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Stack Processing in REXX

 
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ribinmathew

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PostPosted: Mon Jan 19, 2009 10:15 pm    Post subject: Stack Processing in REXX
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Hi All,

I'm in the process of developing a tool in REXX which has to search for a string in flat PS file and when found, i need to copy some particular number of records above and below the line containing that particular string to another PS file.

The real problem I'm facing is, the file which has to be read contains very huge number of records so that operation of reading and searching using stem variables is not possible. So I need to go for a STACK operation of reading file into STACK and thereafter writing records from STACK into file is required. As I'm not that familier to STACK operations, can anybody help me out.

Thanks in advance
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Pedro

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PostPosted: Mon Jan 19, 2009 10:27 pm    Post subject: Reply to: Stack Processing in REXX
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Quote:
operation of reading and searching using stem variables is not possible.

The typical problem with large files is that your region gets full (you run out of private memory).

You still use memory when you use the STACK! Surprise! For a large number of records, your private memory will still get full.

When working with large files, the recommendation is to use a process that reads a manageable number of records, say 10000, into the stem with EXECIO. Then process those 10000 before continuing to the next.
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ribinmathew

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PostPosted: Thu Jan 22, 2009 10:14 pm    Post subject: Reply to: Stack Processing in REXX
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Hi,

Thanks for your reply. Actually I'm facing some probs with processing the file after splitting it, as you suggested. I used the method of populating a consistent number of records into stem variables and process it and then continue the same process with calling the same logic repeatedly. But the problem is that you need to resume reading the file from the record where I stopped processing during the last iteration and I did so by coding the same logic repeatedly depending on the number of records present record. But this is not a consistent logic or solution for the problem I'm facing because number of records in each file varies from thousands to lakhs. Can any one suggest a solution for this problem in file processing.

Thnaks in advance.
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expat

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PostPosted: Thu Jan 22, 2009 10:24 pm    Post subject:
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Read THIS topic so see how it works.
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dick scherrer

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PostPosted: Thu Jan 22, 2009 11:04 pm    Post subject:
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Hello,

You might consider doing this in batch using something other than rexx. . .

I believe it is neither a good candidate for an "online" process, nor a good candidate for rexx icon_neutral.gif
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Peter Poole

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PostPosted: Mon Jan 26, 2009 5:13 am    Post subject: Re: Stack Processing in REXX
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ribinmathew wrote:
Hi All,

I'm in the process of developing a tool in REXX which has to search for a string in flat PS file and when found, i need to copy some particular number of records above and below the line containing that particular string to another PS file.

Thanks in advance


Are the number(s) of required records above and below a successfully selected line constant(s)?

If so, all you need to do is set up an array of the required number of previous records and then process the file one record at a time. When you get a hit, pull in the previous lines from that array and call a routine to read the next set of lines. When you don't get a hit, shuffle the records in the array up by one and add the current line to the bottom of the array.

It's probably not the most elegant solution, but it should do what you asked for.

Cheers.
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Pedro

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PostPosted: Mon Jan 26, 2009 10:23 pm    Post subject: Reply to: Stack Processing in REXX
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Quote:
But this is not a consistent logic or solution for the problem I'm facing because number of records in each file varies from thousands to lakhs.


It is not clear what problem you are having. Use EXECIO to ask for a certain number of records. But I think the zero element of the stem will have the actual number for records retrieved. It should not matter how many records are actually in the file.
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Peter Poole

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PostPosted: Tue Jan 27, 2009 1:09 am    Post subject:
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As I understand the spec (Mathew, please correct me if I'm speaking through my bottom!)

On finding a qualifying record, he needs to take x records previous to that one and y records subsequent to that. If he reads the file in stemmed 'blocks' of 500 - or any other number - and gets a match on the seond record of the second 'block' then his previous record requirement may well take him to the last few records in 'block' 1, which he's just overwritten by reading 'block' 2....

Cheers!
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enrico-sorichetti

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PostPosted: Tue Jan 27, 2009 1:25 am    Post subject: Reply to: Stack Processing in REXX
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I do not understand why people want to complicate their lives
there is a wondeful utility called ISRSUPC that produces this output

Code:

