Blogs

execute_for_fetch experimental support now in Perl DBD::ODBC 1.34_1

I have uploaded DBD::ODBC 1.34_1 to CPAN. This release adds very experimental support for a native execute_for_fetch method to DBD::ODBC which means you can do multiple row inserts/updates/deletes much quicker than using DBI's default execute_for_fetch (so long as you are using execute_for_fetch or execute_array and using column-wise binding).

Native execute_for_fetch support can often be as much as 30 or 40 times faster in my experiments (depending on data sent and odbc_batch_size) when inserting rows and even more if you do it in a transaction and even faster if you disable index updates until after the commit. Read on for why.

By default DBD::ODBC will use the new execute_for_fetch and there are some differences between what happens when you use DBD::ODBC with DBI's default execute_for_fetch and DBD::ODBC's. To disable the ODBC one you can set the new odbc_disable_array_operations attribute. I've listed the potential difference below. I'd love people to test this. It may be missing some special workarounds for a few drivers but I'm working my way through those.

New 1.33 release of Perl DBD::ODBC

I've just uploaded DBD::ODBC 1.33 to CPAN.

This release contains no new changes since the 1.32_5 development release but is the official release for all the 1.32 dev series. The complete changes can be found below. The main thrust has been Unicode improvements.

The most significant enhancements are:

  • unicode support for catalog/schema/table/column names in table_info and column_info
  • now using SQLGetTypeInfoW on unicode builds
  • new odbc_driver_complete attribute to allow interaction with ODBC dialogs on Windows.
    I'd really like to hear from anyone who uses this as I've had no feedback so far - just drop me an email if you have
  • and bug fixes:

    • remove a debugging printf - sorry, most embarrassing.

Adding Perl DBI execute_for_fetch support to DBD::ODBC

In a rare moment (I hope) of stupidity last weekend when I was a little bored (bad cold stopped me doing what I really wanted to do) I looked through the DBD::ODBC TO_DO list and saw the "implement execute_array/execute_for_fetch" item which has been in that file for years. I know for sure implementing it will be a lot faster than using DBI's default methods (which effectively do a row at a time) mostly because I wrote an ODBC tutorial years ago showing how much faster binding arrays of parameters is (Easysoft ODBC-ODBC Bridge Performance White Paper) but I also knew it would be a PITA to write. The main problem is that DBD::ODBC has loads of workarounds for broken drivers and special cases.

New 1.32_4 development release of Perl DBD::ODBC

I've uploaded the 4th development release of DBD::ODBC 1.32. This version improves Unicode support in metadata functions even further. My intention is to release this as a full version in the next week unless I get a load of bug reports. The changes since 1.31 are:

Unicode support in Perl DBI - DBD differences

NOTE: This is very much a document in progress so please bare that in mind when reading it - I will be updating it.

There is an ongoing discussion on the dbi-dev mailing list about unicode support in DBI. I've been trying to collect information on DBD support for Unicode in the hope it will help show whether there are inconsistencies in DBDs and whether the Perl DBI could help defining Unicode support. Originally, I thought about doing a talk at the London Perl Workshop but I've been rather preoccupied with personal issues and didn't think I'd even make the LPW until early last week. What follows is a very cut down version of a large document I started writing to catalogue Unicode support in DBDs. I've not done some DBDs yet - notably DB2 (because I no longer have it, although castaway on #dbix-class ran some code for me) and Postgres (because I know people are currently working on Unicode support in DBD::Pg). If you have a DBD I've not covered I'd love to hear from you and especially if you can take one of my examples and change it to work for your DBD.

New 1.32_2 development release of Perl DBD::ODBC

I have just uploaded 1.32_2 development release of DBD::ODBC. This contains one rather nice enhancement for Windows users which adds the new odbc_driver_complete attribute described as below. This allows DBD::ODBC on Windows to obtain a window handle which means if the ODBC Driver Manager or ODBC Driver needs to throw a dialogue to complete the data source or perhaps re-enter an expired password it can. Any testing will be greatly appreciated. The full changes since 1.31 are:

Perl's PERL_UNICODE and failing tests

Increasingly I'm seeing reports of modules failing (e.g., t/test_autoencoding_conversion.t fails and Gofer test failures with PERL_UNICODE=AS and PERL_UNICODE and smokes) when PERL_UNICODE is set - I see others saying much the same thing and apparently eve

Unicode discussion on Perl dbi-dev mailing list

I use unicode data with DBD::Oracle and DBD::ODBC and don't have any issues with either of those DBDs although it appears others may have. I don't use Postgres or MySQL any more (well not really and certainly not with unicode) and it appears each DBD handles unicode data a little differently. If you have an interest in unicode support in DBI/DBDs and think you have some worthwhile input you might want to watch this thread in dbi-dev.

Faster HTTP usage

What module do you use when doing any kind of HTTP programming - LWP? By far the most popular module for the HTTP protocol in Perl and one which just works and works well with a minimal amount of application code. Now you might be put off by the 123 bug reports in the LWP rt queue but in all my time I've never hit one myself - other than an issue which was not LWP but Perl and to do with tainted data used with LWP (see Why is taint mode so slow?).

Problems building a compatible Perl DBD::ODBC with unixODBC driver manager on 64 bit UNIX platforms

I maintian DBD::ODBC but I am wrestling with problems coping with 64 bit platforms. The problem is rather complex but I'm hoping that by describing it here someone will help come up with a logical answer to at least stop DBD::ODBC building in circumstances which are suspect.

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