EXPORT - FastExport

Topic

Usage Notes

Attributes of the Destination File

On mainframe‑attached client systems, the attributes of the destination file must be compatible with the export data records that will be written there. (Compatibility is not a problem on network‑attached UNIX and Windows client systems.)

On mainframe‑attached z/OS systems, the attributes vary, depending on:

Teradata Database data types in the mainframe‑attached z/OS environments are described in Table 32. Use this information to calculate the size of the exported data rows to assign appropriate values to the attributes of the destination file.

Block Size Specification

Two 64K‑byte buffers are allocated for each session being used to transmit data from Teradata Database to the client system.

The minimum block size that must be allocated is one which will hold the largest possible parcel returned by Teradata Database.

If the specified block size is not large enough to hold the largest possible parcel, Teradata Database returns an error to the SELECT statement and the utility is abnormally terminated.

For a complete description of the parcel sizes, see:

Command Placement and Frequency

One EXPORT command is required for each export task in a FastExport job script. Place it anywhere between the BEGIN EXPORT command and the END EXPORT command that specify the export task.

MODE Specifications

Both the INDICATOR and RECORD mode specifications return data in a client internal format with variable‑length records:

Data records returned in indicator mode, however, have a set of bit flags that identify the columns that have a null value.

For a complete description of these modes, see:

Multiple SELECT Statements

If the export task specified multiple SELECT statements, the export data is returned in statement order. All response data for statement 1 is followed by the response data for statement 2, and so forth.

If the same SELECT statement is executed multiple times, then the results of the first iteration are returned and processed before the second iteration of the SELECT statement is sent to Teradata Database.

SELECT Statement Processing

If the export task specified multiple SELECT statements, the response data for all statements is returned in statement order – all response data for statement 1 will be first, followed by the data for statement 2, and so forth.

If a single SELECT statement is executed multiple times, the results of the first iteration are returned and processed before the second SELECT statement is sent to Teradata Database.

z/OS fileid Usage Rules

A DDNAME must obey the same construction rules as Teradata SQL column names except that:

The DDNAME must obey the applicable rules of the external system and may reference a sequential or VSAM data set and may reference a sequential or VSAM data set.

If the DDNAME represents a data source on magnetic tape, the tape may be either labeled or nonlabeled, as supported by the operating system.

RECFM

Description

FB

LRECL must be exactly equal to the number of bytes of data being returned. The LRECL cannot be larger.

For RECFM=FB, the BLKSIZE must also be a multiple of the LRECL. If not, records may be truncated, resulting in possible data integrity problems, or FastExport may append.

Explicitly adding BLKSIZE to the JCL eliminates the possibility of using an invalid default BLKSIZE.

VB

Logical record length (LRECL) and block size (BLKSIZE) parameters should be large enough to accommodate the largest record that is anticipated.

VBS or VS

Maximum logical record length can exceed the physical length for a given data set.

Spanned records, either blocked or unblocked, use a well‑established straightforward protocol to break or segment records across blocks where necessary.

While an individual segment never exceeds the length of a block, the logical record that it is a part of can span multiple blocks, and even volumes. Thus spanned records are the only way to create output files with rows whose length exceed the 32K‑byte block size, up to the maximum of 64K bytes that is supported by Teradata Database.

Even though the maximum LRECL that can be specified with JCL is 32,760, there is no practical limit on the actual length of spanned records.

For output consisting of records exceeding this maximum LRECL (greater than approximately 32K, for example), simply specify LRECL=X. There is no other special JCL requirement for creating such records when using the VBS or VS record format.

Always specify the BLKSIZE according to the performance characteristics of the target device or media. This usually means specifying the largest possible BLKSIZE.

In some cases, the performance of the FastExport utility may be improved by specifying RECFM=VBS when:

The spanned/blocked format maximizes data packing. Because fewer blocks are required to convey the same number of logical records, the FastExport job runs quicker.

For example, assuming a block size of 32,756 bytes:

Data Type

Output Length

Description

BYTE(n)

n bytes

n bytes

BYTEINT

1 byte

8‑bit signed binary

CHAR(n)

CHARS(n)

CHARACTERS(n)

n bytes

n EBCDIC characters

DATE

4 bytes

32‑bit integer in the internal date format of Teradata Database.

For details, see Database Design (B035‑1094) and SQL Data Types and Literals (B035‑1143).

Note: If a DATEFORM command has been used to specify ANSIDATE as the DATE data type, the FastExport utility internally converts each DATE data type to a CHAR(10) field.

DECIMALx

DECIMAL(x)

DECIMAL(x,y)

(x+1) / 2 bytes

x packed decimaldigits and sign

FLOAT

FLOATING

8 bytes

64‑bit (double‑precision) floating point

GEOSPATIAL DATA

maximum 64000

FastExport does not support Geospatial data represented by LOBs.

INTEGER

4 bytes

32‑bit signed binary

LONG VARCHAR

m+2 characters where m<=n

Same as VARCHAR (32000) characters

Fixed Length Period Data Types:

PERIOD(DATE)

PERIOD(TIME(n))

PERIOD(TIME(n) WITH TIME ZONE)

max=8 byte

max=12 bytes

max=16 bytes

The precision specified must be 0<n<6:
precision=0 (n/a)

precision=n

precision=n

For details, see Database Design (B035‑1094) and SQL Data Types and Literals (B035‑1143).

Variable Length Period Data Types:

PERIOD(TIMESTAMP(n))

PERIOD(TIMESTAMP(n) WITH TIME ZONE)

max=20 bytes

max=24 bytes

The precision specified must be 0<n<6:

precision=n

precision=n

For details, see Database Design (B035‑1094) and SQL Data Types and Literals (B035‑1193).

SMALLINT

2 bytes

16‑bit signed binary

VARBYTE(n)

m+2 bytes where m<=n

16‑bit integer, count m, followed by m bytes of data

VARCHAR(n)

m+2 bytes where m<=n

16‑bit integer, count m, followed by m EBCDIC characters