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Re: RE: RE: How do I select composite array element that satisfyspecific conditions. - Mailing list pgsql-general

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Subject Re: RE: RE: How do I select composite array element that satisfyspecific conditions.
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In response to Re: RE: RE: How do I select composite array element that satisfyspecific conditions.  ("David G. Johnston" <david.g.johnston@gmail.com>)
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Thank you so much for you suggestion, it is probably a better way to normalize the data to a policy data an using multiple tables.

The millions of table is not true (but there are around 60 database instances), but the hundreds of lines of query are the actual queries provided by current db team (actually, all queries from them are more than 200 lines).

I may try both of them since I am half way around my original plan. 

To link everything to policy number is my original attempt, the reason I give up and apply array is due to the historical transaction data, status update and multiple policies in one contract. But surly, by summarizing and reformatting the current structure, it will reduce significant number of tables and make it relatively easy.

Thank you again for you advice!!

shore


------------------ Original message ------------------
From: "David G. Johnston";
Sendtime: Wednesday, May 23, 2018 10:29 PM
To: "a"<372660931@qq.com>;
Cc: "Charles Clavadetscher"; "pgsql-general";
Subject: Re: RE: RE: How do I select composite array element that satisfyspecific conditions.

On Wed, May 23, 2018 at 6:50 AM, a <372660931@qq.com> wrote:

That is only by saying, the actual information could be much more, and all of them are not in some way, "aligned". 

?Not sure what you are getting at here - "related" is generally the better term and usually during modeling one of the tasks is to identify those relationships even if they seem to be obscure.?  In this case most everything is likely related by policy number one way or another.
 
The results would be millions(which means many) of tables lies in database and each query is hundreds of lines. It is hard to create new query that target your info and it is dangerous to modify any set query.

?I seriously doubt you'd end up with millions of tables...and hundred line queries are likely going to happen in spite of your attempts to simplify.  In fact I'd say the number of "complex" lines will end up being higher - most of the lines in a normal query against a normalized database are verbose but simple.

Now my think was to group data into structures so that I can significantly decrease the amount of table, and since it can hold array, I can actually put historical data into one table for one year, which stops query from multiple historical tables and shrink the size of database.

?An array of composites is a table - your just making things difficult by not actually creating one up front.?

However, I am new to this and do not have experience, so if you could provide any suggestion, it would be extremely grateful from me.

?The scope of this database seems to be a bit much for one's first attempt at doing something like this...?

I'd recommend learning and then applying as much technical normalization as you can to your model and assume that years of modelling theory is going to be a better guide than inexperienced gut instinct.  Starting from a normalized position you can selectively de-normalize and add abstraction layers later when you come across actual problems that you wish to solve.

David J.

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