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  1. postgres_fdw: Fix deparsing of remote column names in stats import.

  2. pgbench: fix verbose error message corruption with multiple threads

  3. Add GiST and btree sortsupport routines for range types

  1. BUG #19486: Regression in SQL-language functions using XML values and IS DOCUMENT

    PG Bug reporting form <noreply@postgresql.org> — 2026-05-18T07:54:29Z

    The following bug has been logged on the website:

Bug reference:      19486
Logged by:          Artem Zarubin
Email address:      a.prototype7@gmail.com
PostgreSQL version: 18.4
Operating system:   Debian 13
Description:        

Hello, I found a regression in SQL-language functions using XML values and
`IS DOCUMENT`.

  Tested commits:

  bad:  98dd6c2046965e51da015681e81c20109be46d71, PostgreSQL 18.4
  bad:  5107398e6d5ecad96f3d1c0efcfc9aa02b9cdff9, PostgreSQL 19devel
  good: e9e7b66044c9e3dfa76fd1599d5703acd3e4a3f5, parent of 0dca5d68
        PostgreSQL 18devel before SQL-function plan cache changes

  The server was configured with:

    ./configure --enable-tap-tests --enable-debug --enable-cassert
--with-libxml

  SQL-script to reproduce:

  CREATE OR REPLACE FUNCTION xml_to_text_no_inline(pXml xml) RETURNS text
  LANGUAGE sql
  IMMUTABLE
  SET search_path = pg_catalog
  AS $$
  SELECT CASE WHEN pXml IS DOCUMENT
              THEN (xpath('/*/text()', pXml))[1]::text
              ELSE pXml::text
         END;
  $$;

  SELECT xml_to_text_no_inline(XMLPARSE(CONTENT '2019-12-16T00:00:00.000'));

  Expected result:

    2019-12-16T00:00:00.000

  Actual result:

  ERROR:  could not parse XML document
  DETAIL:  line 1: Start tag expected, '<' not found
  2019-12-16T00:00:00.000
  ^
  CONTEXT:  SQL function "xpath" statement 1
  SQL function "xml_to_text_no_inline" statement 1

  ---
  Best regards,
  Artem Zarubin
  Postgres Professional: https://postgrespro.com/

  2. Re: BUG #19486: Regression in SQL-language functions using XML values and IS DOCUMENT

    PetSerAl <petseral@gmail.com> — 2026-05-21T18:41:51Z

    >   CREATE OR REPLACE FUNCTION xml_to_text_no_inline(pXml xml) RETURNS text
>   LANGUAGE sql
>   IMMUTABLE
>   SET search_path = pg_catalog
>   AS $$
>   SELECT CASE WHEN pXml IS DOCUMENT
>               THEN (xpath('/*/text()', pXml))[1]::text
>               ELSE pXml::text
>          END;
>   $$;

There is bug in that function. Expectation, that `xpath('/*/text()',
pXml)` will be evaluate only after successful `pXml IS DOCUMENT`
check, is not supported by documentation.
https://www.postgresql.org/docs/current/sql-expressions.html#SYNTAX-EXPRESS-EVAL

The order of evaluation of subexpressions is not defined. In
particular, the inputs of an operator or function are not necessarily
evaluated left-to-right or in any other fixed order.
...
When it is essential to force evaluation order, a `CASE` construct
(see Section 9.18) can be used.
...

`CASE` is not a cure-all for such issues, however. One limitation of
the technique illustrated above is that it does not prevent early
evaluation of constant subexpressions. As described in Section 36.7,
functions and operators marked `IMMUTABLE` can be evaluated when the
query is planned rather than when it is executed. Thus for example
```
SELECT CASE WHEN x > 0 THEN x ELSE 1/0 END FROM tab;
```
is likely to result in a division-by-zero failure due to the planner
trying to simplify the constant subexpression, even if every row in
the table has `x > 0` so that the `ELSE` arm would never be entered at
run time.

While that particular example might seem silly, related cases that
don't obviously involve constants can occur in queries executed within
functions, since the values of function arguments and local variables
can be inserted into queries as constants for planning purposes.
Within PL/pgSQL functions, for example, using an `IF`-`THEN`-`ELSE`
statement to protect a risky computation is much safer than just
nesting it in a `CASE` expression.

  3. Re: BUG #19486: Regression in SQL-language functions using XML values and IS DOCUMENT

    Tom Lane <tgl@sss.pgh.pa.us> — 2026-05-25T21:23:27Z

    PetSerAl <petseral@gmail.com> writes:
>>   CREATE OR REPLACE FUNCTION xml_to_text_no_inline(pXml xml) RETURNS text
>>   LANGUAGE sql
>>   IMMUTABLE
>>   SET search_path = pg_catalog
>>   AS $$
>>   SELECT CASE WHEN pXml IS DOCUMENT
>>               THEN (xpath('/*/text()', pXml))[1]::text
>>               ELSE pXml::text
>>          END;
>>   $$;

> There is bug in that function. Expectation, that `xpath('/*/text()',
> pXml)` will be evaluate only after successful `pXml IS DOCUMENT`
> check, is not supported by documentation.

Yeah, CASE is not strong enough to prevent constant-folding in this
context.  You could try something like

    create or replace function xml_to_text(pXml xml) returns text
    as $$
    select
      coalesce(
        (xpath('/*/text()',
               case when pXml is document then pXml else null end))[1],
        pXml
      )::text;
    $$ language sql immutable;

This works because xpath() is strict so it won't try to do anything
with a NULL input, just return NULL; and then the COALESCE() serves
the purpose of injecting pXml when that happens.

			regards, tom lane