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Date:         Mon, 4 Dec 2006 14:27:25 -0500
Reply-To:     "Fehd, Ronald J. (CDC/CCHIS/NCPHI)" <rjf2@CDC.GOV>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Fehd, Ronald J. (CDC/CCHIS/NCPHI)" <rjf2@CDC.GOV>
Subject:      Re: SQL and Dictionary Tables: slow with many librefs?
Content-Type: text/plain; charset="us-ascii"

> From: Robert Bardos > my recent proposal in another forum of using PROC SQL and the > dictionary tables to answer a simple question related to > dataset variables was questioned by a knowledgeable forum > member telling he had experienced performance problems with > this technique when a large number of librefs was involved. > > My query contained a where statement specifying both a > libname and two memnames (datasets). None of them were > specified using wildcards. So even with a huge number of > librefs, datasets and variables I fail to see where a very > specific dictionary query would be significantly slower than > a combination of similarly specific "proc contents out=" > executions followed by an SQL query over resulting smaller dataset. > > What do you think?

The more librefs+tables -- it's not just librefs, but total MemNames -- you have, the slower you go. I had an application working find in unit testing; when I started doing the integration testing (running all modules sequentially) it just kept getting slower, and slower. reason: I was writing new tables to the libref from which I was using SQL to pick out the last set of names of tables to process in the next step.

I disabled the sql list processing and used <horrors!> global macro variable(s) to pass the data set list.

moral: Not every good trick works everywhere!

Ron Fehd the SQL into:macro maven CDC Atlanta GA USA RJF2 at cdc dot gov

Repetition obfuscates! Repetition reduction enhances elegance! Repetition reduction furthers finesse!

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