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Re: patch: function xmltable

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Craig Ringer <craig(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: patch: function xmltable
Date: 2017-01-14 13:43:26
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers

2017-01-13 21:32 GMT+01:00 Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>:

> Pavel Stehule wrote:
> >
> > I used your proposed way based on Restarget
> Thanks.  Some more tweaking to go yet before I consider this
> committable, but it's much better now.  Here's v28.  I changed a few
> things:
> - make expression evaluation code more orthodox:
>   1. avoid PG_TRY, use a ExprContext shutdown callback instead
>   2. use a "Fast" evaluator, for calls past the first one
>   3. don't look up fmgrinfos until execution time
>   4. don't duplicate get_expr_result_type
> - make parser accept DEFAULT namespace. Only xml implementation barfs.
>   (this means we lost the errposition pointer, but I don't really
>    care. We could fix it if we cared)
> - clean up parse analysis code a little bit
> - move decls/struct defs to better locations in source code
> - remove leftover "namespaces" in TableExprState
> - pgindent the whole mess.
I checked the changes and looks correct - although for some I had not
courage :) - like dynamic change of exprstate->evalfunc

I fixed test, and append forgotten header file

> I don't like the xml.c code and the "evalcols" flag.  That's next on my
> list to fix.

You need some flag to specify if column paths are valid or not.

> I don't think to_xmlstr() is necessary, considering xml_text2xmlChar.
> We could just apply a cast of the source cstring to xmlChar.

is it safe? For one byte encodings?



> --
> Álvaro Herrera      
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment: xmltable-29.patch
Description: text/x-patch (163.5 KB)

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