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Re: Datawarehouse suggestions?

From: <tday6_at_csc.com>
Date: Tue, 04 Sep 2001 07:13:31 -0700
Message-ID: <F001.003819D0.20010904055719@fatcity.com>

I'd definitely go with the partitioning. The only question that I'd have is whether I would make the partition large enough to satisfy a single user's query or small enough that it could reside in the SGA. I guess that that depends on how many users are querying at one time. Just off the top of my head I'd say that if you have more than 10 simultaneous users go with larger partitions. Each individual query may take longer but no query will get stuck in the queue. With the smaller partition, each individual query should be optimized but if there are too many queries, it may take a while before any particular query can get up to bat.

Take it with a grain of salt. Just thinking off the top of my head on the first day back from holiday.                                                                                             

                    "Rachel                                                            
    
                    Carmichael"          To:     Multiple recipients of list ORACLE-L  
    
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Okay, first the rant.... they want me to build a new database to hold logs of every time someone hits a page on our website or uses one of the functions on the site. Without a new server or disk, on a box that currently holds the OLTP database, on a disk array that is RAID 5 and that EMC wants to take BACK disks from. In other words, they want magic. Where did I leave that rabbit and hat?

end rant, here's the setup:

Conservative estimate says that one of the two main tables (at least for now) will grow to a GB in a year or two, the other will hit 500M in that timeframe. Rough estimates of # of rows is 273M for the first table, 70M for
the second over 2 years. Rows are < 200 bytes at max. There will be several
small lookup tables and the number of logging tables will increase over time.

They are NOT talking about purging data, ever. And we are hoping that the volume INCREASES, not decreases or remains the same, which means the space estimates are no more realistic than throwing a dart at a board and picking a number.

Oh yeah, did I mention that they want this to be a reporting database for external customers (read revenue stream) and want these external people to be able to query on any combination of columns -- so they want indexes on EVERY column.

I will have a nightly maintenance window for loads of prior day's data. I'm thinking to do a shutdown, change the init.ora to tune for heavy batch, startup, drop indexes, load data, recreate indexes, shutdown, backup, startup with init.ora tuned for querying.

question:

I've always worked on either batch reporting databases or OLTP, this will be
the first semi, sort of data warehouse for me. Advice please on how to build
this, as I am doing this one from scratch and can plan it.

I'm thinking:

database will be 8.1.7, Solaris 2.7

rbs and temp tablespaces as LMTs, remaining tablespaces dictionary-managed

db_block_size 16K

a "large table" tablespace with initial/next at 10M a "large index" tablespace as above

a "small table" tablespace with initial/next at 16K a "small index" tablespace as above

possibly partitioning (I have to check our licenses) on the timestamp field.

Any suggestions, gotchas, "this is WRONG, here's how to do it" comments?

Thanks

Rachel



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Author: Rachel Carmichael
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Received on Tue Sep 04 2001 - 09:13:31 CDT

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