plpgsql documentation - Mailing list pgsql-patches
From | Chris Browne |
---|---|
Subject | plpgsql documentation |
Date | |
Msg-id | 601wuh686k.fsf_-_@dba2.int.libertyrms.com Whole thread Raw |
Responses |
Re: plpgsql documentation
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List | pgsql-patches |
An article at WebProNews quoted from the PG docs as to the merits of stored procedures. I have added a bit more material on their merits, as well as making a few changes to improve the introductions to PL/Perl and PL/Tcl. Index: plperl.sgml =================================================================== RCS file: /projects/cvsroot/pgsql/doc/src/sgml/plperl.sgml,v retrieving revision 2.52 diff -c -u -r2.52 plperl.sgml --- plperl.sgml 10 Mar 2006 19:10:48 -0000 2.52 +++ plperl.sgml 25 May 2006 22:38:45 -0000 @@ -17,6 +17,12 @@ <ulink url="http://www.perl.com">Perl programming language</ulink>. </para> + <para> The usual advantage to using PL/Perl is that this allows use, + within stored functions, of the manyfold <quote>string + munging</quote> operators and functions available for Perl. Parsing + complex strings may be be easier using Perl than it is with the + string functions and control structures provided in PL/pgsql.</para> + <para> To install PL/Perl in a particular database, use <literal>createlang plperl <replaceable>dbname</></literal>. Index: plpgsql.sgml =================================================================== RCS file: /projects/cvsroot/pgsql/doc/src/sgml/plpgsql.sgml,v retrieving revision 1.88 diff -c -u -r1.88 plpgsql.sgml --- plpgsql.sgml 10 Mar 2006 19:10:48 -0000 1.88 +++ plpgsql.sgml 25 May 2006 22:38:46 -0000 @@ -155,21 +155,36 @@ <para> That means that your client application must send each query to - the database server, wait for it to be processed, receive the - results, do some computation, then send other queries to the - server. All this incurs interprocess communication and may also - incur network overhead if your client is on a different machine - than the database server. + the database server, wait for it to be processed, receive and + process the results, do some computation, then send further + queries to the server. All this incurs interprocess + communication and will also incur network overhead if your client + is on a different machine than the database server. </para> <para> - With <application>PL/pgSQL</application> you can group a block of computation and a - series of queries <emphasis>inside</emphasis> the - database server, thus having the power of a procedural - language and the ease of use of SQL, but saving lots of - time because you don't have the whole client/server - communication overhead. This can make for a - considerable performance increase. + With <application>PL/pgSQL</application> you can group a block of + computation and a series of queries <emphasis>inside</emphasis> + the database server, thus having the power of a procedural + language and the ease of use of SQL, but with considerable + savings because you don't have the whole client/server + communication overhead. + </para> + <itemizedlist> + + <listitem><para> Elimination of additional round trips between + client and server </para></listitem> + + <listitem><para> Intermediate results that the client does not + need do not need to be marshalled or transferred between server + and client </para></listitem> + + <listitem><para> There is no need for additional rounds of query + parsing </para></listitem> + + </itemizedlist> + <para> This can allow for a considerable performance increase as + compared to an application that does not use stored functions. </para> <para> Index: pltcl.sgml =================================================================== RCS file: /projects/cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v retrieving revision 2.39 diff -c -u -r2.39 pltcl.sgml --- pltcl.sgml 10 Mar 2006 19:10:48 -0000 2.39 +++ pltcl.sgml 25 May 2006 22:38:46 -0000 @@ -25,22 +25,27 @@ <title>Overview</title> <para> - PL/Tcl offers most of the capabilities a function - writer has in the C language, except for some restrictions. + PL/Tcl offers most of the capabilities a function writer has in + the C language, with a few restrictions, and with the addition of + the powerful string processing libraries that are available for + Tcl. </para> <para> - The good restriction is that everything is executed in a safe - Tcl interpreter. In addition to the limited command set of safe Tcl, only - a few commands are available to access the database via SPI and to raise - messages via <function>elog()</>. There is no way to access internals of the - database server or to gain OS-level access under the permissions of the - <productname>PostgreSQL</productname> server process, as a C function can do. - Thus, any unprivileged database user may be - permitted to use this language. + One compelling <emphasis>good</emphasis> restriction is that + everything is executed from within the safety of the context of a + Tcl interpreter. In addition to the limited command set of safe + Tcl, only a few commands are available to access the database via + SPI and to raise messages via <function>elog()</>. PL/Tcl + provides no way to access internals of the database server or to + gain OS-level access under the permissions of the + <productname>PostgreSQL</productname> server process, as a C + function can do. Thus, unprivileged database users may be trusted + to use this language; it does not give them unlimited authority. </para> <para> - The other, implementation restriction is that Tcl functions cannot - be used to create input/output functions for new data types. + The other notable implementation restriction is that Tcl functions + may not be used to create input/output functions for new data + types. </para> <para> Sometimes it is desirable to write Tcl functions that are not restricted @@ -55,12 +60,12 @@ a user logged in as the database administrator. </para> <para> - The shared object for the <application>PL/Tcl</> and <application>PL/TclU</> call handlers is - automatically built and installed in the - <productname>PostgreSQL</productname> - library directory if Tcl support is specified - in the configuration step of the installation procedure. To install - <application>PL/Tcl</> and/or <application>PL/TclU</> in a particular database, use the + The shared object code for the <application>PL/Tcl</> and + <application>PL/TclU</> call handlers is automatically built and + installed in the <productname>PostgreSQL</productname> library + directory if Tcl support is specified in the configuration step of + the installation procedure. To install <application>PL/Tcl</> + and/or <application>PL/TclU</> in a particular database, use the <command>createlang</command> program, for example <literal>createlang pltcl <replaceable>dbname</></literal> or <literal>createlang pltclu <replaceable>dbname</></literal>. -- (format nil "~S@~S" "cbbrowne" "acm.org") http://www3.sympatico.ca/cbbrowne/advocacy.html If at first you don't succeed, then you didn't do it right! If at first you don't succeed, then skydiving definitely isn't for you.
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