DCLDISKFILE UseKeyBuffer

Estimated reading time: 3 minutes

            [**UseKeyBuffer**](DCLDISKFILEUseKeyBuffer.html)

Optional. UseKeyBuffer specifies whether any keyed operation on the file (e.g. CHAIN) will consider its key parameter to be a key buffer, i.e. it will be considered as containing pieces of the key up to its length. *NO is the default.

• <u>*NO</u> (default) - indicates that the key parameter will not be considered a key buffer.
• *YES - indicates that any keyed operation on the file (e.g. CHAIN) will consider its key parameter to be a key buffer.

Example

For example, assume a file F has two key fields, K1 which is *char len(5) and K2 which is *zoned len(2,0).
Let B7 be a field in the program with type *char len(7) and value "abcde32".
Let B6 be a *char len(6) with value "abcde3".
Let B5 be a *char len(5) with value "abcde".

Assume F has the following records

chain F Key(B7) will read with full key the fourth record, as "abcde" will be moved into the first key field (K1) and 32 will be the moved into the second key field (K2) before the CHAIN. chain F Key(B6) will read with full key the third record, as "abcde" will be moved into the first key field (K1) and 3 with padding will be moved into the second key field (i.e. K2 = 30) chain F Key(B5) will read with partial key the second record, as "abcde" will be moved into the first key field (K1).

Internally the key buffer is put into a CHAR field, and then the CHAR field is chopped into pieces that are either MOVEd or byte-wise converted (as is the case for packed fields) into the key parts. If any MOVE fails you’ll get a runtime error.

If all the MOVEs succeed, and assuming whatever was moved ends up not being an existing key, the I/O operation will return the proper value according to its behavior (‘not found’ for CHAIN for instance, other operations like SETLL may succeed and set flags).

Remarks

The new behavior will occur only if:

• A single field is used in the Key parameter
• The single field is NOT a keylist

Otherwise the “normal” behavior will occur.

Example Program

Using System
Using System.Collections
Using System.Text

BegClass Program

       dcldb name(elm) DBName("elm")

       dcldiskfile myfile DB(elm) File("*LIBL/CSMASTERL2") type(*Input) org(*Indexed) impopen(*no) usekeybuffer(*yes)

       dclds myDS
              dcldsfld oneChar type(*char) len(5)
              dcldsfld one type(*packed) len(9,0) overlay(oneChar)
              dcldsfld two type(*zoned) len(4,0)

       dclfld fld len(9)

       BegSr Main Shared(*Yes) Access(*Public) Attributes(System.STAThread())
              DclSrParm args Type(*String) Rank(1)
              (*new Program()).fil()
       EndSr

       begsr fil
              connect elm
              open myfile
              one = 200
              two = 1994
              fld = myDS.Dump()
              chain myfile Key(fld)             // new behavior
              console.WriteLine( "{0} {1}", CSCUSTNO, CSYEAR )
              chain myfile Key(myDS)            // new behavior
              console.WriteLine( "{0} {1}", CSCUSTNO, CSYEAR )
              chain myfile Key(one, two)        // old behavior
              console.WriteLine( "{0} {1}", CSCUSTNO, CSYEAR )
              Console.ReadLine()
              close myfile
              disconnect elm
       endsr
EndClass

See Also

CLOSE

COMMIT

DCLDS

DCLDSFLD

DCLFLD

DCLPRINTFILE

LOOKUP

OPEN

ROLLBACK

DBFile Class Members

DBFile Class