Enhance Your Cloud Application with HANA Search

     Sometimes in your search queries you need something more powerful than "... WHERE "COMPANY_NAME" like '%Oil%' ... ".  Fortunately SAP HANA provides a built-in search capabilities that allows your application's users "to search tables and views much like they would when searching for information on the Internet." (for details refer "SAP HANA Developer Guide").

     In the following lines, you will find how to setup your Cloud HANA DB table, so you could benefit from HANA search capabilities.

Scenario

     We got a HANA Cloud application, that uses two DB tables (SNWD_PD, SNWD_TEXTS). These tables contain products, and texts associated with them. We want to give our application's users the ability to search for products by name and description. Here are the specific search requirements:

• Make fault tolerant search (fuzzy search in HANA) for the product's name (e.g. if user searches for "mouzePat", find also products for "Mousepad")
• Make linguistic search for the product's description (e.g. if user searches for "mouse", find also products for "mice")
• Score the results by relevance
• Give higher scores (weight) to the results from linguistic search than the ones from fuzzy search

DB Tables Structure

     In the used tables below the columns "NAME_GUID", and "DESC_GUID" refers texts ("PARENT_KEY") for product's name, and description respectively.

• SNWD_TEXTS table structure:

• SNWD_PD table structure:

Prepare Text's (SNWD_TEXTS) DB Table for Search

     HANA search capability is enabled per DB table's column. Such a column has defined fulltext index (existing by default for column types TEXT, SHORTTEXT; for details refer "SAP HANA Developer Guide").

CREATE FULLTEXT INDEX SNWD_TEXTS_TEXT ON "JP_OPINT_WEBSHOP_WEB"."SNWD_TEXTS"(TEXT) FAST PREPROCESS OFF FUZZY SEARCH INDEX ON;

• "FAST PREPROCESS OFF" - enables HANA linguistic search over a DB column
• "FUZZY SEARCH INDEX ON" - increase performance of fuzzy search

Create DB Procedure for Search Execution

     As a result from a search we expect a table with product's information (from "SNWD_PD" table), name and description (from "SNWD_TEXTS" table). We have created a procedure "findProduct" capsulating SQL queries. Meaning of SQL queries is the following:

• "search" - executes fuzzy, and linguistic search for "searchTerm" over "SNWD_TEXTS" table. The desired weights for both searches is used. Score is used latter to sort the results by relevance
• "name" - join product's table with name's search results
• "descr" - join product's table with description's search results
• "search_all" - union search results for product's name and description
• "max_relevance" - leave the best search relevance for a product 
• "result" - group search results by products, and order them by relevance

create procedure findProduct(in searchTerm VARCHAR(100), out result "PRODUCT_RESULT") AS

BEGIN             

     search = SELECT "PARENT_KEY", "TEXT",  SCORE() AS RELEVANCE FROM "SNWD_TEXTS"

               WHERE client='000' AND

               CONTAINS (TEXT, :searchTerm,   FUZZY(0.4), WEIGHT(0.5)) OR

               CONTAINS (TEXT, :searchTerm,   LINGUISTIC, WEIGHT(0.6));

     name = SELECT "PRODUCT".*,

                    "TEXT"."TEXT" AS NAME,

                    DESCRIPTION.text AS DESCRIPTION,

                    RELEVANCE

               FROM "SNWD_PD" AS "PRODUCT"

               INNER JOIN :search AS "TEXT"                           

               ON "TEXT"."PARENT_KEY" = "PRODUCT"."NAME_GUID"

               LEFT OUTER JOIN "SNWD_TEXTS" AS DESCRIPTION                           

                    ON "PRODUCT".DESC_GUID=DESCRIPTION.PARENT_KEY

                         WHERE "PRODUCT".client='000';

     descr = SELECT "PRODUCT".*,

                    "TEXT"."TEXT" AS NAME,

                    DESCRIPTION.text AS DESCRIPTION,

                    RELEVANCE

               FROM "SNWD_PD" AS "PRODUCT"

                INNER JOIN :search AS DESCRIPTION

                ON "DESCRIPTION"."PARENT_KEY" = "PRODUCT"."DESC_GUID"

               LEFT OUTER JOIN "SNWD_TEXTS" as "TEXT"                            

                    ON "PRODUCT".NAME_GUID="TEXT".PARENT_KEY

                         WHERE "PRODUCT".client='000';

     search_all = SELECT * FROM :name UNION SELECT * FROM :descr;

     max_relevance = SELECT MAX(TO_DOUBLE(RELEVANCE)) AS RELEVANCE, PRODUCT_ID

                         FROM :search_all group by PRODUCT_ID;

     result = SELECT PRODUCT.* FROM :search_all PRODUCT

                    INNER JOIN :max_relevance MAX_RELEVANCE

                    ON PRODUCT.RELEVANCE=MAX_RELEVANCE.RELEVANCE AND

                    PRODUCT.PRODUCT_ID=MAX_RELEVANCE.PRODUCT_ID

                    ORDER BY PRODUCT.RELEVANCE DESC;

END;

Search Result

     Here is a search result for "mouzePat":

Try It Yourself

     You may try the described functionality by downloading search_demo.zip. You may see contents of SearchDemo project on GitHub.

Contents of search_demo.zip

• SearchDemoServlet - servlet with simple HTML UI, so you may try search by yourself

Make it works:

1. Unzip search_demo.zip into your web application's "src" folder.
2. Configure your web application's web.xml adding the following lines:

         <servlet>

                    <description></description>

                    <display-name>SearchDemoServlet</display-name>

                    <servlet-name>SearchDemoServlet</servlet-name>

                    <servlet-class>com.sap.demo.search.SearchDemoServlet</servlet-class>

          </servlet>

          <servlet-mapping>

                    <servlet-name>SearchDemoServlet</servlet-name>

                    <url-pattern>/SearchDemoServlet</url-pattern>

          </servlet-mapping>

         <resource-ref>

                    <res-ref-name>jdbc/DefaultDB</res-ref-name>

                    <res-type>javax.sql.DataSource</res-type>

          </resource-ref>

3. Deploy your web application on the cloud
4. Navigate to SearchDemoServlet URL, and try the search