postgresql/src/backend/utils
Michael Paquier 2dd7782217 pageinspect: Fix gist_page_items() with included columns
Non-leaf pages of GiST indexes contain key attributes, leaf pages
contain both key and non-key attributes, and gist_page_items() ignored
the handling of non-key attributes.  This caused a few problems when
using gist_page_items() on a GiST index with INCLUDE:
- On a non-leaf page, the function would crash.
- On a leaf page, the function would work, but miss to display all the
values for included attributes.

This commit fixes gist_page_items() to handle such cases in a more
appropriate way, and now displays the values of key and non-key
attributes for each item separately in a style consistent with what
ruleutils.c would generate for the attribute list, depending on the page
type dealt with.  In a way similar to how a record is displayed, values
would be double-quoted for key or non-key attributes if required.

ruleutils.c did not provide a routine able to control if non-key
attributes should be displayed, so an extended() routine for index
definitions is added to work around the leaf and non-leaf page
differences.

While on it, this commit fixes a third problem related to the amount of
data reported for key attributes.  The code originally relied on
BuildIndexValueDescription() (used for error reports on constraints)
that would not print all the data stored in the index but the index
opclass's input type, so this limited the amount of information
available.  This switch makes gist_page_items() much cheaper as there is
no need to run ACL checks for each item printed, which is not an issue
anyway as superuser rights are required to execute the functions of
pageinspect.  Opclasses whose data cannot be displayed can rely on
gist_page_items_bytea().

The documentation of this function was slightly incorrect for the
output results generated on HEAD and v15, so adjust it on these
branches.

Author: Alexander Lakhin, Michael Paquier
Discussion: https://postgr.es/m/17884-cb8c326522977acb@postgresql.org
Backpatch-through: 14
2023-05-19 12:38:15 +09:00
..
activity Fix assertion failure when updating stats_fetch_consistency in a transaction 2023-05-10 11:24:40 +09:00
adt pageinspect: Fix gist_page_items() with included columns 2023-05-19 12:38:15 +09:00
cache Prevent pgstats from getting confused when relkind of a relation changes 2022-12-02 18:07:47 -08:00
error Remove extraneous blank lines before block-closing braces 2022-04-13 19:16:02 +02:00
fmgr Rename SetSingleFuncCall() to InitMaterializedSRF() 2022-10-18 10:22:40 +09:00
hash Update copyright for 2022 2022-01-07 19:04:57 -05:00
init Fix t_isspace(), etc., when datlocprovider=i and datctype=C. 2023-03-17 12:07:47 -07:00
mb Update copyright for 2022 2022-01-07 19:04:57 -05:00
misc Fix assertion failure when updating stats_fetch_consistency in a transaction 2023-05-10 11:24:40 +09:00
mmgr Fix erroneous Valgrind markings in AllocSetRealloc. 2023-02-21 18:47:46 -05:00
resowner Remove extraneous blank lines before block-closing braces 2022-04-13 19:16:02 +02:00
sort Fix rare sharedtuplestore.c corruption. 2023-01-26 14:53:37 +13:00
time Fix incorrect logic in HaveRegisteredOrActiveSnapshot(). 2022-04-16 16:04:50 -04:00
.gitignore Rearrange makefile rules for running Gen_fmgrtab.pl. 2018-05-03 17:54:18 -04:00
errcodes.txt Add another SQL/JSON error code 2022-07-18 14:27:53 +02:00
Gen_dummy_probes.pl Update copyright for 2022 2022-01-07 19:04:57 -05:00
Gen_dummy_probes.pl.prolog Update copyright for 2022 2022-01-07 19:04:57 -05:00
Gen_dummy_probes.sed Update copyright for 2022 2022-01-07 19:04:57 -05:00
Gen_fmgrtab.pl Update copyright for 2022 2022-01-07 19:04:57 -05:00
generate-errcodes.pl Update copyright for 2022 2022-01-07 19:04:57 -05:00
Makefile Correct Makefile dependencies for catalog scripts 2022-02-14 09:07:09 +07:00
probes.d Update copyright for 2022 2022-01-07 19:04:57 -05:00
README.Gen_dummy_probes Tweak generation of Gen_dummy_probes.pl 2021-05-11 20:02:02 -04:00

# Generating dummy probes

If Postgres isn't configured with dtrace enabled, we need to generate
dummy probes for the entries in probes.d, that do nothing.

This is accomplished in Unix via the sed script `Gen_dummy_probes.sed`. We
used to use this in MSVC builds using the perl utility `psed`, which mimicked
sed. However, that utility disappeared from Windows perl distributions and so
we converted the sed script to a perl script to be used in MSVC builds.

We still keep the sed script as the authoritative source for generating
these dummy probes because except on Windows perl is not a hard requirement
when building from a tarball.

So, if you need to change the way dummy probes are generated, first change
the sed script, and when it's working generate the perl script. This can
be accomplished by using the perl utility s2p.

s2p is no longer part of the perl core, so it might not be on your system,
but it is available on CPAN and also in many package systems. e.g.
on Fedora it can be installed using `cpan App::s2p` or
`dnf install perl-App-s2p`.

The Makefile contains a recipe for regenerating Gen_dummy_probes.pl, so all
you need to do is once you have s2p installed is `make Gen_dummy_probes.pl`
Note that in a VPATH build this will generate the file in the vpath tree,
not the source tree.