CloverDataReader

CloverDataReader 64x64

Short description

Ports

Metadata

CloverDataReader attributes

Examples

Compatibility

See also

Short description

CloverDataReader reads data stored in our internal binary CloverDX data format files. It can also read data from compressed files, or a dictionary.

Data source Input ports Output ports Each to all outputs Different to different outputs Transformation Transf. req. Java CTL Auto-propagated metadata

CloverDX binary file

1

1-n

Ports

Port type Number Required Description Metadata

Input

0

For Input port reading correct data records

Include specific byte/cbyte field

Output

0

For correct data records

Any

1-n

For correct data records

Output 0

Metadata

CloverDataReader does not propagate metadata.

CloverDataReader has no metadata template, but it can extract metadata from CloverDX file and propagate it forward as it would have a template. (Available since CloverETL 4.1.0-M1.)

Metadata on the input port has to include a byte, cbyte or string field.

Metadata on the output port has to be the same as metadata of data from the file.

Metadata can use Autofilling functions.

CloverDataReader attributes

Attribute Req Description Possible values

Basic

File URL

yes

An attribute specifying what data source(s) will be read (CloverDX data file, input port, dictionary). See Supported file URL formats for Readers.

Advanced

Secret key

Key to use for decryption of encrypted files.

Number of skipped records

Number of records to be skipped. See Selecting input records.

0-N

Max number of records

Maximum number of records to be read. See Selecting input records.

0-N

Number of skipped records per source

Skip the first n records of each file.

0-N

Max number of records per source

Reads maximally n records from each file.

0-N

Deprecated

Index file URL

The name of an index file, including the path. If not specified, all records are read.

Start record

Has exclusive meaning: Last record before the first that is already read. Has lower priority than Number of skipped records.

0 (default) | 1-n

Final record

Has inclusive meaning: Last record to be read. Has lower priority than Max number of records.

all (default) | 1-n

Examples

Reading a CloverDX data file

Omitting leading records

Omitting leading records of each file

Reading at most n records in total

Reading at most n records per file

Reading a CloverDX data file

Read all records from the CloverDX data file.

Solution

Set up the File URL attribute.

Attribute Value

File URL

${DATAIN_DIR}/my-clover-file.cdf

CloverDataReader will read all the records from the file(s).

Omitting leading records

You have two CloverDX data files. First 3 records contain unimportant data and should not be read. The unimportant records are in the first file. (The records have been sorted and partitioned for example.)

greengrocers1.cdf

bread
honey
raisins
pears
plums

greengrocers2.cdf

carrot
peas
radish
Solution

Set up the File URL and Number of skipped records attributes.

Attribute Value

File URL

${DATAIN_DIR}/greengrocers1.cdf;${DATAIN_DIR}/greengrocers2.cdf

Number of skipped records

3

CloverDataReader reads the following items:

pears
plums
carrot
peas
radish
Omitting leading records of each file

There are two CloverDX data files: list1.cdf and list2.cdf. Each file starts with one record to be omitted.

list1.cdf

Goods
cardigan
shirt
trousers

list2.cdf

Goods
shoes
sox
Solution

Set up the File URL and Number of skipped records per source attributes.

Attribute Value

File URL

${DATAIN_DIR}/list1.cdf;${DATAIN_DIR}/list2.cdf

Number of skipped records per source

1

CloverDataReader sends the following records to the output:

cardigan
shirt
trousers
shoes
sox
Reading at most n records in total

You have three files stationery1.cdf, stationery2.cdf and stationery3.cdf and you need to read six records in total from all files.

stationery1.cdf

pen
pencil
marker
paintbrush

stationery2.cdf

ink
water colors
oil colors

stationery3.cdf

notebook
coloring book
Solution

Set up the File URL and Max number of records attributes.

Attribute Value

File URL

${DATAIN_DIR}/stationery1.cdf;${DATAIN_DIR}/stationery2.cdf;${DATAIN_DIR}/stationery3.cdf

Max number of records

6

CloverDataReader sends all 4 records from stationery1.cdf and 2 of 3 records from stationery2.cdf to the output port. No record from the file stationery3.cdf is sent to the output port as the limit has been reached already.

pen
pencil
marker
paintbrush
ink
water colors
Reading at most n records per file

You have three CloverDX data files (stationery[1-3].cdf) from the previous example. Read at most 3 records from each file.

Solution

Set up the File URL and Max number of records per source attributes.

Attribute Value

File URL

${DATAIN_DIR}/stationery1.cdf;${DATAIN_DIR}/stationery2.cdf;${DATAIN_DIR}/stationery3.cdf

Max number of records per source

3

CloverDataReader reads 3 records from stationery1.cdf, 3 records from stationery2.cdf and 2 of 2 records from stationery3.cdf.

pen
pencil
marker
ink
water colors
oil colors
notebook
coloring book

Compatibility

Version Compatibility Notice

2.9

CloverDataWriter also writes a header to output files with the version number. For this reason, CloverDataReader expects that files in CloverDX binary format contain such a header with the version number. CloverDataReader 2.9 cannot read files written by older versions nor these older versions can read data written by CloverDataWriter 2.9.

4.0

The internal structure of the zip archive has changed. Graphs that rely on the structure will stop working. Graphs that use plain zip file URL without internal entry specification are not affected: CloverDataReader with File URL zip:(${DATAOUT_DIR}/employees.zip)#DATA/employees will need to be fixed to use zip:(${DATAOUT_DIR}/employees.zip) instead.

4.1.0-M1

CloverDataReader can extract metadata template from CloverDX file. It can be seen as a metadata template corresponding to the file.

4.4.0-M2

CloverDataReader can read from input port just from byte or cbyte field.