Showing posts with label optimizer. Show all posts
Showing posts with label optimizer. Show all posts
Wednesday, February 23, 2022

When explaining a query that is accessing a partitioned table, what does the Pstart=KEY or Pstop=KEY indicate?

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The Pstart=KEY or Pstop=KEY indicate that the exact partition cannot be determined at compile time, but will most likely be found during r...
Wednesday, June 12, 2019

How to use dbms_stats.report_col_usage

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set long 10000 select dbms_stats.report_col_usage('SALES', 'ORDERS') from dual; exit Output could look something like thi...
Tuesday, April 17, 2018

Syntax for index hint

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Use /*+ INDEX(table_name index_name) */ For example: set autot trace exp stat select /*+ INDEX(MYTABLE MY_IDX1) */ min(entry_num) from s...
Tuesday, April 10, 2018

More on finding failed autostats jobs

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In a previous post , I showed how to check if an autostats job had succeeded. Recently I had to unlock table stats on a very large parti...
Tuesday, February 13, 2018

Why doesn't dbms_stats.set_schema_prefs seem to work?

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When trying to alter the default settings for statistics gathering on partitioned tables, I had troubles setting schema-level preferences us...
Tuesday, December 5, 2017

How to execute and capture an SQL statement in the SMB at the same time

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An experienced co-worker showed me this neat trick to execute an SQL statement and capture its execution plan in the SQL Plan Management Ba...
Wednesday, November 15, 2017

How to find the number of full table scans

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From the Oracle Documentation : The view DBA_HIST_SEG_STAT view displays historical information about segment-level statistics. This vie...