Lock a table record.

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Posted on by Community Member

Hello,

I want to lock a table record.

When another trying to select that record, it wait, until I unlock the record.

How can I do that?

X++ (AX 2012).

Thanks :)

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Answers (1)

Ivan (Vanya) Kashperuk on at

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you select it for update using the standard X++ syntax

To ensure it actually acquires a lock you need to use pessimistic concurrency

however, it's discouraged in AX, as this is a multi-user environment, and locks cause large delays for other users wanting to update data in the same table

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Community Member on at

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I do:

Station 1:

...

ttsbegin;

myTable.selectForupdate();

...

Station 2:

ttsbegin;

myTable.selectForupdate(); // same record.

... // there is no waiting !!!

I need to do "wait" after myTable.selectForupdate for station 2.

Thanks :)

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Martin Dráb 237,855 Most Valuable Professional on at

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First of all, selectForUpdate() just sets the update flag for the next select statement; it doesn't make any call to database to lock anything. Your snippet doesn't show whether you execute such select statements or not.

Secondly, Ivan clearly wrote that you have to use pessimistic concurrency control, but you didn't mention anything about it. If the table should always use pessimistic concurrency, set its OccEnable property to No. If it should be for the particular selects only, use "select pessimisticLock" or set concurrencyModel() on the buffer.

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Community Member on at

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OK, I will check that out.

Thanks :)

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Community Member on at

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Well,

I did select for update.

i.e:

static void splTestRec1(Args _args)

{

GeneralJournalAccountEntry generalJournalAccountEntry;

;

ttsBegin;

select forupdate generalJournalAccountEntry

where generalJournalAccountEntry.RecId == 12345;

ttsCommit; // *****

}

1. I Ran the above on one session, and the debugger command is before commit ran.

2. I Ran the above on other session, and when doing the "select" statement, I accept that there will be "waiting", and there isn't any.

How can I do lock+wait? Need a code example, please.

Thanks :)

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Verified answer

Martin Dráb 237,855 Most Valuable Professional on at

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Where did you set pessimistic locking, as mentioned in both Ivan's and my answers? Replace forUpdate with pessimisticLock and try it again.

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