Attachment 154131 Details for Bug 21828 – Bug 21828: build $bib_heading_fields only once per invocation

[patch] Bug 21828: build $bib_heading_fields only once per invocation

Bug-21828-build-bibheadingfields-only-once-per-inv.patch (text/plain), 3.16 KB, created by Andreas Roussos on 2023-08-01 19:25:11 UTC

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Creator: Andreas Roussos

Created: 2023-08-01 19:25:11 UTC

Size: 3.16 KB

patch

obsolete

>From b1dce7fa2b1d31af75f9e136c0571fb17f0e3ed9 Mon Sep 17 00:00:00 2001
>From: Andreas Roussos <a.roussos@dataly.gr>
>Date: Tue, 1 Aug 2023 20:49:55 +0200
>Subject: [PATCH] Bug 21828: build $bib_heading_fields only once per invocation
>
>In UNIMARC instances, the run time of link_bibs_to_authorities.pl
>can be reduced by up to 80% and the number of DBI calls
>can be reduced by up to 90% with a very simple fix that
>optimises the constructor of the C4::Heading::UNIMARC object.
>
>Currently, the constructor resets the $bib_heading_fields hash
>*in each invocation* (i.e. for every field the bibliographic
>record contains), then populating it again with the results
>fetched from the database! This is inefficient.
>
>The patch/fix is trivial: we take advantage of the fact that
>$bib_heading_fields is declared at the top of the
>C4::Heading::UNIMARC module and is thus a package variable
>that is in scope for the entire execution of the program
>(more info here: https://stackoverflow.com/q/75317862).
>
>Placing the section that generates the $bib_heading_fields
>hash inside a "unless ( defined $bib_heading_fields )" code
>block is enough to cause a significant reduction in the
>number of "expensive" SQL SELECT queries that must be run.
>
>Test plan:
>
>0) Have a UNIMARC instance with some sample data (the KTD one
>   will do just fine for this experiment).
>
>1) Run the following commands:
>
>    $ ktd --shell
>   k$ DBI_PROFILE=1 ./misc/link_bibs_to_authorities.pl -t
>
>   Observe the output from the script and the DBI profiling info.
>   [You may want to play with different DBI_PROFILE levels (such as
>   2, 4, 6, 8, etc.) to see what's going on under the hood DBI-wise,
>   for reference see: https://metacpan.org/pod/DBI::Profile]
>
>2) Apply this patch.
>
>3) Rerun the script from step 1), it should run a lot faster!
>---
> C4/Heading/UNIMARC.pm | 28 +++++++++++++++-------------
> 1 file changed, 15 insertions(+), 13 deletions(-)
>
>diff --git a/C4/Heading/UNIMARC.pm b/C4/Heading/UNIMARC.pm
>index 9767f751a7..a0a8a3edda 100644
>--- a/C4/Heading/UNIMARC.pm
>+++ b/C4/Heading/UNIMARC.pm
>@@ -68,19 +68,21 @@ my $bib_heading_fields;
> sub new {
>     my $class = shift;
> 
>-    my $dbh = C4::Context->dbh;
>-    my $sth = $dbh->prepare(
>-        "SELECT tagfield, authtypecode
>-         FROM marc_subfield_structure
>-         WHERE frameworkcode = '' AND authtypecode <> ''"
>-    );
>-    $sth->execute();
>-    $bib_heading_fields = {};
>-    while ( my ( $tag, $auth_type ) = $sth->fetchrow ) {
>-        $bib_heading_fields->{$tag} = {
>-            auth_type => $auth_type,
>-            subfields => 'abcdefghjklmnopqrstvxyz',
>-        };
>+    unless ( defined $bib_heading_fields ) {
>+        my $dbh = C4::Context->dbh;
>+        my $sth = $dbh->prepare(
>+            "SELECT tagfield, authtypecode
>+             FROM marc_subfield_structure
>+             WHERE frameworkcode = '' AND authtypecode <> ''"
>+        );
>+        $sth->execute();
>+        $bib_heading_fields = {};
>+        while ( my ( $tag, $auth_type ) = $sth->fetchrow ) {
>+            $bib_heading_fields->{$tag} = {
>+                auth_type => $auth_type,
>+                subfields => 'abcdefghjklmnopqrstvxyz',
>+            };
>+        }
>     }
> 
>     return bless {}, $class;
>-- 
>2.20.1

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