Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??
You would need to modify the modules to be more efficient with memory usage with huge tables. You could either modify Tie::RDBM to use the Pg module for direct PostgreSQL access with cursors. Or modify DBD::Pg to use cursors. Otherwise, the SELECT statement to fetch the keys stores all the data on the client. You might want to investiage MySQL and see if DBD::Mysql uses cursors. It also looks like you will have to modify Tie::RDBM to not cache the values that it fetches.

The important question to ask is whether you really need a tied hash. If you don't need one, then you can do operations more efficiently with custom database accesses. Since PostgreSQL doesn't use cursors, you will have to avoid any queries that return all the keys.

For example, counting the number of keys is doable with a SELECT COUNT(*) FROM table statement. You might want to normalize the database to store each value in a row of a second table. Then you won't need to use Perl serialization to store the data structures. You can the total number of values with SELECT COUNT(*) FROM values. And individual counts for each key: SELECT COUNT(*) FROM values WHERE key = $key.


In reply to Re: Re: Re: iteration through tied hash eat my memory by iburrell
in thread iteration through tied hash eat my memory by ph0enix

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others meditating upon the Monastery: (7)
As of 2024-03-28 10:03 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found