Will having transaction date as the first column of a primary key cause contention

[Former Member]

Hi,

The Sybase IQ 16.0 Performance and Tuning Guide recommends having transaction date (for example) as the first column of a multi-column primary key to "force all data being loaded to be inserted at the end of the HG index structure in a very dense manner".

My question is, if we have multiple jobs loading data into the same table concurrently using RLV, will there be contention at the end of the index, since multiple jobs will be trying to update the table at the same location? That would be a problem in Sybase ASE. Is that an issue in IQ also?

[markmumy · Accepted solution]

No, this shouldn't be an issue.  With RLV you will have row level locking so no contention will be introduced unless you happen to insert 2 rows with the same values and same key.  But then primary key rules would kick in and prevent the second row from coming in.

Mark