hbScanParameter (Variable type)

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Properties specific to hbScanParameter variables
Iterating over data with the filter
Examples of filters

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hbScanParameter (Variable type)

In french: hbParamètreScan

The hbScanParameter type is used to define the parameters for iterating over the records in an HBase database. You can define and change the characteristics of these iteration parameters using different WLanguage properties.

Note: For more details on the declaration of this type of variable and the use of WLanguage properties, see Declaring a variable.

Example

// Connexion
Connexion is hbConnection
Connexion.Server = "MonServeur"
// Description du filtre
MonScan is hbScanParameter
MonScan.Connection = connection
MonScan.Table = "blog"
// Filtre pour toutes les lignes les valeurs des colonnes dont le nom commence par "Titre"
MonScan.Filter = "{ ""type"": ""ColumnPrefixFilter"", ""value"": """ + ...
	Encode("Titre", encodeBASE64) + """ }"
// Parcours selon le filtre et affichage des données filtrées
// La variable de parcours MonRésultat est de type hbRésultatScan
FOR EACH MonRésultat OF MonScan
	Trace("La colonne " + MonRésultat.Colonne.Famille + ":" + ...
		MonRésultat.Colonne.Qualificatif + ...
		" de la ligne " + MonRésultat.Ligne + " vaut " + MonRésultat.Valeur)
END

Properties

Properties specific to hbScanParameter variables

The following properties can be used to handle the description of iteration parameters:

Property name	Type used	Effect

Column	Array of hbColumn	Families or columns (items) found in the result of the iteration.
Connection	hbConnection variable	Connection to the HBase server to be used for the iteration.
EndRow	Buffer	Identifier of the last row (record) of the iteration. This row will not be included in the iteration.
EndTimestamp	DateTime	End date and time for selecting rows. The iteration will only return the rows containing cells up to this date and time.
Filter	Character string	Filter that will be applied during the iteration. This filter is in JSON format. The literal values must be encoded in Base64, by using Encode for example. For more details, see the HBase documentation.
MaxVersion	Integer	Maximum number of versions returned for each cell (value of item). Indeed, a history of values is stored in the HBase database for each cell.
StartRow	Buffer	Identifier of the first row (record) of the iteration. This row will be included in the iteration.
StartTimestamp	DateTime	Start date and time for selecting rows. The iteration will only return the rows containing cells from this date and time.
Table	Character string	Name of the HBase table to iterate over.

Remarks

Iterating over data with the filter

To iterate over data with a filter:

Define the Filter property of the variable.
Use the FOR EACH syntax to initialize the iteration with the filter. The following syntax must be used:
POUR TOUT <Résultat> SUR <Variable de paramétrage de scan>
In this syntax, <Result> is a hbScanResult (see the example).

Examples of filters

Filter on column value: MyFamily:MyQualifier = 'Value'.

MonScan.Filter = ...
"{" + ...
"""type"": ""SingleColumnValueFilter""," + ...
"""op"": ""EQUAL""," + ...
"""family"": """ + Encode("MaFamille", encodeBASE64) + """," + ...
"""qualifier"": """ + Encode("MonQualificatif", encodeBASE64) + """," + ...
"""latestVersion"": true," + ...
"""comparator"": {" + ...
		"""type"": ""BinaryComparator""," + ...
		"""value"": """ + Encode("Valeur", encodeBASE64) + """}" + ...
"}"

Filter the columns whose name starts with "Title":

MonScan.Filter = ...
"{" + ...
  """type"": ""ColumnPrefixFilter""," + ...
  """value"": """ + Encode("Titre", encodeBASE64) + """," + ...
"}"

Filter the data according to several filters:

MonScan.Filter = ...
"{" + ...
  """type"": ""FilterList""," + ...
  """op"": ""MUST_PASS_ALL""," + ...
  """filters"": [" + ...
    "{" + ...
		filtre1 + ...
    "}," + ...
	"{" + ...
		filtre2 + ...
	"}" + ...
  "]" + ...
"}"