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TableMaxReadLockCount |
Wed, Mar 21 2007 9:57 AM | Permanent Link |
"Jose Eduardo Helminsky" | Tim
IŽve been looking the source code of DBISAM (specifically at dbisamen.pas) and I have a doubt about TableMaxReadLockCount. It canŽt be set to 0 (no locks) and the default value is 100. For each 100 records browsed (internally by engine) there is a lock/unlock situation. Some time ago, I have made some tests and check performance impact changing this value to 1 for example and I have realized this became better for shortest values. I know that there are concurrency problems with table (100.000 records locked) but I have a lot of SQL that query old data (no updates) and therefore I think this is not necessary to lock the table to prevent updates. It will improve a lot the performance of SQL query. My question: It canŽbe changed to 0 (no locks) ? Eduardo |
Wed, Mar 21 2007 4:43 PM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Eduardo,
<< It canŽt be set to 0 (no locks) and the default value is 100. For each 100 records browsed (internally by engine) there is a lock/unlock situation. Some time ago, I have made some tests and check performance impact changing this value to 1 for example and I have realized this became better for shortest values. I know that there are concurrency problems with table (100.000 records locked) but I have a lot of SQL that query old data (no updates) and therefore I think this is not necessary to lock the table to prevent updates. It will improve a lot the performance of SQL query. My question: It canŽbe changed to 0 (no locks) ? >> No, it has to be 1 or higher. Setting it to 0 does not prevent the initial lock, it would simply prevent DBISAM from ever releasing the lock, which would cause a serious issue with your database. -- Tim Young Elevate Software www.elevatesoft.com |
Wed, Mar 21 2007 5:01 PM | Permanent Link |
"Jose Eduardo Helminsky" | Tim
> No, it has to be 1 or higher. Setting it to 0 does not prevent the > initial lock, it would simply prevent DBISAM from ever releasing the lock, > which would cause a serious issue with your database. Ok. Got it. Eduardo |
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