Loving Coding & Visual Design

GAE提速方法总结


  • Compiled regular expressions. All regular expressions are parsed and stored in a compiled form. You can store compiled regular expressions in global variables, then use app caching to re-use the compiled objects between requests.

  • GqlQuery objects. The GQL query string is parsed when the GqlQuery object is created. Re-using a GqlQuery object with parameter binding and the bind() method is faster than re-constructing the object each time. You can store a GqlQuery object with parameter binding for the values in a global variable, then re-use it by binding new parameter values for each request.

  • Configuration and data files. If your application loads and parses configuration data from a file, it can retain the parsed data in memory to avoid having to re-load the file with each request.

  • SELECT __key__ queries are faster and cost less CPU than SELECT * queries. Queries that return keys are faster and cost less CPU than queries that return entities, since the keys themselves are already in the index, so the query doesn't need to fetch the actual entities. If you only need the keys from your query results — for example, if you're just going to delete the results — consider using a keys only query.

  • You can batch put, get and delete operations for efficiency

  • Every entity for every App Engine app is stored in a singleBigTable table! Further, when it comes to queries, all the queries that you can execute natively (with the notable exception of those involving 'IN' and '!=' operators - see above) have equivalent execution cost: The cost of running a query is proportional to the number of results returned by that query.

  • Requests to build new indexes are actually added to a queue of indexes that need to be built, and processed by a centralized system that builds indexes for all App Engine apps. At peak times, there may be other index building jobs ahead of yours in the queue, delaying when we can start building your index.

  • useGqlQuery .bind() to 'rebind' the values of the parameters for each query. This is faster than constructing a new query each time, because the query only has to be parsed once:
    q = db.GqlQuery("SELECT * FROM People "
    "WHERE first_name = :first_name "
    "AND last_name = :last_name")
    for first, last in people:
    q.bind(first, last)
    person = q.get()
    print person

  • using re.compile() and saving the resulting regular expression object for reuse is more efficient when the expression will be used several times in a single program.



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