4

I can not use NOLOCK after table names in join statements. Is it even a valid scenario to try to read uncommitted data over JOINs

Naren Karanam
  • 61
  • 1
  • 3
  • 10
  • 3
    You don't need this in Oracle, readers never block writers. Plus: Oracle does not support dirty reads –  Jul 19 '16 at 07:08

1 Answers1

9

The join is irrelevant. NOLOCK isn't used in Oracle. A query will only see committed data (plus any uncommitted changes in the transaction performing the query).

You can write a query such as SELECT * FROM tbl NOLOCK but NOLOCK is simply being used as a table alias and doesn't change the querying mechanism.

Gary Myers
  • 34,963
  • 3
  • 49
  • 74
  • 3
    To add, (NOLOCK) hint is commonly used when executing queries that read many rows as the default read consistency model in SQL Server uses shared locks therefore reads block writes as well as there might happen lock escallation. So even with simple query you can lock whole table or more tables and no one can modify the data until your query finishes. Oracle uses snapshot read consistency and doesn't store locks in memory so there isn't anything like lock escallation there. – Husqvik Jul 19 '16 at 06:16