尽管IndexedDB支持存储Blob，但它不支持对Blob进行索引。可索引属性只能是string、number、Date或Array <string类型|数|如果没有，IndexedDB将忽略对该特定对象的索引。
此外，在示例代码中，您没有引用artworks表，而是尝试单独放置blob，而不是放置包含blob属性的文档。
因此，您可以做的是计算blob内容的散列/摘要，并存储为字符串，您可以使用唯一索引来索引。

var dbArt = new Dexie('TheDatabase');
dbArt.version(1).stores({
    artworks: `
        ++id,
        title,
        album,
        &artworkDigest` // & = unique index of the digest
});

var artworkBlob = getBlob(image); // get it somehow...

// Now, compute hash before trying to put blob into DB
computeHash(artworkBlob).then(artworkDigest => {

    // Put the blob along with it's uniqely indexed digest
    return dbArt.artworks.put({
        title: theTitle,
        album: theAlbum,
        artwork: artworkBlob,
        artworkDigest: artworkDigest
    });
}).then(()=>{
    console.log("Successfully stored the blob");
}).catch(error => {
    // Second time you try to store the same blob, you'll
    // end up here with a 'ConstraintError' since the digest
    // will be same and conflict the uniqueness constraint.
    console.error(`Failed to store the blob: ${error}`);
});

function computeHash (blob) {
    return new Promise((resolve, reject) => {
        // Convert to ArrayBuffer
        var fileReader = new FileReader();
        fileReader.onload = () => resolve(filerReader.result);
        fileReader.onerror = () => reject(filerReader.error);
        fileReader.readAsArrayBuffer(blob);
    }).then (arrayBuffer => {
        // Compute Digest
        return crypto.subtle.digest("SHA-256", arrayBuffer);
    }).then (digest => {
        // Convert ArrayBuffer to string (to make it indexable)
        return String.fromCharCode.apply(
            null, new Uint8Array(digest));
    });
};

旁注：在IndexedDB 2.0中，ArrayBuffer是可索引的（但Blobs仍然不是）。但是，我绝不建议在任何数据库中索引如此大的值。最好还是把文摘编入索引。