By Jarek Jarcec Cecho
Integrating information from a number of resources is vital within the age of huge information, however it could be a demanding and time-consuming job. this convenient cookbook presents dozens of ready-to-use recipes for utilizing Apache Sqoop, the command-line interface software that optimizes information transfers among relational databases and Hadoop.
Sqoop is either robust and bewildering, yet with this cookbook’s problem-solution-discussion layout, you’ll speedy how you can install after which practice Sqoop on your atmosphere. The authors supply MySQL, Oracle, and PostgreSQL database examples on GitHub for you to simply adapt for SQL Server, Netezza, Teradata, or different relational systems.
- Transfer info from a unmarried database desk into your Hadoop ecosystem
- Keep desk info and Hadoop in sync by way of uploading info incrementally
- Import info from a couple of database table
- Customize transferred info via calling a number of database functions
- Export generated, processed, or backed-up info from Hadoop for your database
- Run Sqoop inside Oozie, Hadoop’s really good workflow scheduler
- Load information into Hadoop’s information warehouse (Hive) or database (HBase)
- Handle deploy, connection, and syntax matters universal to precise database vendors
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Additional info for Apache Sqoop Cookbook
Your downstream processing (Hive queries, customized MapReduce task, or Pig script) makes use of a unique consistent for encoding lacking values. you should override the default one. answer you could override the NULL substitution string with the --null-string and --null-non-string parameters to any arbitrary worth. for instance, use the next command to override it to \N: sqoop import \ --connect jdbc:mysql://mysql. instance. com/sqoop \ --username sqoop \ --password sqoop \ --table towns \ --null-string '\\N' \ --null-non-string '\\N' dialogue just about all relational databases let you outline columns as non-compulsory, permitting the columns to be linked to no worth. This lacking details is generally often called the NULL worth. for instance, a BOOL column commonly comprises merely precise values: real and fake. also, the column can include the price NULL if in the course of desk construction you’ve explicitly allowed that column to be not obligatory. Databases frequently shop the NULL worth as an additional bit as well as the column’s ordinary information. With Sqoop aiding the import of knowledge to codecs that don’t natively aid the NULL price (e. g. , CSV file), there's a have to encode the lacking worth into the knowledge itself. by means of default, Sqoop makes use of the string consistent null (lowercased) for representing the lacking price. This default consistent will possibly not fit your wishes in the event that your info can comprise an analogous string consistent as a typical price or in the event that your downstream processing is looking ahead to a unique substitution string consistent. to permit more uncomplicated integration with extra Hadoop atmosphere parts, Sqoop distinguishes among varied situations whilst facing lacking values. For text-based columns which are outlined with style VARCHAR, CHAR, NCHAR, textual content, and some others, you could override the default substitution string utilizing the parameter --null-string. For all different column kinds, you could override the substitution string with the --null-non-string parameter. many of the connectors would possibly not aid assorted substitution strings for various column kinds and hence may possibly require you to specify a similar price in either parameters. Internally, the values laid out in the --null(-non)-string parameters are encoded as a string consistent within the generated Java code. you could make the most of this by means of specifying any arbitrary string utilizing octal illustration with no being concerned approximately right encoding. An unlucky facet influence calls for you to correctly get away the string at the command line in order that it may be used as a sound Java string consistent. be aware that will use \N to encode lacking values, then you definately have to specify \\N at the command line; \ is a distinct break out string personality in Java that would be interpreted via the compiler. Your shell will attempt to unescape the parameters for you, so that you have to enclose these parameters in unmarried charges ('). utilizing double rates (") will reason your shell to interpret the break out characters, altering the parameters earlier than passing them to Sqoop.