==MSG> -CAUTION- Profile changed to CAPS OFF (from CAPS ON) because data
==MSG>           contains lower case characters.
000001 1  ISRSUPC   -   MVS/PDF FILE/LINE/WORD/BYTE/SFOR COMPARE UTILITY- ISPF
000002   LINE-#  SOURCE SECTION                    SRCH DSN: ENRICO.DAF.DISTR(D
000003
000004        4  //*            DSN's of SYS1.xxxxxxxx map into SMPE DDDEFs of
000005        6  //STEPLIB   DD DISP=SHR,DSN=SYS1.SASMMOD1,
000006        9  //          DD DISP=SHR,DSN=SYS1.SGLOSAMP,   Allocation Optimi
000007       11  //          DD DISP=SHR,DSN=SYS1.SASFPMAC,                  Ba
000008       13  //          DD DISP=SHR,DSN=SYS1.MACLIB,
000009       15  //          DD DISP=SHR,DSN=SYS1.MODGEN,
000010       17  //          DD DISP=SHR,DSN=SYS1.SBDTMAC,     Bulk Data Transf
000011       19  //          DD DISP=SHR,DSN=SYS1.SEZACMAC,
000012       21  //          DD DISP=SHR,DSN=SYS1.SICEUSER,
000013       23  //          DD DISP=SHR,DSN=SYS1.NFSMAC,
000014       25  //          DD DISP=SHR,DSN=SYS1.SDVGMAC0,          NetView FT
000015       27  //          DD DISP=SHR,DSN=SYS1.SDBNIMAC,
000016      113  * DFPACS   Set SMFRECNO to nnn in SYS1.SACBCNTL(IGDACSSC)
000017     1608   MNOTE 255,'* macro was not found - it is usually in SYS1.SGL




Code:

Command ===>                                                  Scroll ===> CSR
000018     1625   MNOTE 255,'* macro was not found - it is usually in SYS1.SASF
000019     1642   MNOTE 255,'* macro was not found - it is usually in SYS1.SBDT
000020     1659   MNOTE 255,'* macro was not found - it is usually in SYS1.SICE
000021     1676   MNOTE 255,'* macro was not found - it is usually in SYS1.SDVG
000022     1693   MNOTE 255,'* macro was not found - it is usually in SYS1.SDBN
000023     1710   MNOTE 255,'* macro was not found - it is usually in SYS1.SEZA
000024     1727   MNOTE 255,'* macro was not found - it is usually in SYS1.SEZA
000025     3077           CLC   0(17,R3),=C'SYS1.DFDSS.DEFRAG' Special DEFRAG ?
000026
000027 1  ISRSUPC   -   MVS/PDF FILE/LINE/WORD/BYTE/SFOR COMPARE UTILITY- ISPF
000028       SEARCH-FOR SUMMARY SECTION            SRCH DSN: ENRICO.DAF.DISTR(D
000029
000030  LINES-FOUND  LINES-PROC  DATASET-W/LNS  DATASET-WO/LNS  COMPARE-COLS  L
000031         22        16269            1              0           1:80
000032
000033  PROCESS OPTIONS USED: ANYC
000034
000035  THE FOLLOWING PROCESS STATEMENTS (USING COLUMNS 1:72) WERE PROCESSED:
000036     SRCHFOR  'SYS1.'
000037



as You can see the isrsupc output shows the line where the string was found

it' s trivial to build from the srchfor output a sort step to copy the wanted records
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Peter Poole

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PostPosted: Tue Jan 27, 2009 1:38 am    Post subject:
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If people didn't want to complicate their lives, 90% of today's IT projects might never have been initiated icon_smile.gif

I pretty certain you could probably do the whole process in one swell foop using FileAid, but that would not answer the question asked.

Cheers.
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enrico-sorichetti

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PostPosted: Tue Jan 27, 2009 2:30 am    Post subject: Reply to: Stack Processing in REXX
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the point is that the TS is trying to use the wrong tool icon_biggrin.gif
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Peter Poole

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PostPosted: Tue Jan 27, 2009 2:41 am    Post subject:
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TS?

Cheers.
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dick scherrer

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PostPosted: Tue Jan 27, 2009 2:50 am    Post subject:
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Hello,

TS = Topic Starter. . .

One thought is that while some things are possible, maybe they shouldn't be done. . . Unless somone in the family has the hardware account icon_smile.gif
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enrico-sorichetti

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PostPosted: Tue Jan 27, 2009 2:51 am    Post subject: Reply to: Stack Processing in REXX
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TS ==> topic/thread starter
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enrico-sorichetti

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PostPosted: Tue Jan 27, 2009 3:16 am    Post subject: Reply to: Stack Processing in REXX
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another point....
thats not really a STACK that is needed
( but, as usual, the terminology depends on the poster's background)

from my point of view a STACK ( without a qualifier ) is a LIFO thing

the TS really needs a FIFO thing
and I would rather call it a QUEUE or SLIDING window

and the logic gets really nice when the records hit by the search string fall within the keep distance
( if You work with the sliding window logic it is pretty easy to do it )
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expat

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PostPosted: Tue Jan 27, 2009 12:18 pm    Post subject:
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I'd go with Enricos suggestion of knowing where the lines are, and then simply building the reads around them.

The OP should pursue this track.
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Peter Poole

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PostPosted: Tue Jan 27, 2009 4:43 pm    Post subject:
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TS - grazi. We live, we learn.

For the rest, well:

"There's more than one way to skin a cat" he said, ignoring the piteous mewling as he pinned the tiny paws to the easel....

Mathew, has this helped at all, or have you lost the will to live by now?

Cheers.
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