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First Query Very Slow (~3s) on Chrome (64.0.3282.167)

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#230 7 comments 2 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript, sqlite
Domain
database, web-dev

Research direction

Reproduce the issue using the provided XHR and SQL.Database example, comparing the first SELECT in Chrome 64 with Firefox 58. Start with the Chrome DevTools timing shown in the report and the database-loading path; done means the cause of the slow first query is identified and the regression or behavior is addressed with a verified reproduction.

Written by the indexing model from the issue text.

Description

I'm seeing slow first queries against an database loaded via XHR. All the queries are fairly trivial, and after the first they complete quickly. Here's a picture of the chrome dev-tools:

sqljs first exec slow

Firefox (58.0.2) doesn't have this problem, so perhaps something browser related?

The following JS recreates this:

let db = null;

let experimentUrl = 'https://storage.googleapis.com/axelbrooke-public/experiments/toxic-comment-clf/experiments.sqlite';

(function() {
    let xhr = new XMLHttpRequest();
    xhr.open('GET',
        experimentUrl,
        true);
    xhr.responseType = 'arraybuffer';

    xhr.onload = function (e) {
        let uInt8Array = new Uint8Array(this.response);
        db = new SQL.Database(uInt8Array);
        console.log(new Date(), 'Database created.');
        console.log(queryDb('SELECT * FROM hparams'));
        console.log(new Date(), 'Database loaded.');
        app();
    };
    xhr.send();
})();
Dominant language
JavaScript
Stars
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Forks
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PR merge metrics
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