CloverDataReader reads data stored in our internal binary CloverDX data format files. It can also read data from compressed files, or a dictionary.
|Component||Data source||Input ports||Output ports||Each to all outputs||Different to different outputs||Transformation||Transf. req.||Java||CTL||Auto-propagated metadata|
|CloverDataReader||CloverDX binary file||1||1-n|
|Input||0||For Input Port Reading correct data records||Include specific |
|Output||0||For correct data records||Any|
|1-n||For correct data records||Output 0|
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
Metadata on the output port has to be the same as metadata of data from the file.
Metadata can use Autofilling Functions.
An attribute specifying what data source(s) will be read (CloverDX data file, input port, dictionary). See Supported File URL Formats for Readers.
|Number of skipped records|
Number of records to be skipped. See Selecting Input Records.
|Max number of records|
Maximum number of records to be read. See Selecting Input Records.
|Number of skipped records per source||Skip the first ||0-N|
|Max number of records per source||Reads maximally ||0-N|
|Index file URL|
The name of an index file, including the path. If not specified, all records are read.
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|
|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|
Read all records from the CloverDX data file.
Set up the File URL attribute.
CloverDataReader will read all the records from the file(s).
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.)
bread honey raisins pears plums
carrot peas radish
Set up the File URL and Number of skipped records attributes.
|Number of skipped records||3|
CloverDataReader reads the following items:
pears plums carrot peas radish
There are two CloverDX data files:
Each file starts with one record to be omitted.
Goods cardigan shirt trousers
Goods shoes sox
Set up the File URL and Number of skipped records per source attributes.
|Number of skipped records per source||1|
CloverDataReader sends the following records to the output:
cardigan shirt trousers shoes sox
You have three files
stationery3.cdf and you need to read six records in
total from all files.
pen pencil marker paintbrush
ink water colors oil colors
notebook coloring book
Set up the File URL and Max number of records attributes.
|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
is sent the output port as the limit has been reached already.
pen pencil marker paintbrush ink water colors
You have three CloverDX data files (
stationery[1-3].cdf) from the previous example.
Read at most 3 records from each file.
Set up the File URL and Max number of records per source attributes.
|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
pen pencil marker ink water colors oil colors notebook coloring book
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.
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 can extract metadata template from CloverDX file. It can be seen as a metadata template corresponding to the file.
CloverDataReader can read from input port just from