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ravindran1185
New User
Joined: 03 Nov 2008
Posts: 7
Location: Chennai
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Hi,
The scenario is to read the last but previous line of a PS file all the times.
i have explained two logics 1) the Count-1 logic, But the file may contain millions of record. 2) reading the PS file backwards, but No key will be specified for that file.
If anybody knows the optimized logic, please post here.
Thanks in advance. |
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salltm
New User
Joined: 21 Aug 2008
Posts: 8
Location: china
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| it is difficult .. i suggest you create a index of the file..use the key way to read the file... |
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Escapa
Senior Member
Joined: 16 Feb 2007
Posts: 1399
Location: IL, USA
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| Code: |
//STEP0100 EXEC PGM=ICETOOL
//SYSOUT DD SYSOUT=*
//TOOLMSG DD SYSOUT=*
//DFSMSG DD SYSOUT=*
//IN DD dsn=your input file
//OUT DD dsn=your output file
//TOOLIN DD *
SUBSET FROM(IN) TO(OUT) KEEP INPUT LAST(2)
/*
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Now I will read first record of output file (which is actually second last record of input file) |
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expat
Global Moderator
Joined: 14 Mar 2007
Posts: 8797
Location: Welsh Wales
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| salltm wrote: |
| it is difficult .. i suggest you create a index of the file..use the key way to read the file... |
How would you create an index for a PS file ? |
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superk
Global Moderator
Joined: 26 Apr 2004
Posts: 4652
Location: Raleigh, NC, USA
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| ravindran1185 wrote: |
| 2) reading the PS file backwards... |
I hope you know that's not possible. |
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gcicchet
Senior Member
Joined: 28 Jul 2006
Posts: 1702
Location: Australia
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Hi.
I know fileaid allows you to read the file backwards.
Gerry |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
Why are the last 2 records needed?
If the file is huge (hundreds of millions of records or whatever) suggest that when the file is created, the process could create another little file that contains only the last 2 records. . . Or these 2 entries might be put in some database table . . . Or. . . |
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