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Rescind unsafe deduplication support.

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bpchar equality ignores trailing spaces, so equal values in a column
with no length specifier can have different images.  Similarly,
oidvector equality intentionally pays no attention to the array lower
bound field.  We nevertheless allowed nbtree deduplication to be used
with indexes built with bpchar_ops, bpchar_pattern_ops, or
oidvector_ops.  A posting list split could therefore place a TID in an
index tuple whose key was equal to, but not bytewise identical to, the
corresponding table value.  This allowed index-only scans to return
subtly wrong results.

To fix, drop support function 4 from the affected opclasses (we can't
change catalog contents on branches 14 through 18, so we just disable
deduplication by adding hard-coding to the relevant support functions).
Deliberately leave the oidvector opclass alone on branches 14 through
18, though.  Disallowing oidvector deduplication on these branches would
make pg_amcheck report that pg_proc_proname_args_nsp_index has a corrupt
metapage, needlessly alarming users.

System catalog oidvector values always have a lower bound of 0, so the
issue can't cause harm there; a user can only hit it by indexing an
oidvector column that stores the output of a function like trim_array().
It seems very unlikely that any user would ever do that.

Users should REINDEX any B-Tree index on a bpchar column.

Author: Shihao Zhong <zhong950419@gmail.com>
Co-authored-by: Peter Geoghegan <pg@bowt.ie>
Reported-by: Ke <kehan5800@gmail.com>
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Bug: #19749
Discussion: https://postgr.es/m/19749-d46adf7c7d910b07@postgresql.org
Discussion: https://postgr.es/m/CAGRkXqQQ311Lg=62x5UdZtPuRFgpT6XpPMw4X9E3tgbTu162Mw@mail.gmail.com
Backpatch-through: 14
This commit is contained in:
Peter Geoghegan
2026-10-06 18:21:39 -04:00
parent 98c41fed6f
commit a32b8dc986
7 changed files with 35 additions and 52 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
contrib/amcheck/verify_nbtree.c
View File

@@ -33,7 +33,6 @@
#include "verify_common.h"
#include "catalog/index.h"
#include "catalog/pg_am.h"
#include "catalog/pg_opfamily_d.h"
#include "common/pg_prng.h"
#include "lib/bloomfilter.h"
#include "miscadmin.h"
@@ -329,24 +328,10 @@ bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool rea
errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
RelationGetRelationName(indrel))));
if (allequalimage && !_bt_allequalimage(indrel, false))
{
bool has_interval_ops = false;
for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
{
has_interval_ops = true;
break;
}
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
RelationGetRelationName(indrel)),
has_interval_ops
? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
: 0));
}
RelationGetRelationName(indrel))));
/* Check index, possibly against table it is an index on */
bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,

16
doc/src/sgml/btree.sgml
View File

@@ -875,10 +875,18 @@ options(<replaceable>relopts</replaceable> <type>local_relopts *</type>) returns
<itemizedlist>
<listitem>
<para>
<type>text</type>, <type>varchar</type>, and <type>char</type>
cannot use deduplication when a
<emphasis>nondeterministic</emphasis> collation is used. Case
and accent differences must be preserved among equal datums.
<type>text</type> and <type>varchar</type> cannot use deduplication when
a <emphasis>nondeterministic</emphasis> collation is used. Case and
accent differences must be preserved among equal datums.
</para>
</listitem>
<listitem>
<para>
<type>character</type> (and its aliases <type>char</type> and
<type>bpchar</type>) cannot use deduplication. Trailing spaces are
disregarded when comparing two values, but must be preserved among
equal datums.
</para>
</listitem>

2
src/include/catalog/catversion.h
View File

@@ -57,6 +57,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 202610021
#define CATALOG_VERSION_NO 202610061
#endif

