Re: Is Cursor Plan an SQL Trace Execution Plan ? ........... Basic Qs

  • From: Nigel Thomas <nigel_cl_thomas@xxxxxxxxx>
  • To: VIVEK_SHARMA@xxxxxxxxxxx, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 7 Sep 2007 00:22:40 -0700 (PDT)


The question Alvaro didn't answer: 

Qs 1 Why is the Old Hash Value i.e 3246265085 the SAME for the SAME SQL Script 
for BOTH the Databases i.e NON-RAC & 2-Node RAC-ASM? 

The hash value is calculated from the SQL text only. The SQL text is the same 
on both databases therefore so is the hash value. The hash value is just a 
convenient way of "labeling" the SQL so that instead of having to compare what 
can be very large text strings (eg 4000 chars or more) you can match (and 
index) on a short hash, and then use the text itself only to distinguish the 
rare cases where two different SQL statements have the same hash value and so 
would collide in a hash table.

Regards Nigel

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