From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: turon.david@seznam.cz
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16743: psql doesn't show whole expression in stored column
Date: Wed, 25 Nov 2020 11:15:39 -0500
Message-ID: <464990.1606320939@sss.pgh.pa.us> (raw)
In-Reply-To: <426714.1606316633@sss.pgh.pa.us>
References: <16743-7b1bacc4af76e7ad@postgresql.org>
<286182.1606232817@sss.pgh.pa.us>
<7a1faa2c-d4d1-67fd-03fe-29ef7e240301@enterprisedb.com>
<426714.1606316633@sss.pgh.pa.us>
I wrote:
> Peter Eisentraut <peter.eisentraut@enterprisedb.com> writes:
>> I think we should get rid of the truncating. Otherwise, there is no way
>> to actually get the full information, is there? (Other than pg_dump or
>> manual catalog queries.)
> That'd be okay with me. It's always seemed a little odd that we do that
> for attrdefs but not anything else.
Here's a proposed patch for that.
After looking a bit closer, I saw that the memory leak I was worried
about before is not real, because the code passes mustfree = true to
printTableAddCell. However, I still don't like it one bit, because you
need some undocumented and fragile assumptions about the relationship
between attidentity and attgenerated to conclude that we won't instead
have a false free() attempt on something that mustn't be free'd. So I
think we should adjust the code to track mustfree explicitly, as done
below.
Should we back-patch this? I think that the truncation behavior became
significantly more of a problem with the addition of the GENERATED
feature; before that it was clearer what was going on. So I'm mildly
inclined to back-patch to v12 where that came in.
regards, tom lane
Attachments:undo-attrdef-truncation.patch (text/x-diff, 1.7K) downloaddiff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.cindex 07d640021c..14150d05a9 100644--- a/src/bin/psql/describe.c+++ b/src/bin/psql/describe.c@@ -1842,7 +1842,7 @@ describeOneTableDetails(const char *schemaname,
{
/* use "pretty" mode for expression to avoid excessive parentheses */
appendPQExpBufferStr(&buf,
- ",\n (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid, true) for 128)"+ ",\n (SELECT pg_catalog.pg_get_expr(d.adbin, d.adrelid, true)"
"\n FROM pg_catalog.pg_attrdef d"
"\n WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef)"
",\n a.attnotnull");
@@ -2045,7 +2045,8 @@ describeOneTableDetails(const char *schemaname,
{
char *identity;
char *generated;
- char *default_str = "";+ char *default_str;+ bool mustfree = false;
printTableAddCell(&cont, PQgetvalue(res, i, attcoll_col), false, false);
@@ -2061,12 +2062,15 @@ describeOneTableDetails(const char *schemaname,
else if (identity[0] == ATTRIBUTE_IDENTITY_BY_DEFAULT)
default_str = "generated by default as identity";
else if (generated[0] == ATTRIBUTE_GENERATED_STORED)
- default_str = psprintf("generated always as (%s) stored", PQgetvalue(res, i, attrdef_col));+ {+ default_str = psprintf("generated always as (%s) stored",+ PQgetvalue(res, i, attrdef_col));+ mustfree = true;+ }
else
- /* (note: above we cut off the 'default' string at 128) */
default_str = PQgetvalue(res, i, attrdef_col);
- printTableAddCell(&cont, default_str, false, generated[0] ? true : false);+ printTableAddCell(&cont, default_str, false, mustfree);
}
/* Info for index columns */
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, peter.eisentraut@enterprisedb.com, turon.david@seznam.cz, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16743: psql doesn't show whole expression in stored column
In-Reply-To: <464990.1606320939@sss.pgh.pa.us>
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