7
src/include/catalog/pg_amproc.dat
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@@ -30,9 +30,6 @@
{ amprocfamily => 'btree/bpchar_ops', amproclefttype => 'bpchar',
amprocrighttype => 'bpchar', amprocnum => '2',
amproc => 'bpchar_sortsupport' },
{ amprocfamily => 'btree/bpchar_ops', amproclefttype => 'bpchar',
amprocrighttype => 'bpchar', amprocnum => '4',
amproc => 'btvarstrequalimage' },
{ amprocfamily => 'btree/bytea_ops', amproclefttype => 'bytea',
amprocrighttype => 'bytea', amprocnum => '1', amproc => 'byteacmp' },
{ amprocfamily => 'btree/bytea_ops', amproclefttype => 'bytea',
@@ -224,8 +221,6 @@
{ amprocfamily => 'btree/oidvector_ops', amproclefttype => 'oidvector',
amprocrighttype => 'oidvector', amprocnum => '1',
amproc => 'btoidvectorcmp' },
{ amprocfamily => 'btree/oidvector_ops', amproclefttype => 'oidvector',
amprocrighttype => 'oidvector', amprocnum => '4', amproc => 'btequalimage' },
{ amprocfamily => 'btree/text_ops', amproclefttype => 'text',
amprocrighttype => 'text', amprocnum => '1', amproc => 'bttextcmp' },
{ amprocfamily => 'btree/text_ops', amproclefttype => 'text',
@@ -273,8 +268,6 @@
{ amprocfamily => 'btree/bpchar_pattern_ops', amproclefttype => 'bpchar',
amprocrighttype => 'bpchar', amprocnum => '2',
amproc => 'btbpchar_pattern_sortsupport' },
{ amprocfamily => 'btree/bpchar_pattern_ops', amproclefttype => 'bpchar',
amprocrighttype => 'bpchar', amprocnum => '4', amproc => 'btequalimage' },
{ amprocfamily => 'btree/money_ops', amproclefttype => 'money',
amprocrighttype => 'money', amprocnum => '1', amproc => 'cash_cmp' },
{ amprocfamily => 'btree/money_ops', amproclefttype => 'money',

2
src/test/regress/expected/btree_index.out
View File

@@ -765,8 +765,6 @@ select * from btree_bpchar where f1::bpchar like 'foo%';
fool
(2 rows)
-- get test coverage for "single value" deduplication strategy:
insert into btree_bpchar select 'foo' from generate_series(1,1500);
--
-- Perform unique checking, with and without the use of deduplication
--

40
src/test/regress/expected/opr_sanity.out
View File

@@ -2225,25 +2225,27 @@ LEFT JOIN pg_amproc AS amp ON amp.amprocfamily = opf.oid AND
WHERE am.amname = 'btree' AND
amp.amproc IS DISTINCT FROM 'btequalimage'::regproc
ORDER BY 1, 2, 3;
proc | opfamily_name | opclass_name | opcintype
--------------------+------------------+------------------+------------------
btvarstrequalimage | bpchar_ops | bpchar_ops | character
btvarstrequalimage | text_ops | name_ops | name
btvarstrequalimage | text_ops | text_ops | text
btvarstrequalimage | text_ops | varchar_ops | text
| array_ops | array_ops | anyarray
| float_ops | float4_ops | real
| float_ops | float8_ops | double precision
| interval_ops | interval_ops | interval
| jsonb_ops | jsonb_ops | jsonb
| multirange_ops | multirange_ops | anymultirange
| numeric_ops | numeric_ops | numeric
| range_ops | range_ops | anyrange
| record_image_ops | record_image_ops | record
| record_ops | record_ops | record
| tsquery_ops | tsquery_ops | tsquery
| tsvector_ops | tsvector_ops | tsvector
(16 rows)
proc | opfamily_name | opclass_name | opcintype
--------------------+--------------------+--------------------+------------------
btvarstrequalimage | text_ops | name_ops | name
btvarstrequalimage | text_ops | text_ops | text
btvarstrequalimage | text_ops | varchar_ops | text
| array_ops | array_ops | anyarray
| bpchar_ops | bpchar_ops | character
| bpchar_pattern_ops | bpchar_pattern_ops | character
| float_ops | float4_ops | real
| float_ops | float8_ops | double precision
| interval_ops | interval_ops | interval
| jsonb_ops | jsonb_ops | jsonb
| multirange_ops | multirange_ops | anymultirange
| numeric_ops | numeric_ops | numeric
| oidvector_ops | oidvector_ops | oidvector
| range_ops | range_ops | anyrange
| record_image_ops | record_image_ops | record
| record_ops | record_ops | record
| tsquery_ops | tsquery_ops | tsquery
| tsvector_ops | tsvector_ops | tsvector
(18 rows)
-- **************** pg_index ****************
-- Look for illegal values in pg_index fields.

3
src/test/regress/sql/btree_index.sql
View File

@@ -411,9 +411,6 @@ explain (costs off)
select * from btree_bpchar where f1::bpchar like 'foo%';
select * from btree_bpchar where f1::bpchar like 'foo%';
-- get test coverage for "single value" deduplication strategy:
insert into btree_bpchar select 'foo' from generate_series(1,1500);
--
-- Perform unique checking, with and without the use of deduplication
--