[MikeR]

Для карсоты решения еще раз приведу утверждения

1 С чего все началось:

ttsbegin;
    WHILE(TRUE)
    {
        SELECT FIRSTONLY current WHERE current.InvGuid == InvGUID;
        InvGUID = current.ParentInvGUID;

        SELECT FIRSTONLY parent WHERE current.ParentInvGUID == parent.InvGUID;

        if(parent)
        {
            //parentDistr.disableCache();
            SELECT FIRSTONLY
            FORUPDATE parentDistr
            WHERE parentDistr.InvGUID == InvGUID &&
                parentDistr.TransRecId == inventoryGuidInvoice.TransRecId
                //...........
                && parentDistr.JuridicalPersonId == inventoryGuidInvoice.JuridicalPersonId;

            if(parentDistr)
            {
                parentDistr.AMOUNTCUR += inventoryGuidInvoice.AmountCur;//слияние к предку
                //.......
                parentDistr.Update();
            }
            else
            {
                parentDistr.data(InventoryGuidInvoice);
                parentDistr.InvGUID = parent.InvGUID;
                parentDistr.insert();
            }
        }
        else
        {
            break;
        }

        current.clear();
    }
    ttscommit;

2 Моя формулировка

while select
{
	ttsbegin;
	select forupdate 
	ttscommit;
}

3 Что гласит документация :

DO NOT: Hold database locks for longer than is necessary.
DO: Limit the transaction scope by grabbing locks at the latest possible time and
releasing locks as early as possible.

4 Не корректный код, читай в п1

ttsBegin; 
 
while select ItemId 
    from salesLine 
{ 
    select firstOnly forUpdate ItemType, ItemBuyerGroupId  
       from inventTable 
           where inventTable.ItemId == salesLine.ItemId; 
 
    If (inventTable && (inventTable.ItemType == InventItemType::Item)) 
    { 
         inventTable.ItemBuyerGroupId = ; 
         inventTable.update(); 
    } 
} 
 
ttsCommit;

5 Корректный код

while select ItemId 
    from salesLine 
{ 
    select firstOnly forUpdate ItemType, ItemBuyerGroupId  
       from inventTable 
           where inventTable.ItemId == salesLine.ItemId; 
 
    If (inventTable && (inventTable.ItemType == InventItemType::Item)) 
    { 
        ttsBegin; 
        inventTable.ItemBuyerGroupId = ; 
        inventTable.update(); 
        ttsCommit; 
    } 
}