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POSQLite and Javascript : Checking for existence of data before inserting OR letting SQLite throw an exception
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  1. POSQLite and Javascript : Checking for existence of data before inserting OR letting SQLite throw an exception
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    copied!<p>My primary question is which approach is faster.</p> <p><strong>Some briefing</strong> </p> <p>I'm developing an application using Mozilla.</p> <p>I have this one module where I capture some data and store it in database. The data comes in intermittently. No duplicates are to be stored. For discussion sake we can assume a table with just one column, and let's name that column is named 'keyword'. So if we get a keyword that's already in database we do not store it again. And yes, we have set this column as PRIMARY KEY and made it UNIQUE. :)</p> <p><strong>The query I have is:</strong></p> <p>1) Before I insert this new data into the database, shall I do a DB call and check if the keyword exists or not; if it doesn't exists put it into DB? Something like:</p> <pre><code>function insert_keyword(keyword) { if(!SQL.exists(keyword)) { SQL.insert(keyword); } } </code></pre> <p>OR</p> <p>2) I just insert and let the database handle the condition, effectively letting it throw an exception, which I catch.</p> <pre><code>function insert_keyword(keyword) { try { SQL.insert(keyword); } catch (e) { // keyword exists! } } </code></pre> <p>I know catching an exception and not doing anything is bad! So I'm not looking for what is good and what is bad :) . What I want to understand is which approach would be the fastest. (Specifically in relation to Mozilla, JavaScript and SQLite but general comments are welcomed!)</p> <p><strong>Sidenotes:</strong> <em>The <strong>SQL.</strong> syntax I've used is just for illustration purpose. You may assume that I create SQL statements, execute them and fetch the result, or assume it is a JavaScript library call which does all the dirty work.</em></p> <p><strong>This question is a bit like this one:</strong></p> <p><a href="https://stackoverflow.com/questions/405359/should-i-check-for-db-constraints-in-code-or-should-i-catch-exceptions-thrown-by">Should I check for DB constraints in code or should I catch exceptions thrown by DB</a></p> <p>But I want to understand the performance related differences specifically, as the application I'm working on needs to be as fast as possible (which application doesn't? ;) )</p>
 

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