Configure Elasticsearch stopwords

What are stopwords?

In general, stopwords are a language’s most common words that search engines filter out after processing text. Originally, when disk space and memory were extremely limited, every kilobyte saved meant a significant improvement in performance. Therefore, search engines achieved performance gains by ignoring certain words and keeping the index small.

Although we have more storage today, performance is still important. Elasticsearch, like other search engines, still uses stopwords to improve performance.

You must manage your Elasticsearch stopwords using .csv files located in the <magento_root>/vendor/magento/module-elasticsearch/etc/stopwords directory or the <magento_root>/app/code/Magento/Elasticsearch/etc/stopwords/ directory, depending on how you installed the Magento software.

For more information about how Elasticsearch uses stopwords, see the following resources:

• Stopwords: Performance Versus Precision
• Pros and Cons of Stopwords
• Using Stopwords
• Stopwords and Performance

Configure stopwords

Elasticsearch stopwords are located in the <magento_root>/vendor/magento/module-elasticsearch/etc/stopwords directory. Magento ships with one .csv file containing stopwords for our default locales and an additional file, stopwords.csv, which has stopwords for any locale that is not represented by another .csv file.

The default lifetime for stopwords file cache is 15 minutes.

See one of the following topics for more information:

• Edit stopwords for an existing locale
• Create stopwords for a new locale
• To change the directory from your module

Edit stopwords for an existing locale

To edit stopwords:

1. Log in to your Magento server, or switch to, the Magento file system owner.

2. Use a text editor to open a stopword file in the <magento_root>/vendor/magento/module-elasticsearch/etc/stopwords directory.

   .csv files use the naming convention stopwords_<locale_code>.csv. For example, the German stopword file is named stopwords_de_DE.csv.

3. Add words, remove words, or change words in the file.

   (Each stopword in a file starts on a new line.)

4. Save your changes and exit the text editor.

5. Clean the Magento configuration cache.

   • Magento Admin: System > Tools > Cache Management. Select the Configuration checkbox and, from the list above it, click Refresh. Click Submit to complete the action.

   • Command line: As the Magento file system owner, enter the following command:

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     php <magento_root>/bin/magento magento cache:clean config
     

6. Check the results by searching for terms on your storefront.

Create stopwords for a new locale

To add stopwords for a locale:

1. Log in to your Magento server, or switch to, the Magento file system owner.

2. Use a text editor to create a stopword file named stopwords_<locale_code>.csv in the <magento_root>/vendor/magento/module-elasticsearch/etc/stopwords directory.

   For example, to create stopwords for the Italian locale, name the file stopwords_it_IT.csv.

3. In your stopword file, make sure each stopword is on a separate line.
4. Save your changes and exit the text editor.
5. In the same directory, open esconfig.xml in a text editor.

6. Add a line to esconfig.xml as follows:

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   <LOCALE_CODE>stopwords_LOCALE_CODE.csv</LOCALE_CODE>
   

   For example, to add an Italian stopword file, add the following line:

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   <it_IT>stopwords_it_IT.csv</it_IT>
   

7. Save the changes to esconfig.xml and exit the text editor.

8. Clean the Magento configuration cache.

   • Magento Admin: System > Tools > Cache Management. Select the Configuration checkbox and, from the list above it, click Refresh. Click Submit to complete the action.

   • Command line: As the Magento file system owner, enter the following command:

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     php <magento_root>/bin/magento magento cache:clean config
     

9. Check the results by searching for terms on your storefront.

Change the stopword directory

This section discusses how to optionally change the default stopword directory from one of the following:

• <magento_root>/vendor/magento/module-elasticsearch/etc/stopwords
• <magento_root>/app/code/Magento/Elasticsearch/etc/stopwords/

The location depends on how you installed the Magento software. If you cloned the Magento 2 GitHub repository, the path is under app/code. If you installed a compressed archive or a metapackage, the path is under vendor.

To change the directory:

1. As the Magento file system owner, open the Elasticsearch di.xml in a text editor.

   If you cloned the repository, it’s located at app/code/Magento/Elasticsearch/etc/di.xml

   If you got an archive or the metapackage, it’s located at vendor/magento/module-elasticsearch/etc/di.xml

2. Change the value of fileDir to the desired directory:

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   <type name="Magento\Elasticsearch\SearchAdapter\Query\Preprocessor\Stopwords">
       <arguments>
           <argument name="stopwordsDirectory" xsi:type="string">app/code/Magento/Elasticsearch/etc/stopwords</argument>
       </arguments>
   </type>
   

Save your changes to di.xml and exit the text editor.

To change the directory from your module

1. Create a new module

2. In your module etc/di.xml add instructions:

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   <type name="Magento\Elasticsearch\SearchAdapter\Query\Preprocessor\Stopwords">
       <arguments>
          <argument name="stopwordsModule" xsi:type="string">Your_Module</argument>
          <argument name="stopwordsDirectory" xsi:type="string">stopwords</argument>
       </arguments>
   </type>
   

3. In your module, create the directory etc/stopwords, with the corresponding .csv.

Save your changes to di.xml and exit the text editor.