postgresql/contrib
Tom Lane 19a541143a Add an explicit representation of the output targetlist to Paths.
Up to now, there's been an assumption that all Paths for a given relation
compute the same output column set (targetlist).  However, there are good
reasons to remove that assumption.  For example, an indexscan on an
expression index might be able to return the value of an expensive function
"for free".  While we have the ability to generate such a plan today in
simple cases, we don't have a way to model that it's cheaper than a plan
that computes the function from scratch, nor a way to create such a plan
in join cases (where the function computation would normally happen at
the topmost join node).  Also, we need this so that we can have Paths
representing post-scan/join steps, where the targetlist may well change
from one step to the next.  Therefore, invent a "struct PathTarget"
representing the columns we expect a plan step to emit.  It's convenient
to include the output tuple width and tlist evaluation cost in this struct,
and there will likely be additional fields in future.

While Path nodes that actually do have custom outputs will need their own
PathTargets, it will still be true that most Paths for a given relation
will compute the same tlist.  To reduce the overhead added by this patch,
keep a "default PathTarget" in RelOptInfo, and allow Paths that compute
that column set to just point to their parent RelOptInfo's reltarget.
(In the patch as committed, actually every Path is like that, since we
do not yet have any cases of custom PathTargets.)

I took this opportunity to provide some more-honest costing of
PlaceHolderVar evaluation.  Up to now, the assumption that "scan/join
reltargetlists have cost zero" was applied not only to Vars, where it's
reasonable, but also PlaceHolderVars where it isn't.  Now, we add the eval
cost of a PlaceHolderVar's expression to the first plan level where it can
be computed, by including it in the PathTarget cost field and adding that
to the cost estimates for Paths.  This isn't perfect yet but it's much
better than before, and there is a way forward to improve it more.  This
costing change affects the join order chosen for a couple of the regression
tests, changing expected row ordering.
2016-02-18 20:02:03 -05:00
..
adminpack Update copyright for 2016 2016-01-02 13:33:40 -05:00
auth_delay Update copyright for 2016 2016-01-02 14:19:48 -05:00
auto_explain Update copyright for 2016 2016-01-02 13:33:40 -05:00
btree_gin pgindent run for 9.5 2015-05-23 21:35:49 -04:00
btree_gist Fix assorted inconsistencies in GiST opclass support function declarations. 2016-01-19 12:04:36 -05:00
chkpass Avoid returning undefined bytes in chkpass_in(). 2015-02-14 12:20:56 -05:00
citext Fix incorrect declaration of citext's regexp_matches() functions. 2015-05-05 15:51:22 -04:00
cube Fix assorted inconsistencies in GiST opclass support function declarations. 2016-01-19 12:04:36 -05:00
dblink Update copyright for 2016 2016-01-02 13:33:40 -05:00
dict_int Update copyright for 2016 2016-01-02 13:33:40 -05:00
dict_xsyn Update copyright for 2016 2016-01-02 13:33:40 -05:00
earthdistance Add missed CREATE EXTENSION ... CASCADE regression test adjustment. 2015-10-03 21:31:51 +02:00
file_fdw Add an explicit representation of the output targetlist to Paths. 2016-02-18 20:02:03 -05:00
fuzzystrmatch Remove new coupling between NAMEDATALEN and MAX_LEVENSHTEIN_STRLEN. 2016-01-22 11:53:06 -05:00
hstore Make hstore_to_jsonb_loose match hstore_to_json_loose on what's a number. 2016-02-03 12:04:02 -05:00
hstore_plperl Use LOAD not actual code execution to pull in plpython library. 2016-01-11 20:06:36 -05:00
hstore_plpython Use LOAD not actual code execution to pull in plpython library. 2016-01-11 20:06:36 -05:00
