Devart Forums

Hi

I have read a lot of forum entries about record locking, but I seem to be the only person experiencing this problem This is my first foray into InnoDB tables. Have always used MyISAM before.

edAccount is a TQuery.

When I run the following code:

if Mode='Edit' then
try
edAccount.Lock(lrImmediately);
edAccount.RefreshRecord;
edAccount.Edit;
except
on E: EMyError do
if E.ErrorCode=1205 then
begin
MsgDlg('This record is being edited by someone else.'#13'Please try again later.', ['Ok'], cmtWarning);
ModalResult:=mrCancel;
end;
end;

When the record is being edited the program waits the set time (I've set it to 5 secs), then the BDS debugger kicks up the EMySQLException and EMtError

#HY000Lock wait timeout exceeded; try restarting transaction

as expected. However, the program then hangs. Doesn't even get to the error handler.

The TQuery has already been set to FullRefresh = True

I have looked at the Demo and can't see anything wrong.

What have I done wrong? Is there a setting I have missed?

If you call the Lock or the Edit methods for a record locked by other connection, on executing this operation MySQL server returns control and generates the error when the time, adjusted as the value of the innodb_lock_wait_timeout system variable, is up.
You should set the value of this variable in the MySQL server configuration file.

I have already set the

innodb_lock_wait_timeout=5

It's after the 5 sec wait that the error messages are displayed, but then the program hangs. Doesn't even get to the error handler in the program. Also, the component is a TMyQuery not TQuery.

Both this and the other problem I've posted are in the same form.

We could not reproduce the problem.
Please send a complete small sample to dmitryg*crlab*com to demonstrate it, including script to create and fill table.

Also supply us the following information
- exact version of Delphi;
- exact version of MyDAC. You can see it in the About sheet of TMyConnection Editor;
- exact version of MySQL server and MySQL client. You can see it in the Info sheet of TMyConnection Editor.

Delphi BDS 2006 v10.0.2558.35231 Update 2, Hotfixed
MyDAC v5.20.1.14 for Delphi 2006
MySQL v5.0.21-community-nt
TMyConnection - Direct

I have found the problem is when the Lock command is processed, it doesn't get as far as the Edit command.

Below is the MySQL Server config settings.

I have also e-mailed you my Delphi units.

