparison
lock tables t1 write;
insert into t1 values ("aaaaaaaaa");
SET SESSION debug="+d,maria_flush_whole_page_cache,maria_crash";
* crashing mysqld intentionally
set global maria_checkpoint_interval=1;
ERROR HY000: Lost connection to MySQL server during query
* recovery happens
* rebuilding index (until we have recovery of index)
repair table t1 quick;
Table Op Msg_type Msg_text
mysqltest.t1 repair status OK
* testing that checksum after recovery is as expected
select if(substring("mysqltest.t1 1464212580",instr("mysqltest.t1 1464212580",".t1")) = substring("mysqltest_for_comparison.t1 1464212580",instr("mysqltest_for_comparison.t1 1464212580",".t1")),"ok","failure");
if(substring("mysqltest.t1 1464212580",instr("mysqltest.t1 1464212580",".t1")) = substring("mysqltest_for_comparison.t1 1464212580",instr("mysqltest_for_comparison.t1 1464212580",".t1")),"ok","failure")
ok
use mysqltest;
select * from t1;
a
00000000
00000000
00000000
insert into t1 values ("00000000");
flush table t1;
* copied t1 for comparison
lock tables t1 write;
insert into t1 values ("aaaaaaaaa");
SET SESSION debug="+d,maria_flush_states,maria_flush_whole_log,maria_crash";
* crashing mysqld intentionally
set global maria_checkpoint_interval=1;
ERROR HY000: Lost connection to MySQL server during query
* recovery happens
* rebuilding index (until we have recovery of index)
repair table t1 quick;
Table Op Msg_type Msg_text
mysqltest.t1 repair status OK
* testing that checksum after recovery is as expected
select if(substring("mysqltest.t1 1952283440",instr("mysqltest.t1 1952283440",".t1")) = substring("mysqltest_for_comparison.t1 1952283440",instr("mysqltest_for_comparison.t1 1952283440",".t1")),"ok","failure");
if(substring("mysqltest.t1 1952283440",instr("mysqltest.t1 1952283440",".t1")) = substring("mysqltest_for_comparison.t1 1952283440",instr("mysqltest_for_comparison.t1 1952283440",".t1")),"ok","failure")
ok
use mysqltest;
select * from t1;
a
00000000
00000000
00000000
00000000
insert into t1 values ("00000000");
flush table t1;
* copied t1 for comparison
lock tables t1 write;
insert into t1 values ("aaaaaaaaa");
SET SESSION debug="+d,maria_flush_whole_log,maria_crash";
* crashing mysqld intentionally
set global maria_checkpoint_interval=1;
ERROR HY000: Lost connection to MySQL server during query
* recovery happens
* rebuilding index (until we have recovery of index)
repair table t1 quick;
Table Op Msg_type Msg_text
mysqltest.t1 repair status OK
* testing that checksum after recovery is as expected
select if(substring("mysqltest.t1 2440354300",instr("mysqltest.t1 2440354300",".t1")) = substring("mysqltest_for_comparison.t1 2440354300",instr("mysqltest_for_comparison.t1 2440354300",".t1")),"ok","failure");
if(substring("mysqltest.t1 2440354300",instr("mysqltest.t1 2440354300",".t1")) = substring("mysqltest_for_comparison.t1 2440354300",instr("mysqltest_for_comparison.t1 2440354300",".t1")),"ok","failure")
ok
use mysqltest;
select * from t1;
a
00000000
00000000
00000000
00000000
00000000
drop table t1;
* shut down mysqld, removed logs, restarted it
use mysqltest;
CREATE TABLE t1 (
i int,
b blob default NULL,
c varchar(6000) default NULL
) ENGINE=MARIA CHECKSUM=1;
* copied t1 for feeding_recovery
INSERT INTO t1 VALUES (1, REPEAT('a', 5000), REPEAT('b', 5000));
UPDATE t1 SET i=3, b=CONCAT(b,'c') WHERE i=1;
SELECT LENGTH(b) FROM t1 WHERE i=3;
LENGTH(b)
5001
flush table t1;
* copied t1 for comparison
SET SESSION debug="+d,maria_flush_whole_log,maria_crash";
* crashing mysqld intentionally
set global maria_checkpoint_interval=1;
ERROR HY000: Lost connection to MySQL server during query
* copied t1 back for feeding_recovery
* recovery happens
* rebuilding index (until we have recovery of index)
repair table t1 quick;
Table Op Msg_type Msg_text
mysqltest.t1 repair status OK
* testing that checksum after recovery is as expected
select if(substring("mysqltest.t1 3472399915",instr("mysqltest.t1 3472399915",".t1")) = substring("mysqltest_for_comparison.t1 3472399915",instr("mysqltest_for_comparison.t1 3472399915",".t1")),"ok","failure");
if(substring("mysqltest.t1 3472399915",instr("mysqltest.t1 3472399915",".t1")) = substring("mysqltest_for_comparison.t1 3472399915",instr("mysqltest_for_comparison.t1 3472399915",".t1")),"ok","failure")
ok
use mysqltest;
SELECT LENGTH(b) FROM t1 WHERE i=3;
LENGTH(b)
5001
drop table t1;
drop database mysqltest_for_feeding_recovery;
drop database mysqltest_for_comparison;
drop database mysqltest;