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02-27-2008, 04:41 AM
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 Faster Runstats? Running DB2/UDB 8.1 on Linux, 16G RAM, 8 processors. We are currently converting data from legacy systems and after importing large amounts of data into multiple tables, I run a script that executes runstats on all columns with distribution on all columns and detailed indexes for every table in the database. At first, I had the default setting for stat_heap_sz, but increased it to 20000 and then 100000 and still haven't seen any improvement in speed. Currently, it takes about 2 hours to execute runstats. Any suggestions for increasing the speed? Thanks, Chris      |
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02-27-2008, 04:41 AM
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| Re: Faster Runstats? cbcobb@gmail.com wrote: > Running DB2/UDB 8.1 on Linux, 16G RAM, 8 processors. We are currently > converting data from legacy systems and after importing large amounts > of data into multiple tables, I run a script that executes runstats on > all columns with distribution on all columns and detailed indexes for > every table in the database. At first, I had the default setting for > stat_heap_sz, but increased it to 20000 and then 100000 and still > haven't seen any improvement in speed. Currently, it takes about 2 > hours to execute runstats. Any suggestions for increasing the speed? STAT_HEAP_SZ doesn't affect performance. Runstats will basically do table and index scans, so you want to tune your bufferpools and prefetching. Look at your tablespace layout and how the tablespace containers are placed on your disk drives. Also you could consider using sampling via the TABLESAMPLE and SAMPLED INDEXES option. Or, (make IBM happy) and license the database partitioning feature. :-) |
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02-27-2008, 04:42 AM
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| Re: Faster Runstats? <cbcobb@gmail.com> wrote in message news:1124725588.787604.289380@g47g2000cwa.googlegr oups.com... > Running DB2/UDB 8.1 on Linux, 16G RAM, 8 processors. We are currently > converting data from legacy systems and after importing large amounts > of data into multiple tables, I run a script that executes runstats on > all columns with distribution on all columns and detailed indexes for > every table in the database. At first, I had the default setting for > stat_heap_sz, but increased it to 20000 and then 100000 and still > haven't seen any improvement in speed. Currently, it takes about 2 > hours to execute runstats. Any suggestions for increasing the speed? > > Thanks, > > Chris > Most likely you do not need distribution on all columns. Key columns is enough. This is especially true now that you have run it once with all columns. |
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