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9.2 Sorting Files

To sort files, use the DCL command SORT. Specify the names of the files to be sorted, separated by commas, followed by the name of the ordered output file to be created.

Optionally, you can specify a key for each field on which you want to sort. Each key includes the following information:

If you do not specify any keys, Sort assumes there is only one key and that this key field:

The following two examples use the default key.

  1. In this example, the file NAMES.LST is sorted in ascending order:


    This command creates the ordered output file BYNAME.LST, as shown in Figure 9-1.

    Figure 9-1 List Sorted in Ascending Order

  2. In this example, the files NAMES.LST and NAMES2.LST are sorted into the ordered output file BYNAME.LST. Sort treats the files as if they were one large file:


See Section 9.9 for a complete list of SORT qualifiers.

9.2.1 Defining a Key

Use the /KEY qualifier to define a key. When specifying multiple keys, use a separate /KEY qualifier for each key.

Table 9-2 describes the five elements that comprise a key.

Table 9-2 /KEY Qualifier Values
Key Element Value Description
Key position POSITION: n The position of the first byte of the key field within the record. The first byte in a record is position 1. POSITION: n is required.
Key size SIZE: n The length of the key field. SIZE: n is required except for floating-point data.

The data type you specify for the key determines what values are acceptable when specifying size. The following table lists the possible values for each type of data and the units used to specify the size of the key.
Data Valid Range Units
Character 1 through 32,767 Characters
Binary 1, 2, 4, 8, or 16 (For the high-performance Sort/Merge utility, the size of a binary data type key must be 1, 2, 4, or 8 bytes. Support of a 16-byte binary key is deferred to a future OpenVMS Alpha release.) Bytes
Decimal 1 through 31 Digits
Floating-point No value is necessary.

For decimal data, if the decimal sign is stored in a separate byte, that byte is not counted toward the size of the data.

If you specify a key that extends beyond the end of a record, Sort treats the missing characters as null characters.

Data type CHARACTER Character data. CHARACTER is the default data type.
  BINARY Binary data.

SIGNED --- Signed binary or decimal data. SIGNED is the default for binary and decimal data.

UNSIGNED --- Unsigned binary or decimal data.

  F_FLOATING F_FLOATING format data.
  D_FLOATING D_FLOATING format data.
  G_FLOATING G_FLOATING format data.
  H_FLOATING On VAX systems, H_FLOATING format data. (Not currently supported by the high-performance Sort/Merge utility.)
  S_FLOATING On Alpha systems, IEEE S_FLOATING format data.
  T_FLOATING On Alpha systems, IEEE T_FLOATING format data.
  DECIMAL Decimal data.

TRAILING_SIGN --- Trailing sign decimal data. TRAILING_SIGN is the default for decimal data.

LEADING_SIGN --- Leading sign decimal data. The leading sign must be in the first position of the field and the field must be left zero padded.

OVERPUNCHED_SIGN --- Overpunched decimal data. OVERPUNCHED_SIGN is the default for decimal data.

SEPARATE_SIGN --- Separate sign decimal data.

  ZONED Zoned decimal data. (Not currently supported by the high-performance Sort/Merge utility.)
  PACKED_DECIMAL Packed decimal data.
Sort order ASCENDING Orders the sorting operation in ascending alphabetical or numerical order. ASCENDING is the default order.
  DESCENDING Orders the sorting operation in descending alphabetical or numerical order.
Key priority NUMBER: n Specifies the order of priority of each key if you do not list multiple keys in the order of their priority. A value of 1 to 255 can be specified.

If the data in the key fields is not character data, you must specify the data type. The following data types are recognized by the Sort/Merge utility:
S_FLOATING, IEEE (Alpha systems only)  
T_FLOATING, IEEE (Alpha systems only)  

The items in brackets are defaults and need not be specified.


For decimal string data, the Sort/Merge utility reports an invalid digit in the input string differently for VAX and Alpha systems. On VAX systems, you receive a message that the invalid digit (or reserved operand) is converted to a valid decimal string for comparison purposes. On Alpha systems, Sort/Merge performs the same conversion but does not display a message. In both cases, the data from the input file is written to the output file without change.