Thanks



MySQL server version: 5.0.21-community-nt
MySQL client version: Direct

auto_increment_increment 1
auto_increment_offset 1
automatic_sp_privileges ON
back_log 50
basedir C:\Program Files\MySQL\MySQL Server 5.0\
binlog_cache_size 32768
bulk_insert_buffer_size 8388608
character_set_client latin1
character_set_connection latin1
character_set_database latin1
character_set_filesystem binary
character_set_results latin1
character_set_server latin1
character_set_system utf8
character_sets_dir C:\Program Files\MySQL\MySQL Server 5.0\share\charsets\
collation_connection latin1_swedish_ci
collation_database latin1_swedish_ci
collation_server latin1_swedish_ci
completion_type 0
concurrent_insert 1
connect_timeout 5
datadir D:\Work\TMSSQL\
date_format %Y-%m-%d
datetime_format %Y-%m-%d %H:%i:%s
default_week_format 0
delay_key_write ON
delayed_insert_limit 100
delayed_insert_timeout 300
delayed_queue_size 1000
div_precision_increment 4
engine_condition_pushdown OFF
expire_logs_days 0
flush OFF
flush_time 1800
ft_boolean_syntax + -><()~*:""&|
ft_max_word_len 84
ft_min_word_len 4
ft_query_expansion_limit 20
ft_stopword_file (built-in)
group_concat_max_len 1024
have_archive YES
have_bdb NO
have_blackhole_engine NO
have_compress YES
have_crypt NO
have_csv NO
have_example_engine NO
have_federated_engine NO
have_geometry YES
have_innodb YES
have_isam NO
have_ndbcluster NO
have_openssl DISABLED
have_query_cache YES
have_raid NO
have_rtree_keys YES
have_symlink YES
init_connect
init_file
init_slave
innodb_additional_mem_pool_size 7340032
innodb_autoextend_increment 8
innodb_buffer_pool_awe_mem_mb 0
innodb_buffer_pool_size 319815680
innodb_checksums ON
innodb_commit_concurrency 0
innodb_concurrency_tickets 500
innodb_data_file_path ibdata1:10M:autoextend
innodb_data_home_dir d:\work\tmssql\
innodb_doublewrite ON
innodb_fast_shutdown 1
innodb_file_io_threads 4
innodb_file_per_table OFF
innodb_flush_log_at_trx_commit 1
innodb_flush_method
innodb_force_recovery 0
innodb_lock_wait_timeout 5
innodb_locks_unsafe_for_binlog OFF
innodb_log_arch_dir
innodb_log_archive OFF
innodb_log_buffer_size 4194304
innodb_log_file_size 63963136
innodb_log_files_in_group 2
innodb_log_group_home_dir .\
innodb_max_dirty_pages_pct 90
innodb_max_purge_lag 0
innodb_mirrored_log_groups 1
innodb_open_files 300
innodb_support_xa ON
innodb_sync_spin_loops 20
innodb_table_locks ON
innodb_thread_concurrency 10
innodb_thread_sleep_delay 10000
interactive_timeout 28800
join_buffer_size 131072
key_buffer_size 164626432
key_cache_age_threshold 300
key_cache_block_size 1024
key_cache_division_limit 100
language C:\Program Files\MySQL\MySQL Server 5.0\share\english\
large_files_support ON
large_page_size 0
large_pages OFF
license GPL
local_infile ON
log OFF
log_bin OFF
log_bin_trust_function_creators OFF
log_error .\SERVER.err
log_slave_updates OFF
log_slow_queries OFF
log_warnings 1
long_query_time 10
low_priority_updates OFF
lower_case_file_system OFF
lower_case_table_names 1
max_allowed_packet 1048576
max_binlog_cache_size 4294967295
max_binlog_size 1073741824
max_connect_errors 10
max_connections 100
max_delayed_threads 20
max_error_count 64
max_heap_table_size 16777216
max_insert_delayed_threads 20
max_join_size 4294967295
max_length_for_sort_data 1024
max_prepared_stmt_count 16382
max_relay_log_size 0
max_seeks_for_key 4294967295
max_sort_length 1024
max_sp_recursion_depth 0
max_tmp_tables 32
max_user_connections 0
max_write_lock_count 4294967295
multi_range_count 256
myisam_data_pointer_size 6
myisam_max_sort_file_size 107374182400
myisam_recover_options OFF
myisam_repair_threads 1
myisam_sort_buffer_size 214958080
myisam_stats_method nulls_unequal
named_pipe OFF
net_buffer_length 16384
net_read_timeout 30
net_retry_count 10
net_write_timeout 60
new OFF
old_passwords OFF
open_files_limit 622
optimizer_prune_level 1
optimizer_search_depth 62
pid_file D:\Work\TMSSQL\SERVER.pid
prepared_stmt_count 8
port 3306
preload_buffer_size 32768
protocol_version 10
query_alloc_block_size 8192
query_cache_limit 1048576
query_cache_min_res_unit 4096
query_cache_size 104857600
query_cache_type ON
query_cache_wlock_invalidate OFF
query_prealloc_size 8192
range_alloc_block_size 2048
read_buffer_size 61440
read_only OFF
read_rnd_buffer_size 258048
relay_log_purge ON
relay_log_space_limit 0
rpl_recovery_rank 0
secure_auth OFF
shared_memory OFF
shared_memory_base_name MYSQL
server_id 0
skip_external_locking ON
skip_networking OFF
skip_show_database OFF
slave_compressed_protocol OFF
slave_load_tmpdir C:\WINDOWS\TEMP\
slave_net_timeout 3600
slave_skip_errors OFF
slave_transaction_retries 10
slow_launch_time 2
sort_buffer_size 262136
sql_mode
sql_notes ON
sql_warnings ON
storage_engine MyISAM
sync_binlog 0
sync_frm ON
system_time_zone GMT Daylight Time
table_cache 256
table_lock_wait_timeout 50
table_type MyISAM
thread_cache_size 8
thread_stack 196608
time_format %H:%i:%s
time_zone SYSTEM
timed_mutexes OFF
tmp_table_size 108003328
tmpdir
transaction_alloc_block_size 8192
transaction_prealloc_size 4096
tx_isolation REPEATABLE-READ
updatable_views_with_limit YES
version 5.0.21-community-nt
version_comment MySQL Community Edition (GPL)
version_compile_machine ia32
version_compile_os Win32
wait_timeout 28800

Thank you for information. We have reproduced this problem and fixed it. This fix will be included in the next MyDAC build.

When will the next update be released. I don't mean to nag, but I could really do with the fix for this locking problem. Thanks

We are planning to release the new MyDAC build in two or three weeks.
We will post an announcement at this forum after the new build is available.

Hi

Any chance you could e-mail me the fix, please?

Sorry to be a nuisance, but it is really holding me up.

If so, please e-mail to alan*technikraft.co.uk

Thanks

Have received and tried the update and I'm pleased to say that it now works.

Thanks