intagg Fix typos in some error messages thrown by extension scripts when fed to psql. 2014-08-25 18:30:37 +02:00
intarray Fix assorted inconsistencies in GIN opclass support function declarations. 2016-01-19 22:32:22 -05:00
isn Update copyright for 2016 2016-01-02 13:33:40 -05:00
lo Fix typos in some error messages thrown by extension scripts when fed to psql. 2014-08-25 18:30:37 +02:00
ltree Fix assorted inconsistencies in GiST opclass support function declarations. 2016-01-19 12:04:36 -05:00
ltree_plpython Use LOAD not actual code execution to pull in plpython library. 2016-01-11 20:06:36 -05:00
oid2name Add file version information to most installed Windows binaries. 2014-07-14 14:07:52 -04:00
pageinspect Restructure index access method API to hide most of it at the C level. 2016-01-17 19:36:59 -05:00
passwordcheck Update copyright for 2016 2016-01-02 13:33:40 -05:00
pg_buffercache pgindent run for 9.5 2015-05-23 21:35:49 -04:00
pg_freespacemap Fix typos in some error messages thrown by extension scripts when fed to psql. 2014-08-25 18:30:37 +02:00
pg_prewarm Update copyright for 2016 2016-01-02 13:33:40 -05:00
pg_standby Don't use function definitions looking like old-style ones. 2015-08-15 17:25:00 +02:00
pg_stat_statements Change the way that LWLocks for extensions are allocated. 2016-02-04 16:43:04 -05:00
pg_trgm Fix assorted inconsistencies in GiST opclass support function declarations. 2016-01-19 12:04:36 -05:00
pgcrypto Fix typos in comments 2016-02-01 11:43:48 +01:00
pgrowlocks Optimize locking a tuple already locked by another subxact 2015-04-10 13:47:15 -03:00
pgstattuple Fix multiple bugs in contrib/pgstattuple's pgstatindex() function. 2016-02-18 15:40:35 -05:00
postgres_fdw Add an explicit representation of the output targetlist to Paths. 2016-02-18 20:02:03 -05:00
seg Fix assorted inconsistencies in GiST opclass support function declarations. 2016-01-19 12:04:36 -05:00
sepgsql Update copyright for 2016 2016-01-02 13:33:40 -05:00
spi Collection of typo fixes. 2015-05-20 16:56:22 +03:00
sslinfo Fix error message wording in previous sslinfo commit 2015-09-08 11:10:20 -03:00
start-scripts Fix typo in linux startup script. 2015-04-26 09:43:15 -04:00
tablefunc Update copyright for 2016 2016-01-02 13:33:40 -05:00
tcn Update copyright for 2016 2016-01-02 13:33:40 -05:00
test_decoding Update copyright for 2016 2016-01-02 13:33:40 -05:00
tsearch2 Fix assorted inconsistencies in GIN opclass support function declarations. 2016-01-19 22:32:22 -05:00
tsm_system_rows Update copyright for 2016 2016-01-02 13:33:40 -05:00
tsm_system_time Update copyright for 2016 2016-01-02 13:33:40 -05:00
unaccent Update copyright for 2016 2016-01-02 13:33:40 -05:00
uuid-ossp Update copyright for 2016 2016-01-02 13:33:40 -05:00
vacuumlo Update copyright for 2016 2016-01-02 13:33:40 -05:00
xml2 Replace a bunch more uses of strncpy() with safer coding. 2015-01-24 13:05:42 -05:00
contrib-global.mk Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
Makefile Finish removing pg_audit 2015-05-28 12:48:25 -04:00
README Rename 'gmake' to 'make' in docs and recommended commands 2014-02-12 17:29:19 -05:00

The PostgreSQL contrib tree
---------------------------

This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree.  This does not preclude their
usefulness.

User documentation for each module appears in the main SGML
documentation.

When building from the source distribution, these modules are not
built automatically, unless you build the "world" target.  You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.

Some directories supply new user-defined functions, operators, or
types.  To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command.  In a fresh database,
you can simply do

    CREATE EXTENSION module_name;

See the PostgreSQL documentation for more information about this
procedure.