In Figure 9-2, each record in the file EMPLOYEE.LST consists of three fields: (1) a department name, (2) an account number, and (3) an employee name.

Figure 9-2 Record Fields in a List

The following examples illustrate how to sort the records in EMPLOYEE.LST both with, and without, a key field:

  1. In this example, EMPLOYEE.LST is sorted by account number, using the /KEY qualifier to describe the account number field:


    This command specifies that the key field (the account number) starts in position 5, is 4 characters long, contains decimal data, and should be sorted in ascending order (the default). Figure 9-3 shows the results of this Sort operation.

    Figure 9-3 Sorting by Key Field

  2. This example shows how to sort the file EMPLOYEE.LST without specifying a key field:


    Because no key is specified, Sort assumes the default characteristics. Figure 9-4 shows the result of this Sort operation.

    Figure 9-4 Sorting with Default Key Records

    Sort treats each record in EMPLOYEE.LST as one key of character data. In this example, each record includes a department name, an account number, and an employee name. If Sort finds a duplicate department name, it sorts the names by account number. If it then finds a duplicate account number, it sorts by employee name. Note that the account number is part of the record. Unless you specify otherwise, it is treated as character data.

9.2.2 Multiple Key Fields

You can sort with more than one key (up to a limit of 255 keys). You can specify multiple keys in order of their priority with the primary key first, the secondary key next, and so on. Alternately, you can specify a key's priority using NUMBER:n. Each key can be ascending or descending.

In the following example, the file EMPLOYEE.LST is sorted by the employee name key first and then (where there are identical names), by the account number:


Figure 9-5 shows the results of this Sort operation.

Figure 9-5 Sorting with Multiple Key Fields

In the following example, records are sorted first by the department name in descending order, then by the employee name in ascending order:

_$ /KEY=(POSITION:10,SIZE:15) -

Figure 9-6 shows the results of this Sort operation.

Figure 9-6 Sorting with Multiple Key Fields (Ascending and Descending Order)

9.2.3 Identical Key Fields

By default, Sort/Merge keeps records with identical key fields but does not necessarily maintain the same order in which they appeared in the input file. To control the way in which records with identical keys are sorted, specify one of the following qualifiers:

The /STABLE and /NODUPLICATES qualifiers are incompatible. You cannot specify both qualifiers on the same command line.

In the following example, records with duplicate account numbers are eliminated from the file EMPLOYEE.LST:


Figure 9-7 shows the results of this Sort operation.

Figure 9-7 Sorting with Identical Key Fields

9.2.4 Noncharacter Data

If you sort records that contain items other than character data, specify the data type of each key. In addition, take care in calculating starting positions and sizes because the items being compared can occupy more than 1 byte.

If you are sorting a file that contains 20 characters followed by 3 floating-point numbers in F_floating format, the positions are as follows:

To sort the file by the third floating-point number, specify the key field as follows:


You do not need to specify the size of the floating-point number because it is fixed at four bytes.

9.2.5 Output File Organization

By default, Sort produces an output file with the same file organization as that of the first input file. To specify a different output file organization, include one of the following qualifiers after the output file specification on the Sort command line:

In the following example, a sequential file is produced after the indexed sequential file EMPLOYEE.LST is sorted:


9.2.6 Sorting Process

Sort arranges files using one of the internal processes: record, tag, address, or indexed. (The high-performance Sort/Merge utility supports only the record process. Implementation of tag, address, and index processes is deferred to a future OpenVMS Alpha release.) The process you specify can affect the efficiency of the Sort operation. Refer to Section 9.8 for information about optimizing a Sort or Merge operation.

The following table describes the four types of process. Use the /PROCESS=type qualifier to specify the sort process.
Sort Process type Description
Record RECORD Keeps records intact while sorting and produces an output file consisting of complete records. Record is the default sorting process.
Tag TAG Sorts the key fields only and then rereads the input file to produce an output file of complete records. The net result is the same as for a complete record sort.

A tag sort is useful if disk space is low because it typically uses less work file space during the sorting. In most cases, a tag sort is slower than a record sort because it requires extra time to reread the input file.

Address ADDRESS Sorts the key fields only and produces an output file that is an index of record file addresses (RFAs) in binary format.

