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.IX Title "Bio::DB::GFF::Adaptor::dbi::caching_handle 3pm"
.TH Bio::DB::GFF::Adaptor::dbi::caching_handle 3pm "2020-01-13" "perl v5.30.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Bio::DB::GFF::Adaptor::dbi::caching_handle \-\- Cache for database handles
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 5
\& use Bio::DB::GFF::Adaptor::dbi::caching_handle;
\& $db  = Bio::DB::GFF::Adaptor::dbi::caching_handle\->new(\*(Aqdbi:mysql:test\*(Aq);
\& $sth = $db\->prepare(\*(Aqselect * from foo\*(Aq);
\& @h   = $sth\->fetch_rowarray;
\& $sth\->finish
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module handles a pool of database handles.  It was motivated by
the \s-1MYSQL\s0 driver's {mysql_use_result} attribute, which dramatically
improves query speed and memory usage, but forbids additional query
statements from being evaluated while an existing one is in use.
.PP
This module is a plug-in replacement for vanilla \s-1DBI.\s0  It
automatically activates the {mysql_use_result} attribute for the mysql
driver, but avoids problems with multiple active statement handlers by
creating new database handles as needed.
.SH "USAGE"
.IX Header "USAGE"
The object constructor is
Bio::DB::GFF::Adaptor::dbi::caching_handle\->\fBnew()\fR.  This is called
like \s-1DBI\-\s0>\fBconnect()\fR and takes the same arguments.  The returned object
looks and acts like a conventional database handle.
.PP
In addition to all the standard \s-1DBI\s0 handle methods, this package adds
the following:
.SS "dbi_quote"
.IX Subsection "dbi_quote"
.Vb 6
\& Title   : dbi_quote
\& Usage   : $string = $db\->dbi_quote($sql,@args)
\& Function: perform bind variable substitution
\& Returns : query string
\& Args    : the query string and bind arguments
\& Status  : public
.Ve
.PP
This method replaces the bind variable \*(L"?\*(R" in a \s-1SQL\s0 statement with
appropriately quoted bind arguments.  It is used internally to handle
drivers that don't support argument binding.
.SS "do_query"
.IX Subsection "do_query"
.Vb 6
\& Title   : do_query
\& Usage   : $sth = $db\->do_query($query,@args)
\& Function: perform a DBI query
\& Returns : a statement handler
\& Args    : query string and list of bind arguments
\& Status  : Public
.Ve
.PP
This method performs a \s-1DBI\s0 \fBprepare()\fR and \fBexecute()\fR, returning a
statement handle.  You will typically call \fBfetch()\fR of \fBfetchrow_array()\fR
on the statement handle.  The parsed statement handle is cached for
later use.
.SS "debug"
.IX Subsection "debug"
.Vb 6
\& Title   : debug
\& Usage   : $debug = $db\->debug([$debug])
\& Function: activate debugging messages
\& Returns : current state of flag
\& Args    : optional new setting of flag
\& Status  : public
.Ve
.SS "attribute"
.IX Subsection "attribute"
.Vb 6
\& Title   : attribute
\& Usage   : $value = $db\->attribute(AttributeName , [$newvalue])
\& Function: get/set DBI::db handle attribute
\& Returns : current state of the attribute
\& Args    : name of the attribute and optional new setting of attribute
\& Status  : public
\&
\&  Under Bio::DB::GFF::Adaptor::dbi::caching_handle the DBI::db
\&  attributes that are usually set using hashref calls are unavailable.
\&  Use attribute() instead.  For example, instead of:
\&
\&    $dbh\->{AutoCommit} = 0;
\&
\&  use
\&
\&    $dbh\->attribute(AutoCommit=>0);
.Ve
.SH "BUGS"
.IX Header "BUGS"
Report to the author.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1DBI\s0, Bio::DB::GFF, bioperl
.SH "AUTHOR"
.IX Header "AUTHOR"
Lincoln Stein <lstein@cshl.org>.
.PP
Copyright (c) 2001 Cold Spring Harbor Laboratory.
.PP
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.