Why spool, capture and then execute when you can do it all in one: declare l_ndv number; l_dummy number; l_srec dbms_stats.statrec; beginfor r in (select owner, table_name, column_name, null partition_name from DBA_TAB_COL_STATISTICS
histogram <> 'NONE' [ and possibly other criteria ] union allselect owner, table_name, column_name, partition_name from DBA_PART_COL_STATISTICS
histogram <> 'NONE' [ and possibly other criteria ] ) loop dbms_stats.get_column_stats ( ownname => r.owner, tabname => r.table_name, colname => r.column_name, partname => r.partition_name, stattab => null, statid => null, distcnt => l_ndv, density => l_dummy, nullcnt => l_dummy, srec => l_srec, avgclen => l_dummy); dbms_stats.set_column_stats ( ownname => r.owner, tabname => r.table_name, colname => r.column_name, partname => r.partition_name, distcnt => l_ndv); end loop; end; and no fighting with quotes :-)I believe if you have subpartitions you will need to export the statistics to a stattab table, manipulate the statistics there and then re-import as there is no set_column_stats for subpartitions.
At 06:23 PM 3/26/2007, Allen, Brandon wrote:
At first I was thinking that Alberto's procedure would still be required for retrieving the current stats and then resetting just the distcnt value. However, after thinking it through for a while, I realized what you were probably both thinking the whole time, which is that with this simplified method, you can just use a simple SELECT statement on all_tab_col_statistics to retrieve the current num_distinct value and plug it into the set_column_stats procedure for all columns that currently have histograms, thereby creating a script that can be used to very quickly remove all existing histograms. It took me a while to get all the single quotes just right, but here is the working version for anyone else that might find it helpful: select 'execute dbms_stats.set_column_stats(''' || owner || ''',''' || table_name || ''',''' || column_name || ''', distcnt=>''' || num_distinct || ''');' from all_tab_col_statistics where histogram <> 'NONE'; Sample Output: ---------------------------------------------------------------------- execute dbms_stats.set_column_stats('SCOTT','T','C1', distcnt=>'2421'); execute dbms_stats.set_column_stats('SCOTT','T','C2', distcnt=>'2425'); execute dbms_stats.set_column_stats('SCOTT','T','C3', distcnt=>'2421'); Thanks again to Wolfgang and Alberto! Regards, Brandon -----Original Message----- From: Alberto Dell'Era [mailto:alberto.dellera@xxxxxxxxx] Sent: Friday, March 16, 2007 4:43 PM To: breitliw@xxxxxxxxxxxxx Cc: Allen, Brandon; Oracle-L@xxxxxxxxxxxxx Subject: Re: Any quick way to remove histograms? Much simpler :) - interesting. On 3/16/07, Wolfgang Breitling <breitliw@xxxxxxxxxxxxx> wrote: > > I also did a quick check and just using > > exec > dbms_stats.set_column_stats(user,'table_name',colname=>'column_name',d > istcnt=> > <num_distinct>); > > will remove the histogram without removing the low_value and high_value. > > > > At 01:40 PM 3/16/2007, Alberto Dell'Era wrote: > >On 3/16/07, Allen, Brandon <Brandon.Allen@xxxxxxxxxxx> wrote: > >>Is there any faster way to remove histograms other than re-analyzing > >>the table? I want to keep the existing table, index & column stats, > >>but with only 1 bucket (i.e. no histograms). > > > >You might try the attached script, that reads the stats using > >dbms_stats.get_column_stats and re-sets them, minus the histogram, > >using dbms_stats.set_column_stats. > > > >I haven't fully tested it - it's only 10 minutes old, even if I have > >slightly modified for you another script I've used for quite some > >time - and the spool on 10.2.0.3 seems to confirmthat the histogram > >is, indeed, removed, while all the other statistics are preserved. I > >have also reset density to 1/num_distinct, that is the value you get > >if no histogram is collected.Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it.
Regards Wolfgang Breitling Centrex Consulting Corporationwww.centrexcc.com
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