by Charlie Callaway | Jun 24, 2018 | Uncategorized
A recent query I had to tune had a WHERE clause similar to this: where t.myno = 1 and t.jz1 not in(3,4,5) and (nvl(t.amount,0) != 0) and nvl(t.status,'!') != 'J' Notice the NVL functions. Let’s look at the first one. nvl(t.amount,0) != 0 In...
by Charlie Callaway | Jun 10, 2018 | Uncategorized
Sooner or later you come across a poor performing statement that you just know you could fix…if only you could add a hint. There’s one index it should use, a join order you prefer, or perhaps you are upgrading and would prefer that THIS statement not use the new...
by Charlie Callaway | May 27, 2018 | Uncategorized
Every so often I will look at an AWR report for a slow system, and updates to the data dictionary table SEQ$ will show up as a top resource consumer. This is usually because sequences are defined using NOCACHE. In this post we show why this matters and how to avoid...
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