An address sort is faster than a record sort but you must write a program to associate the record addresses with the records of the input file.

Indexed INDEX Sorts the key fields only and produces an output file of keys and RFAs (in binary format).

As with an address sort, an index sort is faster than a record sort, but you must write a program to associate the record addresses with the records of the input file.

9.3 Specifying a Collating Sequence

Characters are sorted according to a collating sequence. For files that contain character data, you can use the /COLLATING_SEQUENCE=sequence qualifier to specify the collating sequence. The following table describes the collating sequence options:
Collating Sequence sequence Description
ASCII ASCII The default collating sequence for character data. The ASCII sequence orders numbers (0 to 9) first, then uppercase letters (A to Z), and then lowercase letters (a to z).
EBCDIC EBCDIC Generates an output file that is ordered in EBCDIC sequence. The data remains in the ASCII representation. The EBCDIC sequence orders lowercase letters (a to z) first, then uppercase letters (A to Z), and then numbers (0 to 9).
DEC Multinational character set MULTINATIONAL The multinational collating sequence collates characters according to the DEC Multinational character set (refer to Appendix A). In the MULTINATIONAL character sequence, characters are ordered according to the following rules:
  • All diacritical forms of a character are given the collating value of the character (A', A", A` collate as A).
  • Lowercase characters are given the collating value of their uppercase equivalents (a collates as A, a" collates as A").
  • If two strings compare as equal, tie-breaking is performed. The strings are compared to detect differences due to diacritical marks, ignored characters, or characters that collate as equal although they are actually different. If strings still compare as equal, another comparison is done based on the numeric codes of the characters. In this final comparison, lowercase characters are ordered before uppercase.
National character set (NCS) Collating sequence name The named collating sequence must be defined in an NCS library. For more information, see the OpenVMS National Character Set Utility Manual.

(The high-performance Sort/Merge utility does not support the National Character Set (NCS) collating sequences. Support for NCS collating sequences is deferred to a future OpenVMS Alpha release.)

User-defined sequence (sequence-string) Specifies a user-defined collating sequence. User-defined collating sequences are supported only through specification files and not through the command line interface.

(The high-performance Sort/Merge utility does not support user-defined collating sequences. Support for user-defined collating sequences is deferred to a future OpenVMS Alpha release.)

    Define a collating sequence by specifying a string of single or double characters or ranges of single characters. (A double character is any set of two single characters collated as if they were one character. For example, "CH" can be defined to collate as "C".) This string should be enclosed in parentheses.

You can also represent characters by their corresponding octal, decimal, or hexadecimal values using the radix operators: %O, %D, %X.

You must observe the following rules when defining your collating sequence:

  • Enclose characters in quotation marks ("").
  • Separate each character and character range with a comma (,), and enclose the entire list in parentheses.
  • Give all the characters appearing in the character keys in the Sort or Merge operation a collating value. Any character not given a collating value will be ignored unless the FOLD or MODIFICATION options are specified.
  • Do not define a character more than once.
  • Do not specify the null character by using quotation marks (""). Instead, use a radix operator such as %X0.
  • Specify quotation marks by enclosing them within another set of quotation marks ("" "") or by using a radix operator.

The following string defines a collating sequence in which the double character LL collates as a single character between L and M.



Exercise caution when using the multinational collating sequence to sort or merge files for further processing. Sequence-checking procedures in most programming languages compare numeric characters. Normal sequence checking does not work because the multinational sequence is based on actual graphic characters, not the codes representing those characters.

The following examples demonstrate the creation of user-defined collating sequences for use in specification files. See Section 9.7 for information about specification files.


    This /COLLATING_SEQUENCE qualifier with an IGNORE option specified results in the following fields being compared as equal before tie breaking:

           252 3412 

  2. /COLLATING_SEQUENCE=(SEQUENCE=("A"-"L","LL","M"-"R","RR","S"-"Z")) 

    This /COLLATING_SEQUENCE qualifier defines a sequence in which the double character LL collates as a single character between L and M, and the double character RR collates as a single character between R and S. These double characters would otherwise appear in their usual alphabetical order. By default, this user-defined sequence does not define any other characters, such as lowercase a to z.

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