Sponsored Content
Full Discussion: Optimizing query
Special Forums UNIX and Linux Applications Optimizing query Post 302130445 by kahuna on Monday 6th of August 2007 09:06:11 AM
Old 08-06-2007
I made a test table with a single varchar field and no index. I loaded it with 30,000 records and an additional 30 duplicate records. I ran the following queries.

Code:
select count(*) FROM tableA
WHERE rowid not in
(SELECT MIN(rowid) FROM tableA GROUP BY column1);

1 hour 12 minutes 58 seconds

Code:
select count(*) FROM tableA A1
WHERE column1 in (SELECT column1 FROM tableA GROUP BY column1 having count(*)
> 1)
and rowid != (select min(rowid) from tableA A2 where A1.column1 = A2.column1);

1 second

Code:
select count(*) from tableA a
     where rowid <> ( select max(rowid)
                        from tableA b
                       where b.column1 = a.column1);

6 min 29 sec

Your mileage may vary.

Last edited by kahuna; 08-06-2007 at 11:04 AM..
 

10 More Discussions You Might Find Interesting

1. Filesystems, Disks and Memory

Optimizing the system reliability

My product have around 10-15 programs/services running in the sun box, which together completes a task, sequentially. Several instances of the each program/service are running in the unix box, to manage the load and for risk-management reasons. As of now, we dont follow a strict strategy in... (2 Replies)
Discussion started by: Deepa
2 Replies

2. Filesystems, Disks and Memory

optimizing disk performance

I have some questions regarding disk perfomance, and what I can do to make it just a little (or much :)) more faster. From what I've heard the first partitions will be faster than the later ones because tracks at the outer edges of a hard drive platter simply moves faster. But I've also read in... (4 Replies)
Discussion started by: J.P
4 Replies

3. Shell Programming and Scripting

Optimizing for a Speed-up

How would one go about optimizing this current .sh program so it works at a more minimal time. Such as is there a better way to count what I need than what I have done or better way to match patterns in the file? Thanks, #declare variables to be used. help=-1 count=0 JanCount=0 FebCount=0... (3 Replies)
Discussion started by: switch
3 Replies

4. OS X (Apple)

Optimizing OSX

Hi forum, I'm administrating a workstation/server for my lab and I was wondering how to optimize OSX. I was wondering what unnecessary background tasks I could kick off the system so I free up as much memory and cpu power. Other optimization tips are also welcome (HD parameters, memory... (2 Replies)
Discussion started by: deiphon
2 Replies

5. Shell Programming and Scripting

Optimizing the code

Hi, I have two files in the format listed below. I need to find out all values from field 12 to field 20 present in file 2 and list them in file3(format as file2) File1 : FEIN,CHRISTA... (2 Replies)
Discussion started by: nua7
2 Replies

6. Shell Programming and Scripting

Optimizing awk script

Can this awk statement be optimized? i ask because log.txt is a giant file with several hundred thousands of lines of records. myscript.sh: while read line do searchterm="${1}" datecurr=$(date +%s) file=$(awk 'BEGIN{split(ARGV,var,",");print var}' $line) ... (3 Replies)
Discussion started by: SkySmart
3 Replies

7. Shell Programming and Scripting

Optimizing search using grep

I have a huge log file close to 3GB in size. My task is to generate some reporting based on # of times something is being logged. I need to find the number of time StringA , StringB , StringC is being called separately. What I am doing right now is: grep "StringA" server.log | wc -l... (4 Replies)
Discussion started by: Junaid Subhani
4 Replies

8. Shell Programming and Scripting

Optimizing find with many replacements

Hello, I'm looking for advice on how to optimize this bash script, currently i use the shotgun approach to avoid file io/buffering problems of forks trying to write simultaneously to the same file. i'd like to keep this as a fairly portable bash script rather than writing a C routine. in a... (8 Replies)
Discussion started by: f77hack
8 Replies

9. Shell Programming and Scripting

Optimizing bash loop

now, i have to search for a pattern within a particular time frame which the user will provide in the following format: 19/Jun/2018:07:04,21/Jun/2018:21:30 it is easy to get tempted to attempt this search with a variation of the following awk command: awk... (3 Replies)
Discussion started by: SkySmart
3 Replies

10. Web Development

Optimizing JS and CSS

Yes. Got few suggestions. - How about minifying resources - mod_expires - Service workers setup https://www.unix.com/attachments/web-programming/7709d1550557731-sneak-preview-new-unix-com-usercp-vuejs-demo-screenshot-png (8 Replies)
Discussion started by: Akshay Hegde
8 Replies
SELECT 
INTO(7) SQL Commands SELECT INTO(7) NAME
SELECT INTO - create a new table from the results of a query SYNOPSIS
SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] * | expression [ AS output_name ] [, ...] INTO [ TEMPORARY | TEMP ] [ TABLE ] new_table [ FROM from_item [, ...] ] [ WHERE condition ] [ GROUP BY expression [, ...] ] [ HAVING condition [, ...] ] [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ] [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ] [ LIMIT { count | ALL } ] [ OFFSET start ] [ FOR UPDATE [ OF tablename [, ...] ] ] INPUTS TEMPORARY TEMP If specified, the table is created as a temporary table. Refer to CREATE TABLE [create_table(7)] for details. new_table The name (optionally schema-qualified) of the table to be created. All other inputs are described in detail for SELECT [select(7)]. OUTPUTS Refer to CREATE TABLE [create_table(7)] and SELECT [select(7)] for a summary of possible output messages. DESCRIPTION
SELECT INTO creates a new table and fills it with data computed by a query. The data is not returned to the client, as it is with a normal SELECT. The new table's columns have the names and data types associated with the output columns of the SELECT. Note: CREATE TABLE AS [create_table_as(7)] is functionally equivalent to SELECT INTO. CREATE TABLE AS is the recommended syntax, since SELECT INTO is not standard. In fact, this form of SELECT INTO is not available in PL/pgSQL or ecpg(1), because they interpret the INTO clause differently. COMPATIBILITY
SQL92 uses SELECT ... INTO to represent selecting values into scalar variables of a host program, rather than creating a new table. This indeed is the usage found in PL/pgSQL and ecpg(1). The PostgreSQL usage of SELECT INTO to represent table creation is historical. It's best to use CREATE TABLE AS for this purpose in new code. (CREATE TABLE AS isn't standard either, but it's less likely to cause confu- sion.) SQL - Language Statements 2002-11-22 SELECT INTO(7)
All times are GMT -4. The time now is 02:54 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy