RE: Chained vs. migrated rows - Any easy way to tell the

From: Christian Antognini <>
Date: Thu, 6 Nov 2008 10:35:33 +0100
Message-ID: <>

Hi Joel

> The difference between dba_tables.chain_cnt and what is contained
> in chained_rows table now is still a mystery. Stats are collected
> nightly.

DBMS_STATS doesn't compute the value chain_cnt. Therefore, there are two possibilities:
1) dba_tables.chain_cnt = 0
2) dba_tables.chain_cnt > 0

If 1, either the table doesn't contain chained/migrated rows or ANALYZE was never used to compute statistics for it.

If 2, at some time in the past the statistics were compute with ANALYZE. Since DBMS_STATS doesn't compute it, you see the value at the time of the last execution of ANALYZE.

Chris Antognini

Troubleshooting Oracle Performance, Apress 2008

Received on Thu Nov 06 2008 - 03:35:33 CST

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