Re: Are level checks still useful? -- RPG400-L

The php side of things will see this also as a fail.
they will need to change their programs to point to the new file.

"we add fields 'ALL THE TIME' in MySQL/MSSQL, and we don't have problems
or have to touch other PHP programs. Why does DB2 for i?"

-gerald

On 11/1/2012 9:27 AM, Charles Wilt wrote:

YES, YES, YES...a thousand times YES. Level checks are useful and it is a
horrible idea to turn them off.

If you want to add fields without recompiling....

1) create a new physical with the new fields (using DDS or SQL DDL)
2) create a logical with the same name and format (fields and keys) as the
original physical
3) repoint existing logicals to the new physical (need to explicitly list
fields if they don't already have their own format)
4) create new one or more new logicals (specifying all fields now in the
new physical)

When you do this process correctly, you end up with every
originally existing object having the same "format level identifier" and
thus it will not cause level checks.

Make sure that from now on your RPG programs using RLA only access a
through a logical and you'll be able to add new fields to the physical
without doing anything to existing logicals or programs. Sure you'd need a
one or more new logicals that include the new fields. But as long as the
new logicals have the same key as an existing, there basicaly no overhead
for them beyond a few bytes of space for the object definition itself. In
addition to not using the new physical on a f-spec, don't use it for
anything like defining a DS with EXTNAME(). The idea is to separate the
physical format of the data from what your HLL apps see.

SQL does this automatically, so SQL programs can access the physical, just
make sure you don't use SELECT * FROM MYNEWPF...

HTH,
Charles

On Thu, Nov 1, 2012 at 9:17 AM, dale janus<dalejanus@xxxxxxxxxxxxxxxxx>wrote:

We are in the slow, gradual process of changing from DDS to DDL.
Actually, we are creating new files with ops navigator and usually not
keeping the create specs. We just use navigator to change the file when
needed. Mostly we need record ID and timestamp, or date fields added.

But we have lots of old files. Yesterday, we needed to add 2 fields to a
file (a timestamp and a record id, both added with DDL in ops nav.)
Since we are adding the fields to the end of the files, we figured this
would be a good time to remove level check from the file. But it did not
work.

Here is our process for adding new fields to a file. We have a library
that contains all our RPG, DDL, CL etc. but no data. We add the new
fields to the file (called DIRECT). We change to level check *no. This
creates an empty file with the new fields.

We write a CL program to copy the data from production library to empty
library using CPYF with *nochk. Then in the production library we delete
all the logicals, rename the existing file to DIRECTOLD. Next CPYF from
the empty library file (now filled with production data and new fields)
to the production library, CRTFILE(*YES) then recreate the logicals.

When checking with DSPFD, both the file in the empty library and
production library say:
Record format level check . . . . . . . . . : LVLCHK *NO

Yet when I run programs against the file DIRECT or its logicals, I get
level check CPF4131errors.

So I had to recompile all the programs anyway.

We are a small shop with just 2 of us. We write all our own code, so we
are quite sure that adding fields to the end of a record will not affect
old programs.

I am RPG guy, my associate is PHP/WEB guy. He just kind of rolls his
eyes at me when I jump through all these hoops to add fields. His PHP
programs just keep on rolling, no matter what the file looks like.

So this long discourse asks two questions.

Why do my RPG programs (some RPG III, some ILE) insist on level check
when the file says LVLCHK *NO?

And

Is level check still useful? The ability to quickly add fields to files
seems to outweigh the comfort of your rpg programs knowing exactly what
the file looks like. Especially when half (uhh, maybe not half but lots
of them) of your programs are PHP.

---